JPH01215184A - Right left pin cushion correction circuit - Google Patents

Abstract

PURPOSE:To attain screen size adjustment without pin cushion distortion by correcting right/left pin cushion distortion proportional to the cube of horizontal amplitude attended with the adjustment of the screen size. CONSTITUTION:A voltage gain of a transistor(TR) Q1 is varied by giving a voltage being a cube of the DC component of a parabolic signal to the emitter of the TR Q1 to control the amplitude of the parabolic signal to be outputted. Thus, the amplitude of the parabolic signal supplied to a capacitor C2 is varied by the voltage proportional to the cube of the DC voltage adjusted by a data (b). Thus, the correction quantity of the pin cushion distortion is made proportional to the cube of the horizontal amplitude thereby applying correct pin cushion correction even when the pattern size is varied freely.

Description

[Detailed Description of the Invention] [Purpose of the Invention] (Field of Application of dRakudo) This invention is a deflection circuit that allows the user to freely adjust the screen size, and is capable of correcting left and right pincushion distortion even when the screen size is changed. This invention relates to a left-right pincushion distortion correction circuit that prevents imbalance.

(Prior Art) Some image display devices, such as television receivers, allow a user to freely adjust the screen size by manually pressing keys on a remote controller. A television receiver having such an adjustment function is constructed as shown in FIG.

In FIG. 2, 11 is a remote control light receiving section that receives key data from a remote control transmitter (not shown), and 12 is a microcomputer (hereinafter referred to as microcomputer) that inputs the signal received by the remote control light receiving section 11 from a predetermined board. When the microcomputer 12 learns the screen size information by decoding the key data, it generates data a and b indicating vertical and horizontal amplitude adjustment values, respectively.

The vertical oscillation circuit 13 receives data a indicating the vertical amplitude and generates a sawtooth voltage A with an adjustable amplitude vpp based on the data a. The sawtooth voltage A drives the vertical output circuit 15 through the vertical drive circuit 14, causing a sawtooth wave current B of amplitude IVEII) to flow into the vertical deflection coil 16. I Vpp is sawtooth voltage A
It is variable depending on the amplitude Vpp of.

Reference numeral 17 denotes a parabola signal generation circuit that generates a parabola signal with a vertical period. In order to correct left and right pincushion distortion, the parabola signal with a vertical period is generated so that the parabolic amplitude becomes large at the center of the screen.

Adjustment of the horizontal amplitude (data b instructing n is input to the parabolic signal generation circuit 17, and the DC voltage VOC of the parabolic signal C generated by this circuit 17 is varied.The signal from the parabolic signal generation circuit 17 is C drives the horizontal output circuit 19 through the parabolic signal amplification circuit 18 to cause a deflection current to flow to the horizontal deflection coil 20. In this case, the amplitude I Hpp of the deflection current is equal to the DC voltage VDC of the parabolic signal C. It can be changed by

In this way, in the cathode ray tube 21, deflection currents with varying amplitudes I Vl)9 and 111Eip can be passed through the vertical and horizontal deflection coils 16 and 20, respectively, depending on the data a and b. Therefore, the user can adjust the screen size by specifying data a and b using the remote control transmitter.

FIG. 3 shows an example of a conventional horizontal deflection circuit, and the parabolic signal amplification circuit and horizontal horn circuit in FIG. 2 will be explained in more detail.

In FIG. 3, the parabolic signal amplification circuit 18 is composed of a transistor Q1, the base of which receives the signal C from the parabolic signal generation circuit 17, and the emitter of which is a resistor R.
1 to the reference 78th point, and the collector is connected to the resistor R
2 to the voltage source terminal Vcc.

On the other hand, the horizontal output circuit 19 has a horizontal output transistor Q2.
The emitter of is connected to the reference potential point, and the collector is connected to the voltage source terminal VB via the coil L3 (flyback transformer winding) and to one end of the horizontal deflection coil Y. The other end of the horizontal deflection coil LY is
It is connected to a reference potential point via a series circuit consisting of a capacitor CI, a coil 2, and a capacitor C2, and together with these series circuits forms a load circuit for the horizontal output transistor Q2. The collector of the transistor Q1 is connected to the coil L.
1 to the intersection of the capacitor C2 and the coil L2 in the load circuit.

Further, a damper diode D1. is connected between the collector and emitter of the horizontal output transistor Q2. Series connection of D2 and
The series-connected resonance capacitors C3 and C4 are each connected in parallel. However, the intersection Di, C217) and the intersection 03, C4 are connected to n, and
The connection point is further connected to the coil L2 and the capacitor C1.
connected to the intersection of

In the above circuit, a parabolic signal Q1 (corresponding to signal C) as shown in Fig. 4a is added to the base of the transistor Q1, and the output terminal of the coil L1 on the collector side is as shown in the figure. A parabolic signal v2 appears. This signal ■2
As shown in FIG. 4C, the deflection current iY is modulated in a parabolic manner, and the left-right pincushion distortion is corrected.

The amplitude of the modulated deflection current is: where K is a constant based on capacitor C1, tS is the scanning period, and V2 is the DC component of signal E, VOC2, and AC interaction, as shown in Figure 4. Which synthesis level is V2 = VAC2 + VDC2 - (2) V AC2 determines the pincushion distortion correction interval, and V DC2 determines the horizontal amplitude. These V AC2 and V DC2
and VACl and VDCI at input parabolic signal V1
Expressing the relationship using resistors R1, R2 and power supply voltage Vcc, substituting these equations (3) and (4) into (2), further substituting equation (5) into (1), xts...(6) Therefore, (
From equation 6), it can be seen that by varying the AC component VACI of signal C, the amount of correction for pincushion distortion changes, and by varying the DC component V DCI, the horizontal amplitude changes.

In this way, the screen size can be adjusted so that the vertical amplitude and the horizontal amplitude change at the same rate.

In the horizontal output circuit, at the start of the deflection operation, both the diodes DI and D2 become conductive, and the voltage VB is accumulated in the capacitor C1 and the voltage V2 is accumulated in C2.

After that, if V2 is smaller than ■8, the diode D
1 is conductive and deflection current iY flows, and when v2 is larger than VB, D2 is conductive and deflection current iY flows. Then, at the end of the scanning period when transistor Q2 is turned off, l)1
, [)2 are both turned off, and equal voltages are accumulated in each capacitor C3 and C4.

As a result, the retrace pulse levels generated by the resonance operation are made equal, and a stable anode voltage is obtained.

By the way, FIG. 5 is an explanatory diagram for explaining left and right pincushion distortion. In FIG. 5, WV indicates the vertical amplitude and Wll indicates the horizontal amplitude. If LO is the distance from the deflection center O to the fluorescent surface, the left-right pincushion distortion amount ΔWH is expressed as follows.

Considering that the ratio (K1) of the vertical amplitude WV and the horizontal amplitude W11 is always constant (usually 3:4), Wv == k 1
- Wll ・(8), so
By substituting equation (8) into equation (7), it is obtained. Equation (9) shows that if you adjust the screen size while keeping the ratio of horizontal amplitude and vertical amplitude constant, the left and right pincushion distortion will increase or decrease in proportion to the cube of the horizontal amplitude, and when adjusted to a certain size, the correction will not be appropriate. Even if it was, there was a drawback that the distortion would increase when adjusted to another nice setting.

(Problem to be Solved by the Invention) In conventional deflection circuits, when the screen size is adjusted, the amount of correction for pincushion distortion increases or decreases in proportion to the cube of the horizontal amplitude, and correct correction may not be corrected depending on how nice the screen is. There was a problem with putting it away.

It is an object of the present invention to provide a pincushion distortion correction circuit which eliminates the above-mentioned problems and allows pincushion distortion correction to be performed normally regardless of screen size adjustment.

[Structure of the Invention] (Means for Solving the Problems) This invention applies a power supply voltage to one end of a horizontal deflection coil via a power supply coil, and connects the other end of this coil to a first capacitor, an amplitude adjustment coil, and a power supply coil. a horizontal output circuit having a load circuit connected to a reference potential point via a series connection of a second capacitor; a parabolic signal generating means for generating a parabolic signal with a vertical period; and amplifying the parabolic signal from the parabolic signal generating means. and a gain control means for controlling the gain of this transistor with a voltage that is the third power of a voltage proportional to the DC component of the parabolic signal, depending on the screen size. This is so that the pincushion distortion correction can be done properly.

(Function) Since the DC voltage of the vertically periodic parabolic signal is a scalar that adjusts the horizontal amplitude, this 0 current voltage is 3
By amplifying the parabolic signal amplifying transistor using the multiplied voltage, the amplification gain of the parabolic signal amplifying transistor can be made proportional to the DC voltage of the parabolic signal, and the amplitude of the parabolic signal changes according to the horizontal amplitude. The pincushion distortion correction is controlled to an appropriate correction amount according to the horizontal amplitude.

(Example) The present invention will be explained below with reference to illustrated embodiments.

FIG. 1 is a circuit diagram showing an embodiment of the left and right pincushion distortion correction circuit according to the present invention.

In FIG. 1, the same components as in FIGS. 2 and 3 are given the same reference numerals. 12 is a microcomputer, and 17 is a parabolic signal generation circuit that generates a parabolic signal with a vertical period whose DC voltage level is varied according to data b from the microcomputer 12.

The signal v1 from the parabolic signal generation circuit 17 is led from the base to the collector of the amplification transistor Q1.

The transistor Q1 has an emitter connected to a reference potential point via a resistor R1, and a collector connected to a voltage source terminal Vcc via a resistor R2. In this embodiment, the amplitude of the parabolic signal output from the collector is controlled by changing the voltage gain of the transistor Q1 by applying a voltage that is the cube of the DC component of the parabolic signal to the emitter of the transistor Q1. It is something.

That is, the signal from the parabolic signal generation circuit 17 is supplied to a low-pass filter 22, and this filter 22 extracts the DC component VDC1 of the parabolic signal qV1. Next, the DC component VDC1 obtains a voltage VOCl3 whose voltage value is raised to the third power in the 3-east circuit 23. Then, this voltage is led out from the base of the variable gain transistor Q3 of Ql to the collector,
Further, the voltage is applied to the emitter of the transistor Q1 through a parallel connection of a resistor R4 and a capacitor C5.

Note that Q2 is a horizontal output transistor, and coil L3
It is driven by the power supply voltage from the voltage source terminal VB supplied via the voltage source terminal VB. Horizontal deflection coil LY, capacitor C1
, a series circuit consisting of coil 2 and capacitor C2 is:
It is connected in series with the coil L3 that guides the electric current m voltage, and forms a load circuit for the transistor Q2. In addition, in the series connection of the deflection coil 1y and the capacitor C1, the parallel connection of the diode D2 and the capacitor C4 is connected to the coil L
A diode D1 and a capacitor C3 are connected in parallel to the series connection of the diode D1 and the capacitor C2, respectively.

This embodiment has the above configuration, so that the amplitude of the parabolic signal supplied to the capacitor C2 is
Since it can be varied by a voltage proportional to the cube of the DC voltage adjusted by data b, the amount of correction for pincushion distortion can be made proportional to the cube of the horizontal amplitude, and the screen size can be changed freely. Also, correct pincushion distortion correction can be performed.

Now, if the resistance between the collector and emitter of the transistor Q3 is RCE, this resistance value is inversely proportional to the voltage VDC1:l which is proportional to the cube of VDC1. From now on, RCE
and V DCI can be expressed as follows, with R2 being a constant. Also, since VDCI is proportional to the horizontal amplitude Wl, equation (10) is: RCE-R3 W113 °-(11) However, (V
OCl − to 2′ −WitK3=! S-! −
, k2'-constant).

R2.

Further, the voltage gain @aV of the transistor Q3 is as follows, assuming that all the alternating current components flow to the capacitor C5, and assuming that the impedance of the capacitor C5 is approximately zero ohm, av = R3-1-R4-WH3''. (12), so the alternating current of the output voltage of transistor Q1 V AC2
is VAC2-R3-1-R4-VACl-WH3=4
・W[13...(13) However, L/ (3-1-R4-VACl for R4-).

Therefore, V AC2 is proportional to the correction amount of the left and right pincushion distortion, and the left and right pincushion distortion is proportional to the cube of the horizontal amplitude.From this, it is possible to correctly correct the left and right pincushion distortion, which is proportional to the cube of the horizontal amplitude. becomes possible.

Note that the above-mentioned embodiment is merely an example, and various modifications can be made without departing from the scope of the claims.

[Effects of the Invention] As explained above, according to the present invention, it is possible to correct the left-right pincushion distortion that is proportional to the cube of the horizontal amplitude that occurs when adjusting the screen size, so it is possible to adjust the screen size without pincushion distortion. - It has a beneficial effect.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an embodiment of the left and right pincushion distortion correction circuit according to the present invention, Fig. 2 is a block diagram showing a configuration for freely adjusting the screen size, and Fig. 3 is a conventional pincushion distortion correction circuit. FIG. 4 is a waveform diagram for explaining the operation of FIG. 3, and FIG. 5 is an explanatory diagram for explaining pincushion distortion. 12... Microcomputer, 17... Parabolic signal generation circuit, 18... Parabolic signal amplification circuit, 19... Horizontal output circuit, 22... Low pass filter, 23... Cubic circuit, Ql. ...Amplification transistor, C2...Horizontal output transistor, C3...Variable gain transistor, R1, R2. R4...Resistance, C5...Condenser. Figure 1 Figure 4

Claims (1)

[Claims] A power supply voltage is applied to one end of the horizontal deflection coil via the coil, and the other end of the horizontal deflection coil is referenced via a series connection of a first capacitor, an amplitude adjustment coil, and a second capacitor. a horizontal output circuit having a load circuit connected to a potential point; a parabolic signal generating means for generating a parabolic signal with a vertical period; a parabolic signal from the parabolic signal generating means, amplified and applied to the second capacitor; It is characterized by comprising: an amplification transistor that modulates the deflection current flowing through the horizontal deflection coil; and gain control means that controls the gain of this transistor with a voltage that is the third power of a voltage that is proportional to the DC component of the parabolic signal. Left and right pincushion distortion correction circuit.