JP2009210565A - Light quantity monitor sensor and image processing system equipped with this - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light quantity monitor sensor which easily and automatically measures light quantity of illumination light from illuminating device even if the illumination light includes intermittent light. <P>SOLUTION: As this sensor uses an integrator circuit 5 to integrate light-receiving signal, pulse light or ambient light (DC light) with different waveforms in crest value, period, pulse width, etc. is also measured. Further it uses valid data output means 10 to output only the effective data on the amount of received light from any light-receiving signal sampling of which has been determined as available. These capabilities are combined each other to enable sampling at relatively lower frequency, therefore, a light quantity of the illuminating device L is easily and automatically measured even if its illumination light includes intermittent light. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a light amount monitor sensor that automatically measures the amount of illumination light of an illumination device and an image processing system including the same.

  Conventionally, as a light amount (brightness) management of illumination light of an illumination device, for example, the amount of illumination light from an illumination device L used in an image processing system S as shown in FIG. It is known to measure (monitor) with a luminance meter or the like to detect a decrease in light amount due to deterioration over time.

  Further, a method of calculating a luminance of illumination light from image information obtained by lighting an LED illumination and using an LED (Light Emitting Diode) as an illumination device L of the image processing system S, and detecting a decrease in the amount of illumination light. Is also known (for example, Patent Document 1).

JP 2007-265287 A

  By the way, in the illuminating device L using an LED or a halogen lamp such as the image processing system S, various lighting such as continuous light for continuous illumination (normal lighting), PWM control lighting, strobe light emission control lighting, and combined lighting thereof. It may be illuminated depending on the method.

  In this case, since the strobe emission control lighting is intermittent illumination light (intermittent light), unlike continuous light that is continuously illuminated, it is not easy to accurately integrate the brightness of the intermittent light. Accordingly, there is a problem that it is difficult to accurately measure the light amount of the illumination device.

  An object of the present invention is to provide a light amount monitor sensor capable of easily and automatically measuring the amount of light even if the illumination light from the illumination device includes intermittent light, and an image processing system including the same. It is said.

  In order to achieve the above object, a light amount monitor sensor according to one configuration of the present invention includes a light receiving unit that outputs a light reception signal based on a light reception amount of illumination light including intermittent light from an illumination device, and an integration that integrates the light reception signal. A circuit, an A / D conversion unit that samples the integrated light reception signal at a predetermined frequency, and a control unit that controls each unit to measure the amount of the illumination light, and the control unit receives the light reception to be sampled Comparing means for comparing the signal voltage with a predetermined set voltage, and when the received light signal voltage is higher than the set voltage, the received light signal sampling is determined to be valid and the effective received light amount data is output. Valid data output means.

  According to this configuration, since the light reception signal is integrated by the integration circuit, it becomes possible to measure pulsed light and stationary light (DC light) having different waveforms such as peak value, period, and pulse width, and the effective data output means Since only the effective received light amount data from the received light signal for which sampling is determined to be effective is output, in combination, sampling at a relatively low frequency is possible, and the illumination light includes intermittent light. In addition, the light quantity of the lighting device can be easily measured automatically. In addition, since a relatively low sampling frequency can be used, the A / D converter can be reduced in cost and size.

  An image processing system according to another configuration of the present invention includes a camera that captures an object, an illumination device in which illumination light on the object includes intermittent light, and the light amount monitor sensor that measures the amount of illumination light of the illumination device. The light quantity monitor sensor control unit further autonomously synchronizes with at least an on mode that autonomously synchronizes with the timing of the intermittent light. A mode switching means for switching to an off mode in which the mode does not operate, and a continuous light reception signal in a synchronized state when a sampling interval of the light reception signal determined to be effective for the intermittent light is shorter than a predetermined time during the on mode And intermittent light processing means for processing the received light signal as invalid in an out-of-synchronization state when the sampling interval is equal to or longer than a predetermined time. There.

  According to this configuration, the synchronization state is determined based on the sampling interval of the received light signal determined to be effective for intermittent light, and the received light signal is processed. Therefore, even if the illumination light includes intermittent light, The amount of light can be measured quickly and accurately.

It is a top view which shows the image processing system provided with the light quantity monitor sensor concerning 1st Embodiment of this invention. It is a block diagram which shows the light quantity monitor sensor of FIG. It is a time chart figure which shows the sampling state of a received light signal. (A), (B) is a time chart figure which shows the sampling state of a received light signal. It is a flowchart which shows operation | movement of the light quantity monitor sensor of FIG. It is a block diagram which shows the light quantity monitor sensor which concerns on 2nd Embodiment of this invention.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an image processing system S including a light quantity monitor sensor 1 according to the first embodiment of the present invention. The image processing system S includes a camera that captures an object (not shown) and an image processing unit that processes an image of the object. The illumination device L includes illumination light that includes intermittent light, and illumination light from the illumination device L. And a light amount monitor sensor 1 for automatically measuring (monitoring) the amount of light. In this image processing system S, a light amount monitor sensor 1 is externally attached to the illumination device L of the image processing device in order to monitor the amount of illumination light.

  FIG. 2 is a block diagram of the light quantity monitor sensor 1. The illuminating device L in FIG. 1 illuminates, for example, an LED by PWM control in which a predetermined PWM control frequency is constant and a pulse width is varied. Moreover, it can illuminate with the continuous light (continuous lighting) which lights continuously, or the intermittent light which lights intermittently like strobe light emission. A fluorescent lamp or a halogen lamp may be used instead of the LED.

  The light quantity monitor sensor 1 in FIG. 2 integrates the light reception signal with an optical fiber 2 that receives illumination light from the illumination device L and a light receiving element 4 that outputs a light reception signal based on the amount of light received from the illumination light. An integrating / amplifying circuit 5 for amplifying, an A / D converter 6 for sampling the integrated / amplified received light signal at a predetermined frequency, and the entire sensor and each part are controlled to automatically measure the amount of illumination light ( And a control unit (control / processing unit) 7 to be monitored. In this example, the predetermined sampling frequency in the A / D converter 6 is lower than the PWM control frequency of the PWM control.

  The control unit 7 includes mode switching means 8, comparison means 9, effective data output means (trigger circuit) 10, and intermittent light processing means 11. The mode switching means 8 switches between an on mode that autonomously synchronizes with the timing of intermittent light such as strobe emission from the lighting device L, and an off mode that does not operate the autonomously synchronized mode.

  The comparison means 9 compares the voltage of the received light signal sampled by the A / D converter 6 with a predetermined set voltage (trigger level). The valid data output means (trigger circuit) 10 determines that the sampling of the received light signal is valid when the voltage of the received light signal is higher than the set voltage (trigger level), and outputs the effective received light amount data. To do. The intermittent light processing means 11 treats the received light signal as a continuous light signal in a synchronized state when the interval of sampling of the received light signal determined to be valid for the intermittent light is shorter than a predetermined time during the on mode, When the sampling interval is equal to or longer than a predetermined time, the received light signal is regarded as invalid in the out-of-synchronization state and processed.

  Further, the light quantity monitor sensor 1 includes a storage device 12 that variably stores a set value such as a set voltage (trigger level), and an input circuit 13 such as a switch that inputs a set value with the trigger level arbitrarily changed. In addition, a display unit 14 and an output circuit 15 are provided. When it is necessary to use a plurality of light quantity monitor sensors 1 at the same time, a connecting circuit 16 is provided.

  The sampling operation of the light quantity monitor sensor 1 when the illumination device L performs illumination by PWM control will be described using the examples of FIGS. FIG. 3 shows a case where an LED is generally illuminated by PWM control. a) is illumination of continuous light (normally lit), and shows a state in which the received light signal is subjected to PWM control at a PWM control frequency of 60 kHz and a duty of 50%, for example. b) shows the waveform of the received light signal after passing through the integrating / amplifying circuit 5. This waveform is always greater than the trigger level. c) shows a state where the light reception signal of b) is sampled by the A / D converter 6 at a frequency of 20 kHz which is lower than the PWM control frequency of 60 kHz. In the off mode where synchronization is not required and the synchronization mode does not operate, as in the case of always lighting, the sampling of the n−1, n, and n + 1 light reception signals is all effective regardless of the trigger level of the comparison means 9. . As a result, effective received light amount data in the received light signal determined to be effective sampling is output.

  Note that sampling is performed by, for example, performing multiple sampling three times at intervals of 3 μs during one sampling and using the average value. It is averaged by performing multiple sampling, and the influence of ripple when the PWM control frequency is low can be reduced.

  FIG. 4 shows a case where the LED is illuminated by PWM control of strobe light emission (intermittent light). Similar to FIG. 3, the PWM control frequency is 60 kHz and the duty is 50%, and the sampling frequency of the A / D converter 6 is 20 kHz, which is lower than this.

  In FIG. 4 (A), it is a case of an on mode that autonomously synchronizes with the timing of strobe emission detected by the light receiving unit 4, and is an illumination of intermittent light as shown in a), and the integration shown in b). As in the case of the received light signal waveform after passing through the amplifier circuit 5, when the sampling interval of the received light signal that is determined to be effective by exceeding the trigger level by the intermittent light processing means 11 is less than 5 seconds, for example, in a synchronized state The signal is processed as a continuous light reception signal. As shown in c), the (n-1) -th and n-th samplings are effective, and the effective data output means (trigger circuit) 10 outputs effective received light amount data in the received light signal determined to be effective sampling. . On the other hand, since the received light signal sampled at the timing during this period is below the trigger level, this sampling is processed as invalid.

  In the ON mode, even if the lighting is controlled with stroboscopic light and intermittent lighting, if the sampling frequency is 20 kHz, the period (1 / f) is 50 μs, so the light emission time is theoretically about 100 μs. Sampling is possible.

  Further, by sampling the received light signal that is determined to be effective beyond the trigger level and outputting only the effective received light amount data, even if the sampling period of the A / D converter 6 is shifted, the received light signal Even if there are various kinds of sampling timings and the like, the average value of the received light signal is optimized and accurate received light amount data can be obtained.

  As shown in FIG. 4B, in the case where lighting is performed by PWM control of strobe light emission, for example, when synchronization is not possible due to a strobe light emission interval, intermittent light processing means as in b) 11, when the sampling interval of the received light signal determined to be valid is, for example, 5 seconds or more, the received light signal is processed as invalid in the out-of-synchronization state, and sampling is once reset.

  Thus, the intermittent light processing means 11 determines the synchronization state based on the sampling interval of the received light signal that is determined to be effective for the intermittent light, and processes the received light signal. The amount of light can be measured quickly and accurately.

  In order to prevent erroneous detection of disturbance light, the measurement value of the light amount of the illumination device L automatically measured (monitored) by the light amount monitor sensor 1 may be an average value of the values measured many times.

  FIG. 5 is a flowchart for explaining the sampling operation of the light quantity monitor sensor 1. When the sampling process is started (S1), first, after passing the received light signal through the integrating / amplifying circuit 5, the A / D conversion unit 6 samples, for example, at a sampling frequency of 20 kHz and starts A / D conversion (S2). ). In this example, sampling is performed at a frequency 20 kHz lower than the PWM control frequency 60 kHz. At this time, it is confirmed whether or not a trigger input indicating that the received light signal is higher than the trigger level and sampling of the received light signal is valid (S3). If the trigger is input, the trigger flag is set. In the synchronized state (S4), the end of A / D conversion is awaited (S6). When the trigger input is not made, the trigger flag is cleared and in an asynchronous state (S5), and the end of A / D conversion is waited (S6).

  Next, after the A / D conversion is completed, it is confirmed whether or not a trigger input is made (S7), and when the trigger input is still in a synchronized state, the control / processing unit 7 receives the trigger and makes a valid sampling. The received light amount of the effective received light amount data which is determined and output as the received light signal is integrated (S8). Then, the number of integration is incremented by 1 (S9), and the sampling is finished (S10). In this way, the received light amount is integrated only with the effective received light amount data that is output by validating the sampling of the received light signal exceeding the predetermined trigger level. When the trigger input is not in the asynchronous (out of sync) state, it is confirmed whether the sampling interval is within the normal range (S11). For example, if the sampling interval is within the normal range of less than 5 seconds, it is continuous. Considering the received light signal (FIG. 4A), the sampling is finished (S10). If the sampling interval is 5 seconds or more and is not in the normal range, the received light signal is regarded as invalid and sampling is reset once (FIG. 4B), the parameter is cleared (S12), and the sampling is terminated. (S10).

  Accordingly, in the present invention, since the light reception signal is integrated by the integration / amplification circuit 5, it is possible to measure pulsed light and stationary light (DC light) having different waveforms such as peak value, period, and pulse width. In addition, the light reception signal is always sampled, and the effective data output means 10 outputs only the effective light reception amount data from the light reception signal for which sampling is determined to be effective. Sampling at a low frequency is possible, and even if the illumination light from the illumination device L includes intermittent light, the light amount of the illumination device L can be easily measured (monitored) easily. In addition, since a relatively low sampling frequency can be used, the A / D converter 6 can be reduced in cost and size.

  FIG. 6 is a block diagram showing a light amount monitor sensor according to the second embodiment of the present invention. The second embodiment is different from the first embodiment in that the light receiving unit 4 includes a light receiving lens 22 and a light receiving element 3, but the other configurations are the same as those of the first embodiment.

  Similarly to the first embodiment, in the second embodiment, even if the illumination light of the illumination device L includes intermittent light, the light amount of the illumination light can be easily and automatically measured.

  In each embodiment, the light amount monitor sensor 1 is used in the image processing system S. However, the present invention is not limited to this, and the light amount of illumination light from other illumination devices may be measured. The mode switching unit 8 and the intermittent light processing unit 11 may be omitted.

  Further, in each embodiment, the mode switching unit 8 switches between the on mode and the off mode, and autonomous synchronization is established in the on mode based on the detection of the strobe emission of the light receiving unit 4, but the mode switching unit 8 is Further, the mode may be switched to a mode in which synchronization is forcibly performed by a signal from the outside. By this mode switching, for example, the synchronization is forcibly performed by an external signal based on object detection included in the image processing system S of FIG. You may make it take.

  In each embodiment, the valid data output means 10 is provided with a trigger circuit on hardware to determine whether the received light signal sampling is valid. Instead, it is determined on software. May be.

  In each embodiment, the received light signal is sampled at a frequency lower than the PWM control frequency, but may be sampled at a frequency higher than the PWM control frequency.

1: Light quantity monitor sensor 4: Light receiving unit 5: Integration / amplification circuit 6: A / D conversion unit 7: Control unit (control / processing unit)
8: Mode switching means 9: Comparison means 10: Effective data output means (trigger circuit)
11: intermittent light processing means 12: storage device 13: input circuit L such as a switch L: lighting device S: image processing system

Claims (2)

A light receiving unit that outputs a light reception signal based on the amount of received illumination light including intermittent light from the illumination device, an integration circuit that integrates the light reception signal, and an A / D conversion unit that samples the integrated light reception signal at a predetermined frequency; A light quantity monitor sensor comprising a control part for controlling each part to measure the light quantity of the illumination light,
The controller is
A comparing means for comparing the voltage of the light-receiving signal to be sampled with a predetermined set voltage;
When the voltage of the light reception signal is higher than the set voltage, it is determined that sampling of the light reception signal is valid, and includes effective data output means for outputting the effective light reception amount data.
Light intensity monitor sensor. A camera for imaging an object, an illuminating device in which illumination light to the object includes intermittent light, and a light amount monitor sensor according to claim 1 or 2 for measuring the amount of illumination light of the illuminating device. An image processing system for processing an image,
The control unit of the light quantity monitor sensor further includes:
At least a mode switching means for switching between an on mode that autonomously synchronizes with the timing of the intermittent light, and an off mode that does not operate the autonomously synchronized mode, and
When the sampling interval of the received light signal determined to be effective for the intermittent light is shorter than a predetermined time during the on mode, the light receiving signal is processed as a continuous light receiving signal in a synchronized state, and the sampling interval is equal to or longer than the predetermined time. At this time, an image processing system including a light amount monitor sensor, which includes intermittent light processing means for processing the received light signal as invalid in a state of being out of synchronization.

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