JP4228162B2 - TV camera device with exposure control function - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a television camera for image measurement, and relates to a television camera apparatus with an exposure control function having means for automatically controlling the sensitivity of an imaging device.
[0002]
[Prior art]
In a television camera for image measurement, when a subject to be measured has various light reflectances, in order to obtain an appropriate level in the output video signal of the television camera, a video signal of a central portion or a plurality of portions of a captured image, or a gazette In Japanese Laid-Open Patent Publication No. 1-94653, a photo diode for photometry is always detected and output by arranging a series of photodiodes in a place other than a region effective for imaging in the same image sensor chip.
Use these signals to control the aperture of the objective lens, etc., or place a light receiving element or photometric device outside the camera to detect the reflected light of the subject, and control the aperture of the objective lens based on the detection signal. An appropriate level of the camera output video signal is obtained by controlling the charge accumulation time of the device or controlling the video gain.
[0003]
[Problems to be solved by the invention]
However, the image signal captured by the imaging device, the photometric signal, or a light-receiving element or photometric device outside the camera is used to detect the reflected light of the subject to control the aperture of the objective lens, or to store the charge on the imaging device. Since time control or video gain control is performed, a considerable amount of time was required until the camera output video signal reached an appropriate level.
For example, if high-speed image processing of 1800 pieces / minute or more is performed,
1800/60 = 30 (pieces / second)
Thus, it is necessary to perform 30 or more high-speed processing per second. However, since each method requires a time of 3 frames or more due to the response speed of the control system, high-speed image processing is difficult.
In addition, since a special imaging device is manufactured or a light receiving element or a photometric device is arranged outside the camera, the apparatus becomes complicated and the cost is increased, and there are restrictions on the arrangement.
The present invention provides a low-cost television camera device with an exposure control function that eliminates restrictions on the sensitivity control for obtaining an appropriate video level in real time and the arrangement of light receiving elements.
[0004]
[Means for Solving the Problems]
As a result of intensive studies in view of the above, the present inventor has solved this problem by the following means.
(1) In a television camera apparatus, an imaging device for imaging a subject traveling in a certain direction, a drive circuit for driving and controlling the imaging device, a signal processing circuit for amplifying and controlling an output signal of the imaging device, One or a plurality of light receiving elements that photoelectrically convert reflected light of a subject based on a position information signal from a subject position sensor installed outside, and a charge accumulation time of the imaging device based on a photoelectric conversion output level of the light receiving element A charge storage time control circuit for controlling
The light receiving element receives reflected light of a subject one frame or more before the start of scanning of an image of the imaging device in synchronization with the subject's position information signal one frame or more before, and depends on the photoelectric conversion output level A television camera apparatus with an exposure control function, wherein the sensitivity is controlled by controlling the charge accumulation time control circuit and changing the charge accumulation time of the imaging device.
[0005]
(2) Item (1) is characterized in that the light receiving element is disposed in the vicinity of an imaging device of a television camera and is disposed in an image circle of an imaging objective lens of the television camera. TV camera device with exposure control function.
[0006]
(3) The item (1) or (2), wherein the light receiving element is disposed in an image circle of an imaging objective lens of a television camera and on an imaging surface of the imaging objective lens. The television camera apparatus with an exposure control function as described.
[0007]
(4) Further, as a particularly preferable aspect, the light receiving element receives reflected light of the subject one frame before in synchronization with the position information signal of the subject one frame before starting scanning of the image of the imaging device. Then, the charge accumulation time control circuit is controlled according to the photoelectric conversion output level, and the sensitivity is controlled by changing the charge accumulation time of the imaging device. The described television camera device with an exposure control function is proposed.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, an imaging device (hereinafter referred to as CCD), a drive circuit for driving and controlling the CCD, a camera signal processing circuit for amplifying and controlling the output signal of the CCD, and reflection of an object based on a position information signal A light receiving element (hereinafter referred to as PD) that photoelectrically converts light and a charge accumulation time control circuit that controls the charge accumulation time of the CCD by the photoelectric conversion output signal of the PD, and the PD is a subject that travels in a certain direction The CCD receives the reflected light based on the position information signal of the subject one or more frames before the start of scanning of the CCD image, and controls the charge accumulation time control circuit by the photoelectric conversion output signal, and the CCD By changing the charge accumulation time, the sensitivity is controlled and an appropriate video level is output.
[0009]
【Example】
The configuration and operation of the embodiment of the television camera apparatus with an exposure control function of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram of a television camera with an exposure control function according to the present invention.
FIG. 2 is an arrangement schematic diagram of the imaging device and the light receiving element.
FIG. 3 is the same time chart.
FIG. 4 is a relationship diagram between the PD signal level and the CCD charge accumulation time.
1, 2, and 3, 1 is a television camera, 2 is an objective lens, 3 is a CCD, 4 is a camera signal processing circuit, 5 is an output terminal, 6 is a PD, 7 is a photoelectric conversion output signal, and 8 is a light quantity. Measurement circuit, 9 PD output signal, 10 charge accumulation time control circuit, 11 position information signal, 12 charge accumulation time, 13 CCD drive circuit, 14 image circle, 15 CCD mounting surface, 16 belt conveyor Etc., 17 is a position sensor.
[0010]
1 and 2, the PD 6 disposed in the image circle 14 of the imaging objective lens 2 of the TV camera 1 and on the imaging surface on the CCD mounting surface 15 is close to the traveling belt conveyor 16 or the like. The position sensor 17 installed in the position receives the reflected light of the subject in synchronization with the position information signal 11 which has detected the subject position A corresponding to the time one frame before the start of scanning of the image of the CCD 3 or one frame or more before. The photoelectric conversion output signal 7 is sent to the light quantity measurement circuit 8.
The charge accumulation time control circuit 10 operates according to the level of the PD output signal 9 subjected to temperature correction of the light quantity measurement circuit 8 and controls the charge accumulation time 12 and the readout time of the CCD 3 via the CCD drive circuit 13.
The video signal read from the CCD 3 is subjected to signal processing by the camera signal processing circuit 4 and sent from the output terminal 5 to an image processing device (not shown).
[0011]
In FIG. 3, when the position information signal 11 is generated by the position sensor 17 that is installed in the vicinity of the belt conveyor 16 and gives the light receiving timing of the PD 6 to the subject on the belt conveyor 16. The PD 6 determines the light receiving levels I _{L1 to} I _L3 in synchronization with the signal 11, and the PD output signal 9 photoelectrically converted in proportion to the reflectance of the subject is sent to the charge accumulation time control circuit 10.
When the subject at the subject position A detected by the position sensor 17 reaches the subject position B on the camera optical axis, exposure (charge accumulation) of the CCD ₃ corresponding to each signal level of I _{L1 to} I _L3 is started.
The time from the subject position A to the subject position B can be easily predicted because the speed of the belt conveyor 16 is known in advance.
Further, the speed of the belt conveyor 16 or the like may be set in advance so that the time until the subject position A reaches the subject position B corresponds to the time of one frame of the VD signal.
When the exposure of the CCD 3 is completed, the camera VD signal is reset.
[0012]
Based on each level of the PD output signal 9 such as I _L1 , I _L2 , and I _L3 , t ₁ , t ₂ , and t ₃ of the charge accumulation time 12 of the CCD ₃ are determined, and the CCD ₃ is driven via the CCD driving circuit 13. To do.
In FIG. 4, the charge accumulation time 12 of the CCD 3 is inversely proportional to the signal level of the PD output signal 9, and the PD output signal 9 level is high (bright) and short time, and becomes longer as it becomes lower (darker). It will be time.
As a result, the charge accumulation of the CCD 3 is completed, and the video signal read out and output to the output terminal 5 of the camera signal processing circuit 4 has a constant signal level regardless of the reflectance of the subject. Become.
The charge accumulation time 12 may be generated by, for example, the CCD 3 having a continuously variable speed shutter function from 1 / 10,000 second to 1/60 second corresponding to one frame.
The CCD may use an area sensor or a line sensor.
[0013]
【The invention's effect】
According to the present invention, the following effects are exhibited.
1. According to the invention of claim 1 of the present application,
The light receiving element receives the reflected light of the subject one frame or more ahead in synchronization with the position information signal of the subject one frame or more before the start of scanning of the image of the imaging device that images the subject traveling in a certain direction. Since the sensitivity can be controlled by controlling the charge accumulation time control circuit according to the photoelectric conversion output level and changing the charge accumulation time of the imaging device, it is possible to send a video signal for image processing at an appropriate level at high speed in real time.
[0014]
2. According to the inventions of claims 2 and 3 of the present application,
The photoelectric conversion element is placed close to the imaging device of the TV camera, and is placed on the image plane within the image circle of the TV camera's imaging objective lens. Camera can be provided.
[Brief description of the drawings]
FIG. 1 is a block diagram of a television camera with an exposure control function according to the present invention.
FIG. 2 is a schematic diagram of an arrangement of the imaging device and a light receiving element.
FIG. 3 is a time chart of the same.
FIG. 4 is a relationship diagram between a PD signal level and a CCD charge accumulation time.
[Explanation of symbols]
1: TV camera 2: Objective lens 3: CCD 4: Camera signal processing circuit 5: Output terminal 6: PD
7: Photoelectric conversion output signal 8: Light quantity measurement circuit 9: PD output signal 10: Charge accumulation time control circuit 11: Position information signal 12: Charge accumulation time 13: CCD drive circuit 14: Image circle 15: CCD mounting surface 16: Belt Conveyor etc. 17: Position sensor

Claims (3)

In a television camera apparatus, an imaging device for imaging a subject traveling in a certain direction, a drive circuit for driving and controlling the imaging device, a signal processing circuit for amplifying and controlling an output signal of the imaging device, and an externally installed device One or a plurality of light receiving elements that photoelectrically convert the reflected light of the subject based on the position information signal from the subject position sensor, and the charge accumulation time of the imaging device is controlled based on the photoelectric conversion output level of the light receiving element. It is configured with a charge accumulation time control circuit,
The light receiving element receives reflected light of a subject one frame or more before the start of scanning of an image of the imaging device in synchronization with the subject's position information signal one frame or more before, and depends on the photoelectric conversion output level A television camera apparatus with an exposure control function, wherein the sensitivity is controlled by controlling the charge accumulation time control circuit and changing the charge accumulation time of the imaging device. 2. The exposure control function according to claim 1, wherein the light receiving element is disposed in the vicinity of an imaging device of a television camera and is disposed in an image circle of an imaging objective lens of the television camera. TV camera device. 3. The exposure control function according to claim 1, wherein the light receiving element is disposed in an image circle of an imaging objective lens of a television camera and on an imaging surface of the imaging objective lens. TV camera device.

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