Stereoscopic image appreciation eyeglasses with liquid crystal cell voltage control and stereoscopic image display device

Abstract

An infrared polarizing filter is attached to an infrared synchronization signal radiator of a stereoscopic image display device which alternately displays right and left images by time-division with polarized light in one direction to radiate the polarized-light infrared synchronization signal. The problem with the occurrence of crosstalk is solved. Stereoscopic image appreciation eyeglasses have polarizing plates, visual field opening/closing liquid crystal cells and tilt correcting liquid crystal cells. The synchronization signal is received by a receiver mounted on an eyeglass frame. The tilt correcting liquid crystal cells are adjusted by a voltage based on the eyeglass frame tilt angle detected.

Claims

1. Stereoscopic image appreciation eyeglasses for appreciating a stereoscopic image which is composed by displaying alternately right and left images by time division with linear polarized light having the same amplitude direction in a stereoscopic image display device comprising: polarizing plates which are respectively arranged side by side in right and left visual fields of the eyeglasses, and each polarizing direction is set in a same direction, a visual field opening and closing liquid crystal cell which is mounted on front surfaces of the polarizing plates, and can be separately viewed by alternately, opening and closing the right and left visual fields, an infrared light synchronization signal receiver which is placed on an eyeglass frame, and received a polarized infrared light synchronization signal from the stereoscopic image display device, a tilt angle detector which detects a tilt of the eyeglass frame based on the polarized infrared light synchronization signal which is received by the infrared light synchronization signal receiver, a tilt correcting liquid crystal cell which can correct the amplitude direction of the linear polarized light to be orthogonal to the polarizing direction of the polarizing plates according to the tilt of the eyeglass frame, and a controller which drives the visual field opening/closing liquid crystal cells based on synchronization signal data received by the infrared light synchronization signal receiver, and drives the tilt correcting liquid crystal cell based on tilt angle data detected by the tilt angle detector.

2. The stereoscopic image appreciation eyeglasses according to claim 1 wherein a slot for a diopter correction lens holder and a lens pressing spring are provided on a front surface or rear surface of each of the right and left visual fields of the eyeglasses.

3. The stereoscopic image appreciation eyeglasses according to claim 1, being configured so that a diopter correction lens to be attached to a slot for a diopter correction lens holder in the stereoscopic image appreciation eyeglasses and having both its ends, as viewed from a front surface, formed in the shape of a circular arc and having its lower end formed in the shape of a curve having a larger curvature than that of the circular arc at both the ends is detachably attached.

4. The stereoscopic image appreciation eyeglasses according to claim 1, being configured so that a diopter correction lens to be attached to a slot for a diopter correction lens holder in the stereoscopic image appreciation eyeglasses and having both its ends, as viewed from a front surface, formed in the shape of a circular arc and having its lower end formed in the shape of a straight line is detachably attached.

5. Stereoscopic image appreciation eyeglasses for appreciating a stereoscopic image by displaying alternately right and left images by time division with linear polarized light having an amplitude in a common direction with a stereoscopic image display device, comprising: right and left polarizing plates which are respectively arranged side by side in right and left visual fields in a viewing direction of the stereoscopic image appreciation eyeglasses, each of said right and left polarizing plates having a polarizing direction; right and left visual field opening and closing liquid crystal cells respectively mounted adjacent a surface of said right and left polarizing plates, whereby the right and left visual fields are capable of being separately viewed by alternately opening and closing said right and left visual field opening and closing liquid crystal cells; an infrared light synchronization signal receiver placed on the stereoscopic image appreciation eyeglasses and mounted to receive light in the viewing direction of the right and left visual fields, whereby a polarized infrared light synchronization signal from the stereoscopic image display device is capable of being received; a tilt angle detector comprising an infrared polarizing filter placed on the stereoscopic image appreciation eyeglasses and positioned to receive light in the viewing direction of the right and left visual fields, whereby a tilt of the stereoscopic image appreciation eyeglasses is capable of being detected based on a polarized infrared light synchronization signal which is received by said infrared light synchronization signal receiver; right and left tilt correcting liquid crystal cells respectively placed adjacent a surface of said right and left polarizing plates, whereby said right and left tilt correcting liquid crystal cells are capable of changing an amplitude direction of linear polarized light to be orthogonal to the polarizing direction of the right and left polarizing plates according to the tilt of the stereoscopic image appreciation eyeglasses; an opening and closing controller coupled to said right and left visual field opening and closing liquid crystal cells and said infrared light synchronization signal receiver, whereby said opening and closing controller drives said right and left visual field opening and closing liquid crystal cells to open and close based on the polarized infrared light synchronization signal received by said infrared light synchronization signal receiver; and a tilt correcting controller coupled to said tilt angle detector and said right and left tilt correcting liquid crystal cells, whereby said tilt correcting controller is capable of controlling said right and left tilt correcting liquid crystal cells based on the tilt of the stereoscopic image appreciation eyeglasses.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a perspective view of a stereoscopic TV according to the present invention.

(2) FIG. 2 is a front view of stereoscopic image appreciation eyeglasses according to the present invention.

(3) FIG. 3 is a diagram illustrating a configuration of stereoscopic image appreciation eyeglasses according to the present invention.

(4) FIG. 4 is a diagram illustrating an operating condition of the stereoscopic image appreciation eyeglasses according to the present invention.

(5) FIG. 5 is a diagram illustrating another embodiment of the stereoscopic image appreciation eyeglasses according to the present invention.

(6) FIG. 6 is a diagram illustrating still another embodiment of the stereoscopic image appreciation eyeglasses according to the present invention.

(7) FIG. 7A is a front view illustrating another embodiment of the stereoscopic image appreciation eyeglasses according to the present invention.

(8) FIG. 7B is a diagram illustrating a configuration of a tilt angle detector illustrated in FIG. 7A.

(9) FIG. 8 is a front view illustrating an embodiment of stereoscopic image appreciation eyeglasses along which a diopter correction lens holder is attached.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(10) The concept of the present invention will be described with reference to the drawings. FIG. 1 illustrates a stereoscopic image display device. The stereoscopic image display device includes an LCD stereoscopic television set (hereinafter referred to as a stereoscopic TV), for example, and alternately display right and left images by time division on a display 14. Simultaneously, a polarized infrared light synchronization signal radiator 12 installed on a main body 11 of the stereoscopic TV 10 has an infrared polarizing filter 13 attached along its surface, and generates a polarized infrared light synchronization signal.

(11) FIG. 2 is a front view of stereoscopic image appreciation eyeglasses 20 serving as an embodiment of stereoscopic image appreciation eyeglasses according to the present invention. Right and left identical polarizing plates 23.sub.R and 23.sub.L, the polarization direction of which has been tilted by 45 from the polarization direction of the display 14 in the above-mentioned stereoscopic TV 10, are arranged side by side, as illustrated, respectively, in right and left visual fields of the eyeglasses.

(12) Further, two types of liquid crystal cells, i.e., visual field opening/closing liquid crystal cells 21.sub.R and 21.sub.L and tilt correcting liquid crystal cells 22.sub.R and 22.sub.L are respectively installed one over the other, respectively, on front surfaces of the polarizing plates 23.sub.R and 23.sub.L. An infrared light synchronization signal receiver 27 and a tilt angle detector (a tilt angle detecting liquid crystal cell 24, an infrared polarizing filter 25, and an infrared sensor 26) are provided on an eyeglass frame.

(13) FIG. 3 is a diagram illustrating a configuration of the stereoscopic image appreciation eyeglasses illustrated in FIG. 2. An infrared light synchronization signal receiver 37, as illustrated, receives a synchronization signal using polarized infrared light (the synchronization signal need not be polarized) radiated via the infrared polarizing filter 13 in the stereoscopic TV 10. The received synchronization signal is sent to a controller C1, and is converted into a control voltage therein. The control voltage is applied to visual field opening/closing liquid crystal cells 31.sub.R and 31.sub.L. Thus, visual fields of the stereoscopic image appreciation eyeglasses 30 are opened and closed in synchronization with display images that are alternately displayed by time division on the display 14 in the stereoscopic TV 10.

(14) If a viewer tilts his/her head, an orthogonal state between the amplitude direction of the display image, optical rotation of which has been adjusted to open and close the visual fields, and polarizing plates 33.sub.R and 33.sub.L is destroyed, to enter a state where a crosstalk occurs. However, a configuration, using tilt correcting liquid crystal cells 32.sub.R and 32.sub.L, of a tilt angle detector (including a tilt angle detecting liquid crystal cell 34, an infrared polarizing filter 35, and an infrared sensor 36) according to the present invention, illustrated in FIG. 3, is proposed to prevent the crosstalk from occurring by correcting the tilt of the eyeglasses. The tilt angle detector adjusts optical rotation of the polarized infrared light synchronization signal generated from the infrared polarizing filter 13 in the stereoscopic TV 10 using the tilt angle detecting liquid crystal cell 34 and analyzes the synchronization signal using the infrared polarizing filter 35, to detect a tilt angle. If such a function is described, a controller C2 first applies a voltage periodically (e.g., about several times per second) to the tilt angle detecting liquid crystal cell 34. If the applied voltage is gradually raised, an optically rotated state occurring by the tilt angle detecting liquid crystal cell 34 changes, and the amplitude direction of the polarized infrared light, which has been transmitted by the tilt angle detecting liquid crystal cell 34, enters a state orthogonal to the polarization direction of the infrared polarization filter 35. If the orthogonal state occurs, an output of the infrared sensor 36 rapidly decreases to enter a non-output state, to detect a tilt angle. A voltage applied to the tilt angle detecting liquid crystal cell 34 by the controller C2 at this time point is sampled, to detect a tilt angle.

(15) Data representing the above-mentioned detected tilt angle for tilt correction is converted into a control voltage by the controller C2, and the control voltage is applied to the tilt correcting liquid crystal cells 32.sub.R and 32.sub.L. If the viewer tilts his/her head, the orthogonal state at the time of closing the visual fields is destroyed, and a light beam to be blocked slightly slips through the polarizing plates 33.sub.R and 33.sub.L so that a crosstalk occurs. However, according to the present invention, the crosstalk, i.e., leaked light is corrected by the tilt correcting liquid crystal cells 32.sub.R and 32.sub.L, to enter a state completely orthogonal to the polarizing plates 33.sub.R and 33.sub.L. Thus, a light-shielded state at the time of closing the visual fields is always maintained at a maximum.

(16) FIG. 4 is a diagram illustrating an optically rotated state of the stereoscopic image appreciation eyeglasses 30. If display light by the display 14 in the stereoscopic TV illustrated in FIG. 1, described above, is polarized light vibrating in a horizontal direction, for example, the display light is incident on right and left visual fields of the eyeglasses illustrated in FIG. 4. In the left visual field, no voltage is applied to a visual field opening/closing liquid crystal cell 41.sub.L because a switch, as illustrated, is in an opened state so that the display light vibrating in the horizontal direction is transmitted by the visual field opening/closing liquid crystal cell 41.sub.L after being optically rotated by 90 therein, to vibrate in a vertical (up-and-down) direction. On the ether hand, in the right visual field, a voltage is applied to a visual field opening/closing liquid crystal cell 41.sub.R because a switch, as illustrated, is in a closed state so that the display light is transmitted by a visual field opening/closing liquid crystal cell 41.sub.R in the state of vibrating in the horizontal direction. The right and left switches are actually set to be alternately opened and closed automatically in synchronization with the display light in response to the infrared light synchronization signal. Therefore, the display lights, which have been transmitted by the visual field opening/closing liquid crystal cells 41.sub.R or 41.sub.L, are always in a state orthogonal to each other between the right and left visual fields. (However, if the right and left visual fields of the stereoscopic image appreciation eyeglasses are also switched simultaneously with the switching of the right and left images to be alternately displayed by time division on an LCD of the stereoscopic TV, the right and left images of the stereoscopic TV may interfere with each other. To avoid the interference, the right and left visual fields of the eyeglasses need to be simultaneously closed for a predetermined period (a period slightly longer than a period of time during which the right and left images of the stereoscopic TV are switched) at the time point where the right and left images of the stereoscopic TV are switched. Therefore, the display lights may not instantaneously be in the orthogonal state.) A method for turning off a backlight of the stereoscopic TV when the visual fields of the eyeglasses are switched is also implemented. An arrow representing the amplitude direction, on the near side of each of the liquid crystal cells, of the display light is indicated by a solid line, and an arrow representing the amplitude direction, on the far side thereof, of the display light is indicated by a broken line.

(17) The right and left display lights, which have been transmitted by the visual field opening/closing liquid crystal cells 41, as described above, are respectively incident on tilt correcting liquid crystal cells 42 with the amplitude directions being orthogonal to each other. As illustrated in FIG. 4, for example, the display light is incident in the state of vibrating in a vertical (up-and-down) direction in the left visual field. At this time, the display light is incident in the state of vibrating in a horizontal (right-and-left) direction in the right visual field. If the tilt correcting liquid crystal cell 42 is a TN mode liquid crystal, for example, and its operation range (angle) is 90, a bias voltage is always applied to the tilt correcting liquid crystal cell 42 so that the display light enters the state of being optically rotated by 45 that is one-half of 90. The controller C2 converts data representing the above-mentioned detected tilt angle data into a control voltage, and adds and subtracts the control voltage to and from the bias voltage, to drive the tilt correcting liquid crystal cell 42. Since the tilt correcting liquid crystal cells 42.sub.R and 42.sub.L are driven in parallel (in the same direction and simultaneously on the right and left sides), the display lights in the right and left visual fields are maintained in a state orthogonal to each other even after being transmitted by the tilt correcting liquid crystal cells 42. For example, the display light, which has been transmitted by the visual field opening/closing liquid crystal cell 41.sub.L in the left visual field, vibrates in the vertical direction, and is directed toward the polarizing plate 43.sub.L in the state of being optically rotated by 45 by the tilt correcting liquid crystal cell 42.sub.L (being maintained at 45 by the bias voltage). The polarization direction of the polarizing plate 43.sub.L is fixed to 45 parallel to the amplitude direction of the display light, which has been transmitted by the tilt correcting liquid crystal cell 42.sub.L. Therefore, the display light is transmitted by the polarizing plate 43.sub.L, to enter a visual field opened state. On the other hand, the amplitude direction of the display light, which has been transmitted by the tilt correcting liquid crystal cell 42.sub.R in the right visual field, is in a state orthogonal to that in the left visual field. Thus, the amplitude direction of the display light enters a state orthogonal to the right polarizing plate 43.sub.R disposed with its polarization direction being parallel to the left polarizing plate 43.sub.L. Therefore, the display light cannot be transmitted by the polarizing plate 43.sub.R, to enter a visual field closed state.

(18) As described above, the stereoscopic image appreciation eyeglasses 30 illustrated in FIG. 3 in the present invention perform a shutter function for stereoscopic image display light of the stereoscopic TV 10 illustrated in FIG. 1. However, ambient light (surrounding environmental light) is non-polarized light, and vibrates in all directions orthogonal to its travel direction. Therefore, the ambient light is affected by neither the visual field opening/closing liquid crystal cell 31.sub.R and 31.sub.L nor the tilt correcting liquid crystal cells 32.sub.R and 32.sub.L. Therefore, there is no decrease in light amount by the shutter function (conventional liquid crystal shutter eyeglasses also have a shutter function for environmental light, and respective light amounts in right and left visual fields are one-half or less if the right and left visual fields are alternately opened and closed). The fact that there is no shutter function for the surrounding environmental light also has the effect of not causing a flicker due to interference with illumination light. Moreover, only one polarizing plate is used so that not only the stereoscopic TV but also all the visual fields including a surrounding environment look bright. Therefore, this is significantly advantageous in stereoscopic view involving work.

(19) If the stereoscopic image display light, the amplitude direction of which is a horizontal direction, is transmitted by the visual field opening/closing liquid crystal cells 31.sub.R and 31.sub.L, the amplitude direction of the transmitted light is either a horizontal direction or a vertical direction in the right and left visual fields. More specifically, the visual field takes two values, i.e., opened or closed. An intermediate value other than the two values is not preferable because a visual field becomes dark or a crosstalk occurs. Accordingly, the visual field opening/closing liquid crystal needs to be high in response speed. A II-type (OCB (Optically Compensated Birefringence)) liquid crystal, or a ferroelectric liquid crystal (SSFLCD (Surface Stabilized Ferroelectric Liquid Crystal Device), PSS-LCD (Polarization Shielded Smectic Liquid Crystal Device)) is suitable for such an application.

(20) A case where the eyeglasses are put horizontally has been described above. The polarizing plates 33.sub.R and 33.sub.L, together with the eyeglasses, are tilted with the eyeglasses tilted so that their respective tilt angles are different from the above-mentioned angle of 45. Therefore, the orthogonal state at the time of closing the visual fields is destroyed. If this remains so, a crosstalk occurs. If the eyeglasses are tilted, therefore, the light-shielded state at the time of closing the visual fields is always maintained at a maximum by detecting the tilt angle of the eyeglasses using a tilt angle sensor placed on the eyeglasses, and adding or subtracting a tilt correcting control voltage to or from a bias voltage, to correct the amplitude direction of the display light directed toward the polarizing plates 33.sub.R and 33.sub.L to always enter a state orthogonal to the polarization direction of the polarizing plates 33.sub.R and 33.sub.L when the visual fields are closed.

(21) While the tilt of the eyeglasses has been corrected by detecting the tilt angle to adjust an optically rotatable state by the tilt correcting liquid crystal cells 32.sub.R and 32.sub.L, a checking voltage may be applied to the tilt angle detecting liquid crystal cell 34 (by the controller C2) at a frequency of approximately several times per second. This is because a person does not shake his/her head at a so high speed when the person tilts his/her head. Even in a period during which the checking voltage is not applied to the tilt angle detecting liquid crystal cell 34 because the tilt angle is intermediately detected, however, corrected states of the tilt correcting liquid crystal cells 32.sub.R and 32.sub.L need to be held in a certain state. The corrected state, which has been updated when the tilt angle is detected, is held until the next tilt angle is detected, and such an operating condition is always repeatedly continued so that a visually tilted state is always maintained in a horizontal state even if the stereoscopic image appreciation eyeglasses are tilted in any direction. Therefore, a crosstalk is prevented from occurring.

(22) While the tilt correcting liquid crystal cell 32.sub.R, 32.sub.L is disposed behind the visual field opening/closing liquid crystal cell 31.sub.R, 31.sub.L in the embodiment descried in FIG. 3 in the present invention, either one of the liquid crystal cells may be disposed behind the other liquid crystal cell.

(23) A high response speed is not required for the tilt correcting liquid crystal cells 32.sub.R and 32.sub.L. This is because the speed at which the person tilts his/her head is significantly lower than a response speed of the liquid crystal, as described above. Therefore, a conventional TN mode liquid crystal is sufficient. Since an operation range (for optical rotation) of the TN mode liquid crystal is 90, an intermediate position between a position where the head is tilted rightward and a position where the head is tilted leftward is a horizontal position, a voltage may be applied (a bias voltage) so that the tilt correcting liquid crystal cell 32 enters a state of being optically rotated by 45, which is an intermediate value, with the eyeglasses horizontally put.

(24) There is a case where respective applied voltages and characteristics of optically rotated states of the tilt angle detecting liquid crystal cell 34 and the tilt correcting liquid crystal cells 32.sub.R and 32.sub.L may be unproportional to each other. However, in the case, an optical rotation angle can be accurately controlled by a program in which a corrected value is adjusted depending on a parameter in the controller C2.

(25) FIG. 5 illustrates another embodiment of stereoscopic image appreciation eyeglasses. On a frame of stereoscopic image appreciation eyeglasses 50 illustrated in FIG. 5, a tilt angle detector including a tilt angle detecting liquid crystal cell 54, an infrared polarizing filter 55, and an infrared sensor 56 is placed. The stereoscopic image appreciation eyeglasses are configured to calculate detection data of the tilt angle detector and synchronization signal data of a synchronization signal receiver 57 (a tilt angle detecting method and a synchronization signal receiving method themselves are identical to those according to an embodiment, described above) using a controller C, synchronously drive visual field opening/closing and tilt correcting liquid crystal cells 51.sub.R and 51.sub.L, alternately open and close visual fields for display light of the stereoscopic image display device 10 to perform stereoscopic viewing while performing control so that the display light of the stereoscopic image display device, which has been transmitted by the visual field opening/closing and tilt correcting liquid crystal cells 51.sub.R and 51.sub.L, always enter a state orthogonal to the polarization directions of polarizing plates 53.sub.R and 53.sub.L when the visual fields are closed so that a light-shielded state at the time of closing the visual fields always reaches its maximum, to prevent a crosstalk from occurring.

(26) While high-speed responsiveness is required as a material for the visual field opening/closing and tilt correcting liquid crystal cells 51.sub.R and 51.sub.L in the stereoscopic image appreciation eyeglasses having the above-mentioned configuration, an SSFLCD cannot be used. This is because the SSFLCD has a sharp function and cannot display an intermediate value (cannot perform tilt correction). The stereoscopic image appreciation eyeglasses in the configuration according to an embodiment can be made smaller in the number of parts while being slightly narrower in a tilt correction range than in the above-mentioned configuration according to another embodiment.

(27) As a tilt angle detector required to apply a correcting voltage to the tilt correcting liquid crystal cells 32.sub.R and 32.sub.L illustrated in FIG. 3 and the liquid crystal cells 51.sub.R and 51.sub.L illustrated in FIG. 5 in the present invention, described above, a gravity sensor (of a type of detecting an angle of a pendulum or the like and finally converting the angle into an electrical output or a type of finally converting a change in a liquid surface into an electrical output using a liquid surface) and a gyro sensor (e.g., a piezoelectric gyro) can be used. Since the sensors can independently detect the tilt angle of eyeglasses, polarized infrared light serving as a basis for tilt correction is not required. Therefore, the infrared polarizing filter 13 in the stereoscopic TV 10 illustrated in FIG. 1 is not required in the case.

(28) FIG. 6 illustrates another embodiment of stereoscopic image appreciation eyeglasses according to the present invention, where polarizing plates 63 are respectively arranged side by side in right and left visual fields of the eyeglasses. A left tilt correcting liquid crystal cell 62 and a right tilt correcting liquid crystal cell 68, which are opposite in torsional direction, are installed one over the other on a front surface of the polarizing plate 63. Further, a visual field opening/closing liquid crystal cell 61 is further installed on the front surface of the left tilt correcting liquid crystal cell 62. A synchronization signal receiver 67 receives an infrared light synchronization signal radiated from the polarized infrared light synchronization signal radiator 12 in the stereoscopic TV 10 illustrated in FIG. 1, and a controller C1 converts the synchronization signal into a control voltage and applies the control voltage to the visual field opening/closing liquid crystal cells 61.sub.R and 61.sub.L, to open and close right and left visual fields. A state of right and left display lights in this case is equal to that when the right and left display lights are respectively transmitted by the visual field opening/closing liquid crystal cells 41.sub.R and 41.sub.L, described with reference to FIG. 4. In this state, the right and left display lights are in a state where their respective amplitude directions are always orthogonal to each other. The polarized right and left display lights, which vibrate in a state orthogonal to each other, are transmitted by the left tilt correcting liquid crystal cells 62.sub.R and 62.sub.L and the right tilt correcting liquid crystal cells 68.sub.R and 68.sub.L. If no voltage is applied to the left tilt correcting liquid crystal cells 62.sub.R and 62.sub.L and the right tilt correcting liquid crystal cells 68.sub.R and 68.sub.L, however, the display lights are optically rotated once by the left tilt correcting liquid crystal cells 62.sub.R and 62.sub.L while being returned by the right tilt correcting liquid crystal cells 68.sub.R and 68.sub.L, which is opposite in torsional direction to the left tilt correcting liquid crystal cells 62.sub.R and 62.sub.L. This is the same as a state where the left tilt correcting liquid crystal cells 62.sub.R and 62.sub.L and the right tilt correcting liquid crystal cells 68.sub.R and 68.sub.L are not installed. Right and left images, which are analyzed by the polarizing plates 63.sub.R and 63.sub.L and are displayed by time division on the display 14 in the stereoscopic TV 10, are separated.

(29) In the above-mentioned state, if the eyeglasses are tilted, an orthogonal state between the amplitude direction of the display lights at the time of closing the visual fields and the polarization direction of the polarizing plates 63.sub.R and 63.sub.L is destroyed so that a crosstalk may occur. In such a case, a TN (Twisted Nematic) mode liquid crystal is used for the left tilt correcting liquid crystal cells 62.sub.R and 62.sub.L and right tilt correcting liquid crystal cells 68.sub.R and 68.sub.L, for example. The left tilt correcting liquid crystal cells 62.sub.R and 62.sub.L perform correction when the eyeglasses are tilted leftward, and the right tilt correcting liquid crystal cells 68.sub.R and 68.sub.L perform correction when the eyeglasses are tilted rightward so that the tilt of the eyeglasses can be corrected by a total of 180, 90 rightward and 90 leftward. In this case, a bias need not be applied to the left tilt correcting liquid crystal cells 62.sub.R and 62.sub.L and the right tilt correcting liquid crystal cells 68.sub.R and 68.sub.L. If an STN (Super Twisted Nematic) mode liquid crystal is used instead of a case where two TN mode liquid crystals are used one over the other, the number of light crystal cells may be one. Two TN mode liquid crystals are to be used one over the other in consideration of the need to apply a bias thereto when the posture of the eyeglasses is in a horizontal state, and a problem of color displacement and a difficulty of fine adjustment because of a steep tilt, which are characteristic of the STN mode liquid crystal.

(30) To correct the tilt by a total of 180, 90 rightward and 90 leftward, described above, a tilt angle of 180 needs to be detected. A first tilt angle detecting liquid crystal cell 64 and a second tilt angle detecting liquid crystal cell 69, which are illustrated as a tilt angle detector in FIG. 6, can also be optionally rotated by 180 if one STN mode liquid crystal is used. The problem of color displacement is ignored if the STN mode liquid crystal is for tilt angle detection. However, the STN mode liquid crystal is unsuitable because it is difficult to finely adjust because its tilt is steep. Therefore, a controller C2 applies a voltage to the first tilt angle detecting liquid crystal cells 64 and the second tilt angle detecting liquid crystal cell 69, as illustrated, after overlaying the first tilt angle detecting liquid crystal cell 64 and the second tilt angle detecting liquid crystal cell 69 in a state, as illustrated, while coupling respective electrodes of the first tilt angle detecting liquid crystal cell 64 and the second tilt angle detecting liquid crystal cell 69 in a series state or a parallel state. The applied voltage is gradually raised so that polarized infrared light that is transmitted by the first tilt angle detecting liquid crystal cell 64 and the second tilt angle detecting liquid crystal cell 69, which are doubly overlaid, are adjusted to be optically rotated by 0 to 180. Accordingly, the tilt angle is detected by applying a voltage to the first tilt angle detecting liquid crystal cell 64 and the second tilt angle detecting liquid crystal cell 69 after coupling the liquid crystal cells 64 and 69 in series or in parallel, and sampling a voltage at the time point where an output of an infrared sensor 66, as illustrated, rapidly decreases to enter a non-output state. A tilt angle of a total 180, 90 rightward and 90 leftward, can be detected by a similar function to that in the method for detecting the tilt angle of the stereoscopic image appreciation eyeglasses having the above-mentioned configuration illustrated in FIG. 3. Naturally, a voltage applied when the first tilt angle detecting liquid crystal cell 64 and the second tilt angle detecting liquid crystal cell 69 are coupled in series becomes two times that when they are coupled in parallel (in a case where their respective optical rotation functions are the same). Even if a voltage is applied to either one of the first tilt angle detecting liquid crystal cell 64 and the second tilt angle detecting liquid crystal cell 69, and a voltage is sequentially applied to the other tilt angle detecting liquid crystal cell when the applied voltage reaches (exceeds) a prescribed maximum value, a similar function to that when the first and second tilt angle detecting liquid crystal cells 64 and 69 are coupled in serial or in parallel is produced.

(31) When the left tilt correcting liquid crystal cells 62.sub.R and 62.sub.L and the right tilt correcting liquid crystal cells 68.sub.R and 68.sub.L, which are respectively installed in visual fields of the eyeglasses, are tilted leftward or rightward from a horizontal state, they are set to separately operate for leftward tilt or rightward tilt so that a bias need not be applied thereto.

(32) FIG. 7 illustrates a content discussed in Japanese Patent Laid-Open No. 2009-274002 (stereoscopic image appreciation eyeglasses) previously filed by the present applicant, where a polarizing plate 72 in a vertical (up-and-down) direction is installed in right and left visual fields of eyeglasses illustrated in FIG. 7A. Liquid crystal cells 71.sub.R and 71.sub.L are attached to a front surface of the polarizing plate 72. FIG. 7B is a detailed view of a synchronization signal receiver 73 for opening and closing the visual fields of the eyeglasses in synchronization with a display image for a stereoscopic TV, and illustrates a method for detecting a tilt angle. Its functions will be described below.

(33) The infrared polarizing filter 13 on the radiation surface of the infrared light synchronization signal radiator 12 attached along the stereoscopic image display device 10 illustrated in FIG. 1 changes synchronizing infrared light into polarized infrared light. The polarization direction of infrared polarizing filters 74.sub.R and 74.sub.L in the synchronization signal receiver 73 is arranged in a symmetrically tilted state, as illustrated in FIG. 7A when the eyeglasses are put horizontally. In this case, respective outputs of infrared sensors 75.sub.R and 75.sub.L are equal to each other. If the eyeglasses are tilted either rightward or leftward from this state, a difference occurs between the outputs of the infrared sensors 75.sub.R and 75.sub.L. A tilt angle can be detected by previously examining a relationship between the output difference and the tilt.

(34) FIG. 3 illustrates a diopter correction lens optionally attached along stereoscopic image appreciation eyeglasses and an attachment portion. A person's eyesight (diopter) differs from individual to individual. Even in a usual life, many persons use diopter correcting eyeglasses. Even in an object to be viewed, there are a case where a small screen of a personal computer is viewed at a close distance and a case where a relatively large TV is viewed at a slightly far distance. The need to switch eyeglasses depending on a distance from the object also arises. Particularly, a person using reading glasses needs to change the diopter of a correction lens (replace eyeglasses usually used) depending on a distance from the object to be viewed. Accordingly, in stereoscopic image appreciation eyeglasses, i.e., visual field separating eyeglasses, diopter correcting eyeglasses need to be used from individual to individual. However, in the actual situation, the stereoscopic image appreciation eyeglasses are overlaid on the eyeglasses usually used. However, using two types of eyeglasses one over the other is unstable, and is troublesome. Therefore, stereoscopic image appreciation eyeglasses for personal use incorporating a diopter correction lens tailored to the individual can also be prepared. However, a problem occurring when the diopter correction lens is fixed, tailored to the individual is that the stereoscopic image appreciation eyeglasses for personal use cannot be diverted to one for another person (their respective diopters do not match each other). The stereoscopic image appreciation eyeglasses need to be changed depending on an object (a TV or a PC) to be viewed even for personal use.

(35) The best method for solving the above-mentioned problem is to provide a slot for a lens holder on a front surface or a rear surface of the stereoscopic image appreciation eyeglasses and insert the diopter correction lens, as needed. FIG. 8 illustrates a holder (a slot) for retaining the diopter correction lens on the front surface of the stereoscopic image appreciation eyeglasses. The holder is molded integrally with an eyeglass frame (illustration of its main body portion is omitted). A holder portion 80, as illustrated, is provided with a slot 84 into which diopter correction lenses 81.sub.R and 81.sub.L are to be inserted. The diopter correction lenses 81.sub.R and 81.sub.L, which have been inserted into the slot 84, are pressed against the slot 84 using a leaf spring 82. The diopter correction lenses 81.sub.R and 81.sub.L, which have been simultaneously inserted once, do not easily drop off even if the eyeglasses are turned upside down by a shape of the leaf spring 82 and a spring effect.

(36) The diopter correction lens 81 has its right and left ends formed in a circular arc shape. The circular arc shape makes insertion into the slot 84 easy. Further, upper and lower ends of the diopter correction lens 81 are formed in a linear shape, to prevent the diopter correction lenses 81.sub.R and 81.sub.L from rotating (functionally, only the lower end may have a linear shape). Such a rotation preventing function is significantly effective when an astigmatic lens is required as the diopter correction lens. This is because astigmatism correction is performed in a specific direction (angle) so that the diopter correction lens needs to be fixed at a specific position in a rotational direction. A knob 83, as illustrated, has a structure in which aluminum is folded and held therein or is bonded thereto, and can identify the lens by increasing a frictional force against fingers when it is detachably attached to the slot 84 and not only preventing the lens from being contaminated but also being marked.

(37) The stereoscopic image appreciation eyeglasses according to the present invention do not react with ambient light. Therefore, a work environment visual field looks bright in work performed while observing a stereoscopic image. Therefore, the eyeglasses need not be removed even during work other than viewing of a monitor. The function and effect of the stereoscopic image appreciation eyeglasses having this configuration are great.

(38) Various modifications can be made as long as they do not depart from the spirit of the present invention, and the present invention naturally covers the modifications.

INDUSTRIAL APPLICABILITY

(39) Stereoscopic image appreciation eyeglasses according to the present invention are particularly visual field separating eyeglasses for separating right and left visual fields of a stereoscopic image, which is displayed by time division on a television set made of an LCD or a personal computer, to perform stereoscopic viewing, and will be hereafter essential in applications from general appreciation of a stereoscopic image to appreciation of a stereoscopic image such as various types of simulation, education and training, inspection, medical care, and advertisement.

REFERENCE SIGNS LIST

(40) 10 stereoscopic image display device 11 stereoscopic image display device main body 12 polarized infrared light synchronization signal radiator 13 infrared polarizing filter 14 display 20 stereoscopic image appreciation eyeglasses 21.sub.R, 21.sub.L visual field opening/closing liquid crystal cell 22.sub.R, 22.sub.L tilt correcting liquid crystal cell 23.sub.R, 23.sub.L polarizing plate 24 tilt angle detecting liquid crystal cell 25 infrared polarizing filter 26 infrared sensor 27 synchronization signal receiver C1 visual field opening/closing controller C2 tilt correcting controller 30 stereoscopic image appreciation eyeglasses 31.sub.R, 31.sub.L visual field opening/closing liquid crystal cell 32.sub.R, 32.sub.L tilt correcting liquid crystal cell 33.sub.R, 33.sub.L polarizing plate 34 tilt angle detecting liquid crystal cell 35 infrared polarizing filter 36 infrared sensor 37 synchronization signal receiver 41.sub.R, 41.sub.L visual field opening/closing liquid crystal cell 42.sub.R, 42.sub.L tilt correcting liquid crystal cell 43.sub.R, 43.sub.L polarizing plate 50 stereoscopic image appreciation eyeglasses C visual field opening/closing and tilt correcting controller 51.sub.R, 51.sub.L visual field opening/closing and tilt correcting liquid crystal cell 53.sub.R, 53.sub.L polarizing plate 54 tilt angle detecting liquid crystal cell 55 infrared polarizing plate 56 infrared sensor 57 synchronization signal receiver 60 stereoscopic image appreciation eyeglasses 61.sub.R, 61.sub.L visual field opening/closing liquid crystal cell 62.sub.R, 62.sub.L left tilt correcting liquid crystal cell 63.sub.R, 63.sub.L polarizing plate 64 first tilt angle detecting liquid crystal cell 65 infrared polarizing filter 66 infrared sensor 67 synchronization signal receiver 68.sub.R, 68.sub.L right tilt correcting liquid crystal cell 69 second tilt angle detecting liquid crystal cell 71.sub.R, 71.sub.L visual field opening/closing and tilt correcting liquid crystal cell 72.sub.R, 72.sub.L polarizing plate 73 infrared light synchronization signal receiver 74.sub.R, 74.sub.L infrared polarizing plate 75.sub.R, 75.sub.L infrared sensor 80 lens holder 81.sub.R, 81.sub.L diopter correction lens 82 leaf spring 83 knob 84 slot portion