TIMING CONTROLLER

Abstract

A main input interface receives input image data. Memory stores multiple segment data that specify the on/off states of the multiple respective segments that form a segment character on an image frame. A sub input interface receives sub data that specifies the segment character to be displayed. A segment decoder converts the segment character into a raster image based on the sub data and the multiple segment data. An image processing circuit generates output image data to be displayed on a display panel, based on at least one of the input image data and the output data of the segment decoder.

Claims

1. A timing controller comprising: a main input interface structured to receive input image data; memory structured to store a plurality of segment data that correspond to a plurality of respective segments that form a segment character, wherein each segment data specifies on/off states of pixels that correspond to the corresponding segment on an image frame; a sub input interface structured to receive sub data that specifies the segment character to be displayed; a segment decoder structured to generate the segment character in the form of a raster image based on the sub data and the plurality of segment data; an image processing circuit structured to generate output image data to be displayed on a display panel, based on at least one from among the input image data and output data of the segment decoder; and an output interface structured to output the output image data to a data driver.

2. The timing controller according to claim 1, wherein the segment decoder comprises: a multiplexer structured to receive a segment luminance value that corresponds to the on state and a background luminance value that corresponds to the off state, and to select one from among the segment luminance value and the background luminance value thus received; and a timing generator structured to control the multiplexer according to the sub data and the segment data.

3. The timing controller according to claim 1, wherein the image processing circuit selects one from among the input image data and the output data of the segment decoder so as to generate the output image data.

4. The timing controller according to claim 1, wherein the image processing circuit is structured to combine the input image data and the output data of the segment decoder so as to generate the output image data.

5. The timing controller according to claim 1, wherein the image processing circuit is structured to switch between: (i) a mode in which data is selected from among the input image data and the output data of the segment decoder so as to generate the output image data; and (ii) a mode in which the input image data and the output data of the segment decoder are combined so as to generate the output image data.

6. The timing controller according to claim 1, wherein the segment character comprises a plurality of segments designed such that two or more segments have a common shape, and wherein the segment data of the aforementioned two or more segments having the common shape comprises shape data that specifies a shape of the segment and data that specifies a shift amount by which the segment is to be shifted in a vertical direction and a horizontal direction.

7. The timing controller according to claim 1, wherein the sub data comprises a plurality of bits that specify the on/off states of the plurality of respective segments, and wherein the sub input interface comprises a register structured to store the plurality of bits.

8. The timing controller according to claim 1, wherein the sub data comprises a character code that specifies the segment character, and wherein the timing controller further comprises a character decoder structured to convert the character code into a plurality of bits that specify the on/off states of the plurality of respective segments.

9. The timing controller according to claim 1, wherein the segment character is structured as a combination of segments that can be classified into a plurality of different types each having a different shape, wherein the plurality of segment data correspond to the plurality of types of segments, wherein the memory stores description data for each segment character, and wherein the description data comprises: (i) type data that specifies the type of each of the plurality of segments to be used for the corresponding segment character; and (ii) position data that specifies a position of each of the plurality of segments to be used for the corresponding segment character.

10. A timing controller comprising: a main input interface structured to receive input image data; a sub input interface structured to receive sub data that specifies a segment character to be displayed, wherein the segment character is configured as a combination of segments that can be classified into a plurality of different types each having a different shape; memory structured: (i) to store segment data that specifies a shape of the segment for each type; and (ii) to store type data that specifies the types of the plurality of segments to be used for each segment character and position data that specifies a position of each of the plurality of segments to be used for each segment character; a segment decoder structured to generate the segment character in the form of a raster image based on the sub data, the segment data, the type data, and the position data; an image processing circuit structured to generate output image data to be displayed on a display panel based on at least one of the input image data and output data of the segment decoder; and an output interface structured to output the output image data to a data driver.

11. The timing controller according to claim 1, wherein the sub input interface is configured as an SPI (Serial Peripheral Interface) or otherwise an I.sup.2C (Inter-Integrated Circuit) interface.

12. The timing controller according to claim 1, wherein the sub data further comprises first data that specifies a size of the segment character.

13. The timing controller according to claim 1, wherein the sub data further comprises second data that specifies an interval between segment characters.

14. The timing controller according to claim 1, wherein the sub data further comprises an indication of transparency of the segment character.

15. The timing controller according to claim 1, wherein the segment decoder is structured to select one from among the sub data input to the sub input interface from an external circuit and the sub data generated by an internal component of the timing controller, and to generate the segment character in the form of a raster image based on the sub data thus selected.

16. The timing controller according to claim 1, monolithically integrated on a single semiconductor substrate.

17. A display apparatus structured as an in-vehicle display apparatus or otherwise as a medical display apparatus, comprising the timing controller according to claim 1.

18. An electronic device comprising the timing controller according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Embodiments will now be described, by way of example only, with reference to the accompanying drawings which are meant to be exemplary, not limiting, and wherein like elements are numbered alike in several Figures, in which:

[0038] FIG. 1 is a block diagram showing an image display system;

[0039] FIG. 2 is a block diagram showing a timing controller according to an embodiment;

[0040] FIGS. 3A through 3C are diagrams for explaining a segment character;

[0041] FIG. 4A is a diagram showing an example of a sub image, and FIG. 4B is a diagram showing an example of an address map of a register;

[0042] FIG. 5A is a block diagram showing an example configuration of an image processing circuit, and FIG. 5B is a block diagram showing an example configuration of the image processing circuit;

[0043] FIG. 6 is a block diagram showing an example configuration of a segment decoder;

[0044] FIGS. 7A and 7B are operation waveform diagrams each showing the operation of the segment decoder shown in FIG. 6;

[0045] FIGS. 8A through 8C are diagrams for explaining segment data compression;

[0046] FIGS. 9A and 9B are diagrams each showing an in-vehicle display apparatus employing the timing controller;

[0047] FIG. 10 is a perspective view showing an electronic device;

[0048] FIG. 11 is a block diagram showing a part of a timing controller according to a first modification;

[0049] FIG. 12 is a part of a timing controller according to a second modification;

[0050] FIGS. 13A and 13B are diagrams each showing a segment character according to a seventh modification;

[0051] FIGS. 14A and 14B are diagrams each showing a segment character according to an eighth modification;

[0052] FIG. 15A is a diagram showing description data that represents the segment character shown in FIG. 14A, and FIG. 15B is a diagram showing description data that represents the segment character shown in FIG. 14B; and

[0053] FIG. 16 is a diagram showing a part of a timing controller according to the eighth modification.

DETAILED DESCRIPTION OF THE INVENTION

[0054] The invention will now be described based on preferred embodiments which do not intend to limit the scope of the present invention but exemplify the invention. All of the features and the combinations thereof described in the embodiment are not necessarily essential to the invention.

[0055] In the present specification, the state represented by the phrase “the member A is coupled to the member B” includes a state in which the member A is indirectly coupled to the member B via another member that does not affect the electric connection therebetween, in addition to a state in which the member A is physically and directly coupled to the member B.

[0056] Similarly, the state represented by the phrase “the member C is provided between the member A and the member B” includes a state in which the member A is indirectly coupled to the member C, or the member B is indirectly coupled to the member C via another member that does not affect the electric connection therebetween, in addition to a state in which the member A is directly coupled to the member C, or the member B is directly coupled to the member C.

[0057] FIG. 2 is a block diagram showing a timing controller 200 according to an embodiment. The timing controller 200 receives input image data from the graphic controller 110, supplies output image data to the source driver 106, and supplies control signals and synchronization signals to the gate driver 104 and the source driver 106, in the same way as the image display system 100R shown in FIG. 1. The timing controller 200 may be configured as a function IC integrated on a single semiconductor substrate.

[0058] The timing controller 200 includes a main input interface 202, an image processing circuit 204, an output interface circuit 208, a sub input interface 210, memory 212, and a segment decoder 220.

[0059] The main input interface 202, the image processing circuit 204, and the output interface circuit 208 form a circuit block that relates to a display operation for the image data received from the graphic controller 110. Such a circuit block may have the same configuration as that included in the timing controller 200R according to a conventional technique. The main input interface 202 is coupled to the graphic controller 110 via a first line 112, and receives input image data S1. As an interface that couples the main input interface 202 and the graphic controller 110, a high-speed differential serial interface such as an LVDS (Low Voltage Differential Signaling) may be employed.

[0060] The image processing circuit 204 performs various kinds of signal processing on the input image data S1 received via the main input interface 202. The signal processing provided by the image processing circuit 204 is not restricted in particular. That is to say, known techniques may be employed. Examples of such image processing include gamma correction, FRC (Frame Rate Control) processing, RGB mapping, and the like. After the image processing circuit 204 performs the image processing, the output interface circuit 208 outputs the output image data S2 thus subjected to the image processing to the source driver 106.

[0061] The above is the basic configuration of the timing controller 200. The timing controller 200 is capable of displaying an image (which will be referred to as a “sub image” hereafter) based on sub data S3 instead of or otherwise in addition to an image (which will be referred to as a “main image” hereafter) based on the input image data S1. In connection with the display operation for such a sub image, the timing controller 200 includes the sub input interface 210, the memory 212, and the segment decoder 220.

[0062] The sub image is generated using segment characters. FIGS. 3A through 3C are diagrams for explaining such a segment character. A segment character 800 is displayed in the form of an on/off combination of multiple segments 802. FIG. 3A shows a 16-segment character. Identifiers A through P are respectively assigned to the sixteen segments 802 for convenience. FIG. 3B shows an example of a code for representing such a 16-segment character. Such a 16-segment character can be represented by 16-bit data, i.e., 2-byte data. Accordingly, a register (214 in FIG. 2) having a data capacity of 2 bytes may preferably be provided for each character, which allows a letter or a symbol to be uniquely specified.

[0063] FIG. 3C shows examples of characters represented by such a 16-segment character. Specifically, FIG. 3C shows character examples including upper-case letters of the alphabet, Arabic numerals, and other symbols such as “+”, “−”, “#”, and “*”. In addition, such an arrangement is capable of representing other characters, examples of which include lower-case letters of the alphabet, Greek numerals, other symbols, Japanese hiragana characters, Japanese katakana characters, Chinese characters, and other characters for other languages.

[0064] Returning to FIG. 2, the sub input interface 210 is coupled to the graphic controller 110 via a second line 114 that is independent of the first line 112. As such a sub input interface 210, a register access-type interface such as an SPI (Serial Peripheral Interface), an I.sup.2C interface, or the like, may be employed.

[0065] The graphic controller 110 generates the sub data S3 that indicates a segment character to be displayed on the display, instead of or otherwise in addition to the input image data S1. The sub input interface 210 receives the sub data S3 via the second line 114. It should be noted that the independence between the first line 112 and the second line 114 allows the sub input interface 210 to receive the sub data S3 from the graphic controller 110 even in a state in which a malfunction has occurred in the first line 112 or even before a link is established between the main input interface 202 and the graphic controller 110 when the system is started up.

[0066] FIG. 4A is a diagram showing an example of a sub image 900. The sub image 900 displayed on the display panel 102 may include multiple segment characters 800. For simplicity of description and ease of understanding, description will be made assuming that the sub image 900 has fixed regions R1 through RN each of which is capable of displaying a segment character 800. Accordingly, the sub data S3 has no information that specifies the positions of the regions R1 through RN. The sub data S3 specifies the character to be displayed for each region R.

[0067] Description will be made in the present embodiment regarding an arrangement in which the sub data S3 includes multiple bits (16 bits=2 bytes in this example) for each character, which respectively indicate the on/off states of the multiple segments 802 (A through P) assigned for each character. Such an arrangement allows the user of the timing controller 200 to freely display a desired character.

[0068] FIG. 4B is a diagram showing an example of an address map held by the register 214. For example, the register of the sub input interface 210 has a 2-byte address area assigned for each region R. For example, the address areas 0 to 1 correspond to the region R1, and the address areas 2 to 3 correspond to the region R2. The graphic controller 110 writes a value that indicates a character to be displayed, i.e., the sub data S3, to the address that corresponds to each region R.

[0069] The memory 212 stores multiple segment data S4.sub.A through S4p that each indicate the on/off states of the pixels on the image frame with respect to the corresponding one of the multiple segments (A through P in FIG. 3A). The memory 212 may be configured as nonvolatile memory such as ROM (Read Only Memory) or the like. For example, the segment data S4.sub.A represents the on/off state of the segment A, and the segment data S4B represents the on/off state of the segment B. Detailed description will be made later regarding the segment data S4.

[0070] The segment decoder 220 generates a raster image of the segment character 800 to be displayed (conversion into a bitmap format) based on the sub data S3 and the multiple segment data S4. The segment decoder 220 outputs output data S5 in the form of image data (sub image data) of the segment character 800 specified by the sub data S3.

[0071] The image processing circuit 204 receives, as input data, the input image data S1 and the sub image data S5 generated by the segment decoder 220. The image processing circuit 204 generates the output image data S2 to be displayed on the display panel, based on the input image data S1 and the sub image data S5.

[0072] Various kinds of operations and configurations are conceivable for the image processing circuit 204.

[0073] For example, (i) the image processing circuit 204 may select one from among the input image data S1 and the sub image data S5 so as to generate the output image data S2. FIG. 5A is a block diagram showing an example configuration of the image processing circuit 204. The image processing circuit 204 may include a multiplexer 205 configured as an input stage to receive the input image data S1 and the sub image data S5, and to select one from among them according to a control signal SEL1. A processor 206 configured as a downstream stage performs predetermined signal processing on the image data selected by the multiplexer 205. Before a link is established between the main input interface 202 and the graphic controller 110, the image processing circuit 204 may select the sub image data S5. Also, when a malfunction has occurred in the interface that couples the main input interface 202 and the graphic controller 110, the image processing circuit 204 may select the sub image data S5. When the input image data S1 is input normally, the image processing circuit 204 selects the input image data S1. Alternatively, the image processing circuit 204 may select one from among the input image data S1 and the sub image data S5 according to the control data received from the graphic controller 110.

[0074] (ii) Also, the image processing circuit 204 may combine the input image data S1 and the sub image data S5 so as to generate the output image data S2. FIG. 5B is a block diagram showing an example configuration of the image processing circuit 204. The image processing circuit 204 may include an image combination circuit 207 that combines the input image data S1 and the sub image data S5. Examples of such image combination processing include alpha blending and the like. Also, the sub image data S5 is displayed on the regions R1 through RN on which the sub image 900 shown in FIG. 4A is to be displayed. In addition, the input image data S1 may be displayed in the other regions. The processor 206 performs predetermined signal processing on the image thus generated by the image combination circuit 207.

[0075] Also, the main input interface 202 may be configured to be switched between a mode in which the image data to be displayed is selected from among the input image data S1 and the sub image data S5 and a mode in which the input image data S1 and the sub image data S5 are combined. That is to say, both the functions shown in FIGS. 5A and 5B may be implemented.

[0076] The timing controller 200 according to the embodiment allows the display panel 102 to display information using desired segment characters specified in a real-time manner according to the sub data S3, instead of or in addition to a predetermined display pattern as shown in FIG. 1.

[0077] Furthermore, the timing controller 200 is configured to employ such segment characters. In a case in which bitmap information is held for each of multiple alphabetic and numeric characters, e.g., in a case in which each character is represented by (X×Y)-pixel data, such an arrangement requires (X×Y)-bit bitmap data for each character, which requires a very large memory capacity. In contrast, the present embodiment requires the timing controller to have only a small memory capacity.

[0078] The present invention encompasses various kinds of apparatuses and circuits that can be regarded as a block configuration or a circuit configuration shown in FIG. 2, or otherwise that can be derived from the aforementioned description. That is to say, the present invention is not restricted to a specific circuit configuration. More specific description will be made below regarding an example configuration for clarification and ease of understanding of the essence of the present invention and the circuit operation. That is to say, the following description will by no means be intended to restrict the technical scope of the present invention.

[0079] FIG. 6 is a block diagram showing an example configuration of the segment decoder 220. The segment decoder 220 includes a font color generating unit 222, a background color generating unit 224, a multiplexer 226, and a timing generator 228. The font color generating unit 222 generates a first luminance value L1 that indicates the color (font color) of the segment character 800. The background color generating unit 224 generates a second luminance value L2 that indicates the background color. The multiplexer 226 receives the first luminance value L1 and the second luminance value L2. The multiplexer 226 selects one from among the first luminance value L1 and the second luminance value L2 thus received, according to a selection signal SEL2. The timing generator 228 controls the multiplexer 226 based on the sub data S3 and the segment data S4. For example, the timing generator 228 converts a sub image represented by the sub data S3 into a raster image, in synchronization with a pixel clock CLK.sub.PIX. Such an arrangement requires only a simple configuration to convert such a segment character into a raster image. It should be noted that the configuration of the segment decoder 220 is not restricted to such an arrangement.

[0080] FIGS. 7A and 7B are operation waveform diagrams each showing the operation of the segment decoder 220 shown in FIG. 6. FIG. 7A shows the pixels PIX that form three lines (L.sub.i, L.sub.i+1, L.sub.i+2) to be displayed on the display panel 102. Each pixel included in a segment that is to be turned on is shown in black. The timing controller 200 generates RGB data from left-hand pixels to right-hand pixels in every line, from upper lines to lower lines, in synchronization with the pixel clock CLK.sub.PIX. As shown in FIG. 7B, the timing generator 228 generates the selection signal SEL2 in synchronization with the pixel clock CLK.sub.PIX, so as to generate the sub image based on the sub data S3.

[0081] Next, description will be made regarding the segment data S4. With the height of the segment character 800 as Y pixels, and with the width thereof as X pixels, each character is represented by an image including (X×Y) pixels. Accordingly, each segment data S4 can be represented by (X×Y)-bit data (in a case in which data compression as described later is not performed). However, the memory capacity required to store the segment data S4 increases according to an increase in the number of pixels that represent each character. As an example, in a case in which Y=521 and X=380, such an arrangement requires a ROM capacity of (521×380) bits for each segment data. That is to say, such an arrangement requires a ROM capacity of (16×521×380) bits to store all the segment characters A through P.

[0082] In order to solve such a problem, the segment character 800 shown in FIG. 3A is designed to have multiple segments that can be classified into groups, each of which is associated with a common shape. For example, the segments A, B, P, L, E, and F classified into a first group have a common shape and a position relation in which each segment can be obtained by shifting any one of the other segments in the same group. The segments H, J, C, G, N, and D classified into a second group have another common shape. The segments I and M classified into a third group have a yet another common shape. The segments O and K classified into a fourth group have a yet another common shape.

[0083] In order to represent a segment classified into a group including two or more segments having the same shape, the segment data S4 may comprise shape data S7 that represents the shape of the segment and shift data S6 that represents the shift data. Such an arrangement allows the segment data amount to be dramatically compressed, thereby allowing the circuit area of the timing controller to be reduced.

[0084] FIGS. 8A through 8C are diagrams for explaining the segment data compression. Description will be made below directing attention to the first group. FIG. 8A shows an example of a segment character 800 having a font size of 521 (height Y=512 pixels and width X=380 pixels). FIG. 8B shows a common member 804 of the segments A, B, P, L, E, and F, having the same shape, and classified into the first group. The common member 804 has a height of y pixels (y<Y) and a width of x pixels (x<X), which can be represented by (x×y)-bit data. For example, in a case in which x=130 pixels and y=45 pixels, the shape data S7 is configured as (130×45)-bit data.

[0085] Each of the segments A, B, P, L, F, and E can be represented by the common shape data S7 shifted by Δx in the horizontal direction and by Δy in the vertical direction from a given reference position (x.sub.0, y.sub.0). FIG. 8C shows the shift for the segment P. The segment P can be shifted by up to X=380 pixels in the horizontal direction, and can be shifted by up to Y=521 pixels in the vertical direction. Thus, the data S6 that represents the shift amount for each segment is configured as (X+Y)-bit data at most.

[0086] That is to say, the segment data amount with respect to the first group including the segments A, B, P, L, F, and E is represented by the sum of: (i) the data amount of the common shape data S7 (x×y bits) of the multiple segments; and (ii) the data amount represented by multiplying the number of segments (six) by the shift data S6 (X+Y) for each segment. That is so say, in a case of employing such segment data compression, the data amount Z required to represent the segment data that belongs to the first group is represented by Z=x×y+6×(X+Y) bits.

[0087] In contrast, in a case in which such segment data compression is not employed, the data amount Z′ required to represent the segment data that belongs to the first group is represented by Z=(X×Y)×6.

[0088] In a case in which X=380, Y=521, x=130, and y=45, when the segment data compression is employed, such an arrangement requires the data amount Z of 11,256 bits. In contrast, when such segment data compression is not employed, such an arrangement requires the data amount Z′ of 1,187,880 bits. That is to say, such segment data compression allows the segment data amount to be compressed to 1% or less.

[0089] The segment data compression is also applicable to the second group through the fourth group in the same way as the first data. It should be noted that the data format of the segment data is not restricted to such an arrangement described above.

[0090] Lastly, description will be made regarding the usage of the timing controller 200. FIGS. 9A and 9B are diagrams each showing an in-vehicle display apparatus 600 employing the timing controller 200. The in-vehicle display apparatus 600 is embedded in a console 602 in front of a cockpit. The in-vehicle display apparatus 600 receives the input image data S1 to be displayed from a vehicle-side processor, and displays a speedometer 604, a tachometer 606 that indicates the rotational speed of an engine, and a remaining fuel meter 608, based on the input image data S1. In a case in which the vehicle is configured as a hybrid vehicle or an electric vehicle, the input image data S1 further includes the remaining battery charge data, and the timing controller 200 further displays a remaining battery charge gauge based the image data S1 (FIG. 9A).

[0091] When a situation has occurred in which the input image data S1 cannot be displayed via the in-vehicle display apparatus 600, a blackout state occurs in the display panel 102, leading to difficulty in driving the vehicle. In a case in which the timing controller 200 is mounted on the in-vehicle display apparatus 600, in a situation in which the input image data S1 cannot be displayed, such an arrangement generates the sub data S3 that represents substitution information (for displaying a vehicle speed display 610, an engine rotational speed display 612, a remaining fuel display, a remaining battery charge display, etc.). By inputting the sub data S3 thus generated to the in-vehicle display apparatus 600, such an arrangement allows useful information to be displayed in a real-time manner using the segment characters. This provides improved safety.

[0092] Also, when the in-vehicle display apparatus 600 is started up after the user switches on the ignition, such an arrangement allows a given character string such as “PLEASE WAIT . . . ”, a character string that represents the current time, or the like, to be displayed in the form of the sub image data S5 before the input image data S1 can be displayed.

[0093] Also, the timing controller 200 may be employed in a medical display apparatus. The medical display apparatus displays necessary information for medical doctors and nurses in a medical examination, medical treatment, or surgery. The timing controller 200 allows such a medical display apparatus to display important information (e.g., the heart rate, blood pressure, and the like, of the subject) in the form of the sub image data S5 even in a situation in which the input image data S1 cannot be displayed.

[0094] FIG. 10 is a perspective view showing an electronic device 500. The electronic device 500 shown in FIG. 10 may be configured as a laptop PC, a tablet terminal, a smartphone, a portable game machine, an audio player, or the like. The electronic device 500 includes a graphic controller 110, a display panel 102, a gate driver 104, and a source driver 106, each of which is built into a housing 502. A transmission apparatus 120 may be arranged between the timing controller 200 and the graphic controller 110, and may include a differential transmitter, a propagation path, and a differential receiver.

[0095] Description has been made above regarding the present invention with reference to the embodiment. The above-described embodiment has been described for exemplary purposes only, and is by no means intended to be interpreted restrictively. Rather, it can be readily conceived by those skilled in this art that various modifications may be made by making various combinations of the aforementioned components or processes, which are also encompassed in the technical scope of the present invention. Description will be made below regarding such modifications.

[First Modification]

[0096] The data format of the sub data S3 is not restricted to such an arrangement described in the embodiment. FIG. 11 is a block diagram showing a part of a configuration of a timing controller 200a according to a first modification. In this modification, the sub data S3′ received from the graphic controller 110 includes a character code that specifies a segment character. The character code thus employed may be configured as an ASCII (American Standard Code for Information Interchange) code. The segment decoder 220 of the timing controller 200a further includes a character decoder 230 that converts a given character code into multiple bits that indicate the on/off states of the multiple segments.

[0097] With such a modification, the characters and symbols that can be employed are restricted to standard numerals and alphabetic characters. However, such a modification allows the user to specify a desired character code to be displayed without concern for the segment shape and the like.

[Second Modification]

[0098] FIG. 12 is a block diagram showing a part of a configuration of a timing controller 200b according to a second modification. The timing controller 200b further includes an image generating unit 232 that generates local sub data Sib. The image generating unit 232 writes the sub data Sib to the register 214. The sub data to be written to the register 214 is selected from among the external sub data Sia input to the sub input interface 210 from an external circuit and the local sub data Sib generated by an internal component of the timing controller 200b. The sub data thus selected is written to the register 214. The segment decoder 220b converts a given segment character into a raster image based on the sub data written to the register 214. This allows debug information and error information with respect to the timing controller 200b itself to be displayed.

[Third Modification]

[0099] The configuration of the sub input interface 210 is not restricted to such a register access-type configuration. For example, the sub input interface 210 may be configured to employ differential serial transmission as with the first line 112. Also, the sub input interface 210 may be designed as a desired interface.

[Fourth Modification]

[0100] Description has been made in the embodiment regarding an arrangement in which the multiple segment characters 800 that form the sub image 900 each have a fixed font size and position. However, the present invention is not restricted to such an arrangement. For example, each segment character 800 may have a font size that can be selected from among multiple font sizes. In this case, the segment data S4 may preferably be prepared for each font size, and the sub data S3 may preferably include additional data for specifying the font size.

[0101] Also, an arrangement may be made which is capable of specifying the drawing position for each of the multiple segment characters 800. That is to say, an arrangement may be made which is capable of changing the coordinate position for each of the multiple regions R1 through RN. In this case, the sub data S3 may include data that indicates the character interval. Description has been made with reference to FIG. 4A regarding an arrangement in which the sub image 900 is configured as a single line. Also, the sub image 900 may be configured as multiple-line text.

[0102] In addition, the sub data S3 may include a parameter that indicates the alignment in the height direction for each of the multiple segment characters 800 to be drawn on a single line, examples of which include the bottom alignment, top alignment, center alignment, and the like.

[0103] Also, the sub data S3 may further include third data that indicates the transparency of the segment character.

[Fifth Modification]

[0104] In a case in which the sub image is displayed as a superimposed image on a main image configured as a background, a pixel sequence that corresponds to the main image may be input as the second luminance value L2 shown in FIG. 6.

[Sixth Modification]

[0105] Description has been made in the embodiment regarding an arrangement employing such 16-segment characters. However, the present invention is not restricted to such an arrangement. Also, 14-segment characters may be employed (the segments A and B shown in FIG. 3A are configured as a single segment, and the segments E and F are configured as a single segment). Also, 7-segment characters may be employed (each comprising segments A, H, J, P, G, N, F shown in FIG. 3A).

[Seventh Modification]

[0106] FIGS. 13A and 13B are diagrams each showing a segment character according to a seventh modification. Such a segment character 800a is configured as a dot-matrix character formed of multiple dots 806. FIG. 13 shows a (4×7)-dot matrix. However, the number of dots in each of the vertical direction and horizontal direction is not restricted in particular. It can be assumed that the multiple dots 806 are equivalent to the multiple segments 802. It should be noted that each dot 806 is not equivalent to a single pixel of the display panel 102. Rather, each dot 806 includes multiple pixels. The shape of each dot 806 is not restricted to such a rectangular shape. Also, each dot 806 may have other shapes such as a circular shape, a rhombic shape, an octagonal shape, or the like.

[0107] The memory 212 stores multiple segment data each of which specifies the on/off states of the pixels on an image frame for each of the multiple dots 806. With such a dot-matrix character, the multiple dots 806 may be configured to have the same shape. Such an arrangement allows the segment data to be compressed using the method described with reference to FIGS. 8A through 8C.

[0108] Each (4×7)-dot matrix character can be represented by 28-bit data. Accordingly, by preparing a 4-byte (32-bit) register (214 in FIG. 2) for each character, such an arrangement is capable of uniquely specifying a given character or symbol to be displayed.

[Eighth Modification]

[0109] FIGS. 14A and 14B are diagrams each showing a segment character according to an eighth modification. FIG. 14A shows “A” as an upper-case letter of the alphabet. FIG. 14B shows “C” as an upper-case letter of the alphabet. In this modification, each segment character is configured as a combination of multiple types of segments (four types in this example, i.e., segment types A through D). The shape of each segment is not restricted to such a rectangular shape.

[0110] In this modification, the aforementioned multiple segment data S4 correspond to the multiple types of segments. Each segment data S4 specifies the shape of the corresponding segment type (which is represented by the on/off states of the pixels on the image frame, for example).

[0111] In this modification, the data for representing each segment character includes: (i) type data that specifies the segment type for each of the multiple segments to be used; and (ii) position data that specifies the position of each of the multiple segments to be used.

[0112] Description will be made with description data that represents a given character “#” as S30[#]. FIG. 15A is a diagram showing description data S30[A] that represents the segment character “A” shown in FIG. 14A. FIG. 15B is a diagram showing description data S30[C] that represents the segment character “C” shown in FIG. 14B.

[0113] The segment character 300 shown in FIG. 14A is formed of eight segments 301 through 308. Accordingly, the description data S30[A] thereof includes type data S31 that specifies the respective types of the eight segments 301 through 308 and position data S32 that specifies the respective positions of the eight segments 301 through 308. The position may be represented by the coordinate position of the upper-left corner of each segment or otherwise any one of the other corners.

[0114] A segment character 400 shown in FIG. 15A is formed of eight segments 401 through 408. Accordingly, the description data S30[C] thereof includes the type data S31 that specifies the respective types of the eight segments 401 through 408 and the position data S32 that specifies the respective positions of the eight segments 401 through 408.

[0115] The description data S30 may preferably be defined for each character to be used. For example, the upper-case letters of the alphabet “A” through “Z” may be represented by defining 26 sets of description data S30[A] through S30[Z]. Also, the lower-case letters of the alphabet “a” through “z” may be represented by defining 26 sets of description data S30[a] through S30[z]. Also, the numerals “0” through “9” may be represented by defining ten sets of description data S30[0] through S30[9]. In addition, Greek letters, Japanese hiragana characters, Japanese katakana characters, and Chinese characters, may be defined.

[0116] FIG. 16 is a diagram showing a part of a timing controller 200c according to an eighth modification. The memory 212 stores the type data S30 defined for each segment character in addition to the segment data S4 defined for each segment type. The segment decoder 220 receives the sub data S3 that specifies the segment character to be displayed, and reads out the description data S30 that corresponds to the segment character to be displayed.

[0117] For example, when the sub data S3 indicates an instruction to display the letter of the alphabet “A”, such an arrangement assigns a segment of the type A to the coordinate position (x1, y1) as the segment 301 based on the type data S30[A] shown in FIG. 15A. In the same way, such an arrangement assigns a segment of the type A to the coordinate position (x2, y2) as the segment 302. Such an arrangement allows desired characters and symbols to be displayed.

[0118] While the preferred embodiments of the present invention have been described using specific terms, such description is for illustrative purposes only, and it is to be understood that changes and variations may be made without departing from the spirit or scope of the appended claims.