JP3342290B2 - Amplifier circuit for deflection circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in an amplification circuit used in a deflection circuit such as a convergence correction circuit used in a CRT display, a projection television or the like.

[0002]

2. Description of the Related Art A conventional amplification circuit for a deflection circuit will be described below. This circuit is used for an output unit of a convergence correction circuit such as a CRT display or a projection television, and as shown in FIG. 3, an amplifier (not shown) generates a deflection signal (IS) generated by a deflection signal generation circuit (not shown). A circuit for amplifying in 1) and outputting this output voltage (Vout) to a deflecting coil (L) for convergence correction deflects electrons applied to the CRT to perform convergence correction.

As shown in FIG. 3, this circuit includes an amplifier (1), a first power supply circuit (2) for generating a positive power supply voltage (+ Vc) of the amplifier, and a negative power supply voltage (+ Vc) of the amplifier. -Vc) to generate a second power supply circuit (3). Each of the first and second power supply circuits (2, 3) is a booster circuit serving as a so-called pump-up circuit, and includes a booster pump-up capacitor (P
By charging and discharging C1, PC2), a power supply voltage (± Vcc) is generated and supplied during the scanning period, and a doubled power supply voltage (± Vcc × 2) is generated and supplied during the retrace period. This is a circuit for reducing power consumption and increasing efficiency.

FIG. 5 shows the relationship between the output voltage (Vout) and the power supply voltage (± Vc) of this amplifier. As shown in FIG. 5, the output voltage (Vout) of the amplifier is such that a high-voltage flyback pulse is generated during the retrace period, so that a higher power supply voltage is required on the positive side, but during the scanning period. Since the output voltage (Vout) does not increase so much, a power supply voltage as high as the flyback period is not required.

Therefore, simply using a high voltage as a constant voltage as the power supply voltage causes a large power loss during the scanning period,
Since the efficiency decreases, as shown in FIG. 5, the positive power supply (+ Vc
c), the negative power supply (-Vcc) is supplied to the amplifier (1) as the power supply voltage (± Vc), and the positive power supply (+ Vcc) and the negative power supply (-Vcc) are supplied to the amplifier (1) during the retrace period in which a high voltage is required. The doubled voltage (+ Vcc × 2, −Vcc × 2) is supplied to the amplifier (1) as a power supply voltage (± Vc) to reduce power loss and increase efficiency.

The operation of the above circuit will be described below with reference to FIG. The operation of the second power supply circuit (2) is the same as the operation of the first power supply circuit (1), and the description is omitted. Switching circuit (SW1) is OFF during scanning period
Then, the positive power supply (+ Vcc) is supplied to the positive side of the amplifier via the diode (D1). During this time, the pump-up capacitor (PC1) is connected to a diode (D1) as shown in FIG.
→ Pump-up capacitor (PC1) → Resistor (R1) →
It is charged in the charging path of the ground potential (GND), and the potential difference between the electrodes of the pump-up capacitor (PC1) at this time is + Vcc.

After that, in the retrace period, the switching circuit (SW1) is turned on. Then, the power supply voltage (+ Vc) on the positive side of the amplifier (1) is changed to a pump-up capacitor (PC
The electric charge charged in 1) is discharged through the discharge path as shown in FIG. 4, so that the potential is increased by the potential difference between the electrodes of the capacitor, that is, + Vcc, in addition to the positive power supply (+ Vcc). Becomes

The power supply voltage (+ Vc,
-Vc), the amplifier (1) amplifies the deflection signal (IS) with the amplifier (1) and outputs the amplified output voltage (Vout) to the deflection coil (L) for convergence correction. As a result, convergence correction is performed by deflecting electrons emitted to the cathode ray tube. As described above, + Vcc during the scanning period and + Vcc during the retrace period.
Since the power supply voltage is switched in accordance with the period, such as cc × 2, the power consumption loss during the scanning period is lower than that of a circuit that uses a constant high voltage that can respond to a flyback pulse. And improve efficiency.

[0009]

In the circuit shown in FIG. 3, the resistor (R1) provided in the charging path has a small resistance value. This is to define the time constant at the time of charging / discharging of the pump-up capacitor (PC1). Therefore, if a resistor having a large resistance value is used, the time required for charging / discharging becomes longer, and in particular, retrace where a high voltage is required. This is because the power supply voltage cannot follow the rise of the output voltage during the period and the output is distorted.

In the above-mentioned circuit, a relatively high power supply voltage (+ Vcc) is directly applied to the resistor (R1) having a small resistance value as described above, and a relatively large current flows through the resistor (R1). In addition, there is a problem that power consumption is increased. In particular, when the duty ratio during the flyback period increases, the resistance (R
Since the time during which the power supply voltage (+ Vcc) is applied to 1) becomes longer, the loss of power consumption is further increased.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional disadvantages. As shown in FIG. 1, a signal amplifier for amplifying the deflection signal and outputting the amplified signal to a deflection coil is provided. A switch circuit that is turned off during the scanning period and turned on during the retrace period, a first diode whose anode is connected to the constant voltage, and whose cathode serves as an output of the power supply voltage of the signal amplification unit. A charging / discharging capacitor having one end connected to the cathode of the first diode, a transistor having an emitter connected to the other end of the charging / discharging capacitor, and a transistor having a collector and a ground potential. A first resistor connected between the first resistor and a base of the transistor and a ground potential;
And a cathode / anode connected to the other end of the charge / discharge capacitor and the emitter of the transistor, and the anode / cathode is connected to the other end of the switch circuit and the other end of the transistor. A second diode connected between the capacitor and a base, wherein the constant voltage is used as a power supply voltage of the signal amplifying unit while charging the charging / discharging capacitor during a scanning period. And a power supply circuit for boosting the constant voltage by discharging to make the power supply voltage of the signal amplifying unit. The power supply circuit for the deflection circuit further reduces power loss and improves efficiency. Aim.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an amplifier circuit for a deflection circuit according to an embodiment of the present invention will be described with reference to the drawings. This circuit is used for an output section of a convergence correction circuit such as a CRT display or a projection television, and as shown in FIG. 1, an amplifier (not shown) generates a deflection signal (IS) generated by a deflection signal generation circuit (not shown). 11), the output voltage (Vout) is output to a convergence correction deflection coil (L), thereby deflecting electrons irradiated to the cathode ray tube, thereby performing convergence correction.

As shown in FIG. 1, this amplifier circuit has an amplifier (11), a first power supply circuit (12), and a second power supply circuit (13). The configuration of each part of this circuit will be described below. The amplifier (11) is an example of a signal amplifying unit, and amplifies the deflection signal (IS) using a power supply voltage (+ Vc, -Vc) described later and outputs an output voltage (Vout) to the deflection coil (L). Circuit.

The first power supply circuit (12) includes a pump-up capacitor (PC11) during the scanning period as shown in FIG.
The positive power supply (+ Vc) is set to the power supply voltage (+ Vc) of the amplifier (11) while being charged, and discharged from the pump-up capacitor (PC11) during the retrace period to thereby supply the positive power supply (+ Vc).
This is a circuit in which c) is doubled to be used as a power supply voltage of the amplifier (11).

This circuit has one end connected to a fixed positive power supply (+ Vcc), which is turned off during the scanning period and turned on during the retrace period, and a positive power supply (+ Vcc).
Vcc), the anode is connected to the amplifier (1
1) A first diode (D11) that outputs the power supply voltage (+ Vc), and a pump-up capacitor (PC1) having one end connected to the cathode of the first diode (D11).
1) and a PNP transistor (TR1) having an emitter connected to the other end of the pump-up capacitor (PC11).
1), a first resistor (R11) connected between the collector of the transistor (TR11) and the ground potential (GND), and defining a time constant for charging and discharging together with the pump-up capacitor (PC11); A second resistor (R1) connected between the base of the transistor TR11) and the ground potential (GND) and having a higher resistance than the first resistor (R11).
2) a second terminal in which the cathode is connected to the other end of the pump-up capacitor and the emitter of the transistor (TR11), and the anode is connected between the other end of the switch circuit (SW11) and the base of the transistor (TR11). A diode (D12).

This circuit differs from the conventional pump-up circuit shown in FIG. 3 in that a transistor (TR11), a second diode (D12) and a second resistor (R12) are added. Similarly to the first power supply circuit (12), the second power supply circuit (13) supplies a constant negative power supply (-Vcc) to the power supply of the amplifier (11) while charging the pump-up capacitor (PC12) during the scanning period. This is a circuit in which the negative power supply (-Vcc) is doubled by discharging from the pump-up capacitor (PC12) during the retrace period to make the power supply voltage of the amplifier (11). The configuration is symmetrical to the first power supply circuit (12) as shown in FIG.

Subsequently, the operation of the above amplifier circuit will be described below. When the power is first turned on, the first and second
Power supply circuits (12, 13) respectively have a positive power supply (+ Vc
c), a negative power supply (-Vcc) is applied. Next, the deflection signal (IS) is amplified by the amplifier (11) to generate an output voltage (Vout), output to the deflection coil (L), and simultaneously output to the first and second power supply circuits (12, 13). Is done.

The subsequent operations are different between (1) the scanning period and (2) the retrace period, and the two cases will be described with reference to FIG. In the following, the operation of the first power supply circuit (12) will be mainly described,
The operation of the second power supply circuit (13) is the same as the operation of the first power supply circuit (11), and a description thereof will be omitted. (1) Scan period In this period, first, the switch circuit (SW11) is turned off.

At this time, the base potential of the transistor (TR11) does not rise due to the reverse bias caused by the second diode (D12), but remains at the GND potential, while the potential of the emitter rises. A current flows and the transistor (TR11) turns on. Therefore, as shown in FIG. 2, the positive power supply (+ Vcc) → the first diode (D11) → the pump-up capacitor (PC1)
1) → Transistor (TR11) → First resistor (R1
1) → The pump-up capacitor (PC11) is charged through a charging path of ground potential (GND), and the potential difference between the electrodes of the pump-up capacitor (PC) is a positive power supply (+ Vc).
c).

During this period, the positive power supply (+ Vcc) is supplied to the positive side of the amplifier (11) via the first diode (D11).
Is applied to the amplifier (11) and becomes the power supply voltage (+ Vc) of the amplifier (11). Similarly, the negative power supply (-Vcc) is directly applied to the negative side of the amplifier (11), and this is supplied as the power supply voltage (-Vc) of the amplifier (11).

As described above, the positive / negative power supply (+ Vcc, -V
cc) as the first and second power supply voltages (+ Vc, -Vc), the deflection signal (Vin) is amplified by the amplifier (11), and the output voltage (Vout) is output to the deflection coil (L). The convergence correction is performed by deflecting the electrons applied to the convergence. (2) Return period During this period, the switch circuit (SW11) is turned on.

At this time, a positive power supply (+ Vcc) is applied to the second resistor (R12), a current flows therethrough, the base potential of the transistor (TR11) rises, and the transistor (TR11) is turned off. Unlike the prior art, the resistance of the second resistor (R12) is larger than the resistance of the conventional resistor (R1) shown in FIG.
Even if the positive power supply (+ Vcc) is directly applied to the power supply, the current flowing at this time is smaller than that of the related art, and the power consumption at this time can be smaller than that of the related art.

Thus, the transistor (TR11) is turned off.
F, the positive power supply (+ Vc) as shown in FIG.
c) → switch circuit (SW11) → second diode (D12) → pump-up capacitor (PC11) → pump-up capacitor (P
It is discharged from C11). During this period, the pump-up capacitor (PC11) is connected to the positive power supply (+ Vcc) supplied from the first diode (D11) on the positive side of the amplifier.
Is added to the potential difference (+ Vcc) between the electrodes, and the voltage (+ Vcc × 2) that is twice the voltage of the positive power supply is applied to the amplifier (1).
It is supplied as the power supply voltage (+ Vc) of 1). Similarly, on the negative side of the amplifier, a voltage (−Vcc × 2) twice as large as the negative power supply is applied, and this is supplied as the power supply voltage (−Vc) of the amplifier (11).

As described above, the voltage (+
The deflection signal (Vin) is amplified by the amplifier (11) using the first and second power supply voltages (+ Vc, -Vc) which are (Vcc × 2, −Vcc × 2), and the output voltage (Vou) is obtained.
t) is output to the deflection coil (L) to deflect the electrons applied to the cathode ray tube, thereby performing convergence correction.

As described above, according to the amplifier circuit for the deflection circuit according to the present embodiment, in addition to the conventional pump-up circuit having a high efficiency as shown in FIG. 3, the transistor (TR11) and the second A diode (D12) and a second resistor (R1) having a larger resistance value than the first resistor (R11).
2) is connected to the first and second power supply circuits (12, 1).
In the scanning period, charging is performed through a charging path as shown in FIG.

For this reason, the charging time is determined by the time constant of the pump-up capacitor (PC11) and the first resistor (R11). However, since the resistance value of the first resistor (R11) is small, if the above-mentioned time constant is large, In other words, it is possible to avoid a situation in which the time required for charging and discharging becomes longer, and the increase or decrease in the power supply voltage cannot follow the increase or decrease in the output voltage. In the flyback period, the battery is discharged through the discharge path shown in FIG. 2. At this time, the second resistor (R12) directly connected to the positive power supply (+ Vcc) is higher than the first resistor (R11). Since the resistance is high, the current flowing therethrough is small, and since the transistor (TR11) is OFF, the first resistor (R11) having a small resistance value has a high voltage positive power supply (+ Vcc).
Is not directly applied, and no current flows through the first resistor (R11), so that power consumption caused by current flowing through the resistors (R11, R12) can be reduced as compared with the conventional case. .

In this embodiment, an amplifier circuit for convergence correction is described as an amplifier circuit for a deflection circuit. However, the present invention is not limited to this, and may be applied to another deflection circuit such as a vertical deflection circuit. Even when applied, the same effect is achieved.

[0028]

As described above, according to the amplifier circuit for a deflection circuit according to the present invention, in addition to the conventionally used pump-up circuit, a transistor and a second diode are provided.
A second resistor having a larger resistance value than the first resistor is provided. For this reason, during the retrace period, the second resistor directly connected to a constant power supply voltage has a higher resistance than the first resistor, so that less current flows therethrough.
As a result, since a relatively high constant power supply voltage is not directly applied to the first resistor having a small resistance value, and no current flows through the first resistor, a current flows through this resistor. The generated power consumption can be reduced as compared with the conventional case.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of an amplifier circuit for a deflection circuit according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating the operation of an amplifier circuit for a deflection circuit according to an embodiment of the present invention.

FIG. 3 is a circuit diagram of a conventional amplification circuit for a deflection circuit.

FIG. 4 is a diagram illustrating the operation of a conventional amplification circuit for a deflection circuit.

FIG. 5 is a diagram illustrating a relationship between an output voltage of a convergence correction circuit using a pump-up circuit and a power supply voltage.

[Explanation of symbols]

(11) Amplifier (signal amplifying unit) (12) First power circuit (13) Second power circuit (PC11) Pump-up capacitor (charge / discharge capacitor) (SW11, SW12) Switch circuit (TR11) Transistor ( D11) First diode (D12) Second diode (R11) First resistor (R12) Second resistor (IS) Deflection signal (Vout) Output voltage (+ Vcc) Positive power supply (-Vcc) Negative power supply (+ Vc) ) First power supply voltage (+ Vc) Second power supply voltage (L) Deflection coil

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-315093 (JP, A) JP-A-4-334271 (JP, A) JP-A-56-52356 (JP, U) 35868 (JP, B1) (58) Fields surveyed (Int. Cl. ⁷ , DB name) H04N 3/16

Claims (1)

(57) [Claims] A signal amplifier for amplifying a deflection signal and outputting the amplified signal to a deflection coil; a switch circuit having one end connected to a constant power supply voltage and turned off during a scanning period and turned on during a retrace period; A first diode whose anode is connected to the power supply voltage of the first diode and whose cathode serves as the power supply voltage of the signal amplification unit; a charge / discharge capacitor having one end connected to the cathode of the first diode; A transistor having an emitter connected to the other end of the capacitor, a first resistor connected between a collector of the transistor and a ground potential, and a first resistor connected between a base of the transistor and a ground potential. A second resistor having a resistance higher than that of the second resistor, a cathode connected to the other end of the charge / discharge capacitor and an emitter of the transistor, and an anode connected to the switch. A second diode connected between the other end of the switch circuit and the base of the transistor, and the constant power supply voltage is supplied to the signal amplification unit while charging the charge / discharge capacitor during a scanning period. Power supply voltage, and discharge from the capacitor during the retrace period to pre- set the constant power supply voltage.
A power supply circuit for adding and boosting the voltage of the capacitor to make the power supply voltage of the signal amplification section.