JPH0121355Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is a character display mode in which the vertical size of the screen is increased relative to the horizontal cycle so that the displayed characters can be easily seen when displaying dots on a CRT (cathode ray tube). By varying the amplitude of the vertical sawtooth wave in multiple steps, you can easily switch between the graphic display mode and the graphic display mode in which the horizontal:height ratio of the dot pitch is a simple integer value so that the displayed figure is easy to see. This relates to a CRT display device that can

In the conventional CRT display device for dot display,
When adjusting the amplitude of the sawtooth wave of the vertical deflection circuit, as shown in Figure 1, vertical oscillation section 1 and vertical output section 2 are used.
Continuously adjust the semi-fixed resistor 3 inserted between the Ta. This adjustment method has the advantage that the dot pitch ratio is set mainly for character display, so the vertical size is set large and the displayed characters are easy to read. However, in the case of graphical display, the width:height ratio of the dot pitch is not an integer value, which has the disadvantage that conversion for correcting graphic distortion is complicated.
On the other hand, there are CRT display devices in which the width:height ratio of the dot pitch is set as an integer to make it suitable for graphical display, but this has the disadvantage that characters become difficult to read when characters are displayed.

The present invention was devised in view of the above-mentioned points.The present invention has been developed to provide a vertical amplitude signal between the vertical oscillation section and the vertical output section of the vertical deflection circuit for switching the vertical amplitude in multiple stages so that the dot pitch ratio is set in advance. The vertical amplitude switching section can be used to easily switch the display surface of the CRT display between a mode suitable for character display and a mode suitable for graphic display.

Hereinafter, one embodiment of the present invention will be described based on FIGS. 2, 3, and 4. FIG. 2 is a block diagram showing a part of the vertical deflection circuit of a CRT display device, where 1 is a vertical oscillation section and 2 is a vertical output section. Between the vertical oscillation section 1 and the vertical output section 2, there is a semi-fixed resistor 3 installed at a position that will not be adjusted once it is adjusted, and a semi-fixed resistor 3 installed on the front panel etc. so that it can be switched freely from the outside. A vertical amplitude switching section 6, which is formed by connecting a switching switch 4 and a fixed resistor 5 in parallel, is inserted. The semi-fixed resistor 3 is adjusted and fixed so that when the changeover switch 4 is connected to the closed contact 7, the vertical size of the screen becomes larger and a display mode suitable for character display is achieved. Further, the fixed resistor 5 has a resistance value such that when the changeover switch 4 is connected to the open contact point 8, the horizontal:vertical ratio of the dot pitch becomes an integer value of 2:1 or 1:1.

Next, the operation of the present invention will be explained.

When the changeover switch 4 is connected to the closing contact 7, the resistance of the vertical amplitude switching section 6 is zero, so the amplitude of the sawtooth wave of the vertical deflection circuit increases, and the vertical size of the screen also increases. Therefore, as shown in FIG. 3, the character display mode is set in which the characters displayed on the screen 10 of the CRT display device 9 are easy to see.

When the changeover switch 4 is switched to the open contact point 8, the resistance of the vertical amplitude switching section 6 increases from zero to the resistance value of the fixed resistor 5, so that the amplitude of the sawtooth wave becomes smaller. Therefore, as shown in FIG. 4, the width:height ratio of the dot pitch on the screen 10 of the CRT display device 9 becomes an integer value such as 2:1 or 1:1, and the conversion for correcting the graphic distortion is performed. This is a graphical display mode that is unnecessary or simple.

In the embodiment described above, the changeover switch 4 is used to switch between the character display mode and the graphic display mode, but the present invention is not limited to this. For example, as shown in FIG. 5, a three-stage selector switch 11 is used, and the contact 12 is connected to the character display mode, and the contact 14 connected to the resistor 13 is connected to the resistor 15 for the graphic display mode with a dot pitch ratio of 2:1. The contact 16 may be used for a graphic display mode with a dot pitch ratio of 1:1. Further, the vertical amplitude switching section is not limited to the one shown in FIGS. 2 and 5, but as shown in FIG. It may be configured to switch selectively.

Note that when determining the dot pitch ratio in the graphic display mode, it is determined by the dot pitch on the screen. For example, the width x height of the number of dots is
For 640x200, the dot pitch ratio is 2:1, and for 640x400 or 320x200, it is 1:1. In other words, set the width to height ratio to an integer value that is as close as possible.

In each of the above embodiments, the display mode was switched using a manual switch, but the display mode can be automatically switched using a level signal corresponding to the display mode from a TTL (Transister Transistcr Logic) integrated circuit. It would be even more convenient if it could be switched.

Since the present invention is constructed as described above, a character display mode in which the vertical size is increased so that the characters displayed on the screen of the CRT display device are natural and easy to see simply by switching the changeover switch, It is possible to switch to a graphic display mode in which the horizontal:height ratio of the dot pitch on the screen is set to an integer value. For this reason, when displaying characters, the effective display surface of the screen can be enlarged to make effective use of the screen and making it easier to read characters, and when displaying graphics, it is possible to use conversion to correct distortion of figures. is not necessary or can be made easier.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a vertical deflection circuit of a conventional CRT display device, FIG. 2 is a block diagram showing a vertical deflection circuit of an embodiment of a CRT display device according to the present invention, and FIGS. Second
A front view of a CRT display device showing a display example in the figure,
FIGS. 5 and 6 are electrical circuit diagrams showing vertical amplitude switching sections in other embodiments, respectively. 1... Vertical oscillation section, 2... Vertical output section, 3...
Semi-fixed resistor, 4, 11...Selector switch, 5, 1
3, 15, 17, 18...Resistor, 6...Vertical amplitude switching unit, 9...CRT display device, 10...Screen.

Claims (1)

[Claims for Utility Model Registration] (1) Between the vertical oscillation part and the vertical output part of the vertical deflection circuit, the horizontal:vertical ratio of the dot pitch is set in an easy-to-see character display mode and the horizontal:vertical ratio of the dot pitch is What is claimed is: 1. A CRT display device comprising: a vertical amplitude switching section that switches the amplitude of a vertical sawtooth wave in multiple steps in order to switch to a graphic display mode in which the . (2) The vertical amplitude switching section consists of a semi-fixed resistor for character display mode, a fixed resistor for graphic display mode connected in series with this semi-fixed resistor, and a changeover switch parallel to this fixed resistance. A CRT display device according to claim 1, which is a utility model and is capable of being switched between two stages, a character display mode and a graphic display mode, by turning on and off. (3) The vertical amplitude switching section consists of a semi-fixed resistor for character display mode, a fixed resistor for graphic display mode which is connected in parallel with this semi-fixed resistor with one end in common, and the other end of these resistors can be selectively connected. 2. A CRT display device according to claim 1, which is a utility model, and comprises a changeover switch that allows switching between a character display mode and a graphic display mode. (4) The fixed resistors for graphic display in the vertical amplitude switching section consist of two parallel resistors that switch the horizontal:vertical ratio of the dot pitch between 1:1 and 2:1.
A CRT display device according to claim 2 or 3 of the utility model registration claim, wherein the graphic display mode can be switched to two stages.