JP3318969B2 - High voltage pulse generation 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 high-voltage pulse generating circuit for a large-sized video device.

[0002]

2. Description of the Related Art A conventional high-voltage pulse generating circuit of a large-sized video device generates a high-voltage pulse by a high-voltage switching circuit using one last transistor as shown in FIG. In FIG. 3, Q1, R1, R2, and C1 are a transistor, a resistor, and a capacitor that constitute a switching circuit of an input signal. R3 and R4 are transistors Q
1 is a collector resistance for shifting the output voltage. Q
Reference numerals 2, R5 and C2 denote transistors, resistors and capacitors constituting a high voltage switching circuit for generating a high voltage pulse signal.

In the configuration shown in FIG. 3, an input signal supplied to an input terminal 1 includes a transistor Q1 of a first stage and a resistor R1.
To a pulse signal which is switched by a switching circuit composed of R4 and a capacitor C1. A switching circuit composed of an output transistor Q2, a resistor R5 and a capacitor C2 is connected to a power supply 3 Is supplied to the load 4 as a high-voltage pulse with a high voltage.

[0004]

However, in the conventional high-voltage pulse generating circuit, there is a problem that it is very difficult to select a transistor that can withstand the required high-voltage and that the usable ones are expensive. .

It is an object of the present invention to provide a high-voltage pulse generating circuit which can improve the above-mentioned drawbacks and can be easily realized.

[0006]

SUMMARY OF THE INVENTION The present invention, in order to achieve the above object, a switching circuit for switching an input signal, and a voltage shift circuit for shifting the output voltage of the switching circuit, the output voltage of the voltage shift circuit and a high-voltage switching circuit for switching a high voltage in response to said high-voltage switching circuit includes a first resistor
, A second resistor, a third resistor, and the voltage shift circuit
Output terminal is connected to the base, and the emitter is
And one end of the first resistor, and a collector
Is a first transistor connected to one end of the second resistor.
And an emitter connected to one end of the second resistor and the first
And the base is connected to the
The other end of the first resistor, the other end of the second resistor, and the
3 is connected to one end of the resistor and the collector is connected to the load.
A second transistor connected to the first transistor
Resistance between the resistance value of the third resistor has a structure identical.

[0007]

Therefore, according to the present invention, by using two transistors connected in series to a high-voltage switching circuit, a high-voltage pulse generating circuit capable of withstanding a required high-voltage even with low-voltage transistors can be constructed. There is an advantage that it is possible and is inexpensive.

[0008]

1 is a block diagram schematically showing the configuration of a high-voltage pulse generating circuit according to the present invention. An input signal supplied to an input terminal 1 passes through a switching circuit 11 and a bias voltage is applied to The voltage is boosted and converted into a high-voltage pulse signal by the high-voltage switching circuit 13.
Output from

FIG. 2 shows the configuration of a specific embodiment of the present invention. In FIG. 2, 1 is an input terminal to which an input signal is supplied, Q1 is a switching circuit of the input signal, R3,
R4 is a resistor for shifting the output voltage of Q1, Q2, Q3
Is a high-voltage switching circuit, R6 and R7 are resistors that determine the voltage applied to Q2 and Q3, C1 and C2 are capacitors, R
1, R2, R5 and R8 are resistors, 2 is an output terminal for outputting a high voltage pulse signal, 3 is a power terminal for supplying a high voltage VH, and 4 is a load. Note that the values of the resistor 6 and the resistor 7 are the same.

In FIG. 2, the collector-emitter voltage of Q2 is VCE1 and the collector-emitter voltage of Q3 is VCE1.
Let VBE2 be the voltage between the base and the emitter of CE2 and Q3.

Next, the operation of the configuration shown in FIG. 3 will be described. The voltage of the input signal supplied to the input terminal 1 is shifted by the switching circuit and supplied to the base of the transistor Q2 of the high-voltage switching circuit via C2 and R5. This signal causes transistors Q2 and Q3 to
It works as follows. 1) When transistor Q2 is QFF, that is, point A is H
At the i level, the voltage VC1 = VH / 2 and the voltage VB = VH / 2, so that VC1 = VB = VH / 2, and the transistor Q3 is turned off, so that the output voltage VC2 becomes 0V. 2) When transistor Q2 is ON, that is, point A is Lo
At the time of the w level, voltage VC1 = VH-VCE1 voltage VB = VH- (VCE1 + VBE2) Here, since VC1> VB, a potential difference VBE2 is generated between both ends of the resistor R8.

Therefore, since the transistor Q3 is turned on, the output voltage VC2 = VH- (VCE1 + VCE2) Here, since VCE1 and VCE2 are 1 V or less, the output voltage VC2〓VH.

According to 1) and 2), the output voltage VC2 is switched by the transistors Q2 and Q3. The voltage applied to the transistors Q2 and Q3 is a maximum of VH / 2 (V)
Therefore, a high-voltage switching circuit can be configured with transistors having a withstand voltage lower than the voltage VH.

[0014]

Therefore, according to the present invention, by connecting transistors in series, a circuit capable of withstanding a required high voltage can be formed using low withstand voltage transistors. There is an effect that a high-voltage pulse can be easily generated using a transistor.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of a high-voltage pulse generating circuit according to an embodiment of the present invention.

FIG. 2 is a specific circuit diagram of FIG.

FIG. 3 is a circuit diagram of a conventional high-voltage pulse generating circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Switching circuit 12 Voltage shift circuit 13 High voltage switching circuit Q1, Q2, Q3 Transistor C1, C2 Capacitor R1-R8 Resistance

Continuation of the front page (56) References JP-A-52-112261 (JP, A) JP-A-56-140710 (JP, A) JP-A-63-156417 (JP, A) JP-B-47-31546 (JP, A) , B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04N 5/14 H03F 1/22 H03K 17/10

Claims (1)

(57) [Claims] Comprising [1 claim: a switching circuit for switching an input signal, and a voltage shift circuit for shifting the output voltage of the switching circuit, and a high-voltage switching circuit for switching a high voltage according to the output voltage of the voltage shift circuit , The high-voltage switching circuit includes a first resistor
, A second resistor, a third resistor, and the voltage shift circuit
Output terminal is connected to the base, and the emitter is
And one end of the first resistor, and a collector
Is a first transistor connected to one end of the second resistor.
And an emitter connected to one end of the second resistor and the first
And the base is connected to the
The other end of the first resistor, the other end of the second resistor, and the
3 and the collector is connected to the load.
A second transistor connected to the first transistor
Wherein the resistance value of the third resistor is the same as the resistance value of the third resistor .