JPH0666893B2 - Deflection circuit - Google Patents

Description

The present invention relates to an all electrostatic deflection system (Sta-Sta), electromagnetic focusing electrostatic deflection system (Mg-Sta) camera or the like for keeping a constant focus voltage. Regarding the deflection circuit.

2. Description of the Related Art FIG. 3 shows a conventional deflection circuit of all electrostatic deflection type and electromagnetic focusing electrostatic deflection type. In FIG. 3, reference numeral 1 denotes a deflection sawtooth wave generation circuit, and the deflection sawtooth wave generated here is connected to a deflection drive circuit 2 for three deflection sawtooth waves. Reference numeral 3 is an image pickup tube for each correction waveform generation circuit 100, and the output of each deflection drive circuit 2 is connected to the deflection electrode.

This operation will be described. In FIG. 3, the sawtooth wave and the sawtooth wave generated by the deflecting sawtooth wave generation circuit 1 are adjusted in amplitude by a sawtooth wave amplitude adjuster 4 (deflection size adjustment). 1 in FIG. 4 shows the situation. FIG. 3 shows a total centering adjuster for adjusting the direct current component of the polarized sawtooth wave of the polar polarity in the opposite direction, as shown by 2 in FIG. Reference numeral 6 in FIG. 3 is an adjuster for equalizing the polarities and the amplitudes of the polarized sawtooth waves of the polarities, and the balance adjustment of the sawtooth waves is performed as in FIG.

The output of the deflection sawtooth wave generation circuit 1 adjusted here is
It is output to each deflection drive circuit 2 in FIG. Fig. 3
Is a centering adjuster which adjusts the direct current component of the polarization of the sawtooth wave in the opposite direction, and has the same function as the total centering adjuster 5 in FIG. This is an adjuster for performing centering adjustment between the deflection drive circuits 2 as shown in FIG. Further, FIG. 3 shows a focus voltage regulator for changing the direct current component of the polarized sawtooth wave of the polar polarity in the same direction as shown in FIG.

In this way, the conventional deflection device can deflect the image pickup tube.

Problems to be Solved by the Invention However, the conventional deflection circuit described above has a problem that the modulation degree of the image pickup tube cannot always be maximized because the focus voltage stability fluctuates due to temperature changes and the like.

The present invention solves such conventional problems,
It is an object of the present invention to provide an excellent deflection circuit that can always keep the focus voltage constant.

Means for Solving the Problems In order to achieve the above object, the present invention includes a deflection circuit, a deflection waveform addition circuit, a video period gate circuit, a voltage hold circuit, a voltage comparison circuit, and a focus voltage control circuit. Be prepared.

Action The present invention has the following actions due to the above configuration. That is, the direct current component of the deflection waveform (focus voltage)
Changes, the DC component of the output of the deflection waveform adding circuit changes. The voltage comparing circuit detects this change and controls the focus voltage control circuit, so that the focus voltage can be kept constant at all times.

Embodiment FIG. 1 shows the structure of an embodiment of the present invention.
In FIG. 1, 1 to 7 have the same functions as the conventional example. Note that in FIG. 1, one of the deflection drive circuits 2 will be described as an example.

In FIG. 1, reference numeral 9 is a polar saw and sawtooth wave adder circuit, 10 is a video period gate circuit, 11 is a voltage hold capacitor, 12 is a voltage comparator, and 13 is a focus voltage setting device.
Reference numeral 14 is a focus voltage control circuit.

Next, the operation of the above embodiment will be described. In the above embodiment, if the focus voltage (the cross point shown in FIG. 2) changes, the voltage of the deflection sawtooth wave addition circuit 9 also changes. Here, the video period gate circuit 10 gates the voltage for only the video period as shown by 2 in FIG. 2, and the gated voltage is held by the voltage holding capacitor 11.

Next, this held voltage and focus voltage setting device
The voltage of 13 is compared with the voltage comparison circuit 12, and the error voltage is output. This error voltage causes the focus control circuit 14
The focus voltage that fluctuates is controlled to match the focus adjustment voltage.

As described above, according to the above-described embodiment, when the focus voltage fluctuates due to temperature or other factors, the voltage of the deflection sawtooth wave addition circuit changes, and the changed voltage is compared with the voltage of the focus adjuster to determine the error voltage. This has the advantage that the focus control circuit can control the output so that the focus voltage matches the voltage of the focus adjuster. As a result, the focus voltage is always kept constant, so that the modulation degree of the image pickup tube can be maximized.

EFFECTS OF THE INVENTION The present invention has the following effects, as is apparent from the above-mentioned embodiments.

Polarity Polarization deflection waveforms are added, the focus voltage is detected, the detected focus voltage is compared with the voltage set by the focus voltage setting device, and the focus voltage is controlled so that it is always the same as the focus setting voltage. Therefore, the focus voltage can always be kept constant.

[Brief description of drawings]

FIG. 1 is a block diagram of a deflection circuit in an embodiment of the present invention, FIG. 2 is a waveform diagram showing its operation, FIG. 3 is a block diagram of a conventional deflection circuit, and FIG. 4 is a waveform diagram showing its operation. Is. 1 ... Deflection sawtooth wave generation circuit, 2 ... Deflection drive circuit,
3 ... Each correction waveform generating circuit, 4 ... Sawtooth wave amplitude adjuster,
5 ... Total centering adjuster, 6 ... Sawtooth wave balance adjuster, 7 ... Centering adjuster, 8 ... Focus voltage adjuster, 9 ... Deflection sawtooth wave adder circuit, 10 ... Video period gate circuit, 11 ... Voltage hold capacitor, 12 ... Voltage comparator, 13 ... Focus voltage setting device, 14 ... Focus voltage control circuit.

Claims (2)

[Claims] 1. A circuit for adding deflection sawtooth waves of polarities supplied to a deflection electrode of an image pickup tube, means for gated the addition output only for an image period, and holding the voltage thereof.
A deflection circuit provided with means for comparing the hold value with a set value and controlling the deflection sawtooth wave with the difference. 2. A deflection circuit according to claim 1, wherein the adder circuit, the holding means and the control means are provided so as to correspond to the respective image pickup tubes.