JPH0614754B2 - Horizontal center-position adjustment circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described below in the following order.

A. Industrial application fields B. SUMMARY OF THE INVENTION C. Conventional Technology D. Problems to be Solved by the Invention E. Means for Solving Problems F. Action G. Example G-1. Configuration of this embodiment (FIGS. 3 and 4) G-2. Configuration of Horizontal Center Position Adjusting Circuit (Fig. 1) G-3. Operation of the horizontal center position adjusting circuit (FIGS. 1 and 2) Effect of Invention A. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a horizontal center position adjusting circuit for a picture tube used in a color television receiver or the like.

B. SUMMARY OF THE INVENTION According to the present invention, at least one beam position detecting means is provided at each of the left and right ends of a screen inside a picture tube, and a horizontal deflection coil is operated based on an index signal from the beam position detecting means obtained by scanning an electron beam. The horizontal center position is automatically adjusted by controlling the current.

C. 2. Description of the Related Art Generally, in a color television receiver, the screen size may be slightly affected by the fluctuation of the high voltage of the picture tube due to the change of the brightness, and the raster may be affected by the geomagnetism, etc. Be done.

In addition, when the screen size or raster of the picture tube changes in this way, the red, green, and blue primary color signals are switched and supplied to the picture tube based on the output signal that detects the scanning state of the electron beam. In a beam index type color television receiver that reproduces a color image, the switching timing may deviate, resulting in a phenomenon such as a decrease in contrast or color misregistration.

Therefore, it is necessary to eliminate the phenomenon such as the color shift described above by correcting the scanning beam, that is, correcting the horizontal deflection.

The applicant of the present application has previously applied for a horizontal center position adjusting circuit for correcting such horizontal deflection (Japanese Patent Application No. 56-83022).

Further, in a beam index type color television receiver, it is general to perform horizontal center position adjustment, horizontal amplitude adjustment and the like using an index signal.

For example, as shown in FIG. 5, the index stripe 5b is arranged in a wider area than the effective screen 5a, and the horizontal synchronizing pulse H
Adjusting the horizontal center position and the horizontal amplitude by making the time t ₁ from BLK to the start point of the index signal SI or the sum of this time t ₁ and the time t ₂ from the start point of the index signal SI to the end point of the effective screen constant. Adjustments are being made.

D. Invention, as this would to problems solved, the time t ₁ from the horizontal sync pulse HBLK to the start point of the index signal SI or horizontal sync pulse end point of the effective screen from HBLK, to the _time, (t ₁ +
t ₂ ) is detected and is controlled to be constant,
The time t ₁ or (t ₁ + t ₂ ) is changed by the fluctuation of the horizontal amplitude and the fluctuation of the horizontal center position. Therefore, the operation of the horizontal amplitude adjusting circuit and the operation of the horizontal center position adjusting circuit affect each other, and there arises a problem that the stability of control deteriorates.

An object of the present invention is to provide a horizontal center position adjusting circuit which solves this problem and has improved stability.

E. Means for Solving the Problems In order to solve the above-mentioned problems, according to the present invention, at least one beam position detecting means provided at each of the left and right ends of the screen inside the picture tube and the scanning start side from the horizontal synchronizing signal. Detecting means for detecting the difference between the time to the index signal obtained by the beam position detecting means and the time from the index signal obtained by the beam position detecting means on the scanning end side to the next horizontal synchronizing signal; A horizontal center position adjusting circuit is configured by including control means for controlling the current of the horizontal deflection coil according to the detection level.

F. In the horizontal center position adjusting circuit of the present invention, the control means controls the current of the horizontal deflection coil so that the time difference becomes smaller according to the detection level of the time difference obtained by the detecting means. As a result, the position of the horizontal center is stabilized.

G. Embodiment An embodiment in which the present invention is applied to a beam index type color television receiver will be described below with reference to the drawings.

G-1. Configuration of this Embodiment (FIGS. 3 and 4) FIG. 3 is a block diagram showing the configuration of this embodiment. In the figure, the picture tube 31 is of the beam index type, and an index stripe 4b for obtaining the index signal SI is formed inside the tube surface as shown in FIG. The index stripe 4b is wider than the effective screen 4a, and the run-in section 4 is provided on the horizontal scanning start side.
c, the runout section 4d is provided on the horizontal scanning end side.

The index signal SI is used to form a timing pulse for switching the red, green, and blue primary color signals at a predetermined timing. That is, the index signal S
I is detected by the detector 32, and the bandpass filter B
It is input to the phase locked loop PLL 34 via the PF 33.
A clock of a predetermined frequency synchronized with the index signal is supplied from the phase synchronization circuit PLL34 to the ring counter 3
5 is supplied.

The ring counter 35 outputs timing pulses CR, CG, CB for sequentially switching the R, G, B signals of the switch circuit 36 to which the red R, green G, blue B signals are supplied.

The output signal of the switch circuit 36 is supplied to the picture tube 31 via the video amplifier 37, and a color image is reproduced.

The index signal SI is also used in the horizontal center position adjusting circuit 1 according to the present invention. That is, the index signal SI that has passed through the band pass filter 33 is digitized by the A / D converter 39 and then supplied to the horizontal center position adjustment circuit 1 through the pulse processing circuit 40. The signal output from the pulse processing circuit 40 is a run-in pulse RI indicating the beginning of the run-in unit 4c.
Becomes

Further, based on the timing pulse CB output from the ring counter 35, the counter 42 supplies the run-out pulse RO indicating the head of the run-out section 4d to the horizontal center position adjusting circuit 1.

The horizontal center position adjusting circuit 1 includes the run-in pulse RI, the run-out pulse RO and the horizontal synchronizing pulse H.
The horizontal deflection coil HDY38 according to the level of the horizontal center detection circuit 1a to which BLK is supplied and the detection signal corresponding to the shift of the horizontal center detected by the detection circuit 1a.
It comprises a horizontal center output circuit 1b for controlling the current.

G-2. Configuration of Horizontal Center Position Adjusting Circuit (FIG. 1) FIG. 1 is a circuit diagram of the horizontal center position adjusting circuit 1. The circuit 1 determines the time from the horizontal synchronizing pulse HBLK to the run impulse RI as t ₁ , and the run impulse RI.
From the runout pulse RO to t ₂ and the time from the runout pulse RO to the next horizontal synchronizing pulse HBLK is t ₃ , (t ₁ −t ₃ ) is detected, and the horizontal deflection is detected according to the detection result. The position of the horizontal center is adjusted by controlling the current of the coil HDY38. Further, as described above, the horizontal center position adjusting circuit 1 detects the above-mentioned (t ₁ -t ₃ ).
a and a horizontal center output circuit 1 for controlling the current of the horizontal deflection coil HDY38 according to the output of the detection circuit 1a.
b.

The above (t ₁ -t ₃ ) is (t ₁ -t ₃ ) = 0 when the horizontal center is not displaced, and the horizontal center is displaced to the right when viewed from the front of the picture tube (t _1). -T ₃ )
> 0, when it is shifted to the left (t ₁ −t ₃ ) <0.

The horizontal center detection circuit 1a is a logic IC (Inteer) such as D flip-flops 6, 7, an inverter 8, and a NOR 9.
grated circuits) and differential amplifiers 3,
4 and 5, transistors TR11 and TR12 used for controlling the differential amplifiers 3 and 4, and the like.

The output terminals of both the D flip-flops 6 and 7 are fed back to the input D terminal, and the output is inverted each time a pulse is applied to the clock input CK. Further, when the reset terminal becomes "L", the output is reset.

The clock input CK terminal of the D flip-flop 6 is supplied with the run-in pulse RI, and the reset terminal is supplied with the run-out pulse RO. The output Q of the D flip-flop 6 is supplied to the input of the inverter 8 and one input of the NOR 9. Inverter 8
Is supplied to the reset terminal of the D-type flip-flop 7.

The horizontal synchronizing pulse HBLK is supplied to the clock input CK terminal of the D flip-flop 7 and the other input terminal of the NOR 9, and is also supplied to the base of the transistor TR12 via the resistor R5.

The output Q of the D flip-flop 7 is a transistor TR.
The transistor T of the differential amplifier 3 composed of 1 and TR2.
Supplied to the base of R1. The differential amplifier 3 has an active load composed of transistors TR3 and TR4, and a power source E1 for determining an operating point is connected to the base of the transistor TR2.

The emitters of the transistors TR1 and TR2 are commonly connected and connected to the collector of the transistor TR11 via a resistor R6.

The emitter of the transistor TR11 is grounded, and the base is grounded via the resistor R7. Further, the output of the NOR circuit 9 is supplied to the base via the resistor R8.

The output of the differential amplifier 3 is the transistors TR5 and TR6.
Is supplied to the differential amplifier 4. The differential amplifier 4 has an active load composed of transistors TR7 and TR8. The base of the transistor TR5 is connected to the collector of the transistor TR2, and the capacitor C1 whose one end is grounded is connected to the base of the transistor TR5.
The transistor TR6 has a base and a collector connected to each other, and a capacitor C having one end grounded to the base.
2 is connected. The transistors TR5 and TR6
The emitters of are connected in common and are connected to the collector of the transistor TR12 via the resistor R3. The transistor TR12 has its emitter grounded and its base grounded via a resistor R4.

The outputs of the differential amplifier 4 are transistors TR9 and TR1.
0 is supplied to the differential amplifier 5. That is, the collector of the transistor TR6 and the transistor T
The base of R9 is connected. The differential amplifier 5 has a constant current circuit Ic on the emitter side of the transistors TR9, TR10 and load resistors R1, R2 on the collector side. A power source E2 for determining an operating point is connected to the base of the transistor TR10. The detection signal DHC is supplied from the collector of the transistor TR9 to the horizontal center output circuit 1b.

The horizontal center output circuit 1b includes transistors TR23 and TR2 controlled by the horizontal amplitude correction signal HSC, for example.
The voltage is supplied via 4 and the transformer T1. Further, a voltage is supplied to the transistor TR22 of the horizontal output circuit 42 via the primary side of the transformer T1. The horizontal deflection coil HDY38 and the compensation capacitor Cs are connected in series between the collector and the emitter of the transistor TR22.

Both ends of the secondary side of the transformer T1 are diodes D2 and D
3 is connected to the collectors of the transistors TR20 and TR21 respectively, the midpoint terminal is connected to the primary side, and the midpoint of the series circuit of the capacitors C22 and C23 connected between the collectors of the transistors TR20 and TR21. Is also connected to.

The bases of the transistors TR20 and TR21 are commonly connected and the detection signal DHC is supplied. The emitters of the transistors TR20 and TR21 are commonly connected, and are connected to the connection point between the horizontal deflection coil HDY38 and the compensation capacitor Cs via the coil L1 and the resistor R20.

Horizontal center output circuit 1b, the above _(t 1 _-T 3)
The current of the horizontal deflection coil HDY38 is corrected by controlling the voltage at the connection point between the horizontal deflection coil HDY38 and the compensation capacitor Cs in accordance with the detection signal DHC corresponding to.

G-3. Operation of Horizontal Sensor Position Adjustment Rotation FIG. 2 is a timing chart of the horizontal center detection circuit 1a. As shown in the figure, the horizontal synchronizing pulse H
BLK is a stable signal with a cycle th. On the other hand, the run-in pulse RI and the run-out pulse RO may change due to the shift of the horizontal center.

The D flip-flop 6 generates an output pulse HINDX which becomes "L" by the run-out pulse RO and becomes "H" by the run-in pulse RI as shown in FIG.

The D flip-flop 7 outputs the output pulse HINDX.
Is supplied to the reset terminal through the inverter 8 and operates for the clock CK input only during the period when the output pulse HINDX is "L", and thus becomes "H" at the rising of the horizontal synchronizing pulse HBLK. The output pulse HFRNT which becomes "L" at the rising edge of the output pulse HINDX is generated and supplied to the differential amplifier 3.

The NOR circuit 9 generates an output pulse NOR which becomes "H" when both the horizontal synchronizing pulse HBLK and the output pulse HINDX are "L", and supplies the output pulse NOR to the transistor TR11 via the resistor R8.

Since the transistor TR11 is on during the period when the output pulse NOR is "H", the differential amplifier 3 can operate.

As shown in the figure, the time t ₁ from the fall of the horizontal synchronizing pulse HBLK to the rise of the line pulse RI.
Is in the “H” part of the output pulse HFRN, and the time t ₃ from the fall of the runout pulse RO to the rising of the next horizontal synchronizing pulse HBLK is in the “L” part of the output pulse HFRNT.

The transistor TR1 from the time _{t 1} in the output pulse HFRNT is "H" is in the operating state. Since the voltage of the power source E1 is set lower than the voltage of the "H" level, the transistor TR2 does not operate and is turned off. On the other hand, the transistors TR3 and TR4 forming the active load are in the operating state because the bias current flows through the transistor TR1. Therefore, the capacitor C1 is charged through the transistor TR4, and its voltage gradually rises during this period. After the time _{t 1} has elapsed, the output pulse HINDX the above for the transistor TR11 in the "H" at a time _{t 2} is turned off transistors TR1, TR2, TR3, TR4
The voltage of the capacitor C1 becomes off are kept constant V _1. This voltage value V ₁ corresponds to the time t ₁ .

In the time t ₃ when the differential amplifier 3 is then becomes operable, the output pulse HFRNT is the transistor TR1 from an "L" is turned off. On the other hand, the transistor TR2 is in the operating state because the bias current is supplied from the power source E1. Therefore, the voltage of the capacitor C1 is discharged through the transistor TR2, the resistor R6, and the transistor TR11, so that the voltage gradually decreases. This reduced voltage V ₂ corresponds to the time t ₃ .
Voltage _{V 3} in the time _{t 3} has elapsed after the capacitor C1 becomes to correspond to the difference _(V 1 -V _3), and the said time _{t 1} and _{t 2.}

This voltage V ₃ is applied to the differential amplifier 4 and the capacitor C
2, immediately after the time _{t 3} by the transistor TR12 and the like, the horizontal sync pulse HBLK is sampled and held during the period of "H". That is, while the horizontal synchronizing pulse HBLK is "H", the transistor TR12 is
Is turned on, the differential amplifier 4 becomes operable.
At this time, the voltage of the capacitor C2 is
When the voltage is lower than 1, the TR6 is turned off and the transistors TR5, TR7 and TR8 are in the operating state,
Via the transistor TR8, the capacitor C2 is charged until its voltage becomes equal to the voltage of the capacitor C1.

On the contrary, the voltage of the capacitor C2 is equal to that of the capacitor C1.
If the voltage is higher than the voltage of
R7 and TR8 are turned off, the transistor TR6 is activated, and the voltage of the capacitor C2 is the capacitor C2 via the transistor TR6 and the resistor R3.
Discharge until it becomes equal to 1.

Therefore, the voltage of the capacitor C2 is obtained by sampling and holding the voltage of the capacitor C1 while the horizontal synchronizing pulse HBLK is "H" as shown in FIG. Since this voltage corresponds to the above-mentioned (t ₁ -t ₃ ), it changes in accordance with the fluctuations of the run-in pulse RI and the run-out pulse RO, that is, the shift of the horizontal center, and it passes through the differential amplifier 5. Is supplied as a detection signal DHC to the horizontal center output circuit 1b, and the current of the horizontal deflection coil HDY38 is corrected.

Thus the horizontal center position adjustment circuit 1 in accordance with the detection signal DHC corresponding to the above _{(t 1 -t 3), (} t 1 -t 3) becomes smaller as the correction of the current of the horizontal deflection coil HDY38 Therefore, (t ₁ −t
₃ ) = 0, that is, the horizontal center can be kept stable at a predetermined position.

Incidentally, the horizontal position adjusting circuit 1 described above _(t 1 _-t 3)
Is detected and the position of the horizontal center is adjusted. Therefore, for example, even if the horizontal amplitude is changed by a horizontal amplitude adjusting circuit, the above (t ₁ -t ₃ ) is not affected. Therefore, the horizontal center position adjusting circuit and the horizontal amplitude adjusting circuit can operate independently of each other, and the stability of the horizontal center adjusting circuit 1 is improved. As a result, in the beam index type color television receiver to which the present invention is applied, color misregistration or the like due to the fluctuation of the horizontal center is suppressed.

H. As described above, according to the present invention, since the horizontal center position adjusting circuit can be operated independently of the horizontal amplitude adjusting circuit, the horizontal center position adjusting circuit with improved stability can be obtained. Therefore, as shown in the embodiment, in the beam index type color television receiver to which the present invention is applied, color shift and the like due to the fluctuation of the horizontal center are suppressed.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a horizontal center position adjusting circuit according to the present invention, and FIG. 2 is a timing chart for explaining the operation of a horizontal center detecting circuit which constitutes the above circuit. FIG. 3 is a block diagram of the present embodiment in which the present invention is applied to a beam index type color television receiver, and FIG. 4 is a schematic view of index stripes provided on a picture tube of the above-mentioned receiver. FIG. 5 is a diagram for explaining a conventional horizontal center position adjustment method. 1 ... Horizontal center position adjusting circuit 1a ... Horizontal center detecting circuit 1b ... Horizontal center output circuit 3, 4, 5 ... Differential amplifier 6, 7 ... D flip-flop 8 ... Inverter 9 ... NOR TR1, TR2 ... TR11 ... Transistors TR20, TR21, TR22, TR23, TR24 ...
... Transistors R1, R2 ... R8 ... Resistors R20 ... Resistors C1, C2, C22, C23, Cs ... Capacitors E1, E1 ... Power supplies D2, D3 ... Diodes T1 ... Transformer L1 ... Coil 31 ... Image reception Tube 32 ...... Detector 33 ...... Band pass filter 34 ...... Phase synchronization circuit 35 ...... Ring counter 36 ...... Switch circuit 37 ...... Video amplifier 38 ...... Horizontal deflection coil 39 ...... A / D converter 40 ...... Pulse processing circuit

Claims (1)

[Claims] 1. At least one beam position detecting means provided at the left and right ends of the screen inside the picture tube, and a time from a horizontal synchronizing signal to an index signal obtained by the beam position detecting means on the scanning start side. A means for detecting the difference between the index signal obtained by the beam position detecting means on the scanning end side and the time from the next horizontal synchronizing signal, and a control for controlling the current of the horizontal deflection coil in accordance with the detection level of the detecting means. Means for controlling the horizontal center position by stabilizing the horizontal center position by controlling the control means to reduce the time difference.