JPS6310193A - Color display unit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a color display device, and more particularly to a color lookup table that holds a display color for each pixel of image data read out from a video memory.

[Conventional technology]

An example of the configuration of a conventional color display device of this type is shown in FIG.

The arithmetic processing unit 1 has an address bus 20. Data bus 21.
Video memory 3 can be accessed using control signal bus 22 . Further, the display timing control circuit 5
In order to display pixel data stored in the video memory 3, a display address signal 26 and a display access request signal 27 can be outputted to perform read access to the video memory 3. The video memory access control circuit 2 mediates access requests to the video memory 3 and generates access cycles with priority given to display access. At this time, the address for video memory 3 is
A multiplexer in the video memory access control circuit 2 connects the address bus 20 and the display address signal 26.
are selectively switched and supplied to the video memory 3 as the video memory address signal 25.
Video memory access signal 24 is output and video memory 3 is accessed.

In this way, the pixel data in the video memory 3 is sent to the data bus 21 via the data bus buffer 4t, and is supplied to the display circuit as an image data signal. The data bus buffer 4 is controlled by the video memory access control circuit 2 and connects the video memory 3 to the data bus 21 by activating the data bus buffer enable signal 29 in response to an access request from the data processing device 1. do.

Further, the video memory access control circuit 2 sends a wait request signal to the data processing device 1 in order to give priority to the display access when a conflict occurs between the two types of access.
3 and has the function of delaying access to the video memory 3 by the data processing device.

On the other hand, the color lookup table 7 is connected to each of the buses 20, 21, 22 from the data processing device 1 via the color lookup table control circuit 6, and can also be directly accessed by the data processing device 1. The color you want to display on the display device 7 or the color lookup table 7
If the color data is not in the color lookup table 7, the data processing device 1 must change the color data in the color lookup table 7.

To simplify the explanation, it is assumed that the video memory 3 stores 4-bit width data, and 1 byte (4 bits) corresponds to 1 pixel of the display device 9.

FIG. 3 shows the correspondence between the memory space in the video memory 3 and the screen of the display device 9. Pixel data from the first pixel to the m-th pixel are sequentially stored in each address of the video memory 3.)
, pixel data is sequentially read out by display access and displayed on the first pixel P1, second pixel P2, . . . , m-1 pixel Pm-1, m-th pixel Pm of the display device 9. The color lookup table 7 is made up of color registers each storing 16 color data, and the 4-bit pixel data DO to D3 read from the video memory 3 is
One of the six color registers is selected, and the color data stored in the selected color register is output as a color signal 31. In this way, each pixel P1
The color for the pixel data of Pm to Pm is determined, and the video signal synthesis output circuit 8 outputs the color signal 31 and the synchronization signal 3.
2 to form a video signal 33, and the display device 9 displays each pixel P1 to P on the basis of this video signal 33.
Display a color image on m.

[Problem that the invention seeks to solve]

In the above conventional color display device, the video memory 3
The color to be applied to the image data stored in the image data must be selected from the colors corresponding to the color data in the color registers that make up the color look-up table 7. Therefore, the colors that can be immediately selected are the colors that are added to the image data stored in the color register (see Figure 2). In this example, the number is limited to 16). Therefore, if it is desired to display a color other than the colors held in the color look 7, the data processing device IK needs to change the color data in the color lookup table 7.

Changes in color data such as the above greatly complicate the program executed by the data processing device 1, especially when color data that generates a large number of color registers is used repeatedly at a constant cycle (color link, etc.). requires periodic interrupts to change the color data,
In addition to complicating the program, it also requires interrupt processing.
There was a problem in that the burden on the software also increased significantly.

[Means, operations, and effects for solving the problems] In the color display device according to the present invention, the color display section displays a plurality of color lookup tables each storing different color data for the same pixel data. The main point is that the selection circuit selects one of a plurality of color data, and the pulse generation circuit selects one from the pulse generation circuit. This generates a pulse signal that can select a desired color code. This pulse signal is applied to a selection circuit to select one of the plurality of color data read from each color lookup table based on the pixel data. Then,
When trying to add different colors to an image based on the same pixel data, all you need to do is to cause the pulse generation circuit to generate a pulse signal corresponding to the desired color, and the color of the image can be changed simply by instructing the pulse generation circuit. can do. As a result, it is no longer necessary to rewrite the color data stored in the color lookup table every time one data processing device changes the color as in the conventional example, and the software is simplified and the cost is reduced. It is possible to reduce the burden on hardware associated with the shuffling process.

〔Example〕

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

The arithmetic processing unit 101 has an address bus 120. f-Tavas 121. Biomemory 103 using control signal path 122
can be accessed. Further, the display timing control circuit 105 is stored in the video memory 103. Pixel data can be read from the video memory 103 by outputting a display address signal 126 and a display access request signal 127 in order to display image data. The video memory access control circuit 102 arbitrates access requests to the video memory 103, gives priority to display access, and generates access cycles. At this time, the address for the video memory 103 is selectively switched between the address bus 120 and the display address signal 126 by a multiplexer in the video memory access control circuit 102, and the address is sent to the video memory 103 as the video memory address signal 125. At the same time, the video memory access signal 124 is output and the video memory 103 is accessed. Further, pixel data in the video memory 103 is sent to the data bus 121 via the data bus buffer 104, and is supplied to the display circuit as an image data signal.

The data bus buffer 104 is controlled by the video memory access control circuit 102 and the data processing device 1
When accessing from 01, the data bus buffer enable signal 129 is activated to connect the video memory 103 to the data bus 121.

Furthermore, if there is an access conflict between the display timing control circuit 105 and the data processing device 101, the video memory access control circuit 102 outputs a wait request signal 123 to the data processing device 101 in order to prioritize display access. It has a function of delaying access to the video memory 103 by the data processing device 101.

On the other hand, the first color lookup table 107 and the second color lookup table 110 are connected to the buses 120, 121, and 122 of the data processing device 101 via the color lookup table control circuit 106. Processor 101 can independently access multiple color registers within each color lookup table 107, 110.

The memory space of the video memory 103 and the correspondence between the pixel data stored in the video memory 103 and each pixel P1 to Pm of the display device 109 are the same as those of the conventional video memory 3 explained with reference to FIG. Description is omitted for brevity.

The oscillation circuit 111 generates a reference clock 138 by switching between two sets of color lookup tables 107 and 110, and this lock 138 is connected to the programmable frequency dividing circuit 112 as a pulse generation circuit. Supplied. Note that a plurality of oscillators may be used in the programmable frequency dividing circuit 1120s. The programmable frequency divider circuit 112 is connected to the data processing device 101 via the buses 120, 121, 122, and operates according to the conditions set by the data processing device 101.
At the same time, the duty ratio of the frequency-divided pulses is further controlled to generate the multiplexer control signal 1.
Generate 37.

In this embodiment, the first color lookup table 107 and the second color lookup table 110 have the same configuration, and each has 16 color registers. Each color lookup table 107, 11
Color data is stored in each of the 16 color registers 0 and 4-bit pixel data read from the video memory 103 selects any one of the color registers, and the color data of the selected color register is stored. The color data stored therein is output as color signals 131 and 135, and is supplied from the multiplexer 113 as a selection circuit to the video signal synthesis output circuit 108.

Prior to displaying the pixel data on the display device 109, the data processing device 101 previously displays the first . Color data is set in each of a plurality of color registers in the second color lookup table 107 and 110, but for pixel data whose color data needs to be changed periodically, The color data to be changed is stored in the first color lookup table 107.
and the color registers of the second color lookup table 110, respectively.

For example, pixel data r'0,0,0. For the color register corresponding to OJK, color data corresponding to "red" K is set in the first color lookup table 107, and color data corresponding to "evening" is set in the second color lookup table 110. put.

The same color data is set in the color registers corresponding to the pixel data that do not require any other color data changes, and in the color registers of the first and second color lookup tables 107 and 110. After setting such color data, when a display access occurs to the video memory 103 and the pixel data 128 is read from the video memory 103, the pixel data 128 is
Each color lookup table 107, 110 . Color signal 131 from
, 135 are output.

The color signals 131 and 135 are input to a multiplexer 113, and the multiplexer 113 selectively passes the color signals 131 and 135 according to a multiplexer control signal 137 generated by the programmable frequency divider circuit 112, and supplies them to the video signal synthesis circuit 108. For example, the image data 128 read from the video memory 103 is “0,0
, 0°O”, the force 2-signal 131 is “red”.
The color signal 135 represents color data corresponding to "Blue" and K, and the composite color signal 136 output from the multiplexer 113 represents color data corresponding to the divided pulses. Alternate K "red" and "blue"
This means that the color data can be displayed without real-time intervention of the data processing device 101.

On the other hand, the pixel data 128 is “0°0, 0
, OJ, color change does not occur because the same color data is stored in the color registers in both color lookup tables 107 and 110.

Note that in this example, there are 2 color lookup tables.
Although it has been explained as a set, it is also possible to have a force 2-lookup table of 3.4Il1 or more and to switch and display this in order.

In addition, in this embodiment, the two sets of color lookup tables have been described as having the same configuration, but the ones after the second lookup table have only the color register that needs to be changed, and output them. It is also possible to configure the circuit so that only the signal is input to a multiplexer, and the output of the output is directly output without passing through the multiplexer.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, FIG. 2 is a block diagram of a conventional example, and FIG. 3 is a block diagram showing the correspondence between a video memory and a screen of a display device. 103...Video memory, 107,110...
...Color lookup table, 108...
...Video signal synthesis output circuit, 109...Display device, 112...Pulse generation circuit, (programmable frequency dividing circuit), 113...Selection circuit (
multiplexer).

Claims (1)

[Claims] a display device that displays a plurality of pixels based on a video signal; a video memory that stores image information of the plurality of pixels as pixel data; and a display device that adds image information represented by each pixel data read from the video memory. In the color display device, the color specifying section includes a color specifying section that stores color data related to the same pixel data, and a video signal synthesis output circuit that forms a video signal based on the pixel data and the color data. In contrast, a plurality of color look-up tables each storing different color data, a pulse generation circuit that can generate one of a plurality of different pulse signals by selection, and a plurality of color look-up tables each storing different color data; A color display device comprising: a selection circuit that selects one of a plurality of color data output from a color lookup table and sends the selected color data to the video signal synthesis output circuit.