JP2010276990A - Back focus adjusting mechanism for imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a back focus adjusting mechanism that is easily formed in an imaging apparatus. <P>SOLUTION: The back focus adjusting mechanism for the imaging apparatus adjusts a distance between a CMOS (Complementary Metal Oxide Semiconductor)image sensor 3 and a lens composing a lens unit in the imaging apparatus. In this case, in the apparatus body of the imaging apparatus, a mount 4 is disposed for mounting the lens unit at the front side of the apparatus body, and the front side of the mount 4 has a female screw 41. The back focus adjusting mechanism includes: a second screw 42 formed at the rear side of the mount 4 and continuous with the female screw 41; a ring member 5 disposed at the rear side of the mount 4 and rotatable around the optical axis 91 of the lens; and a holding mechanism 6 holding the CMOS image sensor 3 in a place in which the CMOS image sensor is receded by a certain distance toward the rear side from the ring member 5. The ring member 5 has a second male screw 51 that is screwed in the second female screw 42. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a back focus adjustment mechanism for adjusting a distance between a lens constituting a lens unit and an imaging element in an imaging apparatus such as a CCTV (Closed-circuit Television) camera.

  An imaging apparatus such as a CCTV camera includes a device body in which an imaging element such as a CMOS (Complementary Metal Oxide Semiconductor) image sensor is incorporated, and a lens unit. The device body is provided with a lens unit attached to the front side thereof. A mount portion is provided, and a female screw portion is formed on the front side of the mount portion. On the other hand, the lens unit is formed with a male screw portion that engages with the female screw portion of the mount portion.

  In this type of imaging device, conventionally, a ring member is provided on the outer peripheral surface side of the mount portion, and an internal thread portion is formed on the inner peripheral surface of the ring member. The external thread part screwed together with the internal thread part was formed (refer patent document 1). Further, a holding mechanism that holds the image sensor at a position retracted to the back side by a certain distance from the ring member is provided on the back side of the ring member.

  And the back focus adjustment mechanism of the imaging device was comprised by the external thread part of the said mount part, the ring member, and the holding mechanism. That is, by rotating the ring member, the ring member moves forward or backward, thereby adjusting the distance between the lens constituting the lens unit and the image sensor.

JP 2000-184262 A

  However, in the conventional back focus adjustment mechanism, it is necessary to form the male screw part for back focus adjustment separately from the female screw part for attaching the lens unit on the mount part as described above. Manufacturing was complicated.

  Accordingly, an object of the present invention is to provide a back focus adjustment mechanism that can be easily formed in an imaging apparatus.

The back focus adjustment mechanism of the image pickup apparatus according to the present invention includes a back focus that adjusts a distance between a lens constituting the lens unit and the image pickup element in an image pickup apparatus including an apparatus main body including the image pickup element and a lens unit. It is an adjustment mechanism.
Here, the device main body is provided with a mount portion for mounting the lens unit on the front side thereof, and a female screw portion is formed on the front side of the mount portion, while the female screw is provided on the lens unit. A male screw portion that is screwed into the portion is formed. The back focus adjustment mechanism is formed on the back side of the mount part and is provided on the back side of the mount part, and is rotatable around the optical axis of the lens. And a holding mechanism for holding the imaging device at a position retracted to the back side by a certain distance from the ring member. The ring member is screwed into the second female screw portion. Two male screw portions are formed.

In the back focus adjustment mechanism, the ring member moves forward by rotating the ring member in the rotation direction in which the second male screw portion is screwed into the second female screw portion, and the rotation direction is opposite to the rotation direction. When the ring member is rotated, the ring member moves backward. On the other hand, since the image sensor is held at a position retracted from the ring member by a certain distance to the back side by the holding mechanism, the image sensor moves forward or backward following the forward or backward movement of the ring member.
Therefore, by rotating the ring member, the distance between the lens constituting the lens unit and the image sensor, that is, the back focus is adjusted.

According to the back focus adjustment mechanism, it is possible to form the female screw portion and the second female screw portion only by forming one female screw through the mount portion. Therefore, the back focus adjustment mechanism according to the present invention is easily formed in the imaging apparatus as compared with the configuration in which the male screw part is formed separately from the female screw part on the mount part as in the conventional back focus adjustment mechanism. I can do it.
Further, as described above, by forming one female screw through the mount portion to form the female screw portion and the second female screw portion, the second female screw portion for adjusting the back focus can be used for the lens unit. The male screw portion has the same accuracy as the female screw portion into which the male screw portion is screwed.

In the specific configuration of the back focus adjustment mechanism, the holding mechanism includes a chassis that is arranged on the back side of the ring member and is movable along the optical axis, and a spring that biases the chassis toward the ring member. The imaging device is mounted on a chassis.
According to this specific configuration, since the chassis is pressed against the ring member by the biasing force of the spring member, the relative position of the chassis with respect to the ring member may change regardless of whether the ring member moves forward or backward. Absent. Therefore, the image sensor is held at a position retracted to the back side by a certain distance from the ring member.

  In another specific configuration of the back focus adjustment mechanism, an engagement portion and an engagement receiving portion that are engaged with each other are formed on the ring member and the chassis, and the engagement portion and the engagement receiving portion are These have a shape capable of relative rotation around the optical axis.

In still another specific configuration of the back focus adjustment mechanism, the ring member is configured by a gear rotating around the optical axis, and the second male screw portion is formed on the front side of the gear, The rotational force of the motor is transmitted to the gears constituting the ring member.
According to this specific configuration, the position along the optical axis of the ring member changes according to the rotation angle of the motor, and as a result, the position along the optical axis of the imaging element also changes. That is, the position along the optical axis of the image sensor changes according to the rotation angle of the motor. Therefore, the back focus can be adjusted by adjusting the rotation angle of the motor.

In a more specific configuration, the back focus adjustment mechanism includes a measuring unit that measures a component amount of a high-frequency component of an image signal output from the image sensor, and the component amount measured by the measuring unit is maximized. In addition, an autofocus means for controlling the rotation angle of the motor is further provided.
According to the specific configuration, the back focus is automatically adjusted by controlling the rotation angle of the motor as described above.

  The back focus adjustment mechanism of the imaging apparatus according to the present invention can be easily formed in the imaging apparatus.

It is a perspective view which shows the state which has removed the lens unit from the mount part about the imaging device incorporating the back focus adjustment mechanism which concerns on this invention. It is the top view which looked at the back focus adjustment mechanism from the front side. It is sectional drawing which follows the AA line shown by FIG. It is the disassembled perspective view which looked at the back focus adjustment mechanism from the front side. It is the disassembled perspective view which looked at the back focus adjustment mechanism from the back side. It is the perspective view which fractured | ruptured and showed the said back focus adjustment mechanism. It is sectional drawing for demonstrating the state which the ring member of the said back focus adjustment mechanism advanced. It is sectional drawing for demonstrating the state which the ring member of the said back focus adjustment mechanism retracted. It is a flowchart which shows the control procedure of the said back focus adjustment mechanism.

Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.
As shown in FIG. 1, the back focus adjustment mechanism according to the embodiment of the present invention is an image pickup apparatus (10) including a device main body (1) incorporating a CMOS image sensor (3) and a lens unit (2). This is a mechanism for adjusting the distance between a lens (not shown) constituting the lens unit (2) and the CMOS image sensor (3), and its appearance is shown in FIG.

  The device body (1) is provided with a mount portion (4) for mounting the lens unit (2) on the front side thereof, and the mount portion (4) is provided with a front surface (4a) as shown in FIG. ) Through the back surface (4b) is opened, and the inner wall of the through hole (43) has one continuous female screw (44) in at least a part of the region. Is formed.

  On the other hand, as shown in FIG. 1, the lens unit (2) has a male screw portion (21) that is screwed into the female screw (44) from the front surface (4a) side of the mount portion (4). The male screw portion (21) has a height dimension that only engages with a partial region of the female screw (44). The female screw (44) includes a lens unit to the mount portion (4). There is a region where the male screw portion (21) of the lens unit (2) is not screwed when the (2) is mounted.

  Thus, the female screw (44) of the mount part (4) includes a female screw part (41) that forms a region in which the male screw part (21) of the lens unit (2) is screwed, and the lens unit (2). The male screw portion (21) is formed of a second female screw portion (42) that forms a region where the male screw portion (21) is not screwed and is continuous with the female screw portion (41).

  As shown in FIGS. 3 to 5, a ring member (5) that can rotate around the optical axis (91) of the lens (see FIG. 1) is disposed on the back side of the mount portion (4). The ring member (5) is constituted by a spur gear that rotates around the optical axis (91), and a second gear screw (42) is screwed onto the front side of the spur gear. A male screw part (51) is formed.

  Accordingly, by rotating the ring member (5) in the rotational direction in which the second male screw portion (51) is screwed into the second female screw portion (42), the ring member (5) is as shown in FIG. Will move forward. On the other hand, by rotating the ring member (5) in the direction opposite to the rotation direction, the ring member (5) moves backward as shown in FIG.

  As shown in FIGS. 3 to 5, a chassis (61) that can move along the optical axis (91) is disposed on the back surface side of the ring member (5). ) Is urged toward the ring member (5) by a plurality of compression springs (62) supported by a plate (63) to be fixed to the plate. The CMOS image sensor (3) is mounted on the chassis (61) at a position on the optical axis (91).

Here, on the back surface of the ring member (5), as shown in FIGS. 3 and 5, a cylindrical engaging portion (52) centering on the optical axis (91) is projected, while the chassis (61) As shown in FIG. 3 and FIG. 4, an engagement receiving portion (64) engaged with the engagement portion (52) of the ring member (5) is recessed in the front surface of the ring member, as shown in FIG. The inner peripheral surface of the engagement receiving portion (64) is in sliding contact with the outer peripheral surface of the engagement portion (52).
Therefore, the engagement portion (52) of the ring member (5) and the engagement receiving portion (64) of the chassis (61) can be relatively rotated around the optical axis (91) while being engaged with each other. is there.

  As described above, since the chassis (61) is urged toward the ring member (5) by the compression spring (62), the ring member (5) is either advanced or retracted by the rotation of the ring member (5). Even in this case, the engagement between the engagement portion (52) of the ring member (5) and the engagement receiving portion (64) of the chassis (61) is maintained by the biasing force of the compression spring (62). It will be. Accordingly, the relative position of the chassis (61) with respect to the ring member (5) does not change, and as a result, the CMOS image sensor (3) mounted on the chassis (61) has a certain distance from the ring member (5). It will be held at a position retracted only to the back side.

Thus, the above-described chassis (61) and the plurality of compression springs (62) hold the CMOS image sensor (3) in a position retracted from the ring member (5) to the back side by a certain distance. 6) is configured.
As shown in FIGS. 3 and 6, the second female screw portion (42) formed on the back side of the mount portion (4), the ring member (5), and the holding mechanism (6) The back focus adjustment mechanism according to the present embodiment is configured.

In the back focus adjustment mechanism, as described above, by rotating the ring member (5), the ring member (5) moves forward as shown in FIG. 7 or retracts as shown in FIG. On the other hand, since the CMOS image sensor (3) is held at a position retracted from the ring member (5) by a certain distance to the back side by the holding mechanism (6), it follows the forward or backward movement of the ring member (5). Thus, the CMOS image sensor (3) moves forward or backward.
Therefore, by rotating the ring member (5), the distance between the lens constituting the lens unit (2) and the CMOS image sensor (3), that is, the back focus is adjusted.

  As shown in FIG. 6, the chassis (61) on which the CMOS image sensor (3) is mounted further rotates the motor (7) to the motor (7) and the spur gear constituting the ring member (5). A gear mechanism (71) for transmitting force is mounted.

  Thus, in the configuration in which the ring member (5) is driven by the motor (7), the position along the optical axis (91) of the ring member (5) changes according to the rotation angle of the motor (7), and as a result. The position along the optical axis (91) of the CMOS image sensor (3) also changes. That is, the position along the optical axis (91) of the CMOS image sensor (3) changes according to the rotation angle of the motor (7). Therefore, the back focus can be adjusted by adjusting the rotation angle of the motor (7).

  Further, as shown in FIG. 4, a guide groove (65) is formed on the front surface of the chassis (61) so as to overlap with the engagement receiving portion (64). When the engagement portion (52) of the ring member (5) is engaged with the portion (64), a depth is formed such that a gap is formed between the engagement portion (52) and the bottom surface of the guide groove (65). It has a size.

  As shown in FIG. 3, the guide groove (65) is provided with a slide member (66) in the gap formed between the bottom surface and the engaging portion (52). The member (66) can slide in a direction perpendicular to the optical axis (91) along the guide groove (65).

As shown in FIG. 4, the slide member (66) is provided with an infrared cut filter (671) and a glass plate (672) having the same thickness as the infrared cut filter (671). The filter (671) and the glass plate (672) are arranged side by side in the slide direction of the slide member (66). Therefore, by sliding the slide member (66), the infrared cut filter (671) and the glass plate (672) can be selectively disposed at a position on the optical axis (91).
Note that the imaging apparatus (10) according to the present embodiment has a configuration in which the slide member (66) slides by the driving force of the motor (72).

  When an image is acquired by the imaging device (10) in the daytime, since the light taken in from the lens unit (2) includes visible light and infrared light, if the light is given to the CMOS image sensor (3) as it is, Infrared appears as noise in the image. Therefore, in the daytime, the infrared cut filter (671) is disposed on the optical axis (91). Thus, the light taken in from the lens unit (2) is given to the CMOS image sensor (3) after the infrared rays are removed by the infrared cut filter (671). As a result, an image with less noise can be acquired.

  On the other hand, when an image is acquired by the imaging device (10) at night, the light taken from the lens unit (2) hardly contains visible light, so it is necessary to generate an image using infrared rays. Therefore, at night, the glass plate (672) is arranged on the optical axis (91), and the light taken from the lens unit (2) is given to the CMOS image sensor (3) as it is. . As a result, an image can be generated from infrared rays.

However, when the infrared cut filter (671) is changed to the glass plate (672) or the glass plate (672) is changed to the infrared cut filter (671), the back focus is shifted. Even in such a case, the back focus adjustment mechanism can adjust the back focus.
In addition, the back focus adjustment mechanism can adjust the back focus when the image pickup apparatus is shipped from the factory, when the image pickup apparatus is installed, when the lens unit is changed, or when the subject is changed.

According to the back focus adjustment mechanism, the female screw portion (41) and the second female screw portion (42) are formed only by forming one female screw (44) through the mount portion (4). Will be. Therefore, the back focus adjustment mechanism according to this embodiment is compared with a configuration in which a male screw part is formed on the mount part separately from the female screw part as in the conventional back focus adjustment mechanism (see Patent Document 1), It can be easily formed in the imaging device (10).
Further, as described above, one female screw (44) is passed through the mount portion (4) to form the female screw portion (41) and the second female screw portion (42), thereby adjusting the back focus. The second female screw portion (42) has the same accuracy as the female screw portion (41) into which the male screw portion (21) of the lens unit (2) is screwed.

  Next, the control procedure of the back focus adjustment mechanism will be described with reference to the flowchart shown in FIG. The control procedure of the back focus adjustment mechanism is executed by a CPU (Central Processing Unit) (not shown) built in the imaging device (10).

  When the control procedure of the back focus adjustment mechanism is started, first, in step S1, the motor (7) is rotated to reciprocate the CMOS image sensor (3) in a movable range along the optical axis (91). At this time, the amount of the high frequency component of the image signal output from the CMOS image sensor (3) (hereinafter referred to as “AF evaluation value”) is measured in association with the rotation angle of the motor (7). That is, the CPU functions as a measurement unit that measures the AF evaluation value output from the CMOS image sensor (3).

  Next, in step S2, the rotation angle θ1 of the motor (7) that maximizes the AF evaluation value is calculated from the AF evaluation value measured in step S1, and the motor (7) is rotated to the rotation angle θ1. That is, the CPU functions as an autofocus unit that controls the rotation angle of the motor (7) so that the AF evaluation value is maximized.

  Finally, in step S3, the rotation angle θ1 of the motor (7) calculated in step S2 is recorded in a memory (not shown) built in the imaging device (10), thereby controlling the back focus adjustment mechanism. The procedure is complete.

  According to the control procedure of the back focus adjustment mechanism described above, the back focus is automatically adjusted. By enabling automatic adjustment of the back focus in this way, it is possible to accurately adjust the back focus without bothering the operator.

  In addition, each part structure of this invention is not restricted to the said embodiment, A various deformation | transformation is possible within the technical scope as described in a claim. For example, the control procedure of the back focus adjustment mechanism described in the above embodiment is an example, and the present invention is not limited to this. In the back focus adjustment mechanism according to the above embodiment, the back focus adjustment can be automatically executed. Of course, the back focus adjustment mechanism is used to manually adjust the back focus. Also good.

  In addition, the back focus adjustment mechanism according to the above embodiment can be applied to various imaging devices such as a CCTV camera. In the above embodiment, the CMOS image sensor (3) is employed as the image sensor. However, the present invention is not limited to this, and various image sensors such as a CCD (Charge Coupled Device) image sensor are employed. I can do it.

(10) Imaging device
(1) Device body
(2) Lens unit
(21) Male thread
(3) CMOS image sensor (imaging device)
(4) Mount part
(41) Female thread
(42) Second female thread
(5) Ring member
(51) Second male thread
(52) Engagement part
(6) Holding mechanism
(61) Chassis
(62) Compression spring (spring member)
(64) Engagement receiver
(7) Motor
(71) Gear mechanism
(91) Optical axis

Claims (5)

A device body having a built-in image sensor and a lens unit are provided. The device body is provided with a mount portion for mounting the lens unit on the front surface side, and a female screw portion is formed on the front surface side of the mount portion. On the other hand, in the imaging device in which the lens unit is formed with a male screw portion that is screwed into the female screw portion, a back focus adjustment mechanism that adjusts the distance between the lens constituting the lens unit and the imaging element. There,
A second female screw portion formed on the back side of the mount portion and continuing to the female screw portion; a ring member disposed on the back side of the mount portion and rotatable about the optical axis of the lens; A holding mechanism that holds the imaging element at a position retracted to the back side by a certain distance from the ring member, and the ring member has a second male screw portion that is screwed into the second female screw portion. A back focus adjustment mechanism of an imaging apparatus, wherein   The holding mechanism includes a chassis that is disposed on the back side of the ring member and is movable along the optical axis, and a spring member that urges the chassis toward the ring member. The back focus adjustment mechanism of the imaging apparatus according to claim 1, wherein the back focus adjustment mechanism is mounted on the chassis.   The ring member and the chassis are formed with an engaging portion and an engaging receiving portion that are engaged with each other, and the engaging portion and the engaging receiving portion can be relatively rotated around the optical axis. The back focus adjustment mechanism of the imaging apparatus according to claim 1, wherein the back focus adjustment mechanism has an arbitrary shape.   The ring member is constituted by a gear that rotates around the optical axis, and the second male screw portion is formed on the front surface side of the gear, and a rotational force of a motor is applied to the gear constituting the ring member. The back focus adjustment mechanism of the imaging apparatus according to claim 1, wherein the back focus adjustment mechanism is transmitted.   Measuring means for measuring the amount of a high-frequency component of an image signal output from the image sensor; and autofocus means for controlling a rotation angle of a motor so that the component amount measured by the measuring means is maximized. The back focus adjustment mechanism of the imaging apparatus according to claim 4, further comprising:

Images