JPS641822Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field This invention is a so-called intercom that is installed at the entrance or gate and in the living room, and is equipped with a television camera and a monitor (picture tube) to provide an image of visitors in the living room. Regarding a video door phone that allows monitoring.

BACKGROUND TECHNOLOGY AND PROBLEMS In the case of a video door intercom, an image sensor, that is, a television camera is attached to a handset attached to an entrance or gate. Generally speaking, this TV camera has the disadvantage that the target surface can be damaged if strong light is incident on it, but as mentioned above, since the slave unit is installed outdoors, there are many chances for it to be exposed to sunlight, car headlights, etc. There are many risks.

Furthermore, if a constant light image is incident on the device for a long period of time, the light image may remain as an afterimage and overlap with other images, resulting in poor image quality.

As a means to avoid such drawbacks, when strong light enters the television camera, the incident light is blocked by a mechanical shutter, or by an optical filter, such as a polarizing filter or a liquid crystal filter, etc. It is proposed to protect television cameras.

Generally, when a doorbell is used, the handset, or TV camera, starts operating when a visitor's notification (buzzer, etc.) is sent from the handset, or when the base unit picks up the handset based on this notification. A signal based on the image is sent to the base unit, and the image is reproduced on the monitor inside the base unit, but if the shutter is set to operate in the case of strong incident light as described above, when this protection device is activated, In many cases, it is not possible to accurately determine whether there is a malfunction on the base unit side or whether the protection device is operating.

Purpose of the Invention The present invention avoids the above-mentioned drawbacks, and therefore, when the protection device is in operation, it is displayed on the base unit so that the failure state can be distinguished.

Summary of the invention The present invention is a video door intercom that blocks light incident on the TV camera when the amount of light incident on the TV camera of the video door intercom slave unit increases. When the incident light is blocked due to an increase in the amount of light, a display is displayed on the video intercom base unit to notify the interruption of the incident light.

Embodiment An example of a video door phone according to the present invention will be described below with reference to the drawings. 1 is a master unit, 2 is a slave unit, 3 is a commercial AC power supply terminal of the master unit 1, and 4 is a DC power supply for rectifying this.

When the ringing switch 5 of the handset 2 is turned on (closed), current is supplied to the ringing tone generation circuit 8 through the line 6 and the switch 7, which operates to notify the visitor of the visitor.

As is conventionally known, by picking up the handset 9 on the base unit 1, the switch 7 switches to the dotted line state, and a conversation can be made between the handset 9 and the microphone 10 and speaker 11 of the handset 2. . Reference numeral 12 indicates a communication circuit network of the handset 2.

On the other hand, the current to the ringing tone generation circuit 8 described above is simultaneously supplied to the current control time limit circuit 13, and from this point on, the current is supplied to the DC power supply 4 through the circuit 13 for a certain period of time.
The operating current is supplied to the monitor 14 of the base unit 1, and is also supplied to the television camera (video camera) 17 through the line 15 and relay contact 16. At the same time, current is also supplied to the shutter drive circuit 18 to open the shutter 19 and project the subject image onto the camera 17.

As a result, the video signal obtained from the camera 17 is supplied to the monitor 14 of the base unit 1 through the line (coaxial cable or optical fiber) 20, and is displayed on the monitor 14.

Further, the handset 2 is provided with a light sensor 21, and when strong light exceeding a predetermined value is incident on this, a judgment circuit 22 makes a judgment and turns off the relay connection 16, cutting off the drive current to the camera 17. At the same time, the shutter drive circuit 18 is turned off and the shutter 19 is closed to prevent light from entering the camera 17.

Further, in the main device 1, the operating current is supplied to the signal detection circuit 23 at the same time as the monitor 14, and this is configured to operate together with the monitor 14 for the above-mentioned fixed period of time. This detection circuit 23 is supplied with a signal from the camera 17 coming through the line 20, and operates by lighting up a display device 24 such as an indicator lamp when the shutter 19 is blocking the incident light. That's what I do.

This detection circuit 23 can perform various detections.

That is, when a so-called composite video signal, which is a combination of a video signal and a synchronization signal, is sent to the line 20, either the synchronization signal or the video signal is detected. If only a video signal is sent to the line 20 and configured in a so-called power supply synchronization type, the video signal is detected. In this case, when a composite video signal is sent to the line 20, the camera 17 is connected to the monitor 14.
If the operating current is supplied in synchronization with
That is, when the current through the relay contact 16 is supplied only to the shutter drive circuit 18, a video signal is detected.

As described above, when the operating current is supplied to the monitor 14 and the camera 17 through the timer circuit 13, when the respective signals cannot be detected during each of the above-mentioned detections in the signal detection circuit 23, the display device 24 The display is performed by lighting or the like.

According to this configuration, the main unit 1 can switch the
If you raise the limit, you can talk to the handset 2 as usual, but the timer circuit 13 operates and the monitor 14
The camera 17 and the camera 17 are brought into operation, current is also supplied to the shutter drive circuit 18, the shutter 19 is opened, a subject image is captured, and the monitor 14
It will be played at. Therefore, the visitor can be confirmed on the main unit 1 side.

Furthermore, in this state, if strong light
If this is the case, the discrimination circuit 22 is activated by the signal from the optical sensor 21, so in this case, the operating current to the camera 17 is cut off and becomes inactive, and at the same time, the operating current to the camera 17 is cut off, and the shutter drive circuit 18 is also Since the current is cut off, the shutter 19 closes and prevents light from entering the camera 17.

In this case, since no synchronization signal or video signal is sent to the line 20, the detection circuit 23
Since this can be detected and displayed on the display device 24, it can be seen that the shutter 19 is closed on the base unit 1 side, and whether the image is not displayed on the monitor 14 due to a malfunction. Alternatively, it is possible to easily determine whether the shutter 19 is closed or not.

Effects of the invention According to the invention described above, it is extremely easy to determine whether the shutter 19 is closed and no image is displayed on the monitor 14 while the slave unit 2 is operating in the base unit 1, or whether the image is not displayed due to a malfunction. It has the characteristics of being able to recognize the situation and take appropriate measures accordingly.

[Brief explanation of the drawing]

The figure is a block diagram showing an example of a video door intercom according to the present invention. 1 is a master unit, 2 is a slave unit, 14 is a monitor, 17 is a television camera, 19 is a shutter, 23 is a signal detection circuit, and 24 is a display device.

Claims (1)

[Scope of utility model registration request] In a video door intercom which is designed to block the light incident on the TV camera when the amount of light incident on the TV camera increases, when the TV camera is in use and the amount of incident light increases, the amount of light incident on the TV camera increases. 1. A video door intercom characterized in that, when the incident light is interrupted, a display notifying the interruption of the incident light is displayed on the television intercom base unit.