JPS58127987A - Crt display - 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 The present invention relates to a CRT display device having a scrolling function.

In recent years, computers have improved in performance and become cheaper, and even in the field of inexpensive personal computers, output devices using C
Many of them now have RT display devices. Generally, in this field, the display circuit is devised to reduce the display RAM capacity.
Character display types are often used to reduce costs. This is also called the code refresh type, and it is a method that stores the character-by-character address (character code) of the character generator ROM in the refresh memory for CRT display, and has the feature that it can reduce the refresh memory (display RAM) capacity. C to memory
Since it is necessary to memorize the character pattern itself to be displayed on the RT, the display RAM is required several times to several tens of times compared to the code refresh type, and the software that controls the graphics is significantly required. For this reason, the character display type is often used in CRT display devices, which generally require low cost.

In a CRT display device, there is a limit to the number of characters that can be displayed on the CRT screen, and when it is necessary to display outside the effective display area, a scrolling method is generally used. In other words, when displaying outside the effective display area, the desired display area is displayed by moving the display on the CRT up and down. When scrolling the screen, which is the basic function of
Becomes a character unit. Therefore, when you start scrolling, the characters move up line by line, resulting in the same state as if the characters on the entire screen had changed at once. Therefore, this is equivalent to flickering of the entire screen, and the irritation given to the eyes of the computer operator is unpleasant. In order to avoid such discomfort, the graphic display type is designed to scroll in units of one raster, giving the impression that the screen is slowly moving up.

The present invention improves the scrolling function, which is one of the basic functions of a CRT device, in an inexpensive character display type CRT device to a scroll similar to the scrolling of one raster unit in a graphic display type CRT device. The purpose of this invention is to provide a CRT device that is designed to minimize discomfort for users.

Hereinafter, embodiments will be described in detail with reference to the drawings.

FIG. 1 shows the screen state of scrolling in a conventional character display type CRT device. In Figure 1 (
1) is the screen before scrolling, and the character -”ABCD
EFGHI JKLMNO" is displayed as shown in the figure. Now, when one line of scrolling is completed, ABC disappears and PQR appears, and the screen changes as shown in Figure 1 (2), but from (1) to ( The change to 2) occurs instantaneously, and to the computer operator it feels like the screen has flashed, rather than the letters moving up.This can cause considerable fatigue for the operator in jobs that use a lot of scrolling. becomes.

Figure 2 shows scrolling according to the embodiment of the present invention. Figure 2 (1) shows the first screen before scrolling starts.
This is the same as in Figure (1). Figure 2 (2) shows the point where scrolling has started and all the characters have moved up one raster by one minute.Even in this case, unlike the graphic display type scroll, the characters ABC at the top row are not deformed; Figure 2 (2), where the characters move upwards by one minute per raster.
(3) shows the state. In this way, the characters move up one minute per raster, and when the movement for one line is completed, the characters in the next line are changed to "M" in Figure 2 (1).
When NOoo is inserted at the position where it was displayed, one line of scrolling is completed. FIG. 2 (4) shows this state. At this time, 'A B C' at the top row is deleted.

Despite being such an inexpensive character display type, it is possible to scroll characters in units of one raster, and the fatigue on the eyes is extremely reduced.

Next, one embodiment of the present invention will be described in detail with reference to FIG.

FIG. 3 is a circuit diagram showing only the main part of one embodiment. An n-bit shift register 1 consisting of a D type flip-flop receives a vertical synchronizing signal using the horizontal synchronizing signal as a clock. The vertical synchronizing signal 11 is delayed by the unit of the horizontal synchronizing signal 12 by the shift register l, and the delayed vertical synchronizing signal 21°22.23,24,25,26 .・・・
・Output as n. That is, shift register 1 is 11
It has ~in D Philip flops, and creates a delay time per horizontal synchronization signal in each shift unit.

! Figure $4 is a timing chart for explaining the timing of the vertical synchronization signal that is delayed in units of the horizontal synchronization signal. Now, the horizontal synchronization signal 12 in FIG. 3 is expressed as in FIG.
If the vertical synchronization signal 11 in FIG. 3 is represented by 42 in FIG. It will be done. Similarly, since the delayed vertical synchronization signal 23 further includes one shift unit 12, it becomes a signal 44, which is delayed by two horizontal synchronization signals with respect to the signal 41. In this way, the shift register is 1l
-1n Philip flops, so the signal 2
By delaying each of 0 to n by l horizontal synchronizing signal units, a delay of l life can be formed.

Vertical synchronization signal 20 and delayed vertical synchronization signal 2 shown in FIG.
1 to n are applied to the input terminals of multiplexer 2. The multiplexer 2 opens the gates using the gate select signals 31 to 34 and outputs the vertical synchronizing signal 20 - n to the vertical synchronizing signal output line 14 . As shown in FIG. 3, the gate select signals 31 to 34 may be signals obtained by latching data from the data line 40 using software using the data latch 4. Alternatively, the count output of the counter may be used as a gate select signal.

Reference numeral 3 denotes a CRT display, which is controlled by a selected delayed vertical synchronizing signal 14 output from the multiplexer 2, a horizontal synchronizing signal 12, and a video signal 13 to display a predetermined display.

Next, the operation of the embodiment will be explained. First, consider the case where the vertical synchronizing signal 20 is selected to the output line 14 by the multiplexer 2 by the gate select signals 31 to 34.

At this time, since the vertical synchronization signal is at the specified position, the characters are displayed at the specified position on the CRT. Next, by resetting the data in the data latch 4, new gate select signals 31 to 34 are output. This signal causes the multiplexer 2 to open the gate of the delayed vertical synchronization signal 2'1 and output the delayed vertical synchronization signal 21 to the output line 14. Therefore, since the vertical synchronization signal lags behind the specified position by one raster, the character is displayed moved upward by one raster.

FIG. 2 (2) shows a state in which it has moved by l rusks. Similarly, the output of the data latch shown in FIG. 3 is changed so that 22→...→n is output to the output 14 in the same manner. , By doing this, the vertical synchronization signal is sequentially delayed. As a result, the characters are displayed on the CRT display 3 so as to smoothly move up one raster at a time, as shown in FIG.

By changing the contents of the display RAM (not shown) or the display start address at the point where the character has moved by one line, the character “”
By deleting "A B C" and inserting the characters 11 "PQ R", the display on the CRT display 3 changes from (1) to (2), (3), (,4) in the order shown in Fig. 2. .

This completes the upward scrolling. Note that it is clear that scrolling in the downward direction can be easily realized by simply changing the contents (order) of the data latches 4 in FIG. 13.

Further, the unit of scrolling is not limited to one raster, and may be, for example, two raster units.

As explained above, according to the present invention, by adding a simple circuit, the scrolling function of one raster unit, which has been available only in conventionally very expensive graphic display type CRTs, can be realized in an inexpensive character display type. It becomes possible to attach it to a CRT device.

Therefore, the display screen according to the present invention changes in a manner that does not irritate the operator's eyes, so it is possible to display a CR screen that reduces eye fatigue as much as possible.
A T display device can be provided at a low price.

[Brief explanation of the drawing]

Figures 1 (1) and (2) are diagrams showing examples of conventional scrolling in units of lines; Figures 2 (1), (2), (3), and (4) are examples of scrolling in an embodiment of the present invention. FIG. 3 is a circuit diagram showing an embodiment of the present invention. FIG. 4 is a timing chart illustrating the timing of a vertical synchronization signal that is delayed in units of horizontal synchronization signals. Here, 1... shift register, 2... multiplexer, 3... CRT display device, 4... data latch circuit, 11... vertical synchronizing signal, 12... horizontal synchronizing signal, 21- n: Delayed vertical synchronization signal. Patent Application 1, Person Canon Co., Ltd. No. 1 FjA Figure 2 (4) (3) Figure 3

Claims (2)

[Claims] (1) A CRT display device characterized in that a display screen is scrolled by a vertical synchronizing signal and a horizontal synchronizing signal that are delayed by at least l horizontal synchronizing signal units. (2) The CRT display device according to claim 1, wherein the vertical synchronization signal is delayed by a delay element that can set an arbitrary delay time.