JP4737619B2 - Built-in camera - Google Patents

Description

  The present invention relates to a camera with a built-in illumination that can be suitably used as a surveillance camera or the like and can output a surveillance video regardless of day or night.

2. Description of the Related Art Conventionally, as a monitoring camera incorporating an infrared illumination and an illuminance measuring element, for example, a camera that lights an illumination and captures an image when the illuminance is lower than a predetermined value is known. In addition, as this kind of camera, it is disclosed by patent document 1, for example.
JP 2004-229034 A

  However, such a camera with built-in illumination requires an illuminance measuring element for measuring illuminance, and the camera itself tends to be expensive, such as a complicated configuration and an increased number of parts. Have. It is also optimal to control the light emission intensity by the signal from the illuminance measuring element due to the wide range of the camera's imaging range (angle of view), the brightness of the lens, the variation in camera sensitivity, etc. Since it is difficult to set the illuminance and the amount of light incident on the image sensor varies depending on the distance to the subject, it is difficult to establish a correlation between the measurement result of the illuminance measuring element and the level of the video output signal. When used as a surveillance camera, there is also a problem that it is difficult to obtain a highly accurate surveillance video.

  The present invention has been made in view of such circumstances, and its purpose is to simplify the configuration and form the camera at a low cost, and to obtain a highly accurate image regardless of day or night. Is to provide.

In order to achieve such an object, the invention described in claim 1 of the present invention includes an imaging device, an exposure control unit that controls the amount of light incident on the imaging device, an illumination unit, and an illumination control unit, The illumination control unit turns on the illumination unit based on a signal input from the exposure control unit when the amount of light incident on the image sensor has decreased by a predetermined amount after the aperture of the exposure control unit is opened . At the same time, when the illumination unit is turned on, the amount of light incident on the imaging device is gradually reduced when the diaphragm is dimmed by closing a predetermined amount from the fully opened state. It is characterized by.

Then, as in the invention described in claim 2, the exposure control means opens the diaphragm as the first priority when the amount of light incident on the image sensor decreases, and then increases the gain of the automatic gain adjustment amplifier. It is preferable to control as described above .

According to the first or second aspect of the present invention, the illumination control means turns on the illumination means when the amount of light incident on the image sensor is reduced by a predetermined amount after the aperture is opened , and the imaging is performed. Reduces the number of parts by eliminating the need for an illuminance measuring element because the light intensity incident on the element is dimmed by closing a predetermined amount from the fully open state and then dimming. Thus, the structure can be simplified and an inexpensive camera can be obtained, and the light emission intensity can be optimally set by controlling the illumination means, so that a highly accurate image can be obtained regardless of day or night.

In addition, since the illumination control means can control the light emission intensity of the illumination means based on the signal input from the exposure control means and the signal input from the image sensor, the light emission intensity can be controlled by two signals, so that the accuracy is higher. Can be obtained. Furthermore, since the light intensity of the illumination means is gradually reduced when the illuminance of the subject increases due to lighting of the illumination means, it is possible to prevent the blinking phenomenon of the illumination means from occurring, and to achieve higher accuracy. A monitoring image can be obtained. In addition, since there is no occurrence of a state where the diaphragm is excessively squeezed when the illumination means is fully lit, it is possible to save energy and provide a camera with excellent energy saving, and to improve the monitoring image. Along with the improvement in accuracy, it can be suitably applied to surveillance cameras.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
1 to 3 show one embodiment of a camera with built-in illumination according to the present invention, FIG. 1 is a block diagram thereof, FIG. 2 is a waveform diagram showing an example of its operation, and FIG. 3 is a flowchart thereof.

  As shown in FIG. 1, a camera 1 with built-in illumination (hereinafter referred to as camera 1) includes a lens 2, an aperture 3 and an aperture controller 4 as exposure control means, an image sensor 5, a first stage amplifier 6, an automatic gain adjustment amplifier 7 ( AGC 7), 75Ω driver 8, illumination 9 (illumination means), illumination control unit 10 (illumination control means), and the like. Although not shown, the camera 1 is provided with a processing circuit having an appropriate configuration for processing color signals.

  In this camera 1, the light from the subject passes through the lens 2, the exposure amount is limited by the diaphragm 3, and is incident on the image sensor 5, and the light incident on the image sensor 5 is incident on the image sensor 5. It is converted into an electric signal and amplified by the first stage amplifier 6 at a predetermined magnification. Thereafter, the video output signal is amplified by the AGC 7 so that the video output signal level is constant, and the amplified video output signal is output from the video output terminal 11 via the 75Ω driver 8. The diaphragm 3 is controlled by the diaphragm controller 4 so that the output level of the first-stage amplifier 6 is substantially constant, and is closed when the illuminance of the subject is bright and opened when the illuminance of the subject is dark. ing. Further, the illumination control unit 10 controls the light emission intensity of the illumination 9 based on the video signal level from the first stage amplifier 6 and the output signal of the aperture control unit 4.

  Next, an example of the basic operation of the camera 1 configured in this way will be described based on the waveform diagram shown in FIG. 2A shows the control state of the camera 1 with respect to the illuminance (brightness) of the subject, and FIG. 2B shows the state of the video output signal with respect to the illuminance of the subject. First, as shown in region I of FIG. 2, when the illuminance of the subject is sufficiently low (dark), the output level of the first-stage amplifier 6 is low, the amplification factor of the AGC 7 is maximum, and the diaphragm 3 is opened. When the illuminance of the subject gradually increases in this state, the output level of the first-stage amplifier 6 gradually increases, and when the point A is reached, the amplification factor of the AGC 7 starts to decrease as shown in the region II. When the illuminance of the subject further increases and reaches point B, the gain of AGC 7 is minimized, and the aperture controller 4 starts to close the aperture 3 as shown in region III.

  In this way, the level of the video output signal output from the video output terminal 11 of the camera 1 is substantially constant as shown in FIG. 2B over a wide range from when the illuminance of the subject is low to when it is high. In addition, the gain of the AGC 7 and the aperture value of the aperture 3 by the aperture controller 4 are adjusted. When the illuminance of the subject exceeds the point C as shown in the area IV, the illumination control unit 10 cannot control the illumination 9 and the aperture control unit 4 cannot control the aperture 3, and the image is completely white. It becomes a state.

  In FIG. 2A, when the illuminance of the subject decreases, the aperture 3 is opened as the first priority, and then the gain of the AGC 7 is increased. This is because if the gain of the AGC 7 is increased, noise components in the video signal are also amplified and the S / N ratio is lowered. Therefore, priority is given to opening the aperture 3 in order to increase the amount of light incident on the image sensor 5. To make it happen.

  Further, when the illuminance of the subject decreases and the output signal level from the first stage amplifier 6 decreases and reaches the point (1) in FIG. 2, the illumination 9 is turned on by the control signal of the illumination control unit 10. It has become. At this time, the aperture 3 is in the open state and the gain of the AGC 7 is not so high. Just before the S / N ratio is lowered, the state is optimal for lighting the illumination 9. At this time, the illumination 9 may be turned on by detecting that the diaphragm 3 is opened at the point B in FIG. 2, but in this case, there is a possibility that the lighting 9 will blink, which will be described later. In order to further increase the stability of the system, the illumination 9 is turned on when the diaphragm 3 is opened and the illuminance further decreases slightly.

  When the illumination 9 is turned on in this way, the illuminance of the subject increases, that is, moves in the direction of “bright” on the horizontal axis in FIG. 2. Normally, when such control is performed, the illumination 9 The illuminance of the subject to be turned on and the illuminance to be turned off have a certain difference so that the illumination 9 does not repeat blinking. However, there is no problem when the distance between the camera 1 with the built-in illumination 9 and the subject is sufficiently long, but when the distance is close to a certain extent, the video output terminal 11 outputs the signal even when the gain of the AGC 7 is minimized. The signal level becomes too high, and the diaphragm control unit 4 controls the diaphragm 3 to close. As described above, even if the illuminance of the subject is equal, if the distance to the subject is short, the amount of light incident on the image sensor 5 increases. However, for the sake of convenience, the influence of the distance is ignored and the illuminance of the subject is incident on the image sensor 5. It shall indicate the amount of light.

  Then, for example, when the illumination 9 is turned on, the illuminance of the subject reaches the point (2) in FIG. 2. If the illumination 9 is turned off at this point, the illuminance of the subject is reduced again, as shown in FIG. Since the point 1) is reached and the state immediately before the lighting 9 is turned on is restored, the lighting 9 is turned on again. Then, the point of (2) in FIG. 2 is reached, and the illumination 9 is turned off. Such blinking of the illumination 9 occurs repeatedly, and the video output signal output from the camera 1 confirms the subject. It becomes a video signal that can not be. In addition, if the illumination 9 is turned off after the illuminance of the subject reaches the point (4) in FIG. 2, the blinking phenomenon of the illumination 9 can be avoided, but the illumination is illuminated even if the illuminance of the subject becomes sufficiently bright. Since 9 is not turned off, energy is wasted. In the case of the camera 1 of the present invention, the lighting 9 is gradually reduced and extinguished by the lighting control unit 10, so that waste of energy can be eliminated while suppressing the blinking phenomenon.

  Further, if the illumination 9 is fully turned on when the illuminance is reduced to the point (1) in FIG. 2, the illuminance of the subject is sufficiently high and reaches the point (2) in FIG. 2, that is, the aperture 3 is fully opened. When it is in a slightly closed state, the light amount of the illumination 9 is reduced to 2/3. By reducing the light amount of the illumination 9 to 2/3, the output level of the first stage amplifier 6 does not reach the point (1) in FIG. In addition, the lighting 9 is prevented from causing a blinking phenomenon.

  Further, when the illuminance of the subject reaches the point (3) and the point (4) in FIG. 2 when the illumination 9 is fully lit, the control of dimming and extinguishing is similarly repeated. ing. Further, when the illuminance of the subject decreases to the point (1) in FIG. 2 after reaching the point (4) in FIG. 2, the illumination 9 is fully turned on and decreases only to the point (2) in FIG. If not, the illumination 9 is turned on with a brightness of 2/3. By performing such control, no matter how the illuminance of the subject when the illumination 9 is turned on (the illuminance is temporarily high when a person passes near the camera 1) is output from the camera 1. The level of the video output signal can be kept optimal, that is, the video is never darkened.

  FIG. 3 is a flowchart showing an example of the operation of turning on / off / lighting off the illumination 9, which will be described below in association with the waveform diagram of FIG. This flowchart is automatically executed by the illumination control unit 10 and the aperture control unit 4. That is, when a power switch (not shown) of the camera 1 is turned on and set to a monitoring state, for example, the program is started (S100), and it is determined whether or not the output of the first stage amplifier 6 is smaller than (1) in FIG. If this determination S101 is “YES”, the illumination 9 is turned on at 100% (S102), that is, all are turned on. If the determination S101 is “NO”, the output of the first stage amplifier 6 is smaller than (1). The determination S101 is repeated until

  When the illumination 9 is fully lit in step S102, it is determined whether or not the diaphragm 3 is closed from (2) in FIG. 2 (S103). If “YES” in this determination S103, the illumination 9 is lit at 60%. (S104) That is, the lamp is turned off, and this determination S103 is also repeated until “YES”. Then, when the illumination 9 is reduced in step S104, it is determined whether or not the diaphragm 3 is closed from (3) in FIG. 2 (S105). If “YES” in this determination S105, the illumination 9 is turned off. It is turned on at 30% (S106), that is, further reduced from the 60%. In addition, in the case of “NO” in this determination S105, that is, when the diaphragm 3 is opened from (3) in FIG. 2, this is also caused when the diaphragm 3 is opened from (2) in FIG. Including, returning to the determination S101 and repeating the determination S101 and subsequent steps.

  When the illumination 9 is reduced to 30% in step S106, it is determined whether or not the aperture 3 is closed from (4) in FIG. 2 (S107). If “YES” in this determination S107, the illumination 9 is set to 0. % (S108), that is, the light is extinguished, and it is determined whether or not the diaphragm 3 is opened from (3) in FIG. 2 (S110). If “YES” in the determination S110, the process returns to the step S106 to turn on the illumination 9 at 30%. If “NO” in the determination S110, the process returns to the determination S101. On the other hand, if “NO” in the determination S107, it is determined whether or not the aperture 3 is opened from (2) in FIG. 2 (S109). If “YES” in the determination S109, the process returns to the step S104. If “NO” in the determination S109, the process returns to the determination S107.

  In other words, according to this flowchart, the state of the illumination 9 is set to 0% (lights off), 30% (lights off), 60 according to the output of the first stage amplifier 6 and the state of the diaphragm 3 by the control of the illumination control unit 10 and the like. It can be controlled in four stages of% (light reduction) and 100% (all lighting). The above flow chart is an example, and the light reduction state is not limited to two stages of 30% and 60%, and appropriate numerical values such as 50% and 75% can be used. Not only the lighting state but also a flowchart of the reduced lighting state of three or more stages can be used. This also applies to the threshold values (1) to (4) in FIG. 2 as long as the order is not changed.

  As described above, in the camera 1 of the above embodiment, when the illumination control unit 10 determines that the amount of light incident on the image sensor 5 is not sufficient based on the signal input from the aperture control unit 4, the illumination is performed. In order to control the light emission intensity of the illumination 9 in two steps, for example, when it is determined that the amount of light incident on the image sensor 5 is excessive due to the illumination 9 being lit. The illuminance measuring element as in the prior art is not required, the number of parts can be reduced, the configuration can be simplified, the inexpensive camera 1 can be obtained, and the light intensity of the illumination 9 can be controlled by the illumination control unit 10. It can be set optimally and a high-accuracy monitoring image (monitoring video) can be obtained regardless of day or night.

  In addition, since the illumination control unit 10 controls the emission intensity of the illumination 9 based on the signal input from the aperture control unit 4 and the signal input from the first-stage amplifier 6 (image sensor 5), the emission intensity is determined by two signals. Can be controlled, and a more accurate monitoring image can be obtained. Furthermore, when the illumination 9 is turned on and the illuminance of the subject is increased, the amount of light of the illumination 9 is gradually reduced, so that the blinking phenomenon of the illumination 9 can be prevented, and the accuracy is further increased. A monitoring image can be obtained. In addition, since the state in which the diaphragm 3 of the camera 1 is excessively narrowed with the illumination 9 fully turned on is eliminated, it is possible to save energy and provide the camera 1 with excellent energy saving. Accordingly, it is possible to suitably apply to the surveillance camera together with the higher accuracy of the surveillance image.

  FIG. 4 is a block diagram similar to FIG. 1 showing another embodiment of a camera with built-in illumination according to the present invention. Hereinafter, the same parts as those in FIG. The built-in illumination type camera 1 of this embodiment has a built-in human body detection sensor 12 (sensor 12 in the figure), and the lighting command unit 13 turns on the illumination control unit 10 based on the detection signal from the human body detection sensor 12. The configuration is such that a signal is output. Even when the illumination intensity of the subject is reduced, the illumination control unit 10 detects the human body and detects illumination from the lighting command unit 13 unless the lighting command signal is input from the lighting command unit 13. Unless the lighting signal is input, the illumination 9 is not turned on.

  In the camera 1 of the second embodiment, in addition to the same effects as the camera 1 of the first embodiment, an intruder is detected by the human body detection sensor 12 at night when the illumination 9 is turned off. Then, the illumination 9 is turned on, and an intruder can be photographed, and the crime prevention effect by the camera 1 can be further enhanced, and operational effects such as saving energy can be obtained.

  The camera 1 in each of the above embodiments may be a camera using a mechanical aperture lens, or may be an electronic shutter camera using a fixed aperture lens and a CCD as an image sensor. In the case of the electronic shutter system, an electronic shutter control signal can be used as the aperture control signal. In addition, the configuration of the camera 1 in each of the above embodiments is an example. For example, another appropriate amplifier is added or another appropriate driver is used instead of the 75Ω driver. Changes can be made as appropriate without departing from the scope of the invention.

  The present invention can be applied not only to a color camera for monitoring but also to a monochrome camera for monitoring, for example, and to all other cameras such as a day / night camera equipped with an infrared illumination device and having an infrared cut filter removed. Is also applicable.

The block diagram which shows one Embodiment of the camera with a built-in illumination concerning this invention Waveform diagram showing the operation Same flowchart The block diagram which shows other embodiment of the camera with a built-in illumination concerning this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Camera with built-in illumination, 2 ... Lens, 3 ... Aperture, 4 ... Aperture control part, 5 ... Image sensor, 6 ... First stage amplifier, 7 ... Automatic gain adjustment Circuit (AGC), 8 ... 75Ω driver, 9 ... illumination, 10 ... illumination control unit, 11 ... video output terminal, 12 ... human body detection sensor, 13 ... lighting command unit.

Claims (2)

An image sensor, exposure control means for controlling the amount of light incident on the image sensor, illumination means and illumination control means,
The illumination control unit turns on the illumination unit when the amount of light incident on the image sensor decreases by a predetermined amount after opening the aperture of the exposure control unit based on a signal input from the exposure control unit. In addition, when the illumination unit is turned on, the amount of light incident on the imaging device is gradually reduced when the diaphragm is dimmed by closing a predetermined amount from the fully opened state. A camera with built-in illumination. 2. The exposure control unit according to claim 1, wherein when the amount of light incident on the image sensor decreases, the exposure control unit controls to open the diaphragm as a first priority and then to increase the gain of the automatic gain adjustment amplifier. The camera with built-in illumination described in 1.

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