Image detection device and automatic focus adjustment method

Abstract

To provide an image detection device and an automatic focus adjustment method which can achieve an increase in operational speed.SOLUTION: An image detection device 1 includes: an image detection part 10 for detecting an image of a detection object W through a liquid resonance-type varifocal lens system 12; a distance detection part 20 for detecting a detection distance Dst to the detection object W; and a detection control part 30 for controlling the image detection part 10 and the distance detection part 20. The detection control part 30 controls a focal position of the image detection part 10 on the basis of the detection distance Dst detected by the distance detection part 20.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an image detection device and an automatic focusing method. [Background technology]

[0002] In image detection devices, a mechanical focus adjustment mechanism is used in the optical path to adjust the focus when projecting an image of a detection target onto an image sensor. In order to bring the focus adjustment mechanism into focus during image detection, the focus position is scanned, that is, the focus position is changed and a focusing operation is performed by determining the contrast of the image detected at each focus position (see Patent Document 1). In recent years, liquid resonance type variable-focus lens systems have been used in image detection devices. In liquid resonance type variable-focus lens systems, pulsed illumination is performed in synchronization with a predetermined phase angle in a high-frequency drive signal that resonates the liquid, thereby making it possible to obtain an image at a focal position corresponding to the phase angle (see Patent Document 2). In an image detection device using such a liquid resonance type variable focus lens system, the mechanical focus adjustment mechanism described above can be omitted, and it is possible to increase the operation speed, extend the life, and eliminate abrasion dust and the like. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-38319 [Patent Document 2] Japanese Patent Application Publication No. 2017-223651 Summary of the Invention [Problem to be solved by the invention]

[0004] In an image detection device using the aforementioned liquid resonance variable-focus lens system, the focal position can be adjusted in microseconds. However, if the aforementioned image contrast determination is used for the focusing operation, image detection or focus determination processing is required at multiple positions, and considering the image frame rate, the focusing operation requires several hundred milliseconds. Therefore, even in an image detection device using a liquid resonance variable-focus lens system that omits a mechanical focus adjustment mechanism, the operating speed of the focusing operation is limited, resulting in the problem of being unable to increase the overall operating speed of the image detection device. Furthermore, in order to perform the contrast judgment described above, the focal position is changed little by little and image detection is repeated, which requires synchronization between the lens system and the image detection unit, which can easily make the system complicated and, depending on the specifications of the image detection unit, can make it necessary to reconsider the system as an image detection device.

[0005] An object of the present invention is to provide an image detection device and an automatic focus adjustment method that can increase the operating speed. [Means for solving the problem]

[0006] The image detection device of the present invention comprises an image detection unit that detects an image of an object to be detected through a liquid resonance type variable focus lens system, a distance detection unit that detects the detection distance to the object to be detected, and a detection control unit that controls the image detection unit and the distance detection unit, and the detection control unit controls the focal position of the image detection unit based on the detection distance detected by the distance detection unit.

[0007] In this invention, the distance detected by the distance detection unit is used to control the focus position in the image detection unit, thereby eliminating the contrast detection process that lengthened the processing time in conventional focus adjustments and speeding up the focus adjustment operation. Furthermore, not using contrast detection enables automatic focus adjustment at a speed faster than the frame rate of the detected image. By speeding up the focus adjustment operation in this way, the effect of speeding up the image detection operation using the liquid resonance type variable focus lens system can be fully utilized, and the overall operating speed of the image detection device can be increased. Furthermore, in the present invention, the distance detection unit is separated into a separate system from the image detection unit, and can continue to detect the focus position independently of the image detection operation. Since there is no need for mutual synchronization between the distance detection unit and the image detection unit, the system as an image detection device can be prevented from becoming complicated.

[0008] In the present invention, the distance detection unit can be an existing optical distance detection device such as a laser interferometer. It is preferable that the distance detection unit detects the detected distance along the optical axis (image detection optical axis) of the image detection unit directed toward the detection target. Here, the optical axis (distance detection optical axis) of the distance detection unit directed toward the detection target does not necessarily have to be parallel to the detection optical axis of the image detection unit, but may be tilted. When the distance detection optical axis is tilted with respect to the image detection optical axis, the distance detected by the distance detection unit can be converted into the distance in the image detection optical axis direction by geometric calculation. On the other hand, when the detected distance detected by the distance detection unit is used for focus adjustment in the image detection unit, the phase angle of the drive signal of the variable-focus lens system can be calculated based on the detected distance, and focus adjustment can be achieved by changing the image detection timing using pulsed illumination, for example. In the present invention, the procedure for controlling the focal position of the image detection unit based on the separately detected detection distance is to record in advance the correspondence between the phase angle of vibration in the liquid resonance type variable focus lens system and the focal position in the image detection unit, convert the detection distance detected by the distance detection unit into a phase angle, and synchronize the pulsed illumination for image detection with that phase angle.

[0009] In the image detection device of the present invention, the image detection optical axis of the image detection unit directed toward the object to be detected and the distance detection optical axis of the distance detection unit directed toward the object to be detected are arranged parallel to each other at a predetermined interval, and the detection control unit detects the detection distance to the object to be detected using the distance detection unit, and sets the focal position of the image detection unit based on the detection distance when the image detection optical axis passes through the object to be detected for which the detection distance has been detected, and detects an image of the object to be detected using the image detection unit. In this invention, the image detection optical axis and the distance detection optical axis are arranged parallel to each other at a predetermined interval, so image detection can be performed regardless of whether the distance from the image detection device to the object to be detected is close or far. To ensure that the image detection optical axis passes through the detection target portion, the image detection device and the object to be detected are moved relative to each other. For example, a movement mechanism installed on the image detection device or the support portion of the object to be detected can be used. In in-line measurement where the object to be detected is transported on a conveyor, the transport operation of the conveyor can also be used to move the image detection device and the object to be detected relative to each other.

[0010] In the image detection device of the present invention, a detection distance table is provided in which the value of the detection distance to the detection target portion detected by the distance detection unit is recorded in association with position information of the detection target portion in the detection object, and the detection control unit can read out the detection distance value associated with the detection target portion whose image is detected by the image detection unit from the detection distance table and use it as the focal position of the image detection unit. In this invention, the distance detection unit can detect distances to multiple detection target portions of the detection target object in advance and store the distances in a detection distance table. When performing image detection with the image detection unit, the detection distance of the detection target portion for which image detection is performed can be obtained from the detection distance table and set as the focal position of the image detection unit, eliminating the need to perform distance detection each time image detection is performed. Therefore, when repeatedly photographing the same detection target multiple times, sharing distance detection enables efficient operation.

[0011] In the image detection device of the present invention, the image detection optical axis of the image detection unit directed toward the object to be detected and the distance detection optical axis of the distance detection unit directed toward the object to be detected are arranged at an angle so as to intersect at the detection target portion of the object to be detected, and the detection control unit may calculate the focal position of the image detection unit from the detection distance to the detection target portion detected by the distance detection unit. In this invention, the image detection optical axis and the distance detection optical axis are directed toward the same detection target portion, allowing distance detection and image detection to be performed simultaneously. In this case, the distance detection optical axis is disposed at an angle with respect to the image detection optical axis, but the distance in the image detection optical axis direction can be obtained by geometric calculation, and this can be used as the focal position to perform focus adjustment of the image detection unit or image detection. In other words, when an arbitrary detection target portion of the detection target is selected, distance detection by the distance detection unit or focus adjustment of the image detection unit can be performed immediately, allowing image detection operations to be performed efficiently.

[0012] In the image detection device of the present invention, the image detection optical axis of the image detection unit directed toward the detection object and the distance detection optical axis of the distance detection unit directed toward the detection object may be arranged coaxially. In this invention, the image detection optical axis and the distance detection optical axis are coaxial and directed toward the same detection target portion, distance detection and image detection can be performed in the same posture, and focus adjustment of the image detection portion or image detection can be performed using the distance obtained by the distance detection portion as the focal position. Then, when an arbitrary detection target portion of the detection target is selected, distance detection by the distance detection portion or focus adjustment of the image detection portion can be performed immediately, allowing for efficient image detection operations. In the present invention, specific configurations for arranging the image detection optical axis and the distance detection optical axis coaxially include a configuration in which the image detection optical axis and the distance detection optical axis are converged in front of the same objective lens using a beam splitter or the like, a configuration in which the distance detection optical axis is converged from the side of the linear image detection optical axis, or conversely, a configuration in which the image detection optical axis is converged from the side of the linear distance detection optical axis, etc.

[0013] The automatic focus adjustment method of the present invention uses an image detection unit that detects an image of an object to be detected through a liquid resonance type variable focus lens system, and a distance detection unit that detects the detection distance to the object to be detected, and the distance detection unit detects the detection distance to the object to be detected, and controls the focus position of the image detection unit based on the detected detection distance. In the automatic focus adjustment method of the present invention, the same effects as those explained in the image detection device of the present invention can be obtained. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide an image detection device and an automatic focus adjustment method that can increase the operating speed. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a block diagram showing a first embodiment of an image detection device of the present invention. [Figure 2] 4 is a flowchart showing the operation of the first embodiment. [Figure 3] FIG. 4 is a block diagram showing a second embodiment of an image detection device according to the present invention. [Figure 4] FIG. 10 is a schematic diagram showing a detection distance table according to the second embodiment. [Figure 5] 6 is a flowchart showing the operation of the second embodiment. [Figure 6] FIG. 10 is a block diagram showing a third embodiment of an image detection device according to the present invention. [Figure 7] FIG. 10 is a block diagram showing a fourth embodiment of an image detection device according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] [First embodiment] FIG. 1 shows a first embodiment of the present invention. In Figure 1, the image detection device 1 has an image detection unit 10 that detects an image of the detection object W through a liquid resonance type variable focus lens system 12, a distance detection unit 20 that detects the detection distance Dst to the detection object W, and a detection control unit 30 that controls the image detection unit 10 and the distance detection unit 20, and the detection control unit 30 detects the detection distance Dst to the detection object W using the distance detection unit 20 and controls the focal position of the image detection unit 10 based on the detected detection distance Dst. The image detection device 1 is supported by a support mechanism (not shown), and the detection object W is placed on a stage T. A movement mechanism M is installed between the support mechanism and the stage T, and the image detection device 1 and the detection object W can move relative to each other in at least one horizontal direction.

[0017] The image detection unit 10 has an objective lens 11, a variable-focus lens system 12, and an image sensor 13. The objective lens 11 is disposed opposite to the detection target W. The image sensor 13 is a two-dimensional image sensor that uses a semiconductor light-receiving element. A beam splitter 14 is installed between the objective lens 11 and the variable-focus lens system 12. An illumination device 15 is installed to the side of the beam splitter 14. Illumination light Li from the illumination device 15 is reflected by the beam splitter 14 and irradiated onto the detection object W through the objective lens 11. Reflected light Lr reflected by the detection object W is introduced into the image sensor 13 through the beam splitter 14 and the variable-focus lens system 12. As a result, the image sensor 13 detects an image of the detection object W and sends it to the detection control unit 30 as a detected image Img. On the detection object W, the position onto which the illumination light Li from the objective lens 11 is irradiated is the detection target portion Pc, and the reflected light Lr reflected by the detection target portion Pc is returned to the objective lens 11, thereby detecting an image of the detection target portion Pc. The optical axis of the illumination light Li from the objective lens 11 and the optical axis of the reflected light Lr returning to the illumination light Li are defined as the image detection optical axis Ac.

[0018] A lens control unit 16 is connected to the variable-focus lens system 12. The lens control unit 16 supplies a high-frequency drive signal Drv to the variable-focus lens system 12 to resonate the internal liquid and cause it to function as a lens, and also sends a timing signal TS synchronized with the drive signal Drv to the illumination device 15 to perform pulsed illumination of the detection target W. The timing signal TS is synchronized with a predetermined phase angle position of the drive signal Drv, and the focal position of the variable-focus lens system 12 can be adjusted by changing the phase of the timing signal TS. The supply of the drive signal Drv and the phase adjustment of the timing signal TS by the lens control unit 16 are performed in accordance with a control signal CS from the detection control unit 30.

[0019] The distance detection unit 20 has a laser displacement meter 21. The laser displacement meter 21 is, for example, an existing confocal one-dimensional laser displacement meter, and is attached to the side of the lens barrel of the image detection unit 10. The laser displacement meter 21 directs the detection light Ld toward a detection target portion Pd on the surface of the detection target W, and can detect a detection distance Dst to the detection target portion Pd by projecting and receiving the detection light Ld along the same distance detection optical axis Ad. The detected detection distance Dst is sent to the detection control unit 30. Here, the image detection optical axis Ac of the image detection unit 10 directed toward the detection object W and the distance detection optical axis Ad of the distance detection unit 20 directed toward the detection object W are arranged parallel to each other with a predetermined interval Ofs between them.

[0020] The detection control unit 30 is configured with an existing computer system, and can realize predetermined functions by executing loaded programs. The detection control unit 30 detects the detection distance Dst to the detection target portion Pd of the detection object W using the distance detection unit 20 (the state shown by the solid line in Figure 1), and when the image detection optical axis Ac passes through the detection target portion Pd for which the detection distance Dst has been detected (the state shown by the dotted line in Figure 1), sets the focal position of the image detection unit 10 based on the detection distance Dst, and detects an image of the detection object W using the image detection unit 10.

[0021] FIG. 2 shows the operation procedure of the image detection device 1 executed under the control of the detection control unit 30. The detection control unit 30 moves the detection object W using the movement mechanism M, and aligns the distance detection optical axis Ad of the distance detection unit 20 with the detection target portion Pd of the detection object W (process S1). Then, the distance detection unit 20 detects the detection distance Dst to the detection target portion Pd (process S2). Next, the detection control unit 30 moves the detection object W using the movement mechanism M, and aligns the image detection optical axis Ac of the image detection unit 10 with the detection target portion Pd whose distance was detected earlier (process S3). As a result, the detection target portion Pd whose distance was detected earlier becomes the detection target portion Pc of the image detection unit 10. In this state, the detection control unit 30 sends a control signal CS including the detection distance Dst to the lens control unit 16 (process S4). The lens control unit 16 calculates a phase angle position at which the image detection unit 10 will have a focal length corresponding to the detection distance Dst, based on the detection distance Dst and the frequency of the drive signal Drv sent to the variable-focus lens system 12, and sends a timing signal TS synchronized with this phase angle position to the illumination device 15 (process S5). The illumination device 15 emits light in synchronization with the timing signal TS, thereby pulsatingly illuminating the detection object W, and the image sensor 13 detects a detection image Img focused at the detection distance Dst as the focal position (process S6).

[0022] In this embodiment, the detection distance Dst detected by the distance detection unit 20 is used to control the focus position in the image detection unit 10, thereby eliminating the contrast detection process that lengthened the processing time in conventional focus adjustments and speeding up the focus adjustment operation. Furthermore, not using contrast detection enables automatic focus adjustment at a speed faster than the frame rate of the detected image Img. By speeding up the focus adjustment operation in this way, the effect of speeding up the image detection operation by the liquid resonance type variable-focus lens system 12 can be fully utilized, and the overall operating speed of the image detection device 1 can be increased. Furthermore, in this embodiment, the distance detection unit 20 is separated into a separate system from the image detection unit 10, and can continue to detect the focus position independently of the image detection operation. Since there is no need for mutual synchronization between the distance detection unit and the image detection unit, the system as the image detection device 1 can be prevented from becoming complicated.

[0023] In this embodiment, the image detection optical axis Ac and the distance detection optical axis Ad are arranged parallel to each other at a predetermined interval Ofs, so that image detection can be performed in the same manner regardless of whether the distance from the image detection device 1 to the detection target W is close or far. In this embodiment, after detecting the detection distance Dst, the image detection device 1 and the detection object W are moved relative to each other so that the image detection optical axis Ac passes through the detection target portion Pd. This relative movement can be achieved by using a movement mechanism M installed between the support mechanism of the image detection device 1 and the stage T. The movement mechanism M can be an existing movement mechanism provided in the support mechanism of the image detection device 1. Furthermore, in in-line measurement in which the detection object W is transported on a conveyor, the conveyor can serve as the stage T, and the transport operation of the conveyor can also be used to move the image detection device 1 and the detection object W relative to each other, eliminating the need for a separate movement mechanism M.

[0024] Second Embodiment A second embodiment of the present invention is shown in FIG. In the first embodiment shown in FIG. 1, the distance detection unit 20 detects the detection distance Dst for the same detection target portion Pd of the detection target W, and then the image detection unit 10 detects the detection image Img. In contrast to this, in this embodiment, the detection distances Dst for a plurality of detection target portions Pd of the detection target W are detected in advance, and each time the image detection unit 10 detects a detection image Img, the detection distance Dst for the corresponding portion can be read out. For this reason, the image detection device 2 of this embodiment has the same configuration as the image detection device 1 of Figure 1 described above, and a detection distance table 31 that stores the value of the detection distance Dst is set in the memory area of ​​the detection control unit 30. Then, the detection control unit 30 associates the value of the detection distance Dst to the detection target area Pd detected by the distance detection unit 20 with the position information of the detection target area Pd on the detection target object W and records it in the detection distance table 31, and reads out the value of the detection distance Dst associated with the position value at which the image is detected by the image detection unit 10 from the detection distance table 31 and sets it as the focal position of the image detection unit 10.

[0025] 4, detection distance table 31 stores the value of detection distance Dst in association with position information of the detection target portion Pd, with the X-axis coordinate (X1, X2...) of the detection target portion Pd on the detection target W arranged on the horizontal axis and the Y-axis coordinate (Y1, Y2...) of the detection target portion Pd on the detection target W arranged on the vertical axis, and values ​​Hxy (H11, H12...) are recorded as the detection distance Dst for the corresponding XY position. As a result, when a detection target portion Pc through which the image detection optical axis Ac passes is specified, the value Hxy of the detection distance Dst for the corresponding portion is obtained.

[0026] FIG. 5 shows the operation procedure of the image detection device 2 of this embodiment. The detection control unit 30 selects one of a plurality of target portions on the surface of the detection target W as the detection target portion Pd (process S11), moves the detection target W using the movement mechanism M, and aligns the distance detection optical axis Ad of the distance detection unit 20 with the detection target portion Pd of the detection target W (process S12). Then, the distance detection unit 20 detects the detection distance Dst to the detection target portion Pd and records the detection distance Dst in the detection distance table 31 together with the position information of the detection target portion Pd. The detection control unit 30 repeats the above-described steps S11 to S13, and stops the repetition when distance detection of necessary target portions on the surface of the detection target W is completed (step S14).

[0027] Next, the detection control unit 30 receives the designation of the detection target portion Pd by a user instruction or by referring to a designation file (process S21), moves the detection target object W using the movement mechanism M, and aligns the image detection optical axis Ac of the image detection unit 10 with the detection target portion Pd whose distance was previously detected (process S22). Furthermore, the detection distance Dst that is the predetermined distance Ofs from the detection target portion Pd is read from the detection distance table 31 (process S23), and sends a control signal CS including this detection distance Dst to the lens control unit 16 (process S24). The lens control unit 16 calculates a phase angle position at which the image detection unit 10 has a focal length corresponding to the detection distance Dst, based on the detection distance Dst and the frequency of the drive signal Drv sent to the variable-focus lens system 12, and sends a timing signal TS synchronized with this phase angle position to the illumination device 15 (process S25). The illumination device 15 emits light in synchronization with the timing signal TS, thereby pulsatingly illuminating the detection object W, and the image sensor 13 detects a detection image Img focused at the detection distance Dst as the focal position (process S26). The detection control unit 30 repeats the above-described steps S21 to S26, and stops the repetition when image detection of necessary parts of the target portion on the surface of the detection target W is completed (step S27).

[0028] In this embodiment, an image detection unit 10 is used that detects an image of the object to be detected W through a liquid resonance type variable focus lens system 12, and a distance detection unit 20 that detects the detection distance Dst to the object to be detected W. The distance detection unit 20 detects the detection distance Dst to the object to be detected W, and the focal position of the image detection unit 10 is controlled based on the detected detection distance Dst, thereby constituting the automatic focus adjustment method of the present invention.

[0029] In the image detection device 2 of this embodiment, the value of the detection distance Dst to the detection target part Pd detected by the distance detection unit 20 can be recorded in the detection distance table 31 in association with position information of the detection target part Pd on the detection target object W. When performing image detection with the image detection unit 10, the detection distance Dst to the detection target part Pd for which image detection is performed can be obtained from the detection distance table 31 and set as the focal position of the image detection unit 10, eliminating the need to perform distance detection each time image detection is performed. Therefore, when repeatedly capturing multiple images of the same detection target W, sharing distance detection enables efficient operation.

[0030] Third Embodiment FIG. 6 shows a third embodiment of the present invention. In the first embodiment shown in FIG. 1 described above, the image detection optical axis Ac of the image detection unit 10 and the distance detection optical axis Ad of the distance detection unit 20A are arranged parallel to each other, and the detection target portions Pc and Pd are separated by a predetermined distance Ofs, and relative movement or position calculation of the predetermined distance Ofs is required for image detection. In contrast, in this embodiment, the distance detection optical axis Ad of the distance detection unit 20 is arranged at an angle relative to the image detection optical axis Ac of the image detection unit 10, and the image detection optical axis Ac and the distance detection optical axis Ad intersect at the same detection target portion Pc on the surface of the detection target W.

[0031] 6, the image detection device 3 has an image detection unit 10, a distance detection unit 20A, and a detection control unit 30. Of these, the image detection unit 10 and the detection control unit 30 are configured in the same manner as in the first embodiment described above. The distance detection unit 20A has a laser displacement meter 21 similar to that in the first embodiment described above. In this embodiment, detection light Ld from the laser displacement meter 21 is directed toward the detection target location Pc of the image detection unit 10. The detection distance Dst obtained from such distance detection unit 20A is converted into a distance along the image detection optical axis Ac by a correction calculation performed by the detection control unit 30 in accordance with the inclination of the distance detection optical axis Ad, and can be set as the focal position in the image detection unit 10.

[0032] In this embodiment, the image detection optical axis Ac and the distance detection optical axis Ad are directed toward the same detection target portion Pc, allowing distance detection and image detection to be performed simultaneously. In this case, the distance detection optical axis Ad is disposed at an angle with respect to the image detection optical axis Ac, but the distance in the direction of the image detection optical axis Ac can be obtained by geometric calculation, and this can be used as the focal position to perform focus adjustment of the image detection unit 10 or image detection. In other words, when an arbitrary detection target portion Pc of the detection target W is selected, distance detection by the distance detection unit 20A or focus adjustment of the image detection unit 10 can be performed immediately, allowing image detection to be performed efficiently.

[0033] [Fourth embodiment] FIG. 7 shows a fourth embodiment of the present invention. In the first embodiment shown in FIG. 1 described above, the image detection unit 10 and the distance detection unit 20 are independent of each other, the image detection optical axis Ac of the image detection unit 10 and the distance detection optical axis Ad of the distance detection unit 20 are arranged parallel to each other, and the detection target portions Pc and Pd are separated by a predetermined distance Ofs, and relative movement or position calculation of the predetermined distance Ofs is required for image detection. In contrast, in this embodiment, the detection light Ld of the distance detection unit 20B is incorporated into the optical path of the image detection unit 10, and the distance detection optical axis Ad of the distance detection unit 20B and the image detection optical axis Ac of the image detection unit 10 are arranged coaxially.

[0034] 7, the image detection device 4 has an image detection unit 10, a distance detection unit 20B, and a detection control unit 30. Of these, the image detection unit 10 and the detection control unit 30 are configured in the same manner as in the first embodiment described above. The distance detection unit 20B has a laser displacement meter 21 similar to that of the first embodiment described above, and also has a beam splitter 22 between the variable-focus lens system 12 and the objective lens 11 of the image detection unit 10. The detection light Ld from the laser displacement meter 21 is directed to the beam splitter 22 and is arranged to pass from the beam splitter 22 through the objective lens 11 to the detection object W. In such a distance detection unit 20B, the detection light Ld that travels from the laser displacement meter 21 to the detection object W via the beam splitter 22 can detect the detection distance Dst to the detection object W.

[0035] In this embodiment, the focal position of the image detection unit 10 can be set using the detection distance Dst obtained from the distance detection unit 20B. Furthermore, since the distance detection optical axis Ad of the distance detection unit 20B and the image detection optical axis Ac of the image detection unit 10 are arranged coaxially, by selecting any detection target portion Pc on the surface of the detection target W, the detection distance Dst of that portion can be obtained from the distance detection unit 20B, and by adjusting the focal position of the image detection unit 10 using this detection distance Dst, image detection can be performed immediately.

[0036] Other Embodiments The present invention is not limited to the above-described embodiment, and includes modifications within the scope of achieving the object of the present invention. In the above embodiment, the laser displacement meter 21 is used for the distance detection units 20, 20A, and 20B, but a distance detector based on another detection principle may also be used. In the above embodiment, the image sensor 13, which is a two-dimensional image sensor using a semiconductor light receiving element, is used in the image detection unit 10, but it can be replaced with anything that can capture an image and output a signal. In addition to the image sensor 13, an eyepiece may be provided so that the image can be viewed visually. In the above embodiment, the arrangement or combination of the optical elements in the image detection unit 10 and the distance detection units 20, 20A, and 20B is not limited to this, and may be changed as appropriate as long as the configuration provides similar functions. [Industrial Applicability]

[0037] The present invention can be used in an image detection device and an automatic focus adjustment method that can increase the operating speed. [Explanation of symbols]

[0038] 1 to 4...image detection device, 10...image detection unit, 11...objective lens, 12...variable focus lens system, 13...image sensor, 14...beam splitter, 15...illumination device, 16...lens control unit, 20, 20A, 20B...distance detection unit, 21...laser displacement meter, 22...beam splitter, 30...detection control unit, 31...detection distance table, Ac...image detection optical axis, Ad...distance detection optical axis, CS...control signal, Drv...drive signal, Dst...detection distance, Img...detected image, Ld...detection light, Li...illumination light, Lr...reflected light, M...movement mechanism, Ofs...predetermined interval, Pc, Pd...detection target area, S1 to S27...processing, T...stage, TS...timing signal, W...detection target.

Claims

1. The present invention has an image detection unit that detects an image of a detection object through a liquid resonance type variable focus lens system, a distance detection unit that detects a detection distance to the detection object, and a detection control unit that controls the image detection unit and the distance detection unit, The detection control unit controls a focal position of the image detection unit based on the detection distance detected by the distance detection unit.

2. 2. The image detection device according to claim 1, an image detection optical axis of the image detection unit directed toward the detection object and a distance detection optical axis of the distance detection unit directed toward the detection object are arranged in parallel at a predetermined interval, The detection control unit detects the detection distance to the detection target portion of the detection object using the distance detection unit, sets the focal position of the image detection unit based on the detection distance while the image detection optical axis passes through the detection target portion for which the detection distance has been detected, and detects an image of the detection object using the image detection unit.

3. 3. The image detection device according to claim 2, a detection distance table in which the value of the detection distance to the detection target portion detected by the distance detection unit is recorded in association with position information of the detection target portion in the detection object, The detection control unit reads out the detection distance value associated with the detection target portion whose image is detected by the image detection unit from the detection distance table, and sets the value as the focal position of the image detection unit.

4. 2. The image detection device according to claim 1, an image detection optical axis of the image detection unit directed toward the detection object and a distance detection optical axis of the distance detection unit directed toward the detection object are disposed at an angle such that they intersect at a detection target portion of the detection object; The detection control unit is an image detection device that calculates the focal position of the image detection unit from the distance to the detection target portion detected by the distance detection unit.

5. 2. The image detection device according to claim 1, an image detection device in which the image detection optical axis of the image detection unit directed toward the detection object and the distance detection optical axis of the distance detection unit directed toward the detection object are coaxially arranged;

6. An automatic focus adjustment method using an image detection unit that detects an image of a detection object through a liquid resonance type variable focus lens system and a distance detection unit that detects a detection distance to the detection object, in which the distance detection unit detects the detection distance to the detection object and the focal position of the image detection unit is controlled based on the detected detection distance.

Images