JP2024103120A - Image capture device, image capture device control method, and program - Google Patents

Abstract

[Problem] To increase information of important scenes at the timing of detecting an external trigger and to perform shooting without providing a memory for storing image frames. [Solution] An imaging device configured without using a frame memory, comprising: an imaging means for capturing and outputting an image; an output means for outputting image data read from the imaging means to an external device; a receiving means for receiving a first trigger from an external device; a second trigger detection means for detecting a signal input from a terminal as a second trigger; a control means which is a processor for controlling each means of the imaging device based on the first trigger received by the communication means; a storage means for storing a first shooting parameter and a second shooting parameter; and a selection circuit connected to the second trigger detection means and for setting either the first shooting parameter or the second shooting parameter to the imaging means based on the second trigger supplied from the second trigger detection means. [Selected Figure] Figure 1

Description

The present invention relates to an imaging device that captures images by switching the frame rate using an external trigger signal.

To determine whether a product is good or bad during the production process, industrial cameras (machine vision) are often installed in the process and a judgment is made based on the external image of the product. For example, in the solder reflow process, the appearance of the solder is inspected during the process to determine whether the product is good or bad.

When using industrial cameras for visual inspection, inspections are usually performed by taking still images at intervals as the product is completed and then checking the images. However, if a process abnormality occurs, it is not possible to analyze the cause from still images, so it is desirable to take a video of the abnormality at the time it occurs in order to increase the amount of information and analyze the cause of the abnormality.

In addition, industrial cameras transfer captured image data uncompressed to an external device (such as a personal computer (PC)) via a communication I/F, and then use the PC to analyze and inspect the images, so the amount of image data stored in the PC becomes large. For this reason, users require that data not be recorded that is unnecessary for process inspection and analysis when an abnormality occurs. Therefore, it is necessary to increase the amount of information in the image near the trigger signal that indicates the occurrence of an abnormality.

Patent document 1 describes a technology in which, in order to obtain video around the time a trigger signal is detected, captured images are compressed and the oldest images are deleted while being recorded in a ring buffer, and images around the time a trigger signal is detected are obtained from the ring buffer upon trigger detection.

JP 2004-304418 A

However, in the above conventional example, it was not possible to capture an image near the trigger signal time unless a ring buffer (memory) was used. Also, because the image data had to be compressed, it was not possible to capture an uncompressed image near the trigger signal time.

The present invention aims to provide an imaging device that captures images by increasing the amount of information required for analysis at the timing of trigger detection, without providing a memory for storing images.

The imaging device of the present invention is an imaging device configured without using a frame memory, and is characterized by comprising an imaging means for capturing and outputting an image, an output means for outputting image data read from the imaging means to an external device, a receiving means for receiving a first trigger from an external device, a second trigger detection means for detecting a signal input from a terminal as a second trigger, a control means which is a processor for controlling each means of the imaging device based on the first trigger received by the communication means, a storage means for storing a first shooting parameter and a second shooting parameter, and a selection circuit connected to the second trigger detection means and for setting either the first shooting parameter or the second shooting parameter to the imaging means based on the second trigger supplied from the second trigger detection means.

The present invention makes it possible to capture an image by increasing the amount of information about important scenes at the trigger detection timing, without providing a frame memory for storing images.

1 is a diagram illustrating a configuration of an imaging apparatus according to a first embodiment. 4 is a flowchart showing a process of the imaging apparatus according to the first embodiment. FIG. 2 is a conceptual diagram for explaining a captured image according to the first embodiment. 10 is a flowchart showing a process of an imaging apparatus according to a second embodiment. FIG. 11 is a conceptual diagram for explaining a captured image according to a second embodiment.

First Embodiment
A first embodiment of the present invention will be described below. Fig. 1 is a configuration diagram of an imaging device 1. In the imaging device 1, an optical system 10, an imaging element 11, an A/D conversion unit 12, a timing signal generation unit 13, and an exposure time control unit 14 are connected via a bus for transferring data and control commands. Furthermore, an image processing unit 15, a selection circuit 16, a control unit 17, a memory 18, an external input unit 19, and a communication unit 20 are connected via a bus for transferring data and control commands.

The imaging device 1 is configured as an industrial camera used as a machine vision for, for example, process inspection, and is capable of switching the imaging frame rate based on an external trigger signal to capture images.

The optical system 10 is made up of a photographing lens and forms an optical image of the subject on the image sensor 11, which will be described later.

The image sensor 11 performs photoelectric conversion on the light collected by the optical system 10 using a timing signal generated by a timing signal generator 13 (described later), and then outputs an analog image signal to an A/D converter 12 (described later).

The A/D conversion unit 12 converts the analog image signal generated by the image sensor 11 into digital image data using an A/D converter.

The timing signal generating unit 13 has multiple synchronous counters that count with a reference clock that drives the image sensor 11, and generates horizontal synchronous signals, vertical synchronous signals, and image frame numbers based on the counts of the synchronous counters, and outputs them to the image sensor 11 and the exposure time control unit 14 described below. Here, the frame number is, for example, if a certain frame is an odd number, 1, then the next frame is an even number, 2, and thus outputs a value indicating 1 during an odd frame period and 2 during an even frame period.

The exposure time control unit 14 changes the charge accumulation time of the image sensor 11 for each frame based on the vertical synchronization signal and frame number from the timing signal generation unit 13.

The image processing unit 15 performs various correction and development processes on the digital image data output from the A/D conversion unit 12, and then outputs the data via a bus to the communication unit 20, which will be described later.

The selection circuit 16 is electrically connected to an external input unit 19 (described later) and a terminal to which a second trigger signal (described later) is input, and sets either a first shooting parameter (described later) or a second shooting parameter (described later) in the timing signal generation unit 13 based on the level of the second trigger signal. The selection circuit 16 also has the function of a sequencer composed of circuits, and is capable of setting parameters in each component via a bus.

The control unit 17 is a processor that controls each component via the bus.

The memory 18 stores the first and second shooting parameters. It can also be used as a working area for the control unit 17.

The external input unit 19 is electrically connected to an external device, detects the electrical signal level, and supplies the signal value as a second trigger signal to the selection circuit 19. For example, a signal indicating the occurrence of a sudden event, such as an abnormality signal notifying an abnormality in the external device, is used as the trigger.

The communication unit 20 is connected to an external device, a personal computer, etc., via a communication line (not shown), for example, via a USB (Universal Serial Bus). The communication unit 20 outputs image data received from the image processing unit 15 to the external device. The communication unit 20 also receives a control command from the personal computer that embeds a first trigger signal that instructs shooting. The communication unit 20 extracts the first trigger signal level from the received control command and then outputs it via the selection circuit 16 bus.

The first trigger signal requires time to be processed from detection of the trigger signal to output to the selection circuit 16, because the control unit 17 uses interrupt processing to extract the first trigger signal level from the control command in a control command reception interrupt. On the other hand, the second trigger signal electrically detects the signal level input from the external input unit 19, so the process from detection of the trigger signal to output to the selection circuit 19 can be completed in a shorter time than the first trigger signal.

Next, the process of switching the frame rate using a trigger signal of the imaging device of the first embodiment will be described using the flowchart in FIG. 2. This flowchart describes the process of starting shooting using the first trigger or the second trigger. Here, the process in the flowchart in FIG. 2(a) is repeatedly called when performing shooting processing from a process not shown in the figure.

If the control unit 17 detects that the first trigger signal level or the second trigger signal level is High in step S1, the control unit 17 then executes step S2. Otherwise, the control unit 17 then executes step S7.

In step S2, the control unit 17 reads the shooting processing program from the memory 18 and then starts preparation for shooting. The control unit 17 then executes step S3.

In step S3, the selection circuit 16 checks the second trigger signal level of the external input unit 19, and if there is a change in the level of the second trigger signal, executes step S4. If there is no change in the second trigger signal level, the control unit 17 executes step S5.

In step S4, the selection circuit 16 executes the frame rate switching process shown in the flowchart of FIG. 2(b). The frame rate switching process in step S4 is explained below with reference to FIG. 2(b).

In step S100 of FIG. 2(b), the selection circuit 16 acquires the level of the second trigger signal. When the level of the second trigger signal is High, the selection circuit 16 then executes step S101. When the level of the second trigger signal is Low, the selection circuit 16 then executes step S102.

Now, the switching of the shooting frame rate in the first embodiment will be explained with reference to FIG. 3. The captured image 100 is the image captured when the first trigger signal is received. After the capture of the captured image 100, the captured image 101 is captured after an interval D1 when the next first trigger signal is received. In this way, the shooting frame rate is determined by the reception interval D1 of the first trigger signal.

Next, the switching of the shooting frame rate when the second trigger signal goes High will be described. The captured image 110 is an image captured when the second trigger signal goes High. Here, the second trigger signal is, for example, a trigger signal indicating an abnormality, and is therefore held High while the abnormality is detected. For example, when considering a case where a video is shot by shooting 60 images per second, the time interval D2 between the captured images 110 and 111 is approximately 16 ms. While the second trigger signal is High, shooting continues at the interval D2.

This concludes the explanation using Figure 3. Let us return to the explanation of the flowchart in Figure 2(b).

In step S101, the selection circuit 16 sets the second shooting parameters for changing the frame rate so that shooting can be performed at shooting interval D2 while the second trigger signal is High for the timing signal generation unit 13. The selection circuit 16 notifies the control unit 17 that the processing of the flowchart in FIG. 2(b) has ended, and the control unit 17 then executes step S5.

In step S102, the selection circuit 16 sets the first shooting parameters for shooting one image to the timing signal generation unit 13. Next, the selection circuit 16 notifies the control unit 17 that the processing of the flowchart in FIG. 2(b) has ended, and the control unit 17 then executes step S5.

Let's return to the explanation of the flowchart in Figure 2(a).

In step S5, the image sensor 11 is driven using the timing signal generated by the timing signal generation unit 13, and the acquired analog image is converted into a digital image by the A/D conversion unit 12. The converted image is subjected to image processing by the image processing unit 15. The control unit 17 then executes step S6.

In step S6, the communication unit 20 transmits the captured image acquired in step S5 to an external device. The control unit 17 then ends the process.

As described above, it is possible to continuously capture images at a higher frame rate than with the first trigger signal by increasing the amount of information about important scenes when the second trigger signal is detected, without storing the captured images in frame memory.

Second Embodiment
The second embodiment will be described with reference to FIG. 4. The second embodiment is an example in which the exposure time is changed for each captured frame when the second trigger signal is High. It is assumed that the captured image is transmitted from the imaging device 1 to an external device (personal computer) (not shown), and then the image received by the external device is converted into an HDR (High Dynamic Range) image for use in analysis. Since the second embodiment can be realized with the same configuration as the first embodiment, the description of the parts that overlap with the first embodiment will be omitted.

Before explaining the process of Example 2, we will now explain the process of changing the shooting frame rate and exposure time using the conceptual diagram in Figure 5.

Captured image 201 is an image captured when the second trigger signal goes High. After time interval D2, captured image 202 is captured. At this time, exposure time control unit 14 references the frame number of timing signal generation unit 13 and controls timing signal generation unit 13 to change the exposure time for each frame. As a result, captured image 201 becomes an image captured with a short exposure time, and captured image 202 becomes an image captured with a long exposure time. This process is repeated.

Now, let's return to the explanation of Figure 4.

In step S4 of FIG. 2, the selection circuit 16 executes the process of switching the shooting frame rate and exposure time shown in FIG. 4.

In step S200, the selection circuit 16 checks the level of the second trigger signal, and if it is High, the selection circuit 16 next executes step S201. If the level of the second trigger signal is Low, the selection circuit 16 next executes step S203.

Step S201 performs the same process as step S101, so the explanation is omitted. The selection circuit 16 then executes step S202.

In step S202, the selection circuit 16 sets the second shooting parameters in the exposure time control unit so as to perform HDR shooting. The exposure time control unit also references the frame number generated by the timing control unit 13 and controls the timing signal generation unit 13 so as to change the exposure time for each frame. Next, 17 completes the processing of the flowchart in FIG. 4 and executes step S5.

Step S203 performs the same process as step S102, so the explanation is omitted. The selection circuit 16 then executes step S204.

In step S204, the control unit 17 sets the first shooting parameters in the exposure time control unit so as to shoot with a fixed exposure time. Next, the selection circuit 16 notifies the control unit 17 that the processing of the flowchart in FIG. 4 has ended, and the control unit 17 then executes step S5.

As described above, it is possible to continuously capture images with increased important scene information and gradation information at the timing of detection of the second trigger signal without storing the captured images in frame memory.

The present invention has been described in detail above based on preferred embodiments, but the present invention is not limited to these specific embodiments, and various forms within the scope of the gist of the invention are also included in the present invention. Parts of the above-mentioned embodiments may be combined as appropriate.

Claims (9)

An imaging device configured without using a frame memory,
An imaging means for capturing and outputting an image;
an output means for outputting the image data read from the imaging means to an external device;
a receiving means for receiving a first trigger from the external device;
a second trigger detection means for detecting a signal inputted from a terminal as a second trigger;
a control unit that controls each unit of the imaging device based on the first trigger received by the receiving unit;
a storage means for storing the first and second photographing parameters;
an imaging device comprising: a means for setting either the first shooting parameter or the second shooting parameter to the imaging means based on the second trigger supplied from the second trigger detection means, the means being connected to the second trigger detection means. The imaging device according to claim 1, characterized in that the first shooting parameter is a parameter that makes the shooting frame rate lower when the second trigger is Low than when the second trigger is High, and the second shooting parameter is a shooting parameter that makes the shooting frame rate higher when the second trigger is High than when the second trigger is Low. The imaging device according to claim 1, further comprising a means for controlling the exposure time. The imaging device according to claim 3, characterized in that the means for controlling the exposure time changes the exposure time for each shooting frame when the second trigger is high. A method for controlling an imaging device having an imaging means for capturing and outputting an image and configured without using a frame memory, comprising the steps of:
an output step of outputting the image data read from the imaging means to an external device;
a receiving step of receiving a first trigger from an external device;
a second trigger detection step of detecting a signal input from a terminal as a second trigger;
a control step of controlling each means of the imaging device based on the first trigger received in the receiving step;
a storage step of storing the first and second photographing parameters;
and setting either the first shooting parameter or the second shooting parameter in the imaging means based on the second trigger. The method for controlling an imaging device according to claim 5, characterized in that the first shooting parameter is a parameter that makes the shooting frame rate lower when the second trigger is Low than when the second trigger is High, and the second shooting parameter is a shooting parameter that makes the shooting frame rate higher when the second trigger is High than when the second trigger is Low. The method for controlling an imaging device according to claim 1, further comprising an exposure time control step for controlling the exposure time. The method for controlling an imaging device according to claim 7, characterized in that, in the exposure time control step, when the second trigger is high, the exposure time is changed for each shooting frame. A computer-readable program for causing a computer configured without using a frame memory to function as each of the means of the imaging device according to any one of claims 1 to 4.

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