JP3257439B2 - Horizontal position adjustment circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a horizontal position adjusting circuit used for a television receiver.

[0002]

2. Description of the Related Art FIG. 3 is a block diagram showing a conventional horizontal position adjusting circuit. Further, symbols in FIG. 4 and FIG. 5 (a) ~
Each signal waveform of (l) is represented by symbols (a) to (a) in FIG.
For the signal (l), the horizontal axis represents time and the vertical axis represents voltage.
It is shown .

In FIG. 3, a video signal (a) is input from an input terminal 1 to a synchronization separation circuit 2, and a horizontal synchronization signal (b) separated from the synchronization is output from the synchronization separation circuit 2. The horizontal synchronizing signal (b) is input to the first phase detection circuit 3, while a horizontal period pulse signal (c) is output from the horizontal division circuit 5 at the subsequent stage and applied to the first phase detection circuit 3. Is done. The first phase detection circuit 3 compares the phase difference between the horizontal synchronizing signal (b) and the pulse signal (c) of the horizontal cycle, and outputs a signal corresponding to the phase difference. Control the oscillation frequency of the voltage controlled oscillator 4 by a signal corresponding to the phase difference
Ru is. By inputting the output signal of the voltage controlled oscillator 4 to the horizontal frequency dividing circuit 5, a pulse signal (d) synchronized with the video signal (a) and having a different phase from the pulse (c) of the horizontal cycle is output horizontally. Output from the frequency dividing circuit 5. A pulse signal (c) having a horizontal period is applied to one input terminal of a second phase detection circuit 6 having an input terminal pair, and the other input terminal is supplied with a flyback pulse (from a horizontal output circuit 9 at a subsequent stage). h) is input and a pulse signal (c) having a horizontal cycle
And the flyback pulse (h) is detected, and a detection current (i) corresponding to the phase difference is output. The detection current (i) is charged to the capacitor 12 via the pin 13, and this charging generates a phase control voltage V 1 between the terminals of the capacitor 12. Here, the pin 13 is defined as a package pin in the integrated circuit.

Next, the pulse signal (d) is supplied to, for example, two capacitors separately provided inside the phase shift circuit 7.
The signal is converted into two sawtooth signals having a solid waveform (e1) and a broken waveform (e2). The two sawtooth signals (e
1) and (e2) are input to a comparator (not shown ) and individually compared with the phase control voltage V1 generated in the capacitor 12, thereby obtaining the sawtooth signal (e) shown in FIG.
1) and (e2) corresponding to the predetermined voltage V1 of each slope.
Horizontal pulse signal having a rising and falling edge (f) is generated and Eject from the horizontal driving circuit 8.
A flyback pulse (h1) is output from the horizontal output circuit 9 according to the horizontal pulse signal (f).

Next, how to change the horizontal position will be described. The control current generation circuit 10 outputs a constant current (j) that can be set to an arbitrary value. By adding the constant current (j) to the detection current (i), the voltage increases as shown in the waveform (l). As a result, the phase control voltage generated in the capacitor 12 becomes the voltage before the constant current flows. The voltage rises to V2 after flowing from V1. The voltage comparison voltage as indicated by the signal waveform (e) by providing a phase shift circuit 7 is increased, the horizontal pulse signal (f) is the horizontal pulse signal (g) next to Δt only the phase is shifted, thereby
Delayed by a time Δt to the flyback pulse which is the output signal of the horizontal output circuit 9 (h) also flyback pulse shown from the solid line of the flyback pulse (h1) by the broken line (h2). As a result, the television screen moves from right to left
It moves according to the interval Δt.

A case where the capacitor 12 is built in an integrated circuit device will be described. When mounting on a printed circuit board, the choice of capacitor value
A capacitor of about 000 pF is also adopted as a value in a normal selection range. The maximum current value of the phase detection current can be designed to be, for example, 80 μA, and the output current of the control current generation circuit 10 can be designed to be 2.5 μA, corresponding to the value of this capacitor. On the other hand, the value of a capacitor that can be adopted by an integrated circuit device is limited by the area of a chip of the integrated circuit device and the like, and usually 100 pF is adopted as a large-capacity capacitor. If the value of this capacitor is adopted,
The maximum value of the phase detection current is set to about 1/50 of 1.6 μA and the time constant
I need to tell you . Further, the output current of the control current generation circuit 10 also needs to be about 1/50, and the current value in this case is 50 nA.

[0007]

Conventionally, in a horizontal position adjusting circuit used in a television receiver, in order to avoid the influence of a leak current or the like in an IC and to control a horizontal position stably, a leak current is required. Of control current due to presence of
A relatively large capacitor of 100 pF was required to absorb the voltage fluctuation of the path 10 . In order to employ a large-capacity capacitor in an integrated circuit device, a large area corresponding to the value is required. However, a large area tends to cause deterioration of characteristics such as a lapse of capacity over time.

Further, the leakage current at the junction of a transistor in a silicon substrate changes depending on temperature fluctuations, and the operating temperature of the transistor may increase to about 1 nA at 100 ° C. FIG. 6 shows a leakage current I flowing from the collector to the emitter when a voltage V is applied to the collector of the transistor whose base is grounded using the operating temperature as a parameter.
It is a thing . In addition , this leakage current includes a factor of variation in characteristics at the time of manufacturing, and at least 10 n in order to secure a stable operation of the circuit at an operating temperature of 100 ° C. or less.
It is necessary to assume a leakage current of about A for each transistor .

The present invention has been made to solve the above-mentioned conventional problems, and integrates a capacitor for generating a phase control voltage with a relatively small area, and stabilizes a horizontal current stably with respect to a leakage current of a transistor connected to the capacitor. An object of the present invention is to provide a horizontal position adjustment circuit capable of controlling a position.

[0010]

In order to achieve this object, in a horizontal position adjusting circuit according to the present invention, a first horizontal period signal synchronized with a horizontal synchronizing signal of a video signal at a first phase is provided.
Flyback pulse signal applied from pulse signals and the external
The door and the phase comparator and the phase detector circuit for outputting a phase error signal corresponding to the phase difference between the two signals, and a capacitor for outputting the phase smoothed phase control signal voltage by inputting an error signal, a predetermined A control current generating circuit for generating and outputting a DC current having a value, and the DC current of the control current generating circuit.
Current to supply current to the capacitor intermittently.
Stream switching means, and a second synchronization signal for the video signal .
A second horizontal period pulse signal synchronized with the phase of
A control signal voltage and a second horizontal period pulse signal
A third phase delayed in accordance with the phase control signal voltage value;
A phase shift circuit for outputting a horizontal period pulse signal, the
3 and horizontal driving circuit to input horizontal period pulse signal and generates and outputs a horizontal pulse signal, a horizontal output circuit for generating and outputting a flyback pulse signal by inputting the horizontal pulse signal, the horizontal output The flyback of the circuit
Pulse signal to the phase detection circuit and the current switching means.
Signal transmitting means for providing the flyback pulse.
The current switching means supplies a current to the capacitor during a signal period.
The characteristic is to give .

By providing switching means for transmitting the output current of the control current generation circuit to the phase control voltage generation capacitor only during the flyback pulse, the DC current value of the DC current generation circuit can be set to a predetermined time average value. Thus, a high current value can be adopted according to the ratio between the horizontal video period and the period synchronized with the flyback pulse. In this manner, a horizontal position adjustment circuit that can control the horizontal position stably without being affected by the leak current is obtained.

[0012]

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

FIG. 1 is a block diagram showing a horizontal position adjusting circuit according to one embodiment, and FIG. 2 is a signal waveform diagram showing signal waveforms of main parts of FIG. 1, parts having the same functions as in FIG. 3 are denoted by the same reference numerals as in FIG. 3, and the same signals are denoted by the same reference numerals. FIG.
The same signals as those in FIG. 5 are given the same symbols.

Here, reference numeral 11 denotes current switching means for flowing the output current of the control current generating circuit 10 to the phase control voltage generating capacitor 12 only during the flyback pulse (h) which is the output of the horizontal output circuit 9. .

[0015] In FIG. 1, the pulse signal of one horizontal period which is the output of the horizontal dividing circuit 5 to the input terminal of the second phase detecting circuit 6 (c) is input, the horizontal output to another input terminal <br The flyback pulse (h) output from the circuit 9 is input. Here, the phases are compared, and a detection current (i) corresponding to the phase difference between the pulse signal (c) of the horizontal cycle and the flyback pulse (h) is output from the second phase detection circuit 6.
Further, from the control current generating circuit 10 is output set to an arbitrary value can be a constant current for the horizontal position variable (j), the current
It is input to the switching means 11. Here, the inputted flyback pulse from the horizontal output circuit 9 (h) is the current switching means 11, a constant current from the output terminal of the current switching means 11 (j)
Are intermittently switched to output a pulse-like phase control current (k). A control voltage (l) resulting from the addition of the detection current (i) and the pulse-like phase control current (k) is generated in the capacitor 12 for generating a phase control voltage. Increases the average voltage as shown in (l) of FIG. 2, only the increase, the phase control voltage increases, the horizontal pulse which is the output of the horizontal driving circuit 8, the waveform of (f) in FIG. 4 same
The phase is shifted as shown in FIG.

Since the constant current (j) which can be arbitrarily set for varying the horizontal position flows into the capacitor 12 for generating the phase control voltage only during the flyback pulse, the control current flows during the entire horizontal period of about 64 μs. On the other hand, since the control current flowing for adjusting the horizontal position during the flyback pulse period of 11 μs is 64 ÷ 11 = 5.8 , it is possible to flow 5.8 times.

As described above, the control current value of 50 nA when the current flows in the entire horizontal period is about 5.8 times that of the control current value of about 300 nA.
And a sufficiently stable current can be handled with respect to a value of 10 nA which is considered to be present as a leak current.

[0018]

As described above, according to the present invention, the current switching for flowing the control current at the horizontal position only during the flyback pulse period is performed.
By providing exchange means, for adjusting the stable horizontal position
And an excellent horizontal position adjustment circuit capable of realizing the same.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a horizontal position adjustment circuit according to an embodiment of the present invention;

FIG. 2 is a signal waveform diagram of a main part of FIG. 1;

FIG. 3 is a block diagram showing a conventional horizontal position adjustment circuit.

FIG. 4 is a waveform chart showing waveforms of signals of respective parts in FIG. 3;

FIG. 5 is a waveform chart showing signal waveforms of respective parts in FIG. 3;

FIG. 6 is a diagram showing a leakage current of a transistor;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Video signal input terminal 2 Synchronous separation circuit 3 First phase detection circuit 4 Voltage controlled oscillator 5 Horizontal frequency divider 6 Second phase detection circuit 7 Phase shift circuit 8 Horizontal drive circuit 9 Horizontal output circuit 10 Control current generation circuit 11 Current switching means 12 Capacitor 13 Pin

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Nobuo Takeya 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (56) References JP-A-1-114167 (JP, A) JP-A-5-37798 (JP, A) JP-A-62-1588 (JP, A) JP-A-61-283278 (JP, A) Hikaru Hei 3-48968 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04N 3/227

Claims (1)

(57) [Claims] An externally supplied first horizontal period pulse signal synchronized with a horizontal synchronization signal of a video signal at a first phase.
Phase comparison with the flyback pulse signal
Of a phase detector circuit for outputting a phase error signal corresponding to the phase difference, and a capacitor for outputting to input the phase error signal is smoothed phase control signal <br/> voltage, a direct current of a predetermined value A control current generating circuit that generates and outputs the current; a current switching unit that inputs the DC current of the control current generating circuit to intermittently supply a current to the capacitor ; A second horizontal period pulse signal synchronized with a phase and the phase control signal voltage are input, and the phase of the second horizontal period pulse signal is changed to the phase
The third horizontal period pulse delayed according to the control signal voltage value
A phase shift circuit for outputting a scan signal, a horizontal drive circuit for generating and outputting a horizontal pulse signal by inputting a third horizontal period pulse signal, flyback pulse signal by inputting the horizontal pulse signal
A horizontal output circuit for generating and outputting, the said flyback pulse signal of the horizontal output circuit
Signal transmission to be applied to a phase detection circuit and the current switching means
And the current switching means during the flyback pulse signal period.
A horizontal position adjusting circuit for applying a current to the capacitor .