JPS6214581A - Vertical output circuit - Google Patents

Abstract

PURPOSE:To adjust the vertical amplitude stably from the external by comparing the output signal of a vertical amplitude level generated in a feedback resistance and a vertical amplitude control signal from the external with each other and changing the output pulse voltage of a vertical output stage by the comparison output. CONSTITUTION:A vertical amplitude level signal E0 having a pulse width corresponding to the vertical amplitude from a vertical amplitude level detecting circuit 20 and the vertical amplitude control signal from the external are compared with each other and are processed by an operational amplifier 22 to generate a control signal corresponding to the level difference. The voltage between both ends of a feedback resistance RF is fed back to one input of an operational amplifier 6 through a feedback circuit 18, and as the result, the amplifier 6 is so operated that the vertical amplitude is constant. The output of a lamp signal generator 4 is given to the other input of the amplifier 6 through a variable amplifier 23. The amplifier 23 is controlled by the control signal of the output of the amplifier 22 to vary the lamp voltage waveform, thus changing continuously and stably the vertical amplitude from the external.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a vertical output circuit, and particularly to a vertical output circuit suitable for driving a vertical deflection yoke of a television receiver using an IC circuit. be.

[Conventional technology]

FIG. 3 shows a block configuration of a conventional vertical output circuit, in which 2 is an oscillator, 4 is a ramp signal generator that generates a sawtooth wave according to the output of the oscillator 2, and 6 is an operational amplifier (
8 is a first-stage amplifier ff1A, 10 is an upper-stage output transistor with a single-ended push-pull (hereinafter referred to as 5EPP) configuration, 12 is a lower-stage output transistor with a 5EPP configuration, and 14 is a vertical return circuit that receives the output of the 5EPP circuit. A pump amplifier circuit 16 generates a high-level pulse voltage during the line period and supplies the pulse voltage to the upper output transistor 10;
A bias circuit that biases the first stage of the EPP, DY is a vertical deflection yoke, Go is a coupling cosidenser inserted between the 5EPP output and the vertical deflection yoke DY, RF is a feedback resistor, and 18 is the voltage of the feedback resistor RF and the 5EPP A feedback circuit 19 feeds back the output to the operational amplifier 6, and 19 is a volume that adjusts the voltage of the feedback resistor RF.

Next, the operation will be explained. The oscillator 2 generates a square wave synchronized with the vertical synchronization signal, which is converted into a sawtooth wave by the ramp signal generator 4 and compared with the output of the feedback circuit 18 by the operational amplifier 6. And this operational amplifier 6
After the output is amplified by the first stage amplifier 8, the first half and the second half of the sawtooth wave are respectively amplified by the transistors 10 and 12 of the 5EPP circuit, and this 5EPP output and the output of the feedback resistor RF are passed through the feedback circuit 18 to the It is fed back to the operational amplifier 6.

Considering that the current flowing through the vertical deflection yoke, so-called vertical amplitude, is to be varied, the vertical amplitude is varied by feeding back a waveform obtained by varying the voltage of the feedback resistor RF using the volume controller 19 to the operational amplifier 6. In this way, it is common to vary the vertical amplitude by mechanically operating a volume.

[Problem that the invention seeks to solve]

Conventional vertical output circuits are configured as described above, so in order to control the vertical amplitude to a desired level, the volume must be rotated mechanically, and the vertical amplitude can be controlled externally electronically. There were problems such as lack of control.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a completely new vertical output circuit whose vertical amplitude can be varied by an electronic control signal.

[Means for solving problems]

The vertical output circuit according to the present invention includes a vertical amplitude level detection circuit that detects the voltage generated in the feedback resistor, and a second comparison processing circuit that performs a comparison process between the vertical amplitude level signal and the vertical amplitude control signal. This is what I did.

[Effect]

In this invention, since the electronic attenuator controls the output pulse of the vertical output stage, the current flowing through the vertical deflection yoke, the so-called vertical amplitude, is automatically varied by an external electronic control signal.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a vertical output circuit according to an embodiment of the present invention,
In the figure, the same reference numerals as in FIG. 3 indicate the same parts. 2
0 is a vertical amplitude level detection circuit, 21 is a low-pass filter, 22 is an operational amplifier (second comparison processing circuit), and 23 is a variable amplifier (electronic attenuator).

Note that 30 is a front-stage circuit consisting of a vertical oscillator 2 and a ramp signal generator 4, and 40 is a first-stage amplifier FF/A unit 8, an upper stage.

Lower stage output transistors 10, 12, pump amplifier circuit 1
The vertical output stage consists of 4, and 24 is a terminal to which an external vertical amplitude control signal is input.

In addition, FIG. 2(a) shows the input waveform of the vertical amplitude level detection circuit 20, and FIG.
C) shows the output waveform of the low-pass filter 21.

Next, the operation will be explained using FIGS. 1 and 2.

The vertical amplitude level detection circuit 20 divides the voltage waveform of the feedback resistor RF shown in FIG. 2(a) into a high level E1 and a low level E1.
By sampling at a potential of 2, the vertical amplitude is converted into a pulse corresponding to the vertical amplitude as shown in FIG. 2('b). Note that the average level at this time is EO. Next, by passing the output of this vertical amplitude level detection circuit 20 through a low-pass filter 21, a DC potential at a signal level Eo corresponding to the vertical amplitude level can be obtained.

This vertical amplitude level signal EO and an external vertical amplitude control signal are compared in an operational amplifier 22, and a control signal corresponding to the level difference between the two signals is generated.

Here, the voltage across the feedback resistor RF is fed back to one input of the operational amplifier 6 via the feedback circuit 18, and this feedback operates to keep the vertical amplitude constant. On the other hand, the output of the ramp signal generator 4 is a variable amplifier (electronic attenuator)
23 to the other input of the operational amplifier 6.

However, by controlling this variable amplifier 23 with a control signal that is the output signal of the operational term unit 22, the lamp voltage waveform is varied, and by varying the lamp voltage, the deflection current of the vertical output circuit, the so-called vertical amplitude, is varied. can be varied continuously from the outside, and as mentioned above, automatic control is applied by negative feedback of the voltage across the feedback resistor RF, thereby stabilizing the vertical amplitude variation caused by the external control signal. can be done.

In addition, in this embodiment, it is very easy to vary the vertical amplitude by remote control, and since the vertical amplitude is varied by a variable amplifier instead of a polyurethane, it can be integrated into an IC, providing high reliability and adjustment. High precision can be obtained.

〔Effect of the invention〕

As described above, according to the present invention, the vertical amplitude is adjusted to an arbitrary vertical width using an electronic attenuator, and therefore a novel method is provided in which the vertical amplitude can be varied by an external control signal. This has the effect of providing a vertical output circuit.

[Brief explanation of drawings]

1vJJ is a block diagram of a vertical output circuit according to an embodiment of the present invention, and FIG. 2 shows the operation of the device shown in FIG.
1 is a waveform diagram for explanation, and FIG. 3 is a block diagram of a conventional vertical output circuit. 2---Oscillator, 4--Ramp signal generator, 6--
- operational amplifier (comparison processing circuit), 8... first-stage amplifier, 10--5EPP upper-stage output transistor (first transistor), 12...-5EPP lower-stage output transistor (second transistor), 14--Pump up circuit, 16--Bias circuit, 18--Feedback circuit, 30--Pre-stage circuit, 40--Vertical output stage,
-Co...Coupling capacitor, DY...Vertical deflection yoke, RF--Feedback resistor, 20...Vertical amplitude level detection circuit, 21...Low pass filter, 22...
・Operation symbol input terminal. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (2)

[Claims] (1) the first connected to a single-ended push-pull,
a vertical output stage including a second transistor for driving a vertical deflection yoke; a pre-stage circuit including a vertical oscillator for driving the vertical output stage with the output of the vertical oscillator; and a bias for biasing the vertical output stage. The circuit compares a pulse corresponding to the vertical scanning period generated in the preceding circuit with a pulse corresponding to the vertical scanning period generated in a resistor connected in series to the vertical deflection yoke, and generates a pulse according to the comparison result. and a comparison processing circuit applied to the vertical output stage, the detection circuit converting the pulse corresponding to the vertical scanning period generated in the resistor into a vertical amplitude level signal, and the output of the detection circuit and the vertical amplitude a second comparison processing circuit that performs comparison processing with a control signal for controlling the output signal and generates a control signal corresponding to a difference in generation level between the two signals; A vertical output circuit characterized by comprising an electronic attenuator for varying the output according to a control signal from the circuit. (2) The vertical output circuit according to claim 1, wherein the electronic attenuator is a variable amplifier provided between the pre-stage circuit and the vertical output stage.