JPS6218115B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic monitoring device for security or automatic management of machinery, and in particular to
The present invention relates to a video switching device in which one type of monitor device and two monitor device connection types can be selected by selecting and switching means.

Generally, a video switching device, as shown in Fig. 1, connects video cameras 1, 1'...
When connecting the monitor devices 4, 5 via the video cameras 1, 1', etc., and switching between the two monitor devices 4, 5 using the analog switches 2, 3, sequential automatic switching operation or optional Perform selection operation or make any setting, display circuit 6
The green LED 7 lights up to indicate the automatic switching number, and the red LED 8 lights up when an arbitrary selection is made.

Next, each of the automatic switching operation and the arbitrary selection operation will be explained.

() Automatic switching operation The timer 10 operates according to the period set by the variable resistor 9, generating a clock pulse, which is applied to the NAND gate 11 together with the output of the astable multivibrator 12, and the output of the NAND gate 11 is After being waveform-shaped by the NAND gate 13, it is sent to the counter 14. Said counter 1
4 outputs a binary code corresponding to the number of clocks of the clock pulse, and in response to this, the decoder 15 sets the output terminal corresponding to the input binary code to a low level "L", and the inverter 16
A high-active type analog switch 2, which is operated by a high level "H", is driven through. The analog switch 2 selects the video signal vi from the video cameras 1, 1', . . . corresponding to the high level "H" input terminal, and outputs it to the monitor device 4. The counter 14 receives the video signal vi
Count up to the number of channels, return to the lower channel, and repeat the count up.

() Optional selection operation When the function changeover switch 17 is pushed to the position b-b' side as a momentary mechanism, the encoder 18
outputs a binary code corresponding to this, which is applied to the latch circuit 19.

On the other hand, the encoder 18 outputs a control signal indicating that it has been switched on, and triggers the monostable multivibrator 20. The rise of the monostable multivibrator 20 (as an example)
The latch circuit 19 is driven using a time constant of 10 ms) to latch the binary code.

This latched binary code is outputted by the next decoder 21, which sets the output terminal corresponding to the input code to a low level "L", and similarly to the automatic switching operation described above, the inverter 2 inverts the output terminal to a "H" level signal. A video signal is selected by the analog switch 3 and output to the monitor device 5.

Here, in both the automatic switching operation and the arbitrary selection operation described above, the high level "H" control signal applied to the analog switches 2 and 3 is applied to the display circuit 6 that drives the light emitting diode LED, and the control signal is applied to the display circuit 6 that drives the light emitting diode LED, and the control signal is applied to the display circuit 6 that drives the light emitting diode LED. The configuration is such that either the red LED 7 or the green LED 8 lights up, and when the video camera numbers are the same, the red LED 7 gives priority to the green LED 8. Also, set the function selector switch 17 to a-
When set to a', the output from the decoder 15 is "L"
The signal is applied to astable multivibrator 12 via NAND gate 24, causing counter 14 to skip.

However, currently the two monitor devices 4 and 5 mentioned above are
There is a so-called two monitor device connection format in which the video camera is connected to multiple video cameras, and a separate model in which one monitor device is prepared completely separately and either one is used as needed. was. 4 in the figure indicates the number of signal lines and the number of elements in an example in which four video cameras are provided.

Therefore, the present invention aims to eliminate the above-mentioned drawbacks and provide a new video switching device capable of supporting the above-mentioned two formats as a single type of video switching device, which will be described below with reference to the drawings.

FIG. 2 is a block diagram showing the video switching device of the present invention, in which the same elements as in FIG. 1 are given the same figure numbers, and FIG. In the timing chart when connected, 5 is a mode changeover switch with 2 circuits and 2 contacts, 26, 27
is a NAND gate, 28 is a T-type flip-flop (TF/F), and the NAND gates 26 and 27 are
is equivalent to an inverter having a waveform shaping function.

Next, the operation of the present invention will be explained.

() When two monitor devices are connected If the mode selector switch 25 is set to the B side, the load line (LOAD in the figure) of the counter 14 goes to high level "H" and becomes the decoder 21 through the NAND gates 26 and 27. By adding a low level "L" signal and applying a high level "H" signal to the NAND gate 24, the same operation as the conventional video switching device is performed.

() When one monitor device is connected In this case, the automatic switching operation and optional selection operation will be explained below. In this case, the mode changeover switch 25 is set to the A side.

(A) Automatic switching operation When the power is turned on, the function switch 17
In the state shown in the figure, the T flip-flop 28 is reset and the output is at a high level "H".
and the load line of counter 14
LAOD is high level “H”, NAND gate 2
The input terminal 4 becomes high level "H", and the video signal applied through the analog switch 2 is applied to the monitor device 4, and the video is reproduced.

Here, the control signal to the decoder 21 is NAND
The high level becomes "H" through the gate 26, and all the outputs of the decoder 21 become high level "H", so the input to the display circuit 6 becomes low level "L", and the red LED 7 does not light up, while the green LED The LED 8 lights up and each video camera is automatically switched, and in the case of four video cameras, the so-called running operation is performed in which the video cameras are sequentially switched from 1 to 4.

(B) Optional selection operation When the function changeover switch 17 is pushed toward the b-b' side at timing t1 in Fig. _2A , the encoder 18 outputs a binary code (2 bits if there are 4 video cameras) corresponding to the pressed switch. outputs v ₂ and v ₃ ) in the figure, and connects latch circuit 1.
9 is applied.

On the other hand, the encoder 18 outputs a control signal (v ₄ in the figure) indicating that it has been switched on, thereby triggering the monostable multivibrator 20 . The timing of the rise of the monostable multivibrator 20 after a predetermined time (for example, 10ms) (the timing shown in Fig. 2)
At _t2 ), the latch circuit 19 is driven and latches the binary code signal, and this binary code signal is applied to the decoder 21 and the counter 14. At the same time, due to the rise _t2 of the monostable multivibrator 20, T
The F/F 28 is driven and the output is inverted to a low level "L". The low level “L”
The signal sets the load line LOAD of the counter 14 to a low level "L", the control terminal 29 of the decoder 21 to a low level "L", and the control terminal 30 of the astable multivibrator 12 to a high level "H". The astable multivibrator 12 is driven to oscillate at timing _t2 in a high active state, and its output is applied to the counter 14 as a clock pulse.

At this time, the output code of the latch circuit 19 is applied to the counter 14;
Since the load line LOAD is at a low level "L", the code of the latch circuit 19 is output as the output of the counter 14, and the code of the latch circuit 19 is outputted as the output of the counter 14.
5. The video signal vi generated by driving the analog switch 2 and optionally selecting it is output to the monitor device 4, and then the function changeover switch 17 is turned once to b-
When set to the b' side, the output does not change until the output of the T flip-flop 28 is set to a high level "H" in the operation described above.

On the other hand, the control signal to the display circuit 6 is of the same video camera number and is at high level "H".
is input, but as mentioned above, the red LED 7
has priority over the green LED8, the red LED
Only IED7 lights up.

In the above configuration, in an example where four video cameras are connected, there are four input lines and output lines to analog switches 2 and 3, four pairs of red and green LEDs, and a function selector switch 17.
There are four lines, and correspondingly there are two lines from the encoder 18 to the decoder 15.
A book (processed in 2 bits) is provided.

In addition, timing _t4 in FIG _. 3 is the timing when the function changeover switch 17 is turned off, that is, the state shown in FIG.
The energized falling and rising timings of v ₁₁ and v ₁₂ are shown.

As described above, according to the video switching device of the present invention, 1
By using the mode switching means, it is possible to make one model compatible with either type of monitor device connection type or two monitor device connection type, and it can serve as two types of models as in the past. The device of the present invention can exhibit extremely great effects on automatic monitoring systems.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional video switching device, FIG. 2 is a block diagram of the same according to the present invention, and FIGS. Explanation of main drawing numbers 1, 1'...video camera,
2, 3... Analog switch, 4, 5... Monitor device, 7... Display circuit, 8, 9... LED, 10
...Timer, 12 ... Astable multivibrator, 14 ... Counter, 15, 21 ... Decoder, 17 ... Function changeover switch, 18 ... Encoder, 19 ... Latch circuit, 20 ... Monostable multivibrator, 25...Mode changeover switch.

Claims (1)

[Claims] 1. In a video switching device equipped with a camera switching means for automatically switching a plurality of video cameras connected to a monitor device, the plurality of video cameras are automatically switched sequentially, or a predetermined one of them is switched automatically. function changeover switch means for selectively switching between two modes that are set to 1 and arbitrarily selected; mode changeover switch means for selectively changing over the connection of the plurality of monitor devices and the connection of one monitor device; An image comprising a display means provided with two different types of display elements, the display means displaying which of the two modes it is in by switching the mode changeover switch means. Switching device.