JPH09294216A - Amplifier circuit for deflection circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce power consumption more than that of a conventional circuit by providing a transistor(TR), a 2nd diode, and a 2nd resistor whose resistance is higher than that of a 1st resistor, in addition to a pumpup circuit, to the amplifier circuit. SOLUTION: A charge time is determined by the time constant of a pumpup capacitor PC11 and a 1st resistor R11. Since the resistance of the 1st resistor R11 is small, the time constant is not increased, and, hence, it is possible to avoid the situation in which the time required for charge/discharge is extended and the increase/decrease in a power supply voltage cannot follow the increase/ decrease in an output voltage is taking place. Furthermore, discharged through a discharging route during a blanking period, and in this case, a 2nd resistor R12 directly connected to a positive power supply +Vcc has a higher resistance than that of the 1st resistor R11, so that the current flowing therein is small. Moreover, a TR11 is nonconductive and no current flows in the 1st resistor R11, and hence the power consumption due to the current flowing in both resistors 11, 12 can be reduced.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art A conventional amplification circuit for a deflection circuit will be described below. This circuit is a circuit used in the output section of a convergence correction circuit such as a CRT display or a projection television, and as shown in FIG. 3, the deflection signal (IS) generated by a deflection signal generation circuit (not shown) is amplified ( This is a circuit for amplifying the output voltage (Vout) in 1) and outputting the output voltage (Vout) to the deflection coil (L) for convergence correction, thereby deflecting the electrons radiated to the cathode ray tube to perform the 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. A second power supply circuit (3) for generating -Vc). Each of the first and second power supply circuits (2, 3) is a step-up circuit which is a so-called pump-up circuit, and each has a step-up pump-up capacitor (P
By charging / discharging C1 and PC2), a power supply voltage (± Vcc) is generated during the scanning period, and a doubled power supply voltage (± Vcc × 2) that is boosted during the blanking period is generated and supplied. This is a circuit for reducing power consumption and improving efficiency.

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

Therefore, if a constant high voltage is used as the power supply voltage, the power loss during the scanning period is large,
Since the efficiency is lowered, 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 set to 2 during the blanking period when a high voltage is required. The voltage (+ Vcc × 2, −Vcc × 2) that is doubled is supplied to the amplifier (1) as a power supply voltage (± Vc) to reduce power loss and improve 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 thereof will be omitted. The switching circuit (SW1) is OFF during the scanning period.
Then, the positive power supply (+ Vcc) is supplied to the positive side of the amplifier via the diode (D1). During this period, the pump-up capacitor (PC1) is a diode (D1) as shown in FIG.
→ Pump-up capacitor (PC1) → Resistor (R1) →
It is charged through 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.

Then, in the blanking period, the switching circuit (SW1) is turned on. Then, the power supply voltage (+ Vc) on the positive side of the amplifier (1) becomes the pump-up capacitor (PC
Since the electric charge charged in 1) is discharged in the discharge path as shown in FIG. 4, in addition to the positive power supply (+ Vcc), the potential difference between the electrodes of the capacitor, that is, + Vcc is boosted, and therefore + Vcc × 2 Becomes

The power supply voltage (+ Vc,
-Vc), the amplifier (1) amplifies the deflection signal (IS) by the amplifier (1), and outputs the amplified output voltage (Vout) to the deflection coil (L) for convergence correction. As a result, the electrons radiated to the cathode ray tube are deflected to correct the convergence. As described above, + Vcc is applied during the scanning period and + Vcc is applied during the blanking period.
Since the power supply voltage is switched according to the period, such as cc × 2, the loss of power consumption during the scanning period is higher than that of a circuit that uses a constant high voltage that can handle flyback pulses as the power supply voltage. To improve efficiency.

[0009]

In the circuit shown in FIG. 3, the resistor (R1) provided in the charging path has a small resistance value. This defines the time constant for charging / discharging the pump-up capacitor (PC1), so if a capacitor with a large resistance value is used, the time required for charging / discharging will become longer, and a particularly high voltage retrace line is required. This is because the rise of the power supply voltage cannot follow the rise of the output voltage during the period and the output is distorted.

In the above circuit, when discharging, 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 this resistor (R1). However, there arises a problem that power consumption increases. Especially when the duty ratio during the blanking period becomes large, the resistance (R
Since the time period during which the power supply voltage (+ Vcc) is applied to 1) becomes long, this power consumption loss becomes even larger.

[0011]

The present invention has been made in view of the above-mentioned drawbacks of the prior art. As shown in FIG. 1, a signal amplifier for amplifying the deflection signal and outputting it to a deflection coil, and a constant voltage. A switch circuit that has one end connected to it, is turned off during a scanning period and is turned on during a blanking period, and has 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 section. Between 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 charge / discharge capacitor, and between the collector of the transistor and the ground potential. A first resistor connected between the first resistor and a base of the transistor and the ground potential;
A second resistor having a resistance value higher than that of the resistor, a cathode / anode is connected to the other end of the charging / discharging capacitor and the emitter of the transistor, and the anode / cathode is connected to the other end of the switch circuit and the transistor. A second diode connected between the base and the base, wherein the constant voltage is used as the power supply voltage of the signal amplifying unit while charging the charging / discharging capacitor during the scanning period, and the capacitor is removed from the capacitor during the blanking period. An amplification circuit for a deflection circuit, further comprising a power supply circuit for boosting the constant voltage by discharging to use as a power supply voltage of the signal amplification section, further reducing power loss and improving efficiency. To 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 a circuit used in the output part of a convergence correction circuit such as a CRT display or a projection television, and as shown in FIG. 1, a deflection signal (IS) generated by a deflection signal generation circuit (not shown) is amplified ( 11) Amplification is performed and the output voltage (Vout) is output to the deflection coil (L) for convergence correction, thereby deflecting the electrons radiated to the cathode ray tube to perform the 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, amplifies the deflection signal (IS) using a power supply voltage (+ Vc, −Vc) described later, and outputs the output voltage (Vout) to the deflection coil (L). It is a circuit to do.

The first power supply circuit (12) has a pump-up capacitor (PC11) in the scanning period as shown in FIG.
The positive power supply (+ Vcc) is set to the power supply voltage (+ Vc) of the amplifier (11) while being charged, and the positive power supply (+ Vc) is discharged by discharging the pump-up capacitor (PC11) during the blanking period.
It is a circuit that doubles c) to be the power supply voltage of the amplifier (11).

One end of this circuit is connected to a constant positive power source (+ Vcc), which is turned off during the scanning period and turned on during the retrace line period, and a positive power source (+).
The anode is connected to Vcc) and the cathode 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) whose emitter is connected to the other end of the pump-up capacitor (PC11).
1) is connected between the collector of the transistor (TR11) and the ground potential (GND), and defines a time constant for charging / discharging together with the pump-up capacitor (PC11), and a transistor (R11). A second resistor (R1) connected between the base of TR11) and the ground potential (GND) and having a resistance value higher than that of the first resistor (R11).
2), a cathode is connected to the other end of the pump-up capacitor and the emitter of the transistor (TR11), and an anode is connected between the other end of the switch circuit (SW11) and the base of the transistor (TR11). And a diode (D12).

This circuit is different 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) charges the pump-up capacitor (PC12) during the scanning period and supplies a constant negative power supply (-Vcc) to the power supply of the amplifier (11). It is a circuit that doubles the negative power supply (-Vcc) by using the voltage (-Vc) and discharging the pump-up capacitor (PC12) in the blanking period to use the power supply voltage of the amplifier (11). The configuration thereof is symmetrical to that of the first power supply circuit (12) as shown in FIG.

Next, the operation of the above amplifier circuit will be described below. When the power is first turned on, the first and second
Power supply circuit (12, 13) of the 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), which is output to the deflection coil (L) and simultaneously output to the first and second power supply circuits (12, 13). To be done.

Regarding the subsequent operation, the operation is different in (1) scanning period and (2) retrace line period, so these 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 therefore its description is omitted. (1) Scanning period In this period, the switch circuit (SW11) is turned off first.

At this time, the base potential of the transistor (TR11) does not rise due to the reverse bias of the second diode (D12), but it is the GND potential, while the potential of the emitter rises, so that the base of the second resistor (R12) is increased. A current flows and the transistor (TR11) is turned on. Therefore, as shown in FIG. 2, positive power supply (+ Vcc) → first diode (D11) → pump-up capacitor (PC1)
1) → transistor (TR11) → first resistor (R1)
1) → The pump-up capacitor (PC11) is charged through the charging path of ground potential (GND), and the potential difference between the electrodes of the pump-up capacitor (PC) is the positive power supply (+ Vc).
rise to c).

During this period, on the positive side of the amplifier (11), the positive power source (+ Vcc) is supplied 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 source (-Vcc) is directly applied to the negative side of the amplifier (11), and this is supplied as the power source voltage (-Vc) of the amplifier (11).

In this way, the positive / negative power supply (+ Vcc, -V
The deflection signal (Vin) is amplified by the amplifier (11) using cc) as the first and second power supply voltages (+ Vc, -Vc), and the output voltage (Vout) is output to the deflection coil (L). Convergence correction is performed by deflecting the electrons irradiated on the. (2) Return line 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) and a current flows through it, the base potential of the transistor (TR11) rises and the transistor (TR11) turns off. Unlike the prior art, the resistance value of the second resistor (R12) is larger than the resistance value of the conventional resistor (R1) shown in FIG. 3, so that the second resistance (R12) is
Even if a positive power supply (+ Vcc) is directly applied to the device, the current flowing at this time is smaller than in the conventional case, and the power consumption at this time is smaller than in the conventional case.

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

In this way, 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).
t) is output to the deflection coil (L), the electrons radiated to the cathode ray tube are deflected, and the convergence correction is performed.

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

Therefore, the charging time is determined by the time constant of the pump-up capacitor (PC11) and the first resistor (R11), but since the resistance value of the first resistor (R11) is small, the above time constant will not be large. Therefore, it is possible to avoid a situation in which the time required for charging / discharging becomes long and the increase / decrease in power supply voltage cannot follow the increase / decrease in output voltage. Further, during the blanking period, discharge is performed through the discharge path as shown in FIG. 2, and at this time, the second resistor (R12) directly connected to the positive power source (+ Vcc) is more than the first resistor (R11). Since it is a high resistance, a current flowing through it is small, and since the transistor (TR11) is off, a high voltage positive power supply (+ Vcc) is applied to the first resistor (R11) having a small resistance value.
Is not directly applied, and no current flows through the first resistor (R11). Therefore, it is possible to reduce the power consumption caused by the current flowing through the resistors (R11, R12) compared to the conventional case. .

In the present embodiment, the amplification circuit for convergence correction is described as the amplification circuit for the deflection circuit. However, the present invention is not limited to this, and another deflection circuit such as a vertical deflection circuit may be used. Even if it applies, the same effect is produced.

[0028]

As described above, according to the amplifier circuit for the deflection circuit of the present invention, in addition to the conventionally used pump-up circuit, the transistor and the second diode are provided.
A second resistor having a larger resistance value than the first resistor is provided. Therefore, during the blanking period, the second resistance directly connected to the constant power supply voltage has a higher resistance than the first resistance, so that a current flowing through the second resistance is small and the transistor is OF
Due to F, 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. Therefore, current flows through this resistor. The generated power consumption can be reduced as compared with the conventional one.

[Brief description of 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 an operation of the amplifier circuit for the deflection circuit according to the embodiment of the present invention.

FIG. 3 is a circuit diagram of an amplifier circuit for a deflection circuit according to a conventional example.

FIG. 4 is a diagram illustrating an operation of an amplifier circuit for a deflection circuit according to a conventional example.

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

[Explanation of symbols]

(11) Amplifier (Signal Amplifying Unit) (12) First Power Supply Circuit (13) Second Power Supply Circuit (PC11) Pump-up Capacitor (Charging / Discharging Capacitor) (SW11, SW12) Switch Circuit (TR11) Transistor ( D11) First diode (D12) Second diode (R11) First resistance (R12) Second resistance (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

Claims (1)

[Claims] 1. A signal amplification unit for amplifying a deflection signal and outputting it to a deflection coil, a switch circuit having one end connected to a constant power supply voltage, which is turned off during a scanning period and turned on during a retrace line period, A first diode whose anode is connected to the power supply voltage of the first diode and whose cathode is the output of the power supply voltage of the signal amplification section; a charging / discharging capacitor whose one end is connected to the cathode of the first diode; A transistor whose emitter is connected to the other end of the discharging capacitor, a first resistor connected between the collector of the transistor and ground potential, and a transistor connected between the base of the transistor and ground potential, A second resistor having a resistance value higher than that of the first resistor, and a cathode / anode connected to the other end of the charging / discharging capacitor and the emitter of the transistor, A node / cathode is provided with 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 maintained while charging the charging / discharging capacitor during a scanning period. A deflection circuit, comprising: a power supply voltage of the signal amplification unit; and a power supply circuit that boosts the constant power supply voltage by discharging the capacitor in a blanking period to use as the power supply voltage of the signal amplification unit. Amplification circuit for the circuit.