JPH0851550A - Horizontal amplitude temperature drift correction circuit - Google Patents

Abstract

PURPOSE:To prevent the temperature drift of a horizontal amplitude for a cathode ray tube display monitor or the like with a circuit simple in configuration. CONSTITUTION:This correction circuit is constituted of a DC power supply circuit 1 where Zener diodes D1, D2 are provided between a prescribed power supply line and ground, a prescribed output voltage Vo is obtained at a prescribed temperature by the Zener diodes and the output voltage has a prescribed temperature drift and of a horizontal amplitude setting circuit 2 operated by an output voltage from the DC power supply circuit 1 and provided with 1st and 2nd operational amplifiers 2a, 2b or the like whose horizontal amplitude setting voltage S3 has a temperature drift. Then the temperature drift of the horizontal amplitude setting voltage is cancelled by a temperature drift of an output voltage for the correction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a horizontal amplitude temperature drift correction circuit, and more particularly to prevention of horizontal amplitude temperature drift in a cathode ray tube display monitor or the like.

[0002]

2. Description of the Related Art In a display monitor, a television receiver or the like using a cathode ray tube, various measures have been conventionally taken in order to prevent a horizontal amplitude fluctuation (temperature drift) with respect to a change in ambient temperature. FIG. 3 shows an example of the treatment. In the figure, 11 is a stabilized DC power supply (REG) such as a three-terminal regulator, which outputs a predetermined DC voltage V11 from the input DC voltage Vcc. The horizontal amplitude setting circuit 12 operates using the same voltage V11 as a power source. As shown, the horizontal amplitude setting circuit 12 includes a first operational amplifier 12a, a second operational amplifier 12b, and a transistor Q.
11 and the same Q12, etc., the vertical parabolic voltage S11 for left and right pincushion distortion correction is input to the inverting (-) input terminal of the first operational amplifier 12a, and the voltage V11 is input to the positive phase (+) input terminal.
A predetermined voltage obtained by resistance-dividing is applied. Also, a horizontal amplitude control voltage S12 is applied to the base of the transistor Q11,
The voltage is adjusted to set the horizontal amplitude to a predetermined amplitude. Therefore, the output S13 as the horizontal amplitude setting circuit 12, that is, the second
The output S13 of the operational amplifier 12b is a voltage in which the vertical parabolic voltage is superimposed on the horizontal amplitude control voltage S12. The same voltage is sent to the horizontal sawtooth voltage generation circuit 13, and the same generation circuit 13 generates a horizontal sawtooth voltage having a required horizontal amplitude for use in horizontal deflection. As a measure against temperature drift of the horizontal amplitude setting circuit 12 configured as described above, the thermistor TH is provided in the resistance voltage dividing circuit for the positive phase (+) input terminal of the first operational amplifier 12a. The temperature variation of the horizontal amplitude generated in the entire horizontal amplitude setting circuit 12 is prevented by the resistance change of the TH with respect to the temperature change.

[0003]

The above-mentioned horizontal amplitude temperature drift prevention measure shown in FIG. 3 has the required effect in terms of performance. However, in the case of FIG. 3, an expensive power supply circuit such as a three-terminal regulator and a thermistor are used, which is disadvantageous in terms of cost in a situation where product price competition is intense and needs to be improved. On the other hand, the temperature drift of the horizontal amplitude cannot be allowed from the viewpoint of maintaining the performance. The present invention has been made from this point of view, and an object of the present invention is to provide a correction circuit capable of solving the temperature drift of the horizontal amplitude with a simple configuration.

[0004]

According to the present invention, a Zener diode is provided between a predetermined power supply line and a ground, the Zener diode provides a predetermined output voltage under a predetermined temperature, and the output voltage has a required temperature drift. A DC power supply circuit having the following: a horizontal amplitude setting circuit that operates with an output voltage from the DC power supply circuit and has a horizontal amplitude setting voltage having a temperature drift; and a temperature drift of the horizontal amplitude setting voltage, A horizontal amplitude temperature drift correction circuit is provided that is corrected so as to be canceled by the temperature drift of the output voltage.

[0005]

Function: The Zener diode stabilizes the DC power supply voltage for the horizontal amplitude setting circuit. The DC power supply voltage has a certain temperature drift due to the stabilization by the Zener diode. On the other hand, in the horizontal amplitude setting circuit, the thermistor for preventing horizontal amplitude temperature drift, which is conventionally provided, is deleted, so that the horizontal amplitude causes temperature drift. The fluctuation of the power supply voltage due to the temperature drift acts to suppress the temperature drift of the horizontal amplitude. Therefore, if the temperature drift characteristic of the power supply voltage is set by the number of zener diodes and the temperature characteristic so as to cancel the temperature drift of the horizontal amplitude, the temperature drift of the horizontal amplitude is totally prevented.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A horizontal amplitude temperature drift correction circuit according to the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram of an essential part showing an embodiment of a horizontal amplitude temperature drift correction circuit according to the present invention, and FIGS. 2 (A), (B), (C) and (D) are various characteristic diagrams for explaining FIG. Is. In FIG. 1, reference numeral 1 is a stabilized DC power supply circuit, which is connected to the input DC voltage Vcc and the resistor R1.
And the two Zener diodes D1 and D2 obtain the stabilized DC voltage Vo. Reference numeral 2 is a horizontal amplitude setting circuit, which is composed of a first operational amplifier 2a, a second operational amplifier 2b, a transistor Q1, and the same Q2. Reference numeral 3 denotes a horizontal sawtooth voltage generating circuit, which generates a sawtooth voltage for horizontally deflecting a predetermined horizontal amplitude based on the horizontal amplitude setting voltage from the horizontal amplitude setting circuit. As in the case of FIG. 3, the first operational amplifier 2a
The vertical parabolic voltage S1 for correcting the left and right pincushion distortion is input to the inverting (-) input terminal of, and the horizontal amplitude control voltage S2 for adjusting (setting) the horizontal amplitude is applied to the base end of the transistor Q1. Therefore, the output S3 of the horizontal amplitude setting circuit 2, that is, the output S3 of the second operational amplifier 2b is a voltage in which the vertical parabolic voltage S1 is superimposed on the horizontal amplitude control voltage S2.

Next, the operation of the present invention will be described. As shown in FIG. 2A, the relationship (temperature drift) between the horizontal amplitude setting voltage (the output of the second operational amplifier 2b) S3 and the ambient temperature T (° C.) of the horizontal amplitude setting circuit 2 has a negative temperature coefficient,
That is, it has the property of decreasing with increasing temperature. This is determined from the circuit configuration and is a prerequisite for the present invention. Also, the horizontal amplitude setting voltage for the power supply voltage Vo
The relationship with S3 is that the positive temperature coefficient,
That is, it has the property of increasing with increasing Vo.
This is also determined from the circuit configuration.

On the other hand, the fluctuation (temperature drift) of the power supply voltage Vo with respect to the ambient temperature T (° C.) is governed by the temperature characteristics of the Zener diode. The temperature characteristics of the Zener diode differ depending on the Zener voltage. Generally, the Zener voltage is 6V.
It is known that the temperature coefficient is approximately zero in the vicinity, and that a Zener voltage higher than the same voltage has a positive temperature coefficient, and a Zener voltage lower than the same voltage has a negative temperature coefficient. For example, assuming that the circuit of FIG. 1 operates at Vo = 24V (generally, 12V or more is common), it is necessary to use a Zener diode having a positive temperature coefficient and a Zener voltage of 6V or more. And the voltage and temperature characteristics are obtained. That is, the predetermined voltage Vo (here, 24
V) is obtained, and one or a plurality of Zener diodes having a Zener voltage of 6 V or more are provided in series so that the temperature characteristic that can cancel the temperature drift characteristic of FIG. Power supply voltage Vo for ambient temperature T (° C) in this case
2C (temperature characteristic) shows a positive temperature coefficient in which the power supply voltage Vo rises as the ambient temperature T rises, as shown in FIG. 2 (C).

If Vo = 24V in the above example, for example, there is a method of serially connecting Zener diodes having a Zener voltage of 9V and 15V, or a method of serially connecting two Zener voltages of 12V. The former is a combination of different temperature characteristics, and the latter is a combination of the same temperature characteristics. With these combinations, the temperature characteristic [FIG. 2 (C)] of the power supply circuit 1 is made to be a characteristic that can cancel the characteristic of the horizontal amplitude setting circuit 2 of FIG. With such a characteristic, the horizontal amplitude setting voltage S3 can be free from temperature drift as shown in FIG. As a result, the sawtooth voltage generated by the horizontal sawtooth voltage generation circuit 3 has no temperature drift.

[0010]

As described above, according to the present invention, the set voltage temperature drift in the horizontal amplitude setting circuit provided in a display monitor or the like using a cathode ray tube is utilized by the temperature drift characteristic of the stabilized DC power supply circuit with a simple structure. Then, the horizontal amplitude can be stabilized as in the conventional case. The horizontal amplitude temperature drift correction circuit according to the present invention is intended to stabilize the power supply with the Zener diode and to cancel the temperature drift of the horizontal amplitude setting circuit by utilizing the temperature characteristic of the Zener diode. The costly 3-terminal regulator power supply circuit and the thermistor for temperature drift prevention used in the horizontal amplitude setting circuit are not required, and the circuit configuration is simplified. Therefore, the same performance as the conventional one can be realized at low cost.

[Brief description of drawings]

FIG. 1 is a circuit diagram of essential parts showing an embodiment of a horizontal amplitude temperature drift correction circuit according to the present invention.

FIG. 2 is various characteristic diagrams for explaining FIG.
(A) is horizontal amplitude setting voltage S3 for ambient temperature T (° C)
(B) shows the relationship between the power supply voltage Vo and the horizontal amplitude setting voltage S3, and (C) shows the ambient temperature T (° C).
To the power supply voltage Vo, and (D) shows the relationship to the horizontal amplitude setting voltage S3 with respect to the ambient temperature T (° C.).

FIG. 3 is a circuit diagram of a main part showing an example of a conventional horizontal amplitude temperature drift correction circuit.

[Explanation of symbols]

 1 Stabilized DC power supply circuit Vcc Input DC voltage D1 Zener diode D2 Zener diode Vo Stabilized DC output voltage 2 Horizontal amplitude setting circuit 2a First operational amplifier 2b Second operational amplifier Q1 transistor Q2 transistor 3 Horizontal sawtooth voltage generation circuit S3 Horizontal Amplitude setting voltage 11 Stabilized DC power supply 12 Horizontal amplitude setting circuit 13 Horizontal sawtooth voltage generation circuit

Claims (4)

[Claims] 1. A direct current power supply circuit in which a direct current output voltage is stabilized by a Zener diode, and a horizontal amplitude setting circuit which outputs a voltage for setting a horizontal amplitude using the direct current output voltage as a power supply. Horizontal amplitude temperature drift correction circuit. 2. The horizontal amplitude temperature drift correction circuit according to claim 1, wherein the Zener diode is formed by connecting a plurality of Zener diodes having the same characteristics in series. 3. The horizontal amplitude temperature drift correction circuit according to claim 1, wherein the zener diode is formed by connecting a plurality of zener diodes having different characteristics in series. 4. The horizontal amplitude setting circuit inputs a vertical parabolic wave to an inverting input terminal and applies a predetermined voltage obtained by dividing the output voltage from the DC power supply circuit to a positive phase input terminal,
A first operational amplifier that operates with an output voltage from the same DC power supply circuit and a vertical parabolic wave from the first operational amplifier are input to an inverting input terminal, and a horizontal amplitude control voltage for setting horizontal amplitude is input to a positive phase input terminal. 2. A second operational amplifier that receives input and operates with the DC power supply.
The horizontal amplitude temperature drift correction circuit described.