JP5624366B2 - Lighting system - Google Patents

Description

  The present invention relates to a lighting system that images a lighting area and adjusts a light control level of a lighting fixture.

  Conventionally, an image sensor for imaging an imaging area provided in an illumination area by a lighting fixture has been provided. Based on a captured image taken by the image sensor, detection of a person or brightness of the lighting area is detected, and light control of the lighting fixture is performed. An illumination system for adjusting the level is provided (for example, Patent Document 1).

  As an image sensor for this type of illumination system, a CMOS sensor or a CCD camera is used. The brightness of the illumination area is obtained from the average pixel value of the image captured by the image sensor, and the brightness of the illumination area is determined based on this. Adjusting the dimming level of the lighting fixture.

  More specifically, as an initial setting, the illumination area is first kept at an appropriate brightness in the absence of external light, the imaging area in the illumination area is imaged using an image sensor, and the average pixel value of the captured image is calculated. It memorize | stores in a non-volatile memory as a brightness target value. Then, when the operation is actually started, the average pixel value of the image captured by the image sensor is compared with the brightness target value stored in the non-volatile memory, and the lighting device is adjusted so that the average pixel value approaches the brightness target value. Control the dimming level. For example, when the illumination area becomes brighter when external light enters from a window or the like, the average pixel value of the image captured by the image sensor increases, so the dimming level of the luminaire is adjusted so that the average pixel value approaches the brightness target value. Reduce. Thereby, the brightness of the illumination area can be maintained at an appropriate brightness, and the power consumed by the luminaire can be reduced in the daytime when external light is incident, thereby realizing energy saving.

JP 2001-281054 A

  By the way, the image sensor of the above-mentioned illumination system images incident light with a predetermined resolution (for example, 8 bits) and outputs it. If the incident light is brighter than a predetermined brightness, the pixel value is set to an upper limit value (for example, 255).

  Here, for example, when there is a lot of incident external light such as in the daytime and the illumination area is bright, the image captured by the image sensor is an image including many pixels whose pixel values are saturated to the upper limit value. For this reason, even when the illumination area becomes even brighter, the pixel value of the pixel whose pixel value is already the upper limit value does not change, so the relationship between the brightness of the illumination area and the average pixel value of the image is as shown in the graph of FIG. . That is, the linear proportional relationship is obtained in the low brightness area of the illumination region, but the proportional linearity may not be maintained as the brightness increases. Thus, if the relationship between the brightness of the illumination area and the average pixel value of the image is not linearly proportional, it is difficult to accurately determine the brightness of the illumination area from the average pixel value of the image. For this reason, it is determined that the brightness is darker than the actual brightness of the lighting area, and the dimming level of the lighting fixture is set higher than the ideal value, which may consume unnecessary power in the lighting fixture. was there.

  The present invention has been made in view of the above-mentioned reasons. The object of the present invention is to provide a linear proportional relationship between the brightness of the illumination area and the average pixel value of the image regardless of the brightness range. An object of the present invention is to provide an illumination system that reduces the power consumption of an appliance.

In order to achieve the above object, an illumination system of the present application is based on a luminaire, an imaging element that images an irradiated surface illuminated by the luminaire and outputs a captured image including a plurality of pixels, and the captured image. a brightness index value generation means for outputting a brightness index value indicating the brightness of the illuminated surface, and a lighting control means for controlling the dimming level of the lighting device, the lighting control means, as an operation mode, lighting An initial setting mode for setting the dimming level of the fixture to the maximum, and a dimming control mode for controlling the dimming level of the lighting fixture so that the brightness index value falls within a predetermined range with respect to a predetermined brightness target value; has a brightness index value generation means, the pixel values of the picture elements of the captured image when the operation mode of the illumination controller is the initial setting mode is excluded pixel is larger pixel value than a predetermined threshold value effective field the rest of the pixels As, and outputs the brightness index value based on the pixel values of the effective pixel when the operation mode of the illumination control means is a dimming control mode.

In this illumination system, the brightness index value generation means multiplies the brightness detection value obtained from the pixel value of the effective pixel when the operation mode of the illumination control means is the dimming control mode, and a predetermined correction value, It is preferable to obtain a brightness index value.

  According to the illumination system of the present application, the brightness of the illumination area and the average pixel value of the image can be linearly proportional to each other, and an illumination system with reduced power consumption can be provided.

It is a schematic block diagram which shows the illumination system concerning this invention. (A) is the schematic which shows the structure of the illumination system, (b) is the schematic which shows an example of the image imaged with the camera of the illumination system. (A) And (b) is the schematic for demonstrating the initial setting mode of the illumination system. It is a graph which shows the operating characteristic of the illumination system, (a) is before correction | amendment, (b) is a graph for demonstrating the operating characteristic after correction | amendment. It is a graph for demonstrating the conventional illumination system.

  Embodiments of the present invention will be described below with reference to the drawings.

  As shown in FIG. 2A, the illumination system according to the present embodiment includes, for example, a lighting fixture 1 that is installed on a ceiling surface and has a lower illumination area, and a camera 2 that has a part of the illumination area as an imaging area. And a lighting control device 3 that controls the lighting fixture 1 based on the output from the camera 2. This lighting system detects the presence or absence of a person and the brightness change of the illumination area based on a captured image captured by the camera 2 (see FIG. 2B), and adjusts the dimming level of the luminaire 1. This provides a comfortable environment for people in the illumination area and reduces power consumption. In addition, in the following description, the point which detects the change of the brightness of an illumination area and adjusts the light control level of the lighting fixture 1 is demonstrated.

  The luminaire 1 includes a light source such as an LED that is turned on when supplied with power from a commercial power source (not shown), and the light source is turned on and off based on a dimming signal input from the illumination control device 3. The dimming operation such as adjusting the dimming level is performed. In addition, since the light control operation | movement in the lighting fixture 1 is a known technique, it abbreviate | omits about detailed description.

  As shown in FIG. 1, the camera 2 is a general camera having an image sensor 21 such as a CMOS sensor and having an image correction function such as γ correction, and image data based on a video signal imaged by the image sensor 21. Is output to the illumination control device 3.

  More specifically, the camera 2 includes an AD converter 22 that converts an analog signal output from the image sensor 21 into a digital signal, and an ISP (Image Signal Processor) 23 that shapes the output from the AD converter 22 as image data. . The ISP 23 has an AGC (Auto Gain Control) function, and can adjust the signal amplification factor for each pixel of the output captured image based on the signal level of the input digital signal. Thereby, for example, when an image is picked up in a dark state, a picked-up image that can appropriately identify the image pickup region can be output even when the signal level output from the image pickup device 21 is low and the entire image is dark. It is.

  The illumination control device 3 sets a control unit 31 that controls the operation of the illumination control device 3, sets effective pixels to be used for adjusting the dimming level from each pixel value of the image captured by the camera 2, and averages the effective pixels And an image processing unit 32 that calculates a brightness index value based on the above. The illumination control device 3 includes a dimming control unit 33 that outputs a dimming signal for adjusting the dimming level of the lighting fixture 1 based on the brightness index value calculated by the image processing unit 32. Furthermore, the illumination control device 3 includes a storage unit 32 that stores various information and a remote control reception unit 33 that receives an operation signal from a remote control (not shown).

  The illumination control device 3 has an initial setting mode and a dimming control mode as its operation mode, and operates by switching the operation mode based on, for example, an operation signal received by the remote control receiver 35. The initial setting mode is an operation mode for setting effective pixels used for dimming control in the captured image output from the camera 2, and the dimming control mode is based on the effective pixels set in the initial setting mode. This is an operation mode for adjusting the dimming level of the lighting fixture 1.

  The image processing unit 32 operates in accordance with a control signal from the control unit 31, and among the captured images captured by the camera 2, pixels whose pixel values are larger than a predetermined threshold are invalid pixels, and other pixels are valid pixels. The position information indicating the pixel determined to be an effective pixel is stored in the storage unit 34. Further, the image processing unit 32 obtains an average value of pixel values of each pixel determined to be an effective pixel, obtains a correction value from the average pixel value and the upper limit value of the resolution of the camera 2, and stores it in the storage unit 34.

  In addition, the image processing unit 32 calculates an average pixel value for some or all pixels of the captured image captured by the camera 2 and multiplies the average pixel value by the correction value stored in the storage unit 34. In addition, a brightness index value is obtained, and this brightness index value is output to the dimming control unit 34.

  The dimming control unit 34 outputs a dimming signal for adjusting the dimming level of the lighting fixture 1 so that the brightness index value input from the image processing unit 32 approaches a preset brightness target value. For example, when the input brightness index value is larger than the brightness target value, a dimming signal for lowering the dimming level is generated and output to the luminaire 1, and this is then input as the brightness index value. Is repeatedly performed from the brightness target value until it falls within a predetermined error range.

  The storage unit 34 is composed of, for example, a volatile large-capacity memory such as DDRAM (Double Data Rate Synchronous DRAM), and stores effective pixel position information, a brightness index value, and the like obtained by the image processing unit 32.

  Here, the operation of the illumination system will be described. In the following description, the camera 2 has an 8-bit resolution, and each pixel of the captured image output from the camera 2 is described as indicating a pixel value in the range of 0 to 255.

  First, the user operates the remote controller in an environment where no external light is incident on the illumination area, and transmits an operation signal for switching the operation mode to the initial setting mode toward the illumination control device 3. When the remote control receiving unit 33 of the lighting control device 3 receives this operation signal, the control unit 31 switches the operation mode of the lighting control device 3 to the initial setting mode, and uses the dimming control unit 34 to adjust the dimming level of the lighting fixture 1. Set to maximum.

  Next, the control unit 31 causes the storage unit 34 to store, as an effective pixel, a pixel whose pixel value is equal to or less than a predetermined threshold among the captured images captured by the camera 2 using the image processing unit 32. FIG. 3A shows the distribution of effective pixels / ineffective pixels when this threshold value is set to the maximum value (255) of pixel values that can be taken by each pixel of the captured image. In this case, the pixel group β in which the pixel value is saturated (pixel value = 255) is set as an invalid pixel, and the pixel group α excluding the pixel group β (pixel value <255) is stored as a valid pixel in the storage unit 34.

  FIG. 3B shows the distribution of effective pixels / ineffective pixels when this threshold value is set to a value smaller than the maximum pixel value (255) that can be taken by each pixel of the captured image, such as 200, for example. Yes. In this case, a pixel group γ having a pixel value in the range of 200 to 254 and a pixel group β in which the pixel value is saturated (pixel value = 255) are regarded as invalid pixels, and a pixel group α (pixel value) excluding the pixel group β <255) is stored in the storage unit 34 as an effective pixel. In this way, by setting the threshold value to a value smaller than the maximum pixel value, it is possible to prevent the effective pixels from being saturated even when external light is incident and the illumination area becomes bright.

  The image processing unit 32 obtains an average pixel value from the pixel values of each effective pixel, and calculates a correction value within which a value obtained by multiplying the average pixel value and the correction value is within a predetermined range smaller than the upper limit value. The data is stored in the storage unit 34. For example, assuming that the average pixel value of effective pixels is 128, the correction value is 1.5, which is a value obtained by multiplying the average pixel value and the correction value by about 3/4 of the maximum pixel value (255). Set.

  Thereafter, the control unit 31 shifts the operation mode to the dimming control mode. When shifting to the light control mode, the image processing unit 32 obtains the average pixel value of the effective pixels stored in the storage unit 34 from the captured image captured by the camera 2, and multiplies the average pixel value and the correction value. Based on the brightness index value, the dimming control unit 33 adjusts the dimming level.

  Here, the relationship between the illuminance of the illumination area and the brightness index value in the dimming control mode will be described with reference to FIGS. 4 (a) and 4 (b). FIG. 4A shows the relationship between the illuminance of the illumination area and the average pixel value of the captured image captured by the camera 2, where graph a shows ideal characteristics and graph b ′ shows a conventional illumination system. The characteristic when using is shown.

  In this lighting system, in a state where the output of the lighting fixture is maximized, a pixel whose pixel value is saturated is regarded as an invalid pixel, and the brightness index value is obtained from the average pixel value of the valid pixels excluding the invalid pixel. For this reason, as shown in the graph b of FIG. 4A, the illumination area is in a bright state, and even if the pixel values of some pixels are saturated, a linear proportional relationship can be maintained, and the brightness of the luminaire Thus, it is possible to provide an illumination system that improves the accuracy of adjusting the power consumption and reduces power consumption.

  In this case, since pixels with a large luminance value are excluded, the same linear proportional relationship as the graph a indicating the ideal characteristic is shown, but the average pixel value is smaller than before excluding invalid pixels. Value. Therefore, in the present embodiment, the brightness index value is obtained by multiplying the average pixel value obtained from the effective pixels by a predetermined correction value. For this reason, as shown in the graph c of FIG. 4B, the brightness index value with respect to the brightness of the illumination region exhibits characteristics that are substantially equal to the graph a indicating ideal characteristics, and a dynamic range can be ensured. . Accordingly, it is possible to increase the accuracy of adjusting the brightness of the lighting fixture, and to provide a lighting system that can reduce the power consumption by setting the lighting fixture to an appropriate dimming level even in a bright illumination area. Can do.

DESCRIPTION OF SYMBOLS 1 Lighting fixture 2 Camera 21 Imaging sensor 22 AD converter 23 ISP
3 Illumination Control Device 31 Control Unit 32 Image Processing Unit 33 Dimming Control Unit 34 Storage Unit 35 Remote Control Receiver

Claims (2)

An illumination device, an imaging device that captures an illuminated surface illuminated by the illumination fixture and outputs a captured image including a plurality of pixels, and a brightness index that indicates the brightness of the illuminated surface based on the captured image with a brightness index value generation means for outputting a value, and a lighting control means for controlling the dimming level of the lighting device,
The lighting control means includes, as an operation mode, an initial setting mode for setting the dimming level of the lighting fixture to a maximum, and the brightness index value within a predetermined range with respect to a predetermined brightness target value. A dimming control mode for controlling the dimming level of the lighting fixture;
The brightness index value generation means, the pixel values of the picture elements of the captured image excluding the pixel is a large pixel value than a predetermined threshold when the operation mode of the lighting control means is in the initial setting mode And the remaining pixel is an effective pixel, and the brightness index value is output based on the pixel value of the effective pixel when the operation mode of the illumination control means is the dimming control mode. . The brightness index value generation unit multiplies a brightness detection value obtained from a pixel value of the effective pixel when an operation mode of the illumination control unit is the dimming control mode, by multiplying a predetermined correction value, and The illumination system according to claim 1, wherein a brightness index value is obtained.

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