JPH0955867A - Horizontal dynamic hocus circuit - Google Patents

Abstract

(57) Abstract: A horizontal dynamic focus circuit having low power consumption and low circuit loss is provided. A horizontal drive pulse (H.DRIVE) is supplied to the base of a transistor Q1. The magnitude of the current value I2 flowing to the secondary side is changed by the current I1 on the primary side from the power supply voltage Vcc that is proportional to the square of the horizontal frequency, and the hocus voltage is kept constant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a horizontal dynamic hocus circuit capable of switching a horizontal amplitude and supplying an optimum hocus voltage to a hocus electrode of a picture tube even when the horizontal amplitude is switched.

[0002]

2. Description of the Related Art The structure of a conventional horizontal dynamic focus circuit is shown in FIG. In FIG. 4, the parabolic voltage Vin of the horizontal period is input to the operational amplifier Q6 and the predetermined voltage V
Converted to O1 and output. This output voltage is determined by the voltage fed back to the inverting terminal. This voltage is determined by the divided voltage value of the resistor R1 and the resistor R2, and the hocus voltage Vp corresponding to the turn ratio is output to the hocus electrode via the transformer T1.

As the input voltage, a parabolic voltage generated across an S-shaped correction capacitor of a horizontal deflection output circuit (not shown) is usually used. Also, the output parabola voltage V
The required level of p can be obtained by adjusting the feedback resistor R1 or R2.

However, the loss in the operational amplifier Q6 is large, and its heat dissipation has been a serious problem. Further, when the horizontal deflection frequency becomes high, there is a problem that the configuration of parts and the like becomes complicated.

[0005]

That is, there is a problem in that the power consumption of the transistor in the output stage (such as the transistor inside the operational amplifier) increases and the loss increases.

Therefore, an object of the present invention is to provide a horizontal dynamic focus circuit which consumes less power and has less circuit loss.

[0007]

In order to achieve the above-mentioned object, the present invention according to claim 1 of the present invention has a base, an emitter and a collector, and a horizontal drive pulse is supplied to the base, Has a transistor in which a commutation diode and a first capacitor are connected in parallel with each other, an emitter is connected to a reference potential point, a primary winding, and a secondary winding, and one end of the primary winding is the transistor A transformer connected to the collector and having an integrating capacitor connected to the secondary winding, and a voltage source for supplying a DC voltage to the other end of the primary winding via a choke coil. It is a feature.

The voltage generated in the integrating capacitor is supplied to the hocus electrode as a hocus voltage,
The transistor is driven by a horizontal drive pulse to obtain a stable voltage. In addition, a commutation diode and a capacitor are provided in parallel with the transistor in order to compensate the switching speed and the collector potential.

Further, in the invention of claim 2, in addition to the invention of claim 1, means for controlling the output voltage of the voltage source is added in order to stabilize the hocus voltage.

Specifically, a means for converting the voltage into a voltage proportional to the square of the horizontal frequency is provided to control the power supply voltage to be supplied.

Further, in the present invention according to claim 5, a feedback control unit is added so as to detect an error in the hocus voltage and obtain an optimum hocus voltage.

Specifically, the feedback control section can control the hocus voltage to an optimum voltage by controlling the base voltage of the comparison circuit and the second NPN transistor.

[0013]

FIG. 1 shows an embodiment of the present invention.
This will be described with reference to FIG. First, the structure of a portion for reducing loss, which is a characteristic portion of the present invention, will be described. Reduction of loss is performed by switching, and this switching is performed by supplying a horizontal drive pulse (H.DRIVE) to the base of the transistor Q1 whose emitter is connected to the reference potential point and whose collector is connected to one end of the transformer T1. Done. The horizontal drive pulse is supplied from the horizontal oscillation circuit, but the horizontal oscillation circuit is omitted in FIG.

A diode D1 for commutation and a capacitor C1 are connected in parallel between the collector of the transistor Q1 and the reference potential point, and the potential of the collector due to switching is compensated.

The other end of the transformer T1 has a choke coil L.
1 is connected to the power supply Vcc via the power supply circuit 1, and the current I1 is supplied from the power supply Vcc to the primary side of the transformer T1. On the secondary side of the transformer T2, a condenser C2 for integration is connected in parallel.
Is connected to the hocus electrode (not shown) from here.
The voltage Vp is supplied to.

Next, the operation will be described. Transistor Q1
Is driven by a drive pulse (H. DRIVE) of a horizontal cycle, and performs a switching operation in the horizontal cycle. Therefore, in the circuit composed of the transistor Q1, the diode D1, the capacitor C1, and the coil L1 connected to the primary side of the hocus transformer T1, the transistor Q1 is a horizontal output transistor, the diode D1 is a damper diode, and the capacitor C1 is a resonance capacitor. The choke coil L1 can be interpreted as a deflection coil and performs the same operation as a general horizontal deflection output circuit. Therefore, the sawtooth current I1 flows on the primary side of T1 and the sawtooth current I2 flows on the secondary side.
Flows. Since the input impedance of the hocus electrode that supplies the dynamic hocus correction voltage is generally infinite and large, all the current I2 flows through the capacitor C2, so that a parabola voltage obtained by integrating the sawtooth current is present across C2. Is output.

Therefore, the transformer T is adjusted so that the value of the hocus voltage becomes the voltage required for the dynamic hocus correction.
If the relationship between the current I2 flowing through the secondary side of 1 (that is, the primary side power supply voltage Vcc of the transformer T, the inductance of the choke coil L1 and the turns ratio of the hocus transformer T1) and the capacitor C2 is determined, the circuit configuration is extremely easy. It can output dynamic focus voltage. Further, since the circuit on the primary side is a switching operation, the loss can be made almost zero, which is far more efficient than the conventional circuit.

Further, even when operating at a plurality of deflection frequencies, the correction voltage of the dynamic hocus is constant, so that the amplitude of the hocus voltage needs to be constant regardless of the deflection frequency. Here, if the values of the coil and the capacitor are constant, the amplitude of the voltage is a value obtained by time-integrating the current with a constant C2. Therefore, if the constant focus voltage is used, I2 is proportional to the deflection frequency. Need to be bigger.

Since the number of turns of the transformer T1 and other circuit constants do not change, it is necessary to change the power supply voltage Vcc and the primary side current I1 here. FIG. 2 shows an embodiment of the present invention in which the power supply voltage Vcc proportional to the square of the horizontal frequency is configured by changing the switching signal (REG.DRIVE) of the switching regulator. The power supply voltage Vcc is controlled by changing the switching ratio.

The regulator is constructed by using the two-stage switching transistors of the transistors Q3 and Q2. A switching signal (REG.DRIVE) is provided at the bases of the first-stage and second-stage transistors Q3 and Q2.
The signal source (not shown) in this part is
It is configured by a comparison circuit or the like that compares the output voltage B with the reference voltage. This configuration is a basic configuration of a so-called switching regulator, and choke coils L3 and L2 and charging capacitors C4 and C3 are connected to the output stages of the transistors Q3 and Q2, respectively. In this example, the output voltage Vcc proportional to the square of the horizontal frequency is obtained by this switching regulator.

The bias state of the diodes D2 and D3 changes according to the operation of the switching transistors Q2 and Q3. When the transistors Q2 and Q3 are conducting, the diodes D3 and D4 are cut off, and the transistors D2 and D3 are cut off. When Q3 and Q4 become non-conductive, they are biased in the forward direction to supply current to the coils L2 and L3.

Switching signal (REG.DRIVE)
The switching ratio is created by comparing the reference voltage with the output voltage B, and the output voltage B is controlled to a voltage proportional to the reference voltage. That is, the ratio is changed and the transistor Q
The output voltage is increased by increasing the on-time of No. 3. In other words, the output is changed by changing the change width of the current flowing through the coil L3, that is, the energization time.

Generally, in a horizontal deflection circuit which can operate at a plurality of horizontal frequencies, a voltage proportional to the horizontal frequency is created and supplied as a power supply voltage B to the horizontal deflection output circuit as described above. Therefore, the power supply voltage B to the horizontal deflection circuit can be adjusted, and when the power supply voltage B is increased, the deflection current can be increased, so that the amplitude automatically expands.

Further, in the part that outputs the hocus voltage,
Since the voltage on the primary side must be proportional to the square of the horizontal frequency, further multiplication is performed in FIG. 2 to obtain the voltage Vcc proportional to the square. Since this multiplication is performed in the transistor Q2 in synchronization with the horizontal frequency, the output voltage Vcc
Even if the horizontal frequency is changed, a voltage proportional to the square of the horizontal frequency can be obtained.

Therefore, a constant focus voltage can be obtained even if the deflection frequency changes. Even when the horizontal amplitude is changed, the power supply voltage Vcc is adjusted by the square of the voltage amplitude. Therefore, the focus voltage Vp is kept constant regardless of whether the frequency or the amplitude changes.

FIG. 3 shows an example in which a feedback circuit is added to the circuit of FIG. FIG. 3 further includes detection means in addition to the configuration of FIG.
It is an embodiment of the present invention that is devised to accurately obtain the hocus voltage. In FIG. 3, the voltage across the capacitor C2 is divided by the capacitors C5 and C6, and this voltage is supplied to the comparison circuit Q5 via the voltage follower Q4. The capacitors C5 and C6 form a voltage detection unit, and the voltage detected here is abbreviated as DETECT.
Are attached.

In addition, in order to accurately detect the error, the peak value of the focus voltage is detected before the comparison circuit Q5. This peak value detecting unit is a diode D4.
And a capacitor C7. This peak value is supplied to the comparison circuit Q5 at the next stage.

That is, the voltage follower Q4 outputs a stable voltage, and the peak value detector (D4, C).
7) is provided to accurately detect the error.

By comparing the stable voltage thus detected with the reference voltage Vref, the error component of the hocus voltage is detected. This error voltage is supplied to the base of the transistor Q4 to adjust the power supply voltage Vcc. Therefore, by feeding back the error of the hocus voltage, more accurate control of the hocus voltage can be performed.

If the reference voltage is made to follow the horizontal amplitude, the dynamic focus correction amount can be made to automatically follow even when the horizontal amplitude is changed.

In the above embodiment of the invention, the power supply voltage V
Although cc is changed, the present invention is not limited to this, and a saturable reactor may be used in place of the coil to change the inductance and control the primary side current I1. Further, instead of the capacitor, a varactor or a varicap may be used to control the current on the primary side. Further, if the circuit composed of the transistor Q1, the diode D1 and the capacitor C1 is shared by the horizontal deflection output circuit, the circuit can be further simplified.

[0032]

As described above, according to the first aspect of the present invention, the horizontal drive pulse is used together to control the hocus voltage to an optimum voltage to suppress the loss and simplify the entire circuit. It was done.

According to the second aspect of the invention, by controlling the output voltage of the power supply voltage, in addition to the effect of the first aspect of the invention, it is possible to stabilize the hocus voltage.

Further, in the invention according to the fifth aspect, the error of the hocus voltage is detected by the detecting means, and the power supply voltage on the primary side is controlled from the detected signal, so that the hocus voltage can be stabilized. It is a thing.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a horizontal dynamic focus circuit according to one embodiment of the present invention.

FIG. 2 is a diagram for explaining a horizontal dynamic focus circuit according to another embodiment of the present invention.

FIG. 3 is a diagram for explaining a horizontal dynamic focus circuit according to another embodiment of the present invention.

FIG. 4 is a diagram showing a conventional horizontal dynamic focus circuit.

[Explanation of symbols]

 Q1 to Q3 ... Transistors Q4 to Q6 ... Operational amplifier T1 ... Transformer L1 to L3 ... Coil C1 to C7 ... Capacitor

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] August 17, 1995

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claim 4

[Correction method] Change

[Correction contents]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction contents]

The feedback control unit is specifically a power supply path.
Second transistor with collector-emitter path inserted in
Is provided to correct the error of the hocus voltage. here
The output of the comparison circuit (error detection result) to the second
It supplies to the base of the transistor and controls the power supply voltage. Ma
In addition, in order to detect the error accurately,
The detection means for detecting the
The peak value (peak value of error) is detected after the detection means.
There is further provided a peak value detecting means for. This detector
The detection result detected by the stage is compared with the reference voltage and compared.
The resulting error voltage is the control voltage and the second transistor
It was supplied to the base of the data.

Claims (5)

[Claims] 1. A transistor having a base, an emitter and a collector, a horizontal drive pulse is supplied to the base, a commutation diode and a first capacitor are connected in parallel to the collector, and an emitter is connected to a reference potential point. A transformer having a primary winding and a secondary winding, one end of the primary winding being connected to the collector of the transistor, and an integrating capacitor being connected to the secondary winding; A horizontal dynamic hocus circuit comprising a voltage source for supplying a DC voltage via a choke coil at the other end, and a voltage generated in the integrating capacitor is used as a hocus voltage. . 2. A transistor having a base, an emitter and a collector, a horizontal drive pulse is supplied to the base, a commutation diode and a first capacitor are connected in parallel to the collector, and an emitter is connected to a reference potential point. A transformer having a primary winding and a secondary winding, one end of the primary winding being connected to the collector of the transistor, and an integrating capacitor being connected to the secondary winding; On the other end, a voltage source for supplying a DC voltage via a choke coil is provided, and means for utilizing the voltage generated in the integrating capacitor as a hocus voltage, and for stabilizing the hocus voltage, A horizontal dynamic focus circuit comprising: a control unit that controls a DC voltage from the voltage source. 3. The horizontal dynamic hocus circuit according to claim 2, wherein said control means is means for converting a DC voltage from said voltage source into a voltage proportional to a square of a horizontal frequency. A horizontal dynamic hawks circuit characterized by the fact that it is made. 4. The voltage converting means includes a first transistor having a collector connected to the constant voltage source and a base connected to a switching signal source, and one end thereof connected to an emitter of the first transistor. A first inductance for smoothing, a first capacitor connected between the other end of the first inductance and a reference potential point, a collector connected to the other end of the first inductance, and a base having the switching characteristic. A second transistor connected to a signal source for use, a second inductance for smoothing one end of which is connected to the emitter of the second transistor, and the other end of the second inductance and a reference potential point 4. The horizontal dynamic focus circuit according to claim 3, further comprising a second capacitor connected to. 5. The detecting means for detecting a voltage proportional to the hocus voltage from both ends of the integrating capacitor, and a peak for detecting a peak value of an output voltage of the detecting means. Value voltage detection means, comparison means for comparing the output voltage from the peak value detection means with a predetermined reference voltage, a collector / emitter current path is inserted in the DC voltage supply path, and the comparison is made in the base. A horizontal dynamic focus circuit according to claim 2, characterized in that it comprises a second transistor supplied with the output of the means.