ELECTRONIC IMAGER

Abstract

An electronic imager (1) for imaging a photographic medium, comprising at least one array (6) of micromirrors (2), each of which is suitable for reflecting, during a change in position, a light beam coming from at least one light source (3) towards a projecting optical element (4), the change in position of the micromirrors (2) being controlled by a signal modulated at a toggling frequency (fb) of the micromirrors comprised between 1 Hz and 100 kHz.

Claims

1. An electronic imager for imaging a photographic medium, comprising at least one matrix array of micro-mirrors each of which is suitable for reflecting, during a change in position, a light beam originating from at least one light source oward a projecting optical element, the change in position of the micro-mirrors commanded by a signal modulated at a switching frequency of the micro-mirrors ranging from 1 Hz to 100 kHz.

2. The electronic imager of claim 1, wherein the switching frequency of the micro-mirrors is lower than or equal to 50 kHz.

3. The electronic imager of claim 1, wherein the switching frequency of the micro-mirrors is lower than or equal to 1 kHz.

4. The electronic imager of claim 1, comprising a selector for selecting the switching frequency of the micro-mirrors from at least two predefined values.

5. The electronic imager of claim 1, wherein the modulated signal originates from an additional circuit that synthesizes at least one switching frequency of the micro-mirrors, the additional circuit replacing a controller of an imager that commands the change in position of the micro-mirrors at a reference frequency, an output of the additional circuit connected to an input that commands the change in position of the micro-mirrors.

6. The electronic imager of claim 5, wherein the additional circuit is suitable for receiving an instruction as to the choice of a value of the switching frequency from a plurality of predefined values.

7. The electronic imager of claim 1, configured to block and/or turn off at least one portion of the light beam originating from the at least one light source at least during a portion of a duration of the change in position of the micro-mirrors.

8. The electronic imager claim 7, wherein the at least one portion of the light beam originating from said at least one light source is blocked or turned off throughout the duration of the change in position of the micro-mirrors.

9. The electronic imager of claim 7, wherein the at least one portion of the light beam originating from the at least one light source is blocked or turned off with a certain advance and/or a certain delay with respect to the change in position of the micro-mirrors.

10. The electronic imager as claimed in claim 7, comprising at least one electronic shutter arranged to block, when activated, the at least one portion of the light beam.

11. The electronic imager of claim 1, comprising an element for controlling the at least one light source, the element configured to turn off this source at least during one portion of a duration of the change in position of the micro-mirrors.

12. The electronic imager of claim 1, comprising a single matrix array of micro-mirrors and three light sources.

13. An assembly comprising a photographic medium and an electronic imager of claim 1.

14. A method for reproducing images on a photographic medium comprising projecting an image onto the photographic medium with an electronic imager of claim 1.

15. The method of claim 14, wherein the photographic medium comprises three superposed planes corresponding to red, green and blue levels, respectively, and wherein the electronic imager comprises a single matrix array of micro-mirrors and three light sources, with one light source for each respective plane of the medium.

16. The method of claim 15, wherein a light source corresponding to the plane of a desired color level is selected to illuminate the micro-mirrors of the matrix array during a change in their position.

17. A method for recording data using an electronic imager comprising at least one matrix array of micro-mirrors each of which is suitable for reflecting, during a change in position, a light beam originating from at least one light source toward a projecting optical element, the method comprising blocking at least one portion of the light beam originating from the at least one light source and/or turning off the at least one light source, at least during one portion of a duration of the change in position of the micro-mirrors.

18. A method for modifying an electronic imager comprising at least one matrix array of micro-mirrors each of which is suitable for reflecting, during a change in position, a light beam originating from at least one light source toward a projecting optical element, the method comprising: reprogramming a controller of an imager that commands the change in position of the micro-mirrors at a reference frequency configured to subsequently be decreased; or replacing a controller of an imager that commands the change in position of the micro-mirrors at a reference frequency with an additional circuit that synthesizes at least one possible value of a switching frequency of the micro-mirrors, which value ranges from 1 Hz to 100 kHz, the output of the additional circuit connected to an input that commands the change in position of the micro-mirrors.

Description

[0056] The invention will possibly be better understood on reading the following detailed description of nonlimiting examples of implementation thereof, and on examining the appended drawings, in which:

[0057] FIG. 1 shows an electronic imager according to the invention,

[0058] FIG. 2, which was described above, schematically shows an electronic imager according to the prior art comprising three matrix arrays of micro-mirrors, and

[0059] FIG. 3 illustrates the operating principle of the modified imager according to the invention.

[0060] FIG. 1 shows an electronic imager 1 that projects onto a medium 12 and that comprises a matrix array 6 of micro-mirrors 2. A light source 3 illuminates these micro-mirrors 2, which reflect, depending on their position, the light beam either toward a projecting optical element 4, a lens for example, or toward an absorbent element 5.

[0061] The position of the micro-mirrors may correspond to an on state, in which the micro-mirrors are directed toward the light source 3, or to an off state, in which the micro-mirrors are turned away from the light beam. These on and off states relate to the logic levels 1 and 0 of the pixel, respectively.

[0062] The projecting optical element 4 projects onto the medium 12 at least one portion of the reflected light beam when the micro-mirrors 2 are in the on state.

[0063] The absorbent element 5 absorbs at least one portion of the light beam reflected in the off state of the micro-mirrors 2. This absorbent element is for example a black velvet cloth when the light sources are LEDs, this type of absorbent element being sufficient to absorb the surplus of energy distributed by the mirrors. The absorbent element may be a radiator in the case of a very hot light source, a mercury lamp for example.

[0064] As illustrated in FIG. 3, the micro-mirrors 2 rock plus or minus 12° with respect to a stable position corresponding to a flat state. The micro-mirrors 2 reflect the incident light at 24° toward the projecting lens 4 when they are in the on state, and at 72° toward the absorbent element 5 when they are in the off state.

[0065] The imager 1 comprises a controller that drives the change in position of the micro-mirrors 2. As described above, the change in position of the micro-mirrors 2 is commanded by a signal that is modulated at a switching frequency f.sub.b of the micro-mirrors that is comprised between 1 kHz and 100 kHz, and that is especially lower than 1 kHz. For example, to record at 24 images per second and with 16 grayscale levels, the switching frequency f.sub.b of the micro-mirrors is set to 768 Hz.

[0066] In a first embodiment of the invention, the predefined possible values of the switching frequency f.sub.b are stored in a controller of the electronic imager 1, said controller driving the change in position of the micro-mirrors 2 and having been reprogrammed accordingly. The electronic imager comprises, in this case, advantageously, a selector for selecting the switching frequency f.sub.b of the micro-mirrors 2 from at least two predefined values, and better still at least five predefined values.

[0067] In one variant, as shown in FIG. 1, the modulated signal originates from an additional circuit 11 that synthesizes predefined values of the switching frequency f.sub.b of the micro-mirrors 2, this additional circuit 11 replacing the controller, the output of the additional circuit 11 being connected to the input that commands the change in position of the micro-mirrors. Preferably, the additional circuit 11 is suitable for receiving an instruction as to the choice of a value of the switching frequency f.sub.b from a plurality of predefined values.

[0068] Preferably, and as shown in FIG. 3, an electronic shutter 10, for example of electro-optical type, is placed in front of the light source 3. This shutter 10 is configured to block, when activated, at least one portion of the light beam, during at least one portion of the duration of the switch of the micro-mirrors 2, or even throughout the duration of the change in position of the micro-mirrors 2.

[0069] The electronic imager 1 may comprise an element (not illustrated) for controlling the light sources, which element is configured to turn off one or other of the sources at least during one portion of the duration of the change in position of the micro-mirrors 2, or even throughout the duration of the change in position of the micro-mirrors 2.

[0070] The light may be blocked or turned off with a certain advance and/or a certain delay with respect to the change in position of the micro-mirrors 2.

[0071] Preferably, the electronic imager 1 according to the invention comprises only a single matrix array 6 of micro-mirrors 2. Three light sources 3 are advantageously used, one for each of the red, green and blue color levels corresponding to the three superposed planes of the medium 12. For the sake of clarity, a single light source 3 has been shown in FIG. 1. In this case, and contrary to the prior art, there is no need for any prism to be interposed between the light sources 3 and the matrix array 6 of micro-mirrors 2.

[0072] It is particularly advantageous to use the electronic imager 1 according to the invention to reproduce images on a photographic medium 12, especially a strip-shaped photographic medium, and preferably a strip of 35 mm film, with a view to saving digital data resulting from image conversion.

[0073] During the change in position of the micro-mirrors 2, the source corresponding to the plane of the component of desired color is selected. The light beams of the two other sources may be blocked by the shutter 10 placed in front of each thereof, or the sources may be turned off by a controlling element. The invention is not limited to the examples that have just been described. The electronic imager 1 may comprise a different arrangement of matrix arrays of micro-mirrors, of light sources and of shutters and/or elements for controlling the sources.