JPH07111556A - Image pickup device - Google Patents

Abstract

PURPOSE:To provide an image pickup device which can obtain the images at a stable luminance level and without receiving any influence of the luminance change of a light source. CONSTITUTION:Line sensors 3a, 3b and 3c are placed on an image forming surface 2 at a prescribed interval. The outputs of the sensors 3b and 3c are supplied to the delay circuits 11a and 11b respectively. The delayed variables of both circuits 11a and 11b are set at the time difference caused when both sensors 3b and 3c photograph the same part of a subject by the secondary scan on the basis of the sensor 3a. The signals read out of the sensors 3b and 3c are stored in a memory, and the output signals of the sensor 3a and both circuits 11b and 11c are added together by an adder 10. The images which are sampled and held by an S/H circuit 4 and stored in a memory 6 via an A/D converter 5 undergo the signal processing. A mode changeover control circuit 13 controls the mode of a driving circuit 8 based on the detecting result of a flicker detecting circuit 12 of a light source.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup device for scanning a line sensor to pick up a two-dimensional image.

[0002]

2. Description of the Related Art FIG. 10 shows a block diagram of a conventional image pickup device for scanning a line sensor to pick up a two-dimensional image. In the figure, 1 is a lens for forming a subject image, and the subject image is formed on the image forming surface of 2. An in-sensor 3 is arranged on the image plane 2 and converts the subject image into an electric signal and outputs it. The line sensor 3 can capture a two-dimensional image by scanning the image plane 2 in the direction perpendicular to the main scanning direction, that is, in the sub-scanning direction (the direction of the arrow in the drawing). The signal output when the line sensor 3 is at a predetermined position is sampled and held by the sample and hold circuit (S / H circuit) 4, and the analog-
The digital signal is converted by the digital conversion circuit (A / D conversion circuit) 5 into a digital signal and temporarily stored in the memory 6. This operation is repeated while scanning the line sensor 3 in the sub-scanning direction, and a two-dimensional image for one screen is stored in the memory 6. Further, the image stored in the memory 6 is processed by the signal processing 7 and is output as a video signal of a predetermined system. The output signal is connected to a monitor or recorded in a predetermined recording device. The drive circuit 8 drives the line sensor 3, the S / H circuit 4, the A / D conversion circuit 5, the memory 6, the signal processing circuit 7, and generates a drive pulse for sub-scanning the line sensor 3. Circuit.

[0003]

However, in an image pickup apparatus such as the above-mentioned conventional example, when an image of a subject is taken under a light source having a flicker such as a fluorescent lamp, the line sensor is scanned in the sub-scanning direction. However, since the brightness of the light source changes in a predetermined cycle, there is a problem in that an image whose brightness level changes in a predetermined cycle is obtained regardless of the subject image.

The present invention has been made in order to solve such a conventional problem, and it is an object of the present invention to provide an image pickup apparatus capable of obtaining an image having a stable brightness level without being affected by a change in brightness of a light source. To aim.

[0005]

According to a first aspect of the present invention, in an image pickup device for scanning a line sensor to pick up a two-dimensional image, a detecting means for detecting flicker of a light source and an object image are detected. A plurality of line sensors for capturing an image are provided, and the plurality of line sensors are arranged in parallel at a predetermined interval, and the sub-scan is performed while maintaining the interval, and each line sensor shifts by a predetermined time and the same position of the subject image is obtained. As a configuration for capturing an image, when flicker is detected in a light source at the time of capturing, each line sensor adds signals of the same position of an image of a subject captured by shifting by a predetermined time to form one signal. To do.

According to a second aspect of the present invention, in an image pickup apparatus for scanning a line sensor to pick up a two-dimensional image, a detecting means for detecting flicker of a light source and a line sensor for picking up a subject image. A plurality of line sensors are arranged in parallel with each other at a predetermined interval, and sub-scanning is performed while maintaining the interval, and each line sensor is shifted by a predetermined time to capture the same position of the subject image. When a flicker is detected in the light source at that time, the sub-scanning is synchronized with the frequency of the flicker, and the signals at the same position of the object image captured by each line sensor with a predetermined time difference are added to form one signal. It is characterized by

According to a third aspect of the present invention, in an image pickup device for scanning a line sensor to pick up a two-dimensional image, a detecting means for detecting flicker of a light source and a line sensor for picking up a subject image. A plurality of line sensors are arranged in parallel with each other at a predetermined interval, and sub-scanning is performed while maintaining the interval, and each line sensor is shifted by a predetermined time to capture the same position of the subject image. If flicker is detected in the light source at that time, the speed of the sub-scanning is changed according to the frequency of the flicker, and each line sensor adds a signal at the same position of the object image captured by shifting by a predetermined time and adds 1 It is characterized by one signal.

According to a fourth aspect of the present invention, in an image pickup apparatus for scanning a line sensor to pick up a two-dimensional image, a detecting means for detecting flicker of a light source and a line sensor for picking up a subject image. A plurality of line sensors are arranged in parallel with each other at a predetermined interval, and sub-scanning is performed while maintaining the interval, and each line sensor is shifted by a predetermined time to capture the same position of the subject image. When flicker is detected in the light source at that time, the interval between each line sensor is changed according to the frequency of the flicker, and the signals at the same position of the subject image captured by each line sensor are shifted by a predetermined time and added. It is characterized in that it is one signal.

According to a fifth aspect of the present invention, in an image pickup apparatus for scanning a line sensor to pick up a two-dimensional image, a detecting means for detecting flicker of a light source and a line sensor for picking up a subject image. A plurality of line sensors are arranged in parallel with each other at a predetermined interval, and sub-scanning is performed while maintaining the interval, and each line sensor is shifted by a predetermined time to capture the same position of the subject image. When flicker is detected in the light source at the time, select a predetermined number of line sensors from the plurality of line sensors,
It is characterized in that the selected line sensors add signals at the same position of the subject image picked up by being shifted by a predetermined time to form one signal.

[0010]

According to the present invention, when a subject image is captured under a flicker light source such as a fluorescent lamp, which has been a problem in the related art, when the line sensor is scanning in the sub-scanning direction,
Since the brightness of the light source changes in a predetermined cycle, it is possible to solve the problem that the image is affected by the brightness and the brightness level is changed in the predetermined cycle regardless of the subject image.

[0011]

FIG. 1 is a block diagram of an image pickup apparatus for scanning a line sensor according to the present invention to pick up a two-dimensional image. In the figure, those having the same numbers as those in FIG. 10 indicate the same components. In the figure, 1 is a lens for forming a subject image, and the subject image is formed on the image forming surface of 2. Line sensors 3a, 3b, and 3c are arranged on the image plane 2 at predetermined intervals, and convert the subject image into an electric signal and output it. The line sensors 3a, 3b, and 3c scan the image plane 2 in the direction perpendicular to the main scanning direction, that is, in the sub-scanning direction (the direction of the arrow in the figure) while maintaining a predetermined interval, thereby 2 It is possible to capture a three-dimensional image. The outputs of the line sensors 3b and 3c are input to the delay circuits 11b and 11c. The delay amount of each of the delay circuits 11b and 11c is based on the line sensor 3a.
When 3c performs sub-scanning and captures an image, each line sensor is set to a time difference for capturing the same portion of the subject image. Therefore, the output signal of the line sensor 3a and the delay circuit 11
The outputs b and 11c are obtained as signals obtained by imaging the same part of the subject with a predetermined time offset. Further, these delay circuits may be replaced with a memory capable of storing signals for one line. That is, the signals read from the line sensors 3b and 3c may be temporarily stored in the memory and read from the memory at the same time when the signals are read from the line sensor 3a. The output signal of the line sensor 3a and the output signals of the delay circuits 11b and 11c are added by 10 adders, and the added signals are sample-held by a sample-hold circuit (S / H circuit) 4 and analog-digital. The conversion circuit (A / D conversion circuit) 5 converts the analog signal into a digital signal and temporarily stores it in the memory 6. This operation is repeated while scanning the line sensor 3 in the sub-scanning direction, and a two-dimensional image for one screen is stored in the memory 6. Further, the image stored in the memory 6 is processed by the signal processing 7 and is output as a video signal of a predetermined system. The output signal is connected to a monitor or recorded in a predetermined recording device. Further, the drive circuit of 8 is 3a, 3
b, 3c line sensors, S / H circuit 4, A / D conversion circuit 5, memory 6, signal processing circuit 7, delay circuit 11a,
It is a circuit for generating drive pulses for driving 11b and for sub-scanning the line sensors 3a, 3b, 3c. A flicker detection circuit 12 detects flicker of a light source, and a mode switching control circuit 13 controls the mode of the drive circuit 8 according to the detection result of the flicker detection circuit 12. That is, when flicker is detected in the light source by the flicker detection circuit 12, the drive circuit 8 is mode-switched to drive in a mode in which the outputs of the three line sensors are added and the image is picked up as described above. It is controlled by the circuit 13. When no flicker is detected in the light source, only one line sensor is driven and the other two line sensors are not driven, instead of using three line sensors, to save power. The drive circuit 8 is controlled by the mode switching control circuit 13 so that the drive circuit 8 is driven in a mode in which an image of one screen is picked up by sub scanning. Alternatively,
The mode switching control circuit is used to drive the drive circuit 8 in such a mode that the three line sensors are imaged with different settings of the exposure amount and the signals with different exposure amounts are added. By controlling with 13, it is possible to capture an image with a large dynamic range.

FIG. 2 shows a timing chart of the image pickup apparatus in this embodiment. In the figure, a indicates a light source whose luminance level changes in a predetermined cycle, and b indicates a time when the three line sensors 3a, 3b, and 3c image a predetermined same portion of the subject. As shown in the figure, when a subject is photographed under a light source having a periodical luminance change as shown in (a), three line sensors 3a, 3b, and 3c show the same portion of the subject as shown in (b). Takes 3c
Since the line sensors of 3b and 3a are delayed by a predetermined time with respect to the line sensor of 3, the influence of the flicker of the light source can be canceled by adding these output signals. With such a configuration, signals obtained by shifting the same portion of the subject for a predetermined period of time and picked up and used as one signal can cancel the influence of the flicker of the light source, which is a conventional problem. Due to the influence of the flicker of the fluorescent lamp, it is possible to solve the problem that an image in which the brightness level is changed in a predetermined cycle is obtained regardless of the subject image. Further, although the number of line sensors has been described as three in this embodiment, it is needless to say that the number is not limited to three and two or more line sensors may be used. Also, the greater the number, the greater the effect of canceling the influence of the flicker of the light source.

FIG. 3 is a block diagram of an image pickup apparatus according to the second embodiment of the present invention. In the figure, those having the same numbers as those in FIG. In this embodiment, the case where there are two line sensors will be described. In the figure, 14 is a flicker frequency detection circuit for detecting the flicker frequency of the light source detected by the 12 flicker detection circuit, and 15 is the drive circuit 8 in synchronization with the frequency detected by the flicker frequency detection circuit 14. It is a synchronous circuit for driving.

FIG. 4 shows a timing chart of the image pickup apparatus in this embodiment. In the figure, a indicates a light source whose brightness level changes in a predetermined cycle T, and b indicates a time when two line sensors 3a and 3b image a predetermined same portion of a subject.

The operation of this embodiment will be described with reference to FIGS. If the flicker detection circuit 12 detects no flicker in the light source, the mode switching control circuit 13 sets the drive circuit 8 to the flicker-free mode, and performs the normal image pickup operation as described above. When the flicker detection circuit 12 detects flicker in the light source, the flicker frequency detection circuit 14 detects the flicker frequency, and the synchronization circuit 15 drives the drive circuit 8 to synchronize the sub-scanning with the detected frequency. To control. That is,
As shown in FIG. 4, when the flicker cycle of the light source is T, two line sensors 3a and 3b are connected to b1,
As indicated by b2, b3, and b4, image pickup is performed while sub-scanning is performed in synchronization with the flicker, and the output signals of the two line sensors are added. The effect that the influence can be offset is obtained. Further, with such a configuration, it is possible to obtain an effect that the influence of flicker can be canceled even with a line sensor having a small number of two, as compared with the first embodiment. In the description of this embodiment, the case where the number of line sensors is two has been described, but it is needless to say that this is not limited to two and a plurality of line sensors may be used.

FIG. 5 shows a block diagram of an image pickup apparatus according to the third embodiment of the present invention, and FIG. 6 shows a timing chart of the present embodiment. In FIG. 5, 16 is a flicker frequency detection circuit 1
4 is a control circuit for controlling the speed of sub-scanning the line sensor in accordance with the flicker frequency detected in 4, and the other components are the same as those in FIG.

The operation of this embodiment will be described with reference to FIGS. If the flicker detection circuit 12 detects no flicker in the light source, the mode switching control circuit 13 sets the drive circuit 8 to the flicker-free mode, and performs the normal image pickup operation as described above. When the flicker detection circuit 12 detects flicker in the light source, the flicker frequency detection circuit 14 detects the frequency of the flicker and controls the speed of subscanning the line sensors 3a and 3b in accordance with this frequency. . That is, FIG.
When the flicker cycle of the light source is T, the difference in time taken by the two line sensors 3a and 3b to image the same portion of the subject is 1 of the flicker cycle T, as shown in FIG.
The two line sensors are sub-scanned at a speed that is an integral multiple of / 2 or T / 2. That is, where d is the interval between the two line sensors, v is the scanning speed, and T is the flicker period of the detected light source, d and T are constant, so that v = 2d / nT (n is 1 or more). The sub-scanning may be performed at a speed that satisfies the following condition. further,
Since the time difference between the signals output from the two line sensors changes according to this speed, the delay amount of the delay circuit 11b in the drive circuit 8 is changed accordingly. By sub-scanning at such a speed and capturing an image and adding the output signals of the two line sensors, the effect of flicker of the light source can be canceled, as in the previous embodiment. . Further, although the case where the number of line sensors is two has been described in the present embodiment, the number of line sensors is not limited to two, and needless to say, a plurality of line sensors may be used. In this case, there is a time difference of T / 2 when the line sensors at both ends of the line sensor having a plurality of lines image the same portion of the subject.
The sub-scanning may be performed at a speed that is an integral multiple of, or the sub-scanning may be performed at a speed that is such that the time difference between adjacent line sensors capturing the same portion of the subject is an integral multiple of T / 2.

FIG. 7 is a block diagram of an image pickup apparatus according to the fourth embodiment of the present invention. In FIG. 7, reference numeral 17 denotes a control circuit that controls the interval between the two line sensors according to the flicker frequency detected by the flicker frequency detection circuit 14, and the other components are the same as those in FIG. The timing chart of this embodiment is similar to that of FIG.

The operation of this embodiment will be described with reference to FIGS. If the flicker detection circuit 12 detects no flicker in the light source, the mode switching control circuit 13 sets the drive circuit 8 to the flicker-free mode, and performs the normal image pickup operation as described above. When the flicker detection circuit 12 detects flicker in the light source, the flicker frequency detection circuit 14 detects the frequency of the flicker and controls the intervals of the line sensors 3a and 3b according to this frequency. That is, as shown in FIG. 6, when the flicker cycle of the light source is T, 3
The interval between the two line sensors is set so that the difference between the times when the two line sensors a and 3b image the same portion of the subject is 1/2 or an integral multiple of T / 2 of the flicker cycle. do it. That is, when the interval between the two line sensors is d, the scanning speed is v, and the flicker period of the detected light source is T, v and T are constant, so that two line sensors are d = nvT / The interval may be set to satisfy 2 (n is an integer of 1 or more). Furthermore, since the time difference between the signals output from the two line sensors changes according to this interval, the drive circuit 8 changes the delay amount of the delay circuit 11b accordingly. By subscanning the two line sensors set at such intervals and picking up an image, and adding the output signals of each line sensor, the influence of the flicker of the light source is canceled as in the previous embodiment. The effect of being able to do is obtained. Further, although the case where the number of line sensors is two has been described in the present embodiment, the number of line sensors is not limited to two, and needless to say, a plurality of line sensors may be used. In this case, the line sensors at both ends of a plurality of line sensors are set at intervals such that the time difference for imaging the same part of the subject is an integral multiple of T / 2, or each adjacent line sensor is set to The intervals may be set such that the time difference for imaging the same portion is an integral multiple of T / 2.

FIG. 8 shows a block diagram of an image pickup apparatus according to the fifth embodiment of the present invention, and FIG. 9 shows a timing chart of the present embodiment. In FIG. 8, 18 is a flicker frequency detection circuit 1
4 is a selection circuit that switches the switch 19 according to the frequency of the flicker detected in FIG.
Similar to that of.

The operation of this embodiment will be described with reference to FIGS. If the flicker detection circuit 12 detects no flicker in the light source, the mode switching control circuit 13 sets the drive circuit 8 to the flicker-free mode, and performs the normal image pickup operation as described above. When the flicker detection circuit 12 detects flicker in the light source, the flicker frequency detection circuit 14 detects the flicker frequency. Usually, most of the light sources with flicker are fluorescent lamps, and the frequency is 1 as shown in FIGS.
It is 00 Hz or 120 Hz. Therefore, in the present embodiment, three line sensors are provided, and with respect to the line sensor of 3c, the interval up to the line sensor of 3b is set to be the difference between the times when the two line sensors image the same part of the subject. , The flicker period T1 (1/120 seconds) is set to 1/2 or an integral multiple of T1 / 2, and the interval to the line sensor 3a is set so that the two line sensors image the same part of the subject. The difference in the time taken is the flicker cycle T
It is set to be 1/2 of 2 (1/100 seconds) or an integral multiple of T2 / 2. Here, the flicker detection circuit 1
The flicker frequency of the light source detected in 4 is 120 Hz
If so, the switch 19 is connected to the side a in the selection circuit 18, and the outputs of the line sensors 3c and 3b are added. When the frequency of the flicker of the light source is 100 Hz, the switch 19 is connected to the side b in the selection circuit 18, and the outputs of the line sensors 3c and 3a are added. Further, since the time difference between the output signals of the two line sensors is different in the above two modes, the selection circuit 18 controls the drive circuit 8 to switch the delay time of the delay circuit 11c between the two modes. By doing so, it is possible to obtain the same effect as the above-mentioned conventional example, and it is also possible to obtain the effect that it is not necessary to change the sub-scanning speed or the interval between the line sensors according to the frequency of the flicker of the light source. Further, although the case where the number of line sensors is three has been described in the present embodiment, it is needless to say that the number is not limited to three and a plurality of three or more may be used.

[0022]

As described above, according to the present invention, in an image pickup apparatus for scanning a line sensor to pick up a two-dimensional image, a detecting means for detecting flicker of a light source and a line sensor for picking up a subject image. A plurality of line sensors are arranged in parallel with each other at a predetermined interval, and sub-scanning is performed while maintaining the interval, and each line sensor is shifted by a predetermined time to capture the same position of the subject image. When flicker is detected in the light source at that time, by adding signals at the same position of the subject image captured by the respective line sensors by deviating by a predetermined time, to obtain one signal,
When attempting to capture a subject image under a light source with flicker such as a fluorescent lamp, which has been a problem in the past, the brightness of the light source changes at a predetermined cycle while scanning the line sensor in the sub-scanning direction. It is possible to solve the problem that the image is affected and the luminance level is changed in a predetermined cycle regardless of the subject image. Further, with the configuration according to the present invention, since the control corresponding to the frequency of the flicker of the light source is performed, the effect can be canceled regardless of the frequency of the flicker.

[Brief description of drawings]

FIG. 1 is a block diagram of an image pickup apparatus according to a first embodiment of the present invention.

FIG. 2 is a timing diagram of the image pickup apparatus according to the first embodiment of the present invention.

FIG. 3 is a block diagram of an image pickup apparatus according to a second embodiment of the present invention.

FIG. 4 is a timing diagram of the image pickup apparatus according to the second embodiment of the present invention.

FIG. 5 is a block diagram of an image pickup apparatus according to a third embodiment of the present invention.

FIG. 6 is a timing diagram of the image pickup apparatus according to the third embodiment of the present invention.

FIG. 7 is a block diagram of an image pickup apparatus according to a fourth embodiment of the present invention.

FIG. 8 is a block diagram of an image pickup apparatus according to a fifth embodiment of the present invention.

FIG. 9 is a timing diagram of the image pickup apparatus according to the fifth embodiment of the present invention.

FIG. 10 is a block diagram of a conventional imaging device that scans a line sensor to capture a two-dimensional image.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 lens 2 image plane 3 line sensor 4 sample hold circuit 5 A / D conversion circuit 6 memory 7 signal processing circuit 8 drive circuit 10 adder 11 delay circuit 12 flicker detection circuit 13 mode switching control circuit 14 flicker frequency detection circuit 15 synchronization Circuit 16 Scanning speed control circuit 17 Sensor interval control circuit 18 Selection circuit 19 Switch

Claims (9)

[Claims] 1. An image pickup device including a one-dimensional reading element,
In an image pickup apparatus for picking up a two-dimensional image by scanning in the vertical direction, a plurality of image pickup means arranged in parallel at a predetermined interval and a plurality of delay means for delaying the output of the image pickup means by a predetermined time respectively. An image pickup device comprising: an output of the delay means. 2. The image pickup apparatus according to claim 1, further comprising a detection unit that detects a flicker of a light source. 3. The image pickup apparatus according to claim 2, further comprising a frequency detection unit that detects a frequency of a flicker of a light source. 4. The image pickup apparatus according to claim 3, wherein when flicker is detected by a detection unit that detects flicker of a light source, an image pickup operation is performed in synchronization with a frequency detected by the frequency detection unit. An imaging device characterized by the above. 5. The image pickup device according to claim 3, wherein when the flicker is detected by the detecting means for detecting the flicker of the light source, the scanning speed is controlled according to the frequency detected by the frequency detecting means. An imaging device characterized by the above. 6. The image pickup apparatus according to claim 3, wherein when flicker is detected by a detection unit that detects flicker of a light source, an interval between the image pickup units is determined according to a frequency detected by the frequency detection unit. An image pickup apparatus, characterized by controlling. 7. The image pickup device according to claim 3, wherein when the flicker is detected by the detecting means for detecting the flicker of the light source, the plurality of delaying means are provided according to the frequency detected by the frequency detecting means. An image pickup apparatus characterized in that outputs of the above are selectively added. 8. The image pickup apparatus according to claim 2, wherein when the flicker is not detected by the detection unit that detects the flicker of the light source, only one image pickup unit is driven. 9. The image pickup apparatus according to claim 2, wherein when the flicker is not detected by the detection unit that detects the flicker of the light source, the plurality of image pickup units are driven with different exposure amounts.