JPH0317508Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to an incident light detection device for a CCD image sensor that optically detects an object to be detected.

[Prior art]

This type of CCD image sensor optically detects the width and other dimensions of objects to be detected on automated lines, etc., but when too much light enters the sensor, blooming occurs, causing the video signal to blur. Therefore, there is a problem that accurate video signals cannot be obtained and judgments of the width dimension of the object to be detected, etc. become inaccurate.

For this reason, conventionally, the video signal is observed with an oscilloscope and it is determined whether or not blooming is occurring based on whether there is blurring in the waveform, but this method requires an oscilloscope. There is a problem that increases costs over time.

[Purpose of invention]

The present invention was developed in view of the above circumstances, and its purpose is to provide blue light without using an oscilloscope.
The object of the present invention is to provide a device for detecting excessive light incident on a CCD image sensor, which can determine whether or not image processing is occurring and can be manufactured at low cost.

[Summary of the idea]

The present invention provides a latch circuit that latches a video signal from a CCD image sensor or a slice video signal based on the same based on the falling edge of a scan pulse, and includes a determining means for determining the state of the output signal of this latch circuit. It is characterized by its composition.

〔Example〕

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

First, the general structure of the CCD image sensor will be described with reference to FIG. 1 is an image sensor camera, which is equipped with an aperture adjustment mechanism and an optical lens like a normal camera, and also has a large number of light receiving elements, for example 2048 (2048 bits), arranged in a straight line. It is equipped with a photodiode and also a CCD. The image sensor camera 1 is designed to receive the detection light from a light source 3 placed behind the object to be detected by a 2048-bit photodiode through an adjustment mechanism and an optical lens. The light reception signals from the photodiodes are simultaneously transferred to the CCD and output as a video signal VS (see FIGS. 3c and e) based on clock pulses by the charge transfer mechanism of the CCD.

Now, according to FIG. 1, the configuration of the electric circuit of the incident light detection device will be described. 4 is a first input terminal to which the video signal VS from the CCD is applied, which is connected to the input terminal of a binarization circuit 5, and the output terminal of the binarization circuit 5 is a latch circuit D. It is connected to a data input terminal D of a flip-flop circuit 6 of the form. Reference numeral 7 designates a second input terminal to which a scan pulse SP (see FIG. 3a) to be described later is applied, and this is connected to the clock input terminal CK of the flip-flop circuit 6 via a delay circuit 8 and an inverter circuit 9. ing. In this case, the scan pulse SP has a width equivalent to 2048 clock pulses given to the CCD in correspondence with a 2048-bit photodiode, and for example, the clock pulses can be counted by a counter based on an AND condition with the scan pulse SP. If you let me,
The count value is from 1 to 2048 of the photodiode.
It will show the bit number up to. Reference numeral 10 denotes a light emitting diode serving as a determination means, its anode is connected to a DC power supply line 12 at a positive potential +Vcc via a resistor 11, and its cathode is connected to an inverter circuit 13.
is connected to the output terminal of And invar
The input terminal of the flip-flop circuit 13 is connected to the set output terminal Q of the flip-flop circuit 6.

Next, the operation of this embodiment will be explained with reference to FIG. 3.

First, we will discuss a normal case where the CCD image sensor does not cause blooming. Now, when the scan pulse SP rises from the low level to the high level as shown in Figure 3a, the video signal VS
Also, as shown in Figure 3c, the dark level (low level)
The light level starts to rise from the bright level (high level). Since the scan pulse SP is given to the delay circuit 8, the scan pulse SP is delayed by a predetermined time T by the delay circuit 8, and then outputted from the delay circuit 8 as a delayed scan pulse SP' as shown in FIG. 3b. Output. Also, since the video signal VS is given to the binarization circuit 5, the video signal VS is compared with the slice level SL and output from the binarization circuit 5 as a slice video signal SLV as shown in FIG. 3d. be done. after that,
When the scan pulse SP falls from a high level to a low level, the video signal VS would normally also fall from a bright level to a dark level, but in general, the video signal VS has a waveform that becomes dull. This causes a delay in the fall due to the presence of several or tens of dummy bits in the image sensor.
Correspondingly, a delay also occurs when the slice video signal SLV falls from a high level to a low level. In this case, the delay time T of the delay circuit 8 is set to be slightly longer than the fall delay time of the slice video signal SLV in a normal case. Therefore, when the delayed scan pulse SP' from the delay circuit 8 falls from a high level to a low level and the output signal of the inverter circuit 9 rises from a low level to a high level, the flip-flop circuit 6
The slice video signal SLV applied to the data input terminal D of the flip-flop circuit 6 is at a low level, and the set output signal at the set output terminal Q of the flip-flop circuit 6 is at a low level. As a result, the output signal of the inverter circuit 13 becomes high level, and no current flows through the light emitting diode 10.
does not emit light. In addition, if the CCD image sensor does not cause blooming as described above, the video signal when detecting the detected object 2
VS becomes a detection signal VSa that changes from a bright level to a dark level as shown in Figure 3c, and accordingly, the slice video signal SLV also becomes a detection signal that changes from a high level to a low level as shown in Figure 3d.
SLVa, therefore, this detection signal
By reading the count value of the counter at the falling edge and rising edge of SLVa, it is possible to detect from how many bits the detection signal SLVa exists, and by this, the width dimension of the detected object 2 can be detected. can be calculated.

Now, we will discuss an abnormal case where the CCD image sensor is causing blooming. In this case, as shown in Figure 3b, the delayed scan pulse
Even when SP' falls from the high level to the low level, the video signal VS remains at the bright level and the waveform becomes blurred, as shown in Figure 3e, and the detection signal VSa does not completely reach the dark level. The result is a blunted waveform that does not change. Therefore, the delayed scan pulse
When SP' falls from a high level to a low level and the output signal of the inverter circuit 9 rises from a low level to a high level, the slice video signal SLV applied to the data input terminal D of the flip-flop circuit 6 is as shown in FIG. It is at a high level as shown by f, and the set output terminal Q of the flip-flop circuit 6
The set output signal becomes high level. As a result, the output signal of the inverter circuit 13 becomes low level, current flows through the light emitting diode 10, and the light emitting diode 10 emits light, thereby indicating that blooming is occurring. . In this case, the aperture adjustment mechanism of the image sensor camera 1 is adjusted until the light emitting diode 10 stops emitting light to prevent excessive light from entering.

In this way, according to this embodiment, the video signal VS
A flip-flop circuit 6 is provided which latches the slice video signal SLV based on the scan pulse SP at the falling edge of the delayed scan pulse SP' based on the scan pulse SP.
Since the light emitting diode 10 that stops emitting light is provided, it is possible to determine whether or not the CCD image sensor is blooming without using an oscilloscope, unlike the conventional method. Since it can be realized with a simple circuit configuration, it can be manufactured at low cost.

In the above embodiment, the flip-flop circuit 6 latches the slice video signal SLV at the falling edge of the delayed scan pulse SP', but the video signal VS may be latched directly instead.

In addition, the present invention is not limited to the embodiments described above and shown in the drawings; for example, the determining means is not limited to a light emitting diode, but may also be a display device using a liquid crystal, an electrochromic device, etc. Of course, modifications may be made as appropriate without departing from the spirit of the invention.

(Effect of the invention) As explained above, the intrusion detection device for a CCD image sensor of the present invention uses a combination of a latch circuit and a determination means to detect whether blooming is occurring without using an oscilloscope. It can be determined whether
This has the practical effect of being able to be manufactured at low cost.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is an electric circuit diagram, FIG. 2 is a layout configuration diagram showing the detection state by a CCD image sensor, and FIGS. 3 a to 3 are signal waveform diagrams for explaining the operation. It is. In the drawings, 1 is an image sensor camera, 5 is a binary circuit, 6 is a flip-flop circuit (latch circuit), 8 is a delay circuit, and 10 is a light emitting diode (judgment means).

Claims (1)

[Scope of utility model registration request] A CCD comprising a latch circuit that latches a video signal from a CCD image sensor or a slice video signal based on the same based on the falling edge of a scan pulse, and a determination means that determines the state of the output signal of this latch circuit. Image sensor excessive light detection device.