JP3535195B2 - Small tv camera - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small television camera.
You. [0002] 2. Description of the Related Art A conventional TV camera has a 12 Volt power supply.
Although a pond power supply is used, its driving circuit has +15 Vol
A power supply of t and -9 Volt is required. For this reason,
Large DC-DC converter with transformer
To prevent switching noise from affecting other circuits.
It is common to shield to prevent leakage
Was. [0003] However, the DC-DC
Converter circuit and low-pass filter circuit (LPF)
Uses a transformer and shield case for
It became. The present invention relates to a DC-DC converter circuit and
-A DC-DC filter is not used for the pass filter circuit.
BL which has no effect on the TV camera with the converter
The transistor of the power supply circuit is switched only during the K period.
Switching noise to prevent switching noise.
And small TV camera without the shield case
Mera is provided. [0004] SUMMARY OF THE INVENTION The present invention provides a synchronous signal generator.
Unit 1 and timing for generating a timing signal therefrom
Generator 2 and vertical and horizontal scanning based on this timing signal
Vertical driver 3 and horizontal driver that generate a check signal
4, a CCD imaging device 5, and the CCD imaging device 5
A low-pass filter that removes high-frequency components of the output video signal b
Filter 8 and an output amplifier 11 for outputting a video output signal a.
The low-pass filter 8 has an amplification factor of +1.
Active low-pass with amplifier as emitter follower
Power supply circuit 20Two Transis
24, 25 and two capacitors 26, 27 and backflow prevention
Composed of diodesDouble voltage charging type power storage circuitAnd fixed
Voltage IC circuits 28 and 29The power supply circuit 20
The trigger signal c of the synchronous signal generator 1 for triggering the
Signal having a rising part and a falling part during the BLK period of signal b.
No. c₁, C_Two Is a small TV camera. [0005] [Operation] Timing is generated by the pulse of the synchronous signal generator 1.
And outputs the vertical driver 3 and horizontal driver
Driver 4 and the vertical and horizontal synchronous scanning signals
The CD photographing element 5 is driven. This CCD imaging device 5
The video signal b to be output is an active low-pass filter 8.
To remove the high-frequency signal to become the video output signal a.
Sent to a television receiver not shown. [0006] FIG. 1 schematically shows a driving circuit for a television camera.
The timing is generated by the pulse of the synchronization signal generator 1 in the block diagram.
Driving the living creature 2, the vertical driver 3 and the horizontal
The driver 4 is driven and its vertical and horizontal synchronous scanning signals are used.
The CCD imaging device 5 is driven. With this CCD imaging device 5
The obtained video signal b is correlated double sampling circuit 6
, AGC amplifier 7, and active low-pass filter
8, a gamma correction circuit 9, and a blanking insertion synchronization signal.
The high frequency signal is removed by the signal circuit 10 and the output amplifier 11.
The video output signal a shown in FIG.
Sent to the receiver. The output of the low-pass filter 8 is
AGC via the ANKing circuit 12 and the AGC detection circuit 13
The signal is fed back to the amplifier 7. Also correlated double sun
The output of the pulling circuit 6 is an amplifier 14, an iris driver
Then, the lens 16 of the camera is driven via the camera. In the figure
17 is a cable correction circuit. Power supply circuit 20 is double voltage
A 12-volt battery is connected to the terminal 21 of the charging type power storage circuit.
Terry power input, trigger from timing generator 2
At signal c, as described above, +15 Volt and -9 Volt
The drive voltage is generated. FIG. 2 shows the details thereof.
The transistor 23 is triggered by the input trigger signal c.
The transistors 24 and 25 alternate with an appropriate phase difference
On and off when the transistor 24 is on.
Capacitor 27 and when the transistor 25 is on
The capacitor 26 is charged, and the capacitors 26 and 27
The battery is charged at a power supply voltage of 12 Volt.
The voltage of 24 volts, which is the sum of the
The voltage is changed to +15 Volt by the voltage IC circuit 28 and the terminal 30
-12 Volt charged to the capacitor 27
Is changed to -9 Volt by the constant voltage IC circuit 29.
31. As shown in FIG. 3, the video output signal a is
As shown in FIG. 3A, the video signal is as shown in FIG. 3B.
The trigger signal c is, for example, the signal c in FIG.₁like
Standing during the BLK period (video output pause period) of video signal b
Whether there is a rising part and a falling part, the signal c in FIG._TwoNo
The falling part during the first BLK period and the second BLK period
So that there is a rising part. This allows the trigger signal
Switching that occurs when the signal c rises or falls
Since the noise is in the BLK period, the video output signal a
Does not affect the image and therefore seals the power circuit 20
You do not need to do this. FIG. 4 shows an active low-pass filter.
4th order active filter and image enhancement circuit example
It is. The active filter shown in FIG.
In the transistor and the resistor (Q₁, R_Three), (Q_Two, R
₆) With a gain of 1
(Amplification factor 1). 4th active
The basic configuration of the filter is the secondary active filter shown in FIG.
In this case, the filter is cascaded in two stages. Where C₁Is conde
Sensor, C_TwoIs a capacitor, R₁Is a resistor, Amp is a gain
1 amplifier. This basic secondary active filter
It requires an amplifier with a gain of 1 in the frequency band to be handled. FIG.
Medium resistance (R₁, R_Two), (R_Four, R_Five) Is the resistor in FIG.
The capacitors (C, C) in FIG.
C_Two), (C_Three, C_Four) Is the capacitor (C₁,
C_Two). This property is (Equation 1)Indicated by However (Equation 2) And ω = Fω₀And ω₀If you standardize (Equation 3) Here, when Q = 0.5 (Equation 4) Is a curve A in FIG. The value of ωo set on the curve A is doubled.
When the value of Q is 2, the characteristic is as shown by the curve B in FIG.
You. Therefore, 2 having a curve A characteristic and a curve B characteristic
When the next active filter is connected in cascade, the curve C
A fourth-order active filter having the following characteristics is obtained. Characteristics of curve C
Has a steeper falling characteristic than either of the curves A and B.
One. Resistance R in FIG.₇And capacitor C_FiveParallel circuit with
A resistor R in series with₈And capacitor C₆Series circuit with
Capacitor C in parallel with it₇The circuit composed of
This is an example of a simple image enhancement circuit, which enhances the outline of the video.
Is done. Capacitor C₆Is the direct output of the active filter.
It is used so as not to lose the flow value and has a sufficiently large capacity value.
It has no effect in the frequency band of the video signal. R as an example₇
= R₈= 1KΩ, C_Five= 30PF, C₇= 15P
The characteristics at this time are as shown in FIG. [0010] As described above, according to the present invention, double voltage charging is performed.
A power supply circuit 20 comprising an electric storage circuit;
Since the low-pass filter 8 of FIG.
No file is required, and therefore, it can be miniaturized. Ma
The trigger signal c for triggering the power supply circuit 20 is a video signal b
Signal c having a rising portion and a falling portion during the BLK period
₁, C_TwoIs used, the switch generated by this
Ching noise affects the image of the video output signal a.
Therefore, the shield of the power supply circuit 20 becomes unnecessary.
Thus, the size can be further reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram schematically showing an embodiment of the present invention. FIG. 2 is a power supply circuit diagram thereof. FIG. 3 is an output signal diagram of each section. FIG. 4 is a circuit diagram of the low-pass filter. FIG. 5 is a basic configuration diagram of the low-pass filter. FIG. 6 is a graph showing output characteristics with respect to the frequency. FIG. 7 is a graph showing an image enhancement characteristic with respect to the frequency. [Description of Signs] 1 Synchronous signal generator 2 Timing generator 3 Vertical driver 4 Horizontal driver 5 CCD imaging device 8 Low-pass filter 20 Power supply circuit a Video output signal b Video signal c Trigger signal c ₁ , c ₂ signal

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04N 5/225 H02M 3/07 H04N 5/335

Claims (1)

(57) Claims 1. A synchronous signal generator (1), a timing generator (2) for generating a timing signal therefrom, and a vertical and horizontal scanning signal generated from the timing signal. Vertical driver (3) and horizontal driver (4), C
A CD photographing element (5), a low-pass filter (8) for removing a high frequency component of a video signal (b) output from the CCD photographing element (5), and an output amplifier (11) for outputting a video output signal (a) The low-pass filter (8) is an active low-pass filter using an amplifier having an amplification factor of +1 as an emitter follower. The power supply circuit (20) has two transistors (24, 25) and two transistors (24, 25).
It consists of capacitors (26, 27) and a diode for preventing backflow.
The double voltage charging type power storage circuit and the constant voltage IC circuit (2
8, 29), and the trigger signal (c) of the synchronizing signal generator (1) for triggering the power supply circuit (20) is a signal having a rising portion and a falling portion during the BLK period of the video signal (b). (C ₁ , c ₂ ) a small television camera.