JPH08123384A - Display device - Google Patents

Abstract

(57) [Abstract] [Purpose] To obtain a display device capable of displaying as many colors as possible by effectively utilizing the data in the video RAM. [Structure] The video RAM 1 stores a display screen. The color conversion memories 21 and 22 determine the display color based on the content of the video data output from the video RAM 1. The switching means 3 receives the signal for selecting the color conversion memory, selects which of the color conversion memories 21 and 22 to use, and outputs the selected signal to the CRT monitor via the D / A converter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device capable of color display.

[0002]

2. Description of the Related Art The number of display colors of a raster scan type display device is determined by how many gradations each of the three primary colors (RGB) can be expressed. For example, when each gradation of RGB can be expressed in 16 gradations, 16 ³ = 4096 colors can be displayed. Also, the number of simultaneous display colors in one screen is determined by the number of planes of the video RAM that stores information on the display screen. In other words, the number of simultaneous display colors is determined by the number of bits of data per dot. For example, if the number of planes (the number of bits) is 8 (8 bits), 2 ⁸ = 256 kinds of color expressions can be independently performed for each dot. At this time, the number of simultaneous display colors of the display device is 256. is there.

In a display device of such a system, when performing a blinking operation for periodically turning on / off the display,
A method of rewriting the display data to be blinked in accordance with the ON / OFF cycle, and one of the planes for determining the display color is used as the blinking plane.
For the display to be blinked, there is a method of setting a flag on the blinking plane and storing it. Display devices for plant monitoring and the like often use blinking operations for displaying alarms, etc., so it is common to employ the latter method that allows blinking operations instantly without interfering with other display processing by blinking. .

FIG. 9 is a circuit diagram of a conventional display device.
The video RAM 1 stores screen data for each dot, and has a display cycle (general non-interlaced C
At RT, 60 times per second), the screen data of all the pixels are read as video data and displayed. Video data is 3 bits per dot, a0 to a2
Data, of which a2 is allocated for blinking.

The color conversion memory 2 for determining the display color uses the video data a0 to a1 output from the video RAM as an address and determines what kind of color is actually displayed by the color data b-R,
Output as b-G and b-B.

Since the video data a2 is used as a flag indicating the display for blinking, the blink signal e0
And pass the NAND element 61 to generate the color data gate signal g.

The color data gate signal g is used as a signal for determining whether or not the color data b is valid. That is, the color data b and the color data gate signal g are input to the AND element 7, and the display color data c-R, c-G, c-B are generated.

The display color data c-R, c-G, c-B are
The signals are input to the D / A converter 4, and the RGB signals d-R, d-G,
It is converted into d-B and the actual display is performed on the CRT monitor 5 which is a color display.

When blinking is performed, the blink signal e0
Repeats ON / OFF according to the blink cycle. The blink cycle is usually synchronized with the display cycle. For example, the display cycle is set to 60 times and is set to correspond to one blink cycle. Here, the blink signal e0 is ON when the blink color is displayed, and is OFF when the normal color is displayed.
Is.

If the video data a2 is 0, a blink signal
Since the color data gate signal g is always 1 regardless of whether e0 is ON or OFF, the display color is determined by the value of the color data b. When a2 of video data is 1, the blink signal e0 is O
In the case of FF, since the color data gate signal g is 1, the display color is determined by the value of the color data b, but the blink signal e0
Since the color data gate signal g becomes 0 when is ON,
The values of the display color data c are all 0, and colorless display is performed.

Therefore, the video data a2 in which 1 is not displayed is displayed in the normal display color, but the video data a2
In the case where 1 is set, the flicker occurs between the normal display color and the colorless color once per second. This realizes the blink operation.

[0012]

When there are 3 bits of video data, 2 ³ = 8 simultaneous display colors are possible, but since the blinking is performed as described above, the simultaneous display colors are changed to 4 colors. Has been reduced to. In the conventional display device, even if only one color needs to be blinked,
Since one plane of the video RAM is used for blinking, the simultaneous display color has been reduced to 1/2.

Further, the simultaneous display color of the conventional display device is determined by the number of planes of the video RAM, and even a display color which is not used on one screen is counted as a simultaneous display color when it is used on another screen. It was necessary, and the number of display colors on one screen had decreased.

Further, the simultaneous display color in one screen of the conventional display device is determined by the number of planes of the video RAM, and the only way to increase the number of display colors is to increase the number of planes of the video RAM.

Further, the blink system of the conventional display device is as follows:
The color during blinking only erases the display, and when reading the content that is blinking, it was difficult to read because there was a time when the display was off.

The object of the present invention is to perform blinking,
To effectively utilize the data in the video RAM to obtain a display device capable of displaying as many colors as possible. Also,
Another object of the present invention is to obtain a display device in which the number of simultaneous display colors is not limited as much as possible even if different screens have different display colors.

Another object of the present invention is a video RAM.
It is to obtain a display device capable of displaying more colors in one screen without increasing the number of planes. Another object of the present invention is to obtain a display device in which blinking display contents are easy to read.

[0018]

In order to achieve the above object, in the present invention, a video RA storing a display screen is provided.
M, a plurality of color conversion memories for determining a display color based on the contents of the video RAM, and a switching means for receiving a signal for selecting the color conversion memories and selecting which of the color conversion memories is to be used. A display device characterized by having.

[0019]

In the apparatus constructed as described above, since a plurality of color conversion memories are switched by the switching means, many colors can be displayed.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a circuit diagram of the first embodiment. Video RAM1 for storing screen data, and video RAM1
A plurality of color conversion memories 21 and 22 for determining the display color depending on the content of the video data a output from the device and which of the color data b1 and b2 output from the color conversion memory is referred to is selected. Switching means 3 for switching. A multiplexer is suitable as the switching means 3. The switching means 3 selects the color data c by the switching signal e. D
The A / A converter 4 converts the selected display color data c into RGB.
Convert to signal d. C which is an indicator by the RGB signal d
The display on the RT monitor 5 is performed.

A CRT monitor is used as a display device for the purpose of explanation, and a D / A converter is not required and a display device (for example, a liquid crystal display) which directly displays color data has the same structure. realizable.

When this embodiment is used for blink display,
It works as follows. The table of the color conversion memory 21 stores the normal display color, and the table of the color conversion memory 22 stores the display color at the time of blinking. A blink signal synchronized with the display cycle is used as the switching signal e, and the switch 3 determines which color conversion memory is referred to. Therefore, the normal display color is displayed when the color conversion memory 21 is referenced, and the blink color is displayed when the table of the color conversion memory 22 is referenced.

The color conversion memories 21 and 22 are set such that the normal display color is set in the color conversion memory 21 only for the color number to be blinked and the colorless display color is set in the color conversion memory 22, and the color numbers not to be blinked are set. The same color may be set in the color conversion memories 21 and 22.

In this embodiment, when blinking is performed for a certain color, it is necessary to have color numbers in which different display colors are set for 21 and 22. Further, since it is necessary to set the color numbers of the same colors that do not require blinking, two color numbers are required to perform one-color blinking.

Therefore, the number of simultaneously displayed colors decreases by one each time one blink is set, but it does not become 1/2. For the color to be blinked, the normal display color is set in the color conversion memory 21, the color other than the normal display color and not colorless is set in the color conversion memory 22, and the color not to be blinked is the same in both the color conversion memories 21 and 22. When is set, the blink display flickers between the normal display color set in the color conversion memory 21 and the non-colorless color set in the color conversion memory 22, so that the display content is not erased and is easy to see.

Next, the operation of switching and using the color conversion memories for each screen will be described. The switching means 3 determines which color conversion memory to refer to depending on the screen to be displayed. Since the display color can be set independently for each screen,
It is possible to display the number of simultaneous display colors determined by the number of planes of the video RAM for each screen.

The operation of switching and using the color conversion memories depending on the position within one screen will be described. The color conversion memory to be referred to is determined according to the position on the screen in one display cycle.

Therefore, the simultaneous display colors in one screen can be displayed simultaneously (apparent color (simultaneous display color) × (number of color conversion memories)). FIG. 2 is a circuit diagram of the second embodiment.

The video RAM 1 stores screen data. This data is periodically read and output as video data. The video data is composed of data of a0 to a2 with 3 bits per dot.

Color conversion memories 21 and 22 are used as color conversion memories for determining display colors. Color conversion memory 2
Rs. 1 and 22 indicate what color is actually displayed using the video data output from the video RAM 1 as an address.
Output as color data (c-R, c-G, c-B) for each GB.

The D / A converter 4 uses the color data (c-R, c-
G, c-B) are converted into RGB signals (d-R, d-G, d-B) and output to the CRT monitor 5. The blink signal e0 is a signal that repeats 1/0 periodically, is used as an enable signal for the color conversion memory 21, and is also a NOT element.
The inverted blink signal e0 ′ is used as an enable signal of the color conversion memory 22 via 62.

When the blink signal e0 is 0, the color conversion memory 21
Outputs the color data, and when the blink signal e0 is 1, the color conversion memory 22 outputs the color data, so that the enable signal of the memory fulfills the function of the switching means.

Color conversion memory for color information when not blinking
The color information at the time of blinking is stored in the color conversion memory 22. The same color information is stored in the color conversion memories 21 and 22 for the color numbers for which blinking is not performed.

An example of setting data in the color conversion memory is shown in FIG. For example, if it is desired to perform blinking only for green, a color number different from the color number 3 of green, here, color number 7, is set to blink. Color conversion memory
The color number 7 of the table 21 is set to green, and the color number 7 of the table of the color conversion memory 22 is set to black.

The setting of the color conversion tables 21 and 22 is the same when the first embodiment is used for blink display. Color numbers 0 to 6 regardless of whether the blink signal e0 is 0 or 1.
Although the color of is always the same color, the color of color number 7 displays green when the blink signal e0 is 0, and black when it is 1; therefore, blinking the blinking signal ON / OFF in the blinking cycle causes the blinking display. Can be done.

At this time, the colors that can be displayed simultaneously are black, white, red,
7 colors can be displayed in green, blue, yellow and cyan. In this way, when blinking is designated for a certain color, the number of colors that can be expressed is reduced by the number of colors for which blinking is designated, so that the number of simultaneous display colors is reduced to half as in the conventional case, and it is not four colors. However, when blinking is performed for all display colors, the number of simultaneous display colors is four.

With the configuration of this embodiment, if the color conversion tables 21 and 22 are set as shown in FIG. 4, a blink display that is easier to see can be realized. Here, each color data is composed of 2 bits, and an intermediate color display of 4 gradations is possible.
The color data (c-R, c-G, c-B) in FIG. 2 also needs to be configured with 2 bits. With this configuration, the display colors can be expressed in 4 gradations for each of RGB, so that 4 ³ = 64 colors can be expressed, but the number of colors that can be displayed simultaneously is the number of bits of data output from the bidet RAM. Because it is decided 2
³ = 8 colors.

In this example, the color number 7 is used for blinking green, and the blinking color is set to dark green with the intensity of green being 0.33. When the one drawn with color number 7 is displayed, flicker is performed between green and light green for each blink cycle.

As described above, when blinking, the green display does not disappear as in the conventional case, so that the display contents are easy to see. FIG. 5 is a circuit diagram of the third embodiment.

This embodiment has four color conversion memories 21 to 24. Then, the selection signal e1 is a high-speed blink signal,
The selection signal e2 is used as a low speed blink signal, and the selector 6 outputs the memory enable signals f1 to f4 based on these signals, which color conversion memory is to be validated.

FIG. 6 shows the logic of the selector. The high speed blink signal e1 changes from 0, 1, 0, 1 in order from the top. The low speed blink signal e2 is 0, 0, 1, in order from the top.
It changes with 1. That is, the high-speed blink signal e1 is
It changes at twice the cycle of the low speed blink signal e2. e1 and
When the logic of f1 to f4 is set as shown in FIG. 6 in combination with e2, the memory enable signals are set to 0 in the order of f1 to f4 from the top.

FIG. 7 shows a setting example of the color conversion memories 21 to 24 for high speed blinking and low speed blinking. Since the memory enable signals f1 to f4 sequentially change to 0, the color conversion memory
It becomes effective in order from 21 to 24. Therefore, the color number 6 is
It changes in the order green, green, black, black, and color number 7 is green, black,
It changes in the order of green and black. In this way, the one drawn with color number 6 blinks slowly between green and black,
Those drawn with color number 7 blink rapidly between green and black. By such a method, two types of blinks, high speed blinks / low speed blinks, can be realized.

Since it is necessary to use two color numbers in order to set two kinds of blinks of high speed / low speed for a certain color, the simultaneous display colors are reduced by two colors. Further, in the configuration of this embodiment, when the screen numbers are used as the selection signals e1 and e2, different color conversion memories are referred to by the screen numbers.

Since the color conversion memory to be referred to is switched by the selection signals e1 and e2 when the screen is switched, the display color can be determined for each screen. As a result, only the colors required for the screen to be displayed need be registered in the color conversion memory, so the number of simultaneous display colors does not decrease due to the colors used only on another screen, and the video RAM of each screen is not reduced. The number of planes can be displayed simultaneously.

That is, it is possible to realize a display device in which the number of simultaneous display colors is not limited by the display colors of different screens. Further, in the configuration of this embodiment, the selection signal e
As 1 and e2, it is possible to change which color conversion memory is referred to depending on the position of the screen in the display cycle of one screen.

FIG. 8 is a schematic diagram of a screen setting example showing which color conversion memory is to be referred to depending on the position of the screen in the display cycle. The double line G represents the entire screen,
In the G0 area (background area), (e2, e1) = (0, 0)
Next, refer to the table 21 of the color conversion memory. Similarly G1
In the area (area at the bottom of the screen), (e2, e1) = (0, 1)
In the color conversion memory table 22, in the G2 area (area in the window) (e2, e1) = (1, 0), the color conversion memory table 23 is displayed in the G3 area (area in the window) ( Since e2, e1) = (1, 1), the table 24 of the color conversion memory is referred to.

Thus, the display color can be set independently for each of the background, the lower part of the screen, and the window area. For example,
The inside of the window can be displayed in color and the background can be displayed in black and white gradation. When performing gradation display, it is necessary that the color data be composed of 2 bits or more.

For each area of the screen, the number of simultaneous display colors corresponding to the number of planes of the video RAM can be obtained, and the number of apparent simultaneous display colors can be increased. That is, it is possible to realize a display device capable of displaying more colors in one screen without increasing the number of planes of the video RAM.

[0049]

According to the present invention, since a plurality of color conversion memories are switched by the switching means, many colors can be displayed while suppressing the number of planes of the video RAM.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a display device according to a first embodiment.

FIG. 2 is a circuit diagram of a display device according to a second embodiment.

FIG. 3 is a diagram showing a setting example of table contents of a color conversion memory according to a second embodiment.

FIG. 4 is a diagram showing another example of setting the table contents of the color conversion memory of the second embodiment.

FIG. 5 is a circuit diagram of a display device according to a third embodiment.

FIG. 6 is a diagram showing the logic of a selector of the third embodiment.

FIG. 7 is a diagram showing a setting example of table contents of a color conversion memory according to a third embodiment.

FIG. 8 is a schematic diagram of a screen setting example of the third embodiment.

FIG. 9 is a circuit diagram of a conventional display device.

[Explanation of symbols]

1 ... Video RAM, 2, 21, 22, 23, 24 ... Color conversion memory, 3 ... Switching means, 4 ... D / A
Converter, 5 ... CRT monitor, 6 ... Selector,
7 ... AND element, 61 ... NAND element, 62 ...
NOT element, a ... video data, b ... color data, c ... display color data, d ... RGB
Signal, e ... Switching signal, e0 ... Blink signal,
e0 '... Inverted blink signal, e1, e2 ... Selection signal, f1, f2, f3, f4 ... Memory enable signal, g ... Color data gate signal, G ... Whole screen, G0 ...
Background area, G1 ... Bottom area of the screen, G2, G3
... the area within the window.

Claims (8)

[Claims] 1. A video RAM for storing a display screen, a plurality of color conversion memories for determining a display color based on the contents of the video RAM, and which of the color conversion memories receives a signal for selecting the color conversion memory. And a switching means for selecting whether to use the display device. 2. The display device according to claim 1, wherein selection of the color conversion memory by the switching means is switched by a blink signal. 3. The display device according to claim 2, wherein the color data at the time of blink display of the plurality of color conversion memories is set to a color other than colorless. 4. The display device according to claim 1, wherein selection of the color conversion memory by the switching means is switched for each screen to be displayed. 5. The display device according to claim 1, wherein the selection of the color conversion memory by the switching means is switched for each portion within one screen. 6. The display device according to claim 1, wherein the switching unit is a multiplexer. 7. The switching means is a signal to be input to each color conversion memory as an enable signal, and among the signals,
2. The display device according to claim 1, wherein the display device is means for switching by enabling one signal. 8. A video RAM for storing a display screen as a color number for each dot; a first color conversion memory for inputting the color number, outputting a corresponding display color, and inputting a blink signal as an enable signal. And a second color conversion memory for inputting the color number, outputting a corresponding display color, and inputting the blink signal passed through the inverting means as an enable signal. The display device is characterized in that among the display colors corresponding to the color numbers stored in the color conversion memory, the color number set as the blink color is set differently among the color conversion memories.