JPS61205074A - Electrostatic deflection circuit - Google Patents

Abstract

PURPOSE:To attain miniaturization of an electrostatic deflection circuit together with reduction of both power consumption and cost, by using a normal power supply which supplies electric power to other circuit parts of an apparatus in place of a floating power supply to drive the deflecting circuit and varying the center potential of the output voltage of the deflecting circuit with its amplitude kept constant. CONSTITUTION:The minus side of a power supply and the plus side of a power supply 3 are grounded, and a resistance R3, a variable resistance VR1 and a resistance R4 are connected in series between terminals 4e and 4f of a horizontal/vertical deflection circuit 4. The middle terminal of the VR1 is grounded and both the R3 and R4 are set at the same value. The circuits 5 and 6 of an image pickup device and driven by the power supplies 2 and 3. The circuit 4 receives the supply of voltage via both resistances R1 and R2 and delivers the sawtooth wave voltage for horizontal deflection between both terminals 4a and 4b as well as the sawtooth wave voltage for vertical deflection between both terminals 4c and 4d. These sawtooth wave voltages are produced by an ordinary sawtooth wave generating circuit consisting of a constant current circuit and a capacitor.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrostatic deflection circuit for an image pickup tube or the like that focuses and deflects an electron beam using an electric field.

[Conventional technology]

In image pickup tubes, picture tubes, and the like, images are disassembled and assembled by controlling electron beams.

Control of this electron beam includes focusing the electron beam and deflecting the electron beam in the horizontal and vertical directions, and each can be performed using an electric field or a magnetic field.

In the electro-imaging method that uses a magnetic field to focus or deflect an electron beam, for example, a coil is provided outside the image pickup tube, and a current is supplied to the coil to generate a magnetic field. Therefore, it is difficult to downsize the image pickup tube and reduce power consumption.

On the other hand, the electrostatic method, which uses an electric field to focus or deflect an electron beam, does not require a coil outside the tube and is suitable for downsizing and reducing power consumption. Image pickup tubes are conventionally known.

In an imaging device using such an imaging tube, as shown in FIG. 5, a horizontal deflection electrode 51a of an imaging tube 50 is used.

51b, a sawtooth deflection voltage is applied to the vertical deflection electrodes 52a and 52b by a horizontal/vertical deflection circuit 53 to deflect the electron beam.

That is, the output terminal 53a of the horizontal/vertical deflection circuit 53
, 53b, a sawtooth wave for vertical deflection having a voltage amplitude of VPP is output as shown in FIG. 6B. This sawtooth wave is applied to the vertical deflection electrodes 52a and 52b, and the electron beam is deflected in the vertical direction. Further, between the output terminals 53C and 53d of the horizontal/vertical deflection circuit 53,
A sawtooth wave for horizontal deflection having a voltage amplitude of Hpp as shown in FIG. 6A is output. This sawtooth wave is applied to the horizontal deflection electrodes 51a and 51b, and the electron beam is deflected in the horizontal direction. Further, to generate the sawtooth wave, a general sawtooth wave generation circuit composed of a constant current circuit and a capacitor is used.

Incidentally, in such an electrostatic focusing/electrostatic deflection type image pickup tube, the focusing of the electron beam is adjusted by adjusting the center potential of each deflection signal waveform at the same time as the horizontal and vertical deflection. This is done by equally changing the center potential Vc of each of the sawtooth waves for horizontal deflection and vertical deflection shown in FIG. At this time, in order to prevent the amplitude of each sawtooth wave from changing, the horizontal/vertical deflection circuit 53 uses a floating power supply 54 that is not connected to the ground plane of other circuits and supplies the voltage Vo. This floating power supply 54 cannot be shared with other circuits.

[Problem that the invention seeks to solve]

As described above, the electrostatic deflection circuit of the image pickup tube using the conventional electrostatic focusing electrostatic deflection method requires a floating power supply for the purpose of performing focus adjustment. This floating power supply is used only for the deflection circuit and cannot be shared with other circuits, which hinders the miniaturization, lower power consumption, cost reduction, etc. of the imaging device.

The present invention has been made in view of these problems, and enables electron beam focusing adjustment without using a floating power supply, thereby reducing the size and power consumption of an imaging device.
It is an object of the present invention to provide a deflection circuit that is highly effective in reducing costs.

[Means for solving problems]

In order to achieve the above object, the present invention has the following configuration. In other words, a circuit that generates a sawtooth deflection voltage using a constant current circuit, two power supplies with one output terminal of each connected in common, and the other output terminal of each of these two power supplies. two resistors of equal value connected between corresponding terminals of the two power supply terminals of the deflection circuit, and a commonly connected output terminal of the power supply and the two power supply terminals of the deflection circuit; and a variable resistance circuit connected between the electrostatic deflection circuit and the variable resistance circuit.

[For production]

In the electrostatic deflection circuit configured in this way, the deflection circuit is driven according to the voltage difference between the two power supplies. Further, by adjusting the variable resistance of the variable resistance circuit, the potentials of the two power supply terminals of the deflection circuit change in the same amount and direction. Therefore, only the center potential changes while the voltage difference remains constant.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which an electrostatic deflection circuit according to the present invention is applied to an imaging device using an imaging tube will be described below with reference to the drawings.

Figure 1 shows the electrostatic deflection circuit 1 using two positive and negative power supplies.
FIG. 2 is a configuration diagram of a first embodiment of the present invention. In the same figure, the positive voltage V
The power supply 2 of the voltage V0 is connected to the power supply terminal 4e of the horizontal and vertical deflection circuit 4 through a resistor R1, and the power supply 3 of negative voltage -Vo is connected to the power supply terminal 4e of the horizontal and vertical deflection circuit 4 through a resistor R2 having the same resistance value as the resistor R1. is connected to the power supply terminal 4f. The negative side of the power source 2 and the positive side of the power source 3 are grounded. Further, a resistor R3, a variable resistor VRI, and a resistor R4 are connected in series between the terminals 4e and 4f of the horizontal/vertical deflection circuit 4, and the middle terminal of the variable resistor VRI is grounded. Here, the resistor R,8 and the resistor R4 are set to the same value. Circuits 5 and 6 indicate other circuits of the imaging device, and are driven by the power supplies 2 and 3, respectively.

When voltage is supplied through the resistors R, 1, and R2, the horizontal/vertical deflection circuit 4 outputs a sawtooth voltage for horizontal deflection between terminals 4a and 4b, and outputs a sawtooth voltage for vertical deflection between terminals 4c and 4d. Outputs sawtooth wave voltage. This sawtooth wave voltage is generated by a general sawtooth wave generation circuit consisting of a constant current circuit and a capacitor.

Next, such a sawtooth wave generating circuit will be explained.

FIG. 3 is a circuit diagram of a general sawtooth wave generating circuit.

In the figure, a transistor TRI and a resistor 81. R32
, R35 constitute a constant current circuit for capacitor C2, and transistor TR2 and resistors R33, R34, and R35 constitute a constant current circuit for capacitor CI. Further, the capacitor CI is connected to the output terminal 36, and the capacitor C2 is connected to the output terminal 35.

Pulses of opposite polarity are applied to the terminals 33 and 34,
This pulse controls transistors TR3 and TR4. A voltage vc is supplied between terminals 31 and 32.

The operation of this sawtooth wave generating circuit 30 will be explained based on the waveform diagram shown in FIG. First, at time t1, when a negative pulse is applied to the terminal 33 and a positive pulse is applied to the terminal 34, the transistor TR
3. Since TR4 is turned on, the voltage at the output terminal 35 falls to the lower limit of the supply voltage VC, and the voltage at the output terminal 36 rises to the upper limit of the voltage Vc. After that, the capacitor c1. c2 is charged with a constant current, the voltage at the output terminal 35 increases linearly until a pulse is applied again at time t2, and the voltage at the upward bending output terminal 36 decreases linearly until time 12. The voltage vout is the difference between the voltage at the output terminal 35 and the voltage at the output terminal 36.

In this sawtooth wave generating circuit 30, if the supply voltage Vc is constant, the current flowing through the terminals 31 and 32 is also constant.

In the horizontal/vertical deflection circuit 4, two such sawtooth wave generating circuits 30 are used with time constants set for horizontal deflection and vertical deflection.

Next, the drive voltage and center potential of the horizontal/vertical deflection circuit 4 will be explained.

The current flowing through the horizontal/vertical deflection circuit 4 is i, and the horizontal/vertical deflection circuit 4 is
The voltage at the terminal 4e of the vertical deflection circuit is vl, and the voltage at the terminal 4f of the horizontal/vertical deflection circuit is vl.

If the resistance between the midpoint terminal of the variable resistor V1 and the terminal on the resistor R4 side is 4, and the resistance between the midpoint terminal of the VRI and the terminal on the resistor R4 side is rl, then the voltage v1. ＋v
Each l is Vl=(VOia:t)/(1+at4H3+rl)”
)・−・・・・(tlv2=(Vo−iRl)/(
1+几1/cR+3+r2)N...Mountain surface (can be expressed as 2λ).

The difference between the voltages vl and v2 becomes the driving voltage for the horizontal/vertical deflection circuit 4. Here, if rl + r2 = R5 and the resistor R1 is set to be R1) rl, r2, the voltage v1. The difference in v2 is calculated from equations (1) and (2) as follows: 2 R30R5 V□-y2=(vo-""R10R8-..."(3
) can be expressed as Since the right side of equation (3) is a constant, the driving voltage Ml of the horizontal/vertical deflection circuit 4 is
-V2 becomes constant. Further, the voltage v1. From equations (1) and (2), the center potential of v2 (vr+V2)/2 is V1+V2 (Vo-iRl) R,,5-2r2
2-2 ] ding岨j °−゛−゛−=−(4J) Since r2 on the right side of this (4J equation) can be changed by the variable resistor VFLI, the center potential ('/
l+V2)/2 can be adjusted.

Therefore, the drive voltage VI-v2 of the horizontal/vertical deflection circuit 4
While keeping constant, the center potential (vt +V2) /
2 can be changed to adjust the focusing of the electron beam.

Next, as a second embodiment, FIG. 2 shows an electrostatic deflection circuit 20 using two positive power supplies.

In the figure, a power source 21 with a positive voltage vl is connected to a terminal 25a of the horizontal/vertical deflection circuit 25 via a resistor R21, and a terminal 25b of the horizontal/vertical deflection circuit 25 has the same resistance value as the resistor R21. Positive voltage v2 via resistor R22
A power source 22 is connected. Further, one end of a resistor R23 is connected to the terminal 25a, and one end of a resistor R24 having the same resistance value as the resistor R23 is connected to the terminal 25b. The other ends of each of the resistors R23 and R24 are connected to a variable resistor V2 whose one end is grounded. Circuits 23 and 24 are other circuits of the imaging device, and are driven by the power supplies 21 and 22, respectively.

The horizontal/vertical deflection circuit 25 uses the above-mentioned sawtooth wave generation circuit, and the three currents i flowing therein are constant. Here, the voltage at the terminal 25a of the horizontal/vertical deflection circuit 25 is set to Vl,
If the voltage at the terminal 25b is 2, then Vl-V2 becomes the driving voltage for the horizontal/vertical deflection circuit 25.

Also, let the value of the variable resistor VR,2 be r, and RZ8°"
2') If R23 and R24 are set so that r, rcz a =1T='', then R,23,R,2
The currents flowing through 4 will be equal. Therefore, the above-mentioned voltage V-work.

v2 to V1= Vl −R+21 ・(i 10 i o )
・・・・・・River・(5)v, = V2−R21・
(i o i ) −”−(6), and the above driving voltage V, −IA can be expressed as (Equation 51,
From equation (6).

Vl-V2=VI V2 2 ・R21-i
""""' (7). Since i on the right side of equation (9) is constant, Vl-V2 is constant. Also, the center potential (Vl+V2)/2 is based on equations (5) and (6).

Vz+Vz Vl+V2 □=□−几21・i,) ・・・・・・・・・
It can be expressed as (8). Since io on the right side of equation (8) changes by adjusting the variable resistor V&2, the center potential (V +'/z)/2 also changes.

Therefore, it is possible to change the center potential (Vl + Vz)/2· while keeping the driving voltage vl-V3 constant, and it is possible to adjust the focusing of the electron beam.

〔Effect of the invention〕

As described above, the electrostatic deflection circuit according to the present invention does not use a floating power supply, but uses a normal power supply that supplies power to other circuit parts of the device to drive the deflection circuit, and the output of the deflection circuit is Focusing of the electron beam can be adjusted by changing the center potential of the voltage while keeping the negative amplitude constant. Therefore, it is possible to provide an electrostatic deflection circuit that is highly effective in reducing device size, power consumption, and cost.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a first embodiment of an electrostatic deflection circuit according to the present invention, and FIG. 2 is a block diagram of a second embodiment of the electrostatic deflection circuit. FIG. 8 is a circuit diagram of a sawtooth wave generation circuit used in the horizontal and vertical deflection circuits of the first and second embodiments, and FIG. 4 is a signal waveform for explaining its operation. It is a diagram. FIG. 5 is a configuration diagram for explaining a conventional electrostatic deflection circuit, and FIG. 6 is a waveform diagram of a deflection voltage output from this electrostatic deflection circuit. 1.20...... Electrostatic deflection circuit 2.3, 21
．． 22...Power supply 4.25...Horizontal/vertical deflection circuit R1,
FL2. R3, R4, R21, Ft22.几23゜FL
24・・・・・・・・・Resistance VR, 1, VB2
...Song...Song Variable Resistor Figure 1 Figure 2 Figure 6

Claims (1)

[Claims] A deflection circuit that generates a sawtooth deflection voltage using a constant current circuit, two power supplies to which one output terminal of each is commonly connected, and the other output terminal of each of these two power supplies. two resistors of equal value connected between corresponding terminals of the two power supply terminals of the deflection circuit; and a commonly connected output terminal of the power supply and the two power supply terminals of the deflection circuit; and a variable resistance circuit connected between the electrostatic deflection circuits.