JPS60220689A - Picture display driving circuit - Google Patents

Abstract

PURPOSE:To obtain a concise picture display driving circuit which hardly requires adjustment, by installing a variable resistor for making cut-off adjustment of a color cathode-ray tube to the picture display driving circuit. CONSTITUTION:Color difference signals R-Y, G-Y, and B-Y and a luminance signal -Y are inputted and primary signals R, G, and B are supplied to the cathodes BK, GK, and BK of a cathode-ray tube. A picture display driving circuit is composed of transistors (TR) 4, 5, and 6, fixed resistors 16, 17, 25, and 26, and variable resistors 20-22 and picture display signals are inputted from terminals RH, GH, and BH. Variable resistors 23 and 24 absorb the fluctuation of cathode-ray tube gm characteristics and the relative variation of the color difference signals at a DC voltage. Moreover, the variable resistors 20-22 of the picture display driving circuit absorb the cut-off variation of the cathode- ray tube.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a circuit for displaying characters such as channel and volume on a cathode ray tube of a color television receiver (hereinafter referred to as 'F screen display drive 9').
(abbreviated as power circuit).

[Background of the invention]

Problems with the conventional image display drive circuit will be explained with reference to FIG. In Figure 1, the transistor circuit is connected to a color difference signal (-Y, G-Y, B-Y) and a luminance signal (-Y).
Input the Q1 primary color signals (几, G, B) to the cathode of the cathode ray tube (RK, GK).

BK). Here, variable resistor 20°21
．． 22 is for adjusting the power and to-off voltage of the cathode ray tube, and variable resistors 23 and 24 are for adjusting the voltage of the cathode ray tube.
This is to eliminate variations in characteristics and mutual variations in DC voltage of color difference signals. The screen display drive circuit includes transistors 4, 5, 6. Fixed resistors 16-19. Consisting of variable resistors 25 to 26, screen display signals are RH and G, respectively.
H, dH117) Manually applied from the valley terminal. When there is no screen display signal, 几H, qH.

Each terminal of BH is in an open state, and C) transistors 4 to 6 are in an off state. When the screen display signal is input, "u, snow 1. Each terminal of BH is grounded through a transistor (not shown), and a current is drawn through the valley resistor 19, 25, 26, and the current flows through the resistor. By flowing from 9 to 11,
The cathode voltage is F, the beam current is passed, and the characters displayed on the screen on the cathode ray tube are at a high level, and the transistor 7.
Since 1 to 3 are in a cut-off state, in order to make the characters displayed on the screen white, it is necessary to absorb the variations in the cathode ray tubes, especially the variations in the cut-off voltage, so at least two variable resistors are required. There is a problem that 25.26 is required and adjustment is also required.

[Purpose of the invention]

An object of the present invention is to provide a simple screen display drive circuit that does not require adjustment.

[Summary of the invention]

In order to achieve the above object, we have invented a screen display drive circuit that absorbs variations in the power and turn-off voltage of cathode ray tubes.

[Embodiments of the invention]

A first embodiment of the present invention will be described using FIG. 2. The difference from the conventional example is that the connection points of the variable resistors 20 to 22 for absorbing cathode ray tube power and off-state voltage variations are connected to transistors 1 to 22.
The emitters of transistors 4 to 6 were changed from the emitter of transistor 5 to the emitters of transistors 4 to 6, the variable resistors 25 and 26 were changed to fixed resistors, and the resistor 18 between the emitter of transistor 7 and +vB was deleted. By moving the variable resistors 20 to 21 to the side of the #J surface display drive path, the variable resistors 20 to 21 are used to absorb the cutoff variations of the cathode ray tube. Therefore, the variable resistors 25 and 26 for adjusting the white pi, which were conventionally required, can be replaced with fixed resistors. In addition, since variable resistors 20 to 22 were conventionally connected between the emitter ground of transistors 1 to 3,
In order to cut off the transistors 1 to 3, it was not enough to just put the transistor 7 in the cut off state and a resistor 18 was required.
In the figure, even without the resistor 18, if the transistor 7 is turned off, the transistors 1 to 5 are turned off. For this reason, in the conventional example, the force, to-off tA
There is also the advantage that the switch 35 required for maintenance is not required, and that the transistor 7 only needs to be in a cut-off state when adjusting the to-off.

A second embodiment according to the invention is shown in FIG.

Fig. 6 shows an embodiment in which the video output stage is connected to a cassette. Compared to the embodiment shown in Fig. 2, transistors 30 to 32 are added, but the following points are different from the first embodiment. Excellent.

(Because it is connected to a hood, the frequency characteristics of the circuit are wideband, which is advantageous for high-quality reproduction.

(2) Transistors 1 to 6 can be changed to low-voltage, low-power products, and the cost can be reduced even though three transistors are added.

(3) Since there is no half of the output 7J transistors 30 to 32 in the cutoff state, the amount of harmonic component radiation is small, which causes problems in the VHF low channel (1 to 6' in Japan)
f′ yannel) will be slightly disturbed.

〔Effect of the invention〕

As described in the embodiments above, according to the present invention, (1) the number of A phasing variable resistors can be reduced by two.

(2) The second embodiment has the advantage of reducing the number of switches for cut-off adjustment by one, and (6) a reduction in cost can be expected by changing to a low-voltage, low-power transistor.

(4) Less radiation of harmonic components from the output transistor.

It has the advantage of

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing a conventional example, FIG. 2 is a circuit diagram showing a first embodiment of the present invention, and FIG. 3 is a circuit diagram showing a second embodiment of the present invention. 1-7. 30-32...Transistor, 8...Diode, 9-26...Resistor (including variable resistor), 55...
Cutoff adjustment switch, PP 硼八人4effl+
Breath gland dumpling male 1st (BL) (K) () (QH) (BH) 2nd

Claims (1)

[Claims] In order to realize this function in a color television receiver equipped with a function of displaying channels, volume, etc. on a color cathode ray tube, a color television signal drive circuit is connected in parallel, and a circuit for driving the display signal is provided. A screen display drive circuit characterized in that the display signal drive circuit is equipped with a variable resistor for adjusting the cutoff of a cathode ray tube.