JPS602708Y2 - Synchronous signal mixing circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a synchronization signal mixing circuit for a television camera device, and provides a circuit that has a simpler circuit configuration than conventional circuits and can operate reliably.

Recently, with the popularity of video tape recorders, camera devices have been attracting attention as an accessory device.

Camera devices vary in size and performance depending on their use, and FIG. 1 shows a conventional synchronizing signal mixing circuit in a simple compact camera device.

In Figure 1, 1 is a vertical pulse input terminal, 2 is a horizontal pulse input terminal, and each pulse is the output of a vertical pulse generation circuit 3 and a horizontal pulse generation circuit 4, and the output of the oscillator of the device is divided and shaped. Each pulse is passed through a differentiating circuit 5.6 consisting of C1, R□ and C2, R2 to shaping transistors TR1, TR2.
After obtaining a vertical and horizontal synchronizing signal by a common load R3, it is applied to the video output circuit 7 etc. via a coupling capacitor C3.

An example of the pulse generation circuit 3 is shown vertically in FIG.

Its operation is as follows. The output of the oscillator 8 is sent to the divider 9
The signal obtained through C1R7 is divided into voltages by resistors R1R6 and input to the emitter follower transistor TR, and the output from load 9 is passed through the differentiating circuit 10 of C1R7 to the transistor TR
, and the output vertical pulse obtained by shaping is taken out from the load R1.

As shown in FIGS. 1 and 2, the conventional method not only requires vertical pulse and horizontal pulse generation circuits, but also requires two transistors for each pulse.
The circuit configuration is complex, the number of parts is large, and the cost is high, so it has many drawbacks as a simple compact camera device.

The present invention does not have vertical pulse and horizontal pulse generation circuits, and uses the circuit output originally provided for the camera device to obtain input signals for obtaining each synchronization signal. This transistor enables synchronization of synchronization signals.

An embodiment of the present invention will be described below based on the drawings.

In FIG. 3, reference numeral 11 denotes an oscillator built into the camera device, and the output of the oscillator 11 is frequency-divided by a frequency divider 12.
is driven, and the output sawtooth wave of the vertical deflection circuit 13 is inputted to the synchronization signal mixing circuit 16 via the clip circuit 15, and on the other hand, the operation of the horizontal deflection circuit 14 causes a flyback transformer (hereinafter abbreviated as FBT) 17 The flyback pulse generated at We're getting threat output.

Here, vertical deflection circuit 13 horizontal deflection circuit 14 and FBT
17 is originally included in a camera device.

It is a circuit block.

Next, the synchronous mixing circuit 16 including the clip circuit 15.18
A specific example is shown in FIG.

Deflection sawtooth output generated by vertical deflection circuit 13 (fifth
Figure g) is connected to resistor R□ through diode D□.

, R1□, and connect the power supply voltage VCC to the resistor R
1o and R□1, and the signal obtained by this clipping (Fig. 5b) is applied to a differentiating circuit of capacitor C1o and resistor R13, and its output ( By applying FIG. 5c) to the mixing transistor TR6, a vertical synchronizing signal (FIG. 5d) is obtained for the load R16.

On the other hand, the flyback pulse from FBTl 7 (fifth
Figure e) is the resistance R□3. The voltage is divided by R□4, and the pulse obtained by dividing the voltage is clipped by a diode D2 connected between the power supply and the connection point of the resistors R13 and R, and the signal obtained by this clipping (Fig. 5 f) is a capacitor C with a lower capacitance than the differential capacitor C1° in the vertical pulse.
11 and a resistor R□5 to the connection point between the differential capacitor C1゜ and the resistor R1□ in the vertical pulse to obtain an input for creating a horizontal synchronizing signal (Fig. 5g). By adding it to the mixing transistor R5, a horizontal synchronizing signal (FIG. 5h) having a pulse width narrower than the flyback pulse width is obtained in the load R16 in synchronization with the generation of the flyback pulse.

The problem with the above configuration, that is, adding two input signals to the same input terminal, is that the two input signals interfere with each other, so only the synchronization signal corresponding to one of the input signals can be extracted. There is no such thing.

For example, since the horizontal input signal is large, the clip level of the polarization sawtooth wave becomes large, and a vertical polarization clip signal cannot be obtained, so that a vertical synchronization signal may not be obtained.

However, in the present invention, by selecting the values of the resistors R□5 and R□2, it is possible not only to adjust the horizontal and vertical input levels to such an extent that mutual interference does not occur, but also to adjust the capacitor C.

In addition, the capacitance value of C can be selected to an appropriate value with C1o>11, and by setting the reactance to prevent the influence of the other input, the configuration is such that mutual interference between the two manual forces is eliminated.

Furthermore, by selecting the clip level and constant and adjusting the input level of the mixing transistor TR5, the pulse width of the output synchronization signal can be set to an arbitrary width within a certain range, and this synchronization signal is extracted within the blanking period. I can make things possible.

As described above, according to the present invention, the circuit configuration is simpler than the conventional example, so it is possible to reduce the number of parts and the number of man-hours in the manufacturing process, and it is advantageous in terms of cost and ensures reliable circuit operation. It has the advantage that it can be carried out.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a conventional synchronous mixing circuit, Fig. 2 is a block diagram of a conventional vertical pulse generation circuit, Fig. 3 is a block diagram showing an embodiment of the present invention, and Fig. 4 is a configuration of main parts. FIG. 5 is a waveform diagram at each part. 11... Oscillator, 12... Frequency divider, 1
3... Vertical deflection circuit, 14... Horizontal deflection circuit, 15, 18... Clip circuit, 16.
...Synchronous signal mixing circuit, C1o, C11...
...first and second capacitors, R12, R1,...
...First and second resistors, Dl, D2...
・Clip diode, TR5...Mixing transistor.

Claims (1)

[Scope of utility model registration request] The output of the oscillator built into the television camera device is divided by a frequency divider, and the output sawtooth wave of the vertical deflection circuit is operated by the output of the frequency divider. A synchronization signal mixing circuit is connected to the vertical synchronization signal mixing circuit, in which the raw silencing flyback pulse is input to the flyback transformer via the clip circuit by the operation of the horizontal deflection circuit, and a composite output of vertical and horizontal synchronization signals is obtained. Applying a signal obtained by clipping the polarized sawtooth wave to the input terminal of the mixing transistor via a first capacitor and a first resistor,
The signal obtained by clipping the flyback pulse is
is input to the connection point between the first capacitor and the first resistor via a second capacitor having a lower capacitance than the capacitor and a second resistor, and vertical and horizontal threat synchronization signals are generated by the one mixing transistor. A synchronous signal mixing circuit characterized in that it has a configuration that allows it to obtain a synchronized signal.