JP2017103523A - Intercom system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an intercom system where flicker detection speed and precision are improved without depending on a frame rate.SOLUTION: An entrance slave unit 1 includes: a camera 11; an LED 13 for nighttime illumination; and a photo-transistor 14 for detecting illuminance to turn on the LED 13. A room master unit 2 includes a monitor 21 for displaying an image captured by the camera 11. The entrance slave unit 1 includes a flicker control section 15 for determining whether a flicker exists or not and whether indoor or outdoor on the basis of an output of the photo-transistor 14. The flicker control section 15 reduces gain of a first-stage amplifier in an image sensor 11a by a fixed amount when the indoor existence of a flicker is determined, and also reduces a speed of an electronic shutter of the camera 11 at a predetermined rate.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an interphone system that can prevent flicker from occurring even when a camera provided in an entrance unit is in a flicker generation environment such as fluorescent lighting, and can display a captured image satisfactorily in a living room base unit.

An interphone system is widely used in which a camera is provided in the entrance unit so that a visitor video is displayed on the monitor of the parent unit, and the resident can confirm the visitor by video when calling or talking. The camera used in such a system has a built-in image sensor, and the lighting blinking cycle and the scanning cycle of the image sensor are synchronized under the lighting whose brightness varies periodically such as a fluorescent lamp. In some cases, flickering occurs, the luminance level fluctuates on the monitor, or stripes appear, making it difficult to see the image displayed on the monitor.
For this reason, in the conventional intercom system, the flicker is detected based on the captured video information, and a countermeasure for eliminating the flicker has been implemented.
For example, in Patent Document 1, the presence or absence of flicker is determined from luminance data at the same image position in a plurality of frames.

JP 2001-119708 A

  However, since the conventional flicker detection method detects the presence or absence of flicker from the information of the image frame output by the camera, it takes time for detection and correction due to the restriction of the frame rate output by the camera, and the flicker detection accuracy. It was not enough.

  Therefore, in view of such problems, the present invention has an object to provide an interphone system that is independent of the frame rate and has improved flicker detection speed and accuracy.

In order to solve the above-mentioned problem, the invention of claim 1 has an entrance cordless device for a visitor to call a resident, and a living room master phone for a resident to respond to a call from the entrance cordless device. The entrance unit is equipped with a camera, illumination means for night illumination, and an optical sensor for detecting the illuminance for turning on the illumination means, while the living room master unit is provided with a monitor for displaying the captured image of the camera. In the intercom system, the entrance cordless handset has flicker control means for determining the presence or absence of flicker from the output of the optical sensor and performing flicker removal control on the camera based on the determination result.
According to this configuration, since the presence or absence of flicker is determined from the output of the optical sensor for detecting illuminance, the frame rate is not limited. Therefore, it is possible to determine the presence or absence of flicker in a short time and with high accuracy, and it is possible to smoothly display an image from which flicker has been removed.

According to a second aspect of the present invention, in the configuration according to the first aspect, the flicker control means includes a filter means for extracting a direct current component from the output of the optical sensor, and a room for determining indoor / outdoor from the magnitude of the extracted direct current component. An outdoor determination unit is included, and flicker removal control different between indoors and outdoors is performed.
According to this configuration, since flicker processing is performed by determining whether the room is indoors or outdoors, flicker removal control that differs between indoors and outdoors can be performed even in the presence of flicker.

According to a third aspect of the present invention, in the configuration of the second aspect, the camera has an electronic shutter and an image sensor, and the flicker control means determines that the indoor / outdoor determination means is indoors and the flicker control means If flicker is determined, the amplifier gain of the image sensor is reduced by a certain amount, and the shutter speed of the electronic shutter is reduced at a predetermined rate.
According to this configuration, in a room where flicker is likely to occur, an exposure operation can be performed in a flicker cancellation region matched to the room, and an image that is easy to view can be displayed on a monitor with no influence of flicker by simple control. be able to.

  According to the present invention, since the presence or absence of flicker is determined from the information of the optical sensor for detecting illuminance, the frame rate is not limited. Therefore, it is possible to determine the presence or absence of flicker in a short time and with high accuracy, and it is possible to smoothly display an image from which flicker has been removed.

It is a circuit block diagram which shows an example of the intercom system which concerns on this invention. It is a circuit block diagram of a flicker control unit.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will be described below in detail with reference to the drawings. FIG. 1 is a circuit block diagram showing an example of an intercom system according to the present invention. Reference numeral 1 denotes an entrance cordless handset, 2 denotes a living room base phone, and both are connected by a transmission line L1.

  The entrance unit 1 lights a camera 11 for capturing a visitor, a video processing unit 12 for modulating an image captured by the camera 11 to transmit to the living room base unit 2, an LED 13 for night illumination, and an LED 13 for lighting. A phototransistor 14 as an optical sensor that detects the brightness of the light, a flicker control unit 15 that detects flicker from illuminance information output from the phototransistor 14 and generates a control signal for the camera 11, and a call button 16 for calling a resident , A microphone 17a and a speaker 17b for making a call, an acoustic circuit 17 for controlling a call voice, a slave CPU 18 for controlling the entrance slave 1, a slave IF 19 for communicating with the room master 2, and the like.

  The camera 11 includes an image sensor 11a and a video signal generation unit 11b that generates a video signal from the output signal of the image sensor 11a. The flicker control unit 15 includes a first-stage amplifier (amplifier) (not shown) of the image sensor 11a. A signal for controlling the electronic shutter is output.

  FIG. 2 is a circuit block diagram of the flicker control unit 15. As shown in FIG. 2, an indoor / outdoor determination unit 31 that receives a signal from the phototransistor 14 and determines whether the room is outdoor, a flicker determination unit 32 that determines the presence or absence of flicker, an indoor / outdoor determination unit 31, and a flicker determination unit. The camera control value calculation unit 33 that calculates the camera control value in response to the determination result of 32 and the signal generation unit 34 that generates the camera control signal are included. Reference numeral 35 denotes a low-pass filter (LPF) for extracting a DC component of illuminance, and 36 denotes a band-pass filter (BPF) for extracting a flicker component.

  On the other hand, the living room base unit 2 includes a monitor 21 for displaying the captured image of the camera 11, a video processing unit 22 for demodulating the transmitted video signal, a call button 23 for answering the call, and a microphone 24a for calling. And a speaker 24b, an acoustic circuit 24 for controlling the call voice, an operation unit 25 for making various settings, a parent CPU 26 for controlling the living room parent device 2, a parent device IF 27 for communicating with the entrance child device 1, and the like.

  The intercom system configured as described above operates as follows. However, when the call button 16 of the entrance cordless handset 1 is pressed, the room master 2 is called and the camera 11 is activated to display the captured image on the monitor 21 of the room master 2. Since the operation of enabling a call by operating the call button 23 is the same as the conventional one, the description thereof is omitted, and the flicker removal control here will be mainly described.

The phototransistor 14 always outputs illuminance information. Upon receiving the output, the flicker control unit 15 determines the presence or absence of flicker and outputs a control signal. The flicker control unit 15 is activated in conjunction with the activation of the camera 11.
Specifically, an AC component is extracted when the output of the phototransistor 14 passes through the BPF 36, and the flicker determination unit 32 determines whether there is flicker in the lighting environment around the entrance terminal 1 based on the extracted AC component information. Is determined.
Further, a direct current component is extracted when the output of the phototransistor 14 passes through the LPF 35, and the indoor / outdoor determination unit 31 determines whether the output is indoor or outdoor from the magnitude of the direct current component. The indoor / outdoor determination unit 31 performs threshold determination, and determines that the room is indoor if the DC component is smaller than the threshold. In response to the determination results of the indoor / outdoor determination unit 31 and the flicker determination unit 32, the camera control value calculation unit 33 calculates the control value of the camera 11.

  As a result, there are four combinations of the presence / absence of flicker and the indoor / outdoor determination. However, when it is determined that there is no flicker, since control for reducing flicker is not necessary, the camera control value calculation unit 33 controls the control signal. Do not give out. The camera control value calculation unit 33 outputs a control signal to the camera 11 via the signal generation unit 34 for the two patterns of indoor and flickering and outdoor and flickering. To do.

Specifically, when it is determined that the indoor environment is in a flicker generation environment such as a fluorescent lamp or LED, the gain of the first-stage amplifier (not shown) provided in the image sensor 11a of the camera 11 is reduced, and The electronic shutter speed (not shown) is reduced. Note that the gain reduction rate of the first-stage amplifier and the amount of decrease in the electronic shutter speed are values calculated by the camera control value calculation unit 33 (from a plurality of control values set in advance according to the detected flicker size and the DC component size). (Selected value).
As a result, the camera 11 is controlled to perform an exposure operation in the flicker cancel area.

  On the other hand, when it is determined that the outdoor environment is in a flicker generation environment such as a fluorescent lamp, the first-stage amplifier gain of the image sensor 11a is reduced and the electronic shutter speed is reduced as described above. However, the gain reduction amount of the first stage amplifier is not so large as the control in the room, and the reduction amount of the electronic shutter speed is also small. As a result, although the exposure operation of the camera 11 may not be able to completely remove the flicker, the roughness of the image is reduced compared to the case where it is determined that the room is indoors.

Thus, since the presence or absence of flicker is determined from the output of the phototransistor 14 that detects the illuminance for turning on the LED 13 for illumination, there is no restriction on the frame rate. Therefore, it is possible to determine the presence or absence of flicker in a short time and with high accuracy, and it is possible to smoothly display an image from which flicker has been removed.
In addition, since flicker processing is performed by judging indoor / outdoor, different flicker removal control can be performed between indoors and outdoors even in the presence of flicker. An image that can be operated and that is easy to view without the influence of flicker can be displayed on the monitor with simple control.

  In the above embodiment, the control is different between indoors and outdoors, but the same control may be used. In this case, the indoor / outdoor determination unit is not necessary, and the flicker control unit 15 can be configured simply.

  1 .. Entrance cordless handset, 2 .. Living room base unit, 11 .. Camera, 11a .. Image sensor, 13 .. LED (lighting means), 14 .. Phototransistor (light sensor), 15. (Flicker control means), 21 .. monitor, 31 .. indoor / outdoor determination unit (indoor / outdoor determination means), 32 .. flicker determination unit, 33 .. camera control value calculation unit, 35 .. LPF (filter means) ).

Claims (3)

There is an entrance cordless device for a visitor to call a resident, and a living room master device for a resident to respond to a call from the entrance cordless device. In the intercom system in which the illumination unit is further provided with a light sensor for detecting the illuminance for turning on the illumination unit, while the living room base unit is provided with a monitor for displaying a captured image of the camera.
The intercom system according to claim 1, further comprising: flicker control means for determining the presence or absence of flicker from the output of the optical sensor and performing flicker removal control on the camera based on the determination result.   The flicker control means includes a filter means for extracting a direct current component from the optical sensor output and an indoor / outdoor determination means for judging indoor / outdoor from the magnitude of the extracted direct current component. 2. The intercom system according to claim 1, wherein different flicker removal control is performed.   The camera has an electronic shutter and an image sensor, and the flicker control means determines the amplifier gain of the image sensor when the indoor / outdoor determination means determines that the room is indoors and the flicker control means determines that there is flicker. 3. The interphone system according to claim 2, wherein the intercom system is reduced by a certain amount and the shutter speed of the electronic shutter is reduced at a predetermined rate.

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