JPS5836788B2 - Irohiyouji Cairo - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a display circuit, and more particularly to a color display circuit for displaying characters, etc. in color on a cathode ray tube.

When displaying characters, etc. in color on a cathode ray tube, the rise and fall characteristics of color display signal pulses greatly affect the resolution of the displayed content appearing in the image.

Therefore, in a color display circuit that generates display contents such as characters, the steepness of the rise and fall must be taken into consideration.

Recently, the entertainment value of television has increased, and the average viewing time of viewers per day has also increased.In response to this, television receivers that set the program desired by the viewer and receive the predetermined station over time. was developed.

(Hereinafter referred to as program television.) In order to confirm the program set by the user, this television receiver displays the set contents in white or color on the screen as necessary.

The current situation is that there is an increasing need to display information on the screen of a cathode tube.

The circuit diagram shown in FIG. 1 is a circuit diagram showing the color display circuit 1 at the program television development stage described above.

That is, the color display circuit 1 at the development stage includes transistors 3 and 4 that drive the red, green, and blue electron guns of the cathode ray tube 2.
, 5, transistor 4, transistor 5
Transistors 6 are interposed and connected between the emitter electrodes of the transistors and the reference potential, respectively, and are conductive when the respective color display signals are input.
, 7 and a transistor 8 which is normally conductive and is cut off when the transistors 6 and 7 are in operation.

When transistor 8 is cut off by operation of a planking circuit (not shown) and a green or blue color gate signal is injected from color gate terminals 9 and 10, transistor 6 or 7 becomes conductive and its collector current changes to the corresponding color. It is superimposed on the cathode ray tube anode current and a color display is made on the cathode ray tube screen.

When displaying characters or the like on a cathode ray tube in color, a pulse signal is required to have a steep rise and fall in order not to degrade the resolution of the displayed image.

An amplifier that satisfies the steepness of the rise and fall of the pulse is
There are inherent difficulties in circuit design such as stray capacitance, and the above-mentioned difficulties become even more pronounced when a plurality of amplifiers satisfying steepness are provided.

In the color display circuit 1 at the development stage shown in FIG. 1, when displaying an image not in a single color but in multiple colors, it is necessary to supply pulse signals to both color gate terminals 9 and 10. A plurality of amplifiers are required to satisfy the steepness of the rise and fall of the pulse as shown in FIG. 2-22-3.

For this reason, as described above, the provision of a plurality of amplifiers with steep rises and falls causes design difficulties and production cost problems.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide a color display circuit that requires only a single pulse amplifier that satisfies the steepness of rise and fall.

FIG. 3 is a circuit showing an embodiment of the color display circuit according to the present invention.

The color display circuit 20 according to the present invention includes the red, green, and
Transistors 23, 24, 2 that drive the blue electron guns, respectively
transistors 26 and 27 whose controlled current terminals are connected to the base electrode sides of transistors 24 and 25, respectively, whose base electrodes are connected to color gate terminals 2B and 29, respectively, and which become conductive when a color gate pulse signal is generated; and a control end (
A transistor 31 whose base electrode (base electrode) is connected to a character signal terminal 30, and a transistor 32 which is connected in parallel to this transistor and whose control terminal (base electrode) is connected to a planking circuit (not shown). .

The planking circuit (not shown) is operated to shut off the transistor 32, and the character signal terminal 30 is connected to the character signal terminal 30 as shown in FIG.
When a pulse signal with steep rise and fall as shown in FIG.
4 and 25 are all in a conductive state.

In this state, when a green gate pulse signal 4-3 and a blue gate signal 4-4 are injected from the green gate terminal 28 and the blue gate terminal 29, respectively, the transistors 26 and 27
becomes conductive, and the respective color signal currents are superimposed on the collector currents of the transistors 24 and 25, so that color display for one horizontal scan I-I' shown in FIG. 4-4 is performed.

The color display circuit according to the present invention has the transistor 3 as described above.
2, the electron gun drive active elements 23, 24, 25 are connected to the character signal terminal 30.
It becomes conductive only when a pulse signal is supplied to the transistor 31 and the transistor 31 becomes conductive.

Therefore, in order to display one horizontal scan I-I' of the display character shown in FIG. 4-1, a color signal with slow rise and fall as shown in 4-3. When supplied to the character signal terminal 30, the electron gun drive transistor 2 is synchronized with the pulse signal 4-2 with a steep rise and fall.
3, 24, and 25 are electrically connected, so that the resolution of the displayed image is not impaired.

As described above, according to the color display circuit according to the present invention, only one amplifier is required even when displaying an image with multiple colors, and a plurality of amplifiers are required to have steep rises and falls. Problems in circuit design, especially problems in integration, caused by providing a plurality of amplifiers with steep downward slopes can be solved, and problems in production cost and mass productivity can also be solved.

Note that the present invention is not limited to consumer television receivers, but can also be applied to color display circuits for industrial surveillance televisions and the like.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing a color display circuit at the development stage, Figure 2 is a diagram showing a color gate signal that requires sharpness and steepness of fall for character display using the color table circuit, and Figure 3. 4 is a circuit diagram showing a typical embodiment of the color display circuit according to the present invention, and FIG. FIG. 23, 24, 25... Electron gun drive active element, 2
6, 27... Color gate control active element, 31.
...Switching active element.

Claims (1)

[Claims] First, second and third color signals are respectively applied to one base,
The first, second, and third drive transistors that drive the electrodes of the cathode rays of the corresponding colors are connected in common to the collector-emitter current paths and collector-emitter current paths of the first, second, and third drive transistors. , a fourth transistor to which a luminance gate signal corresponding to the display figure is applied to the base, and a color display gate signal is applied to the transistor corresponding to the color to be colored among the first, second, and third drive transistors. 1. A color display circuit comprising at least means for.