JPH08114736A - Fixed focus camera - Google Patents

Abstract

PURPOSE: To provide a fixed focus camera constituted so that out-of-focus caused by the thermal expansion and the thermal contraction of a camera main body or a lens barrel can be corrected. CONSTITUTION: A guide hole 22 is projectingly provided at the upper part of a plate 20 to which a CCD 16 is fitted and a guide hole 24 is projectingly provided at the lower part thereof. An upper guide bar 26 is inserted in the hole 22 and a lower guide bar 28 is inserted in the hole 24 so that the CCD 16 can be moved forward and backward in an optical axis 18 direction. By inserting the tip part of a piezoelectric element 32 in a groove 30 formed on the upper end 20A of the plate 20 and stress-deforming the element 32, the CCD 16 is moved forward and backward along the optical axis 18. A temperature sensor 40 is fitted to the outside circumferential surface of the lens barrel 14 and information showing the temperature of the lens barrel 14 is outputted to a CPU 38. Based on the temperature information, a piezoelectric element driving circuit 36 is controlled by the CPU 38 so that the CCD 16 is moved forward and backward by a quantity required for correcting the out-of-focus caused by the thermal expansion and the thermal contraction of the lens barrel 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixed focus camera,
In particular, the present invention relates to a fixed focus camera applied to a video camera, an electronic still camera or the like using a solid-state image sensor.

[0002]

2. Description of the Related Art A pan-focus type fixed-focus camera using a taking lens with a deep depth of field has a camera body to which a solid-state image sensor (CCD) is attached, and a lens barrel holding the taking lens. It is assembled by fixing. Further, Japanese Laid-Open Patent Publication No. 1-175372 discloses a fixed focus camera which is downsized.

[0003]

However, in the conventional fixed-focus camera, when the camera body and the lens barrel undergo thermal expansion and contraction due to temperature changes, the relative positions of the CCD and the taking lens change. When the expansion amount and the contraction amount are large, there is a drawback that the focus is out of focus and the distant view or the near view is blurred.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a fixed focus camera capable of correcting a focus shift due to thermal expansion and thermal contraction of a camera body and a lens barrel. To do.

[0005]

In order to achieve the above-mentioned object, the present invention fixes a lens barrel holding a photographing lens to a camera body to which an image pickup device is attached, and allows a subject to pass through the photographing lens. In a fixed-focus camera that captures an image with the image sensor, a drive for supporting the image sensor with respect to the camera body so as to be movable back and forth in the direction of the shooting optical axis and moving the image sensor in the direction of the shooting optical axis. It is characterized by the provision of means.

Further, in order to achieve the above object, the present invention fixes a lens barrel holding a photographing lens to a camera body to which an image pickup device is attached, and subjects a subject through the photographing lens to the image pickup device. In the fixed-focus camera that captures images with the above-mentioned, the photographing lens is supported so as to be movable back and forth in the photographing optical axis direction with respect to the lens barrel, and a driving means for moving the photographing lens in the photographing optical axis direction is provided. It is characterized by that.

[0007]

According to the first aspect of the present invention, in the fixed focus camera, when the camera body or the lens barrel is out of focus due to thermal expansion or thermal contraction, the image pickup device is driven by the driving means in the optical axis direction with respect to the camera body. I moved it back and forth to correct the focus shift. The fixed focus camera according to claim 2,
Based on the temperature information from the temperature sensor attached to the camera body and / or the lens barrel, the amount of out-of-focus due to the thermal expansion and contraction of the camera body and / or the lens barrel is calculated, and the imaging is performed by an amount that corrects the amount of deviation. The driving means is controlled so as to move the element. As a result, in the present invention, the focus shift can be automatically corrected.

According to the third aspect of the present invention, in the fixed focus camera, when the camera body or the lens barrel is out of focus due to thermal expansion or thermal contraction, the photographing lens is driven by the driving means with respect to the lens barrel. It was moved back and forth in the direction to correct the focus shift. The fixed focus camera according to claim 4 is based on temperature information from a temperature sensor attached to the camera body and / or the lens barrel.
Or calculate the amount of focus shift due to thermal expansion and contraction of the lens barrel,
The drive means is controlled so that the photographing lens is moved by an amount that corrects the deviation amount. This allows
In the present invention, the focus shift can be automatically corrected.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a fixed focus camera according to the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a sectional view of a main part of a fixed focus camera according to the first embodiment of the present invention. As shown in the figure, a lens barrel 14 holding a taking lens 12 is screwed and fixed to the front surface of the camera body 10. In addition, in the camera body 10, CC
D16 is provided. The CCD 16 is arranged on the optical axis 18 of the taking lens 12 so that a subject image is formed on the light receiving surface 16A of the taking lens 12 through the taking lens 12.

The CCD 16 is fixed to a mounting plate 20, which is arranged in a direction orthogonal to the optical axis 18. A guide hole 22 is formed in the upper portion of the plate 20 and a guide hole 24 is formed in the lower portion thereof. An upper guide rod 26 is inserted into the guide hole 22 and a lower guide rod 28 is inserted into the guide hole 24. Both ends of the upper guide rod 26 and the lower guide rod 28 are supported by the camera body 10 so as to be parallel to the optical axis 18.
Therefore, the CCD 18 is guided by the upper guide rod 26 and the lower guide rod 28 to be movable back and forth in the optical axis 18 direction.

A concave groove 30 is formed on the upper end 20A of the plate 20. The tip of a long piezoelectric element 32 is inserted into the groove 30 through a slit 11 formed in the camera body 10. The piezoelectric element 3
2 is connected to a piezoelectric element drive circuit 36 via a connector 34, and can be stress-deformed in the directions of arrows A and B in the figure by a voltage applied from the piezoelectric element drive circuit 36. Therefore, when the piezoelectric element 32 is stress-deformed in the direction of arrow A in the figure, the tip of the piezoelectric element 32 is moved to the plate 20.
By pressing the left end surface of the groove 30 of the above, the CCD 16 can be extended to the front side of the optical axis 18 via the plate 20. When the piezoelectric element 32 is stress-deformed in the direction of arrow B in the drawing, the tip of the piezoelectric element 32 presses the right end surface of the groove 30 of the plate 20 so that the CCD 16 is retracted to the rear side of the optical axis 18. You can

The piezoelectric element drive circuit 36 is a CPU of the camera.
The voltage value applied to the piezoelectric element 32 is controlled by 38. On the other hand, a temperature sensor 40 is attached to the outer peripheral surface of the lens barrel 14. This temperature sensor 40 is
Information indicating the temperature of the lens barrel 14 is output to the CPU 38, and the CPU 38, based on the temperature information, outputs the CCD.
The piezoelectric element drive circuit 36 is controlled so that 16 is moved back and forth by an amount that corrects the focus shift due to thermal expansion and thermal contraction of the lens barrel 14.

Therefore, according to the fixed-focus camera thus constructed, the CPU 38 controls the piezoelectric element drive circuit 36 based on the temperature information of the lens barrel 14 output from the temperature sensor 40. As a result, the piezoelectric element 32 is driven, and the CCD 16 moves back and forth along the optical axis 18 by an amount that corrects the focus shift due to the thermal expansion and thermal contraction of the lens barrel 14.

As a result, in the fixed focus camera of this embodiment, it is possible to correct the focus shift due to the thermal expansion and thermal contraction of the lens barrel 14. FIG. 2 is a sectional view of a main part of a fixed focus camera according to a second embodiment of the present invention. Regarding the same or similar members as those of the first embodiment shown in FIG.
The same reference numerals are given and the description thereof is omitted.

The fixed focus camera shown in FIG.
The stepping motor 42 is used as the driving means of the. The stepping motor 42 is used for the camera body 10
It is attached to the side surface of the housing 46 which is fixed by screws 44. Further, the screw 48 that is rotated by the driving force of the stepping motor 42 is attached to the housing 4
6 is arranged in parallel with the optical axis 18 and is located at the left end 4 in FIG.
8A is pivotally supported on the housing 46. A screw hole 50 formed in the plate 20 of the CCD 16 is screwed into the screw 48. Therefore, when the stepping motor 42 is driven, the CCD 16 can be moved back and forth in the optical axis 18 direction via the plate 20 by the action of the screw 48 and the screw hole 50.

On the other hand, the stepping motor 42 is connected to a motor driver 52, and the amount of rotation is controlled based on the pulse train voltage signal output from the motor driver 52. The motor driver 52 controls the voltage signal output to the stepping motor 42 by the CPU 38 of the camera. A temperature sensor 40 is attached to the lens barrel 14, and the temperature sensor 40 outputs information indicating the temperature of the lens barrel 14 to the CPU 38, and C
The PU 38 controls the motor driver 52 based on the temperature information so as to move the CCD 16 back and forth by an amount that corrects the focus shift due to the thermal expansion and thermal contraction of the lens barrel 14.

Therefore, according to the fixed-focus camera thus constructed, the CPU 38 controls the motor driver 52 based on the temperature information of the lens barrel 14 output from the temperature sensor 40. As a result, the stepping motor 42 is driven, and the CCD 16 corrects the optical axis 18 by an amount that corrects the focus shift due to the thermal expansion and thermal contraction of the lens barrel 14.
Move back and forth along.

As a result, even in the fixed focus camera of the second embodiment, it is possible to correct the focus shift due to the thermal expansion and thermal contraction of the lens barrel 14. FIG. 3 is a cross-sectional view of a main part of a fixed focus camera according to a third embodiment of the present invention. The same or similar members as those in the first embodiment shown in FIG. The description is omitted.

The fixed-focus camera shown in the figure has a taking lens 12 provided so as to be movable back and forth along an optical axis 18, and the taking lens 12 is moved to correct a focus shift. The lens frame 54 holding the taking lens 12 is provided with a guide hole 56 in its upper part and a guide hole 58 in its lower part. An upper guide bar 60 is provided in the guide hole 56 and a lower guide bar 62 is provided in the guide hole 58. Each is inserted. The upper guide rod 60 and the lower guide rod 62 are supported by the lens barrel 14 at the left end in the drawing and by the camera body 10 at the right end in the drawing so as to be parallel to the optical axis 18. As a result, the photographing lens 12 moves to the upper guide bar 6
It can be moved back and forth in the optical axis 18 direction by being guided by the 0 and lower guide rods 62. A concave groove 64 is formed on the upper end 54A of the lens frame 54, and the piezoelectric element 3 is formed in the groove 64.
The tip of 2 is inserted.

Therefore, even in the fixed-focus camera constructed as described above, the taking lens 12 is caused by thermal expansion and contraction of the lens barrel 14 based on the temperature information of the lens barrel 14 output from the temperature sensor 40. Since it is possible to move back and forth along the optical axis 18 by an amount for correcting the focus shift, it is possible to correct the focus shift due to the thermal expansion and thermal contraction of the lens barrel 14.

FIG. 4 is a sectional view of a main part of a fixed focus camera according to the fourth embodiment of the present invention. The same or similar members as those in the second embodiment shown in FIG. 2 are designated by the same reference numerals. The description thereof will be omitted. The fixed focus camera shown in the figure has a stepping motor 4 as driving means for the CCD 16.
2 is used, and the taking lens 12 is moved back and forth along the optical axis 18 by the driving force of the stepping motor 42. That is, the screw 48 of the stepping motor 42 is screwed into the screw hole 66 formed in the lens frame 54, and the action of the screw 48 and the screw hole 66 allows the taking lens 12 to move.

Therefore, also in the fixed focus camera having such a structure, the focus shift due to the thermal expansion and the thermal contraction of the lens barrel 14 can be corrected similarly to the first to third embodiments. In this embodiment, the taking lens 12 and the CCD 16 are moved back and forth based on the temperature change of the lens barrel 14, but the invention is not limited to this. For example, the temperature sensor 40 may be attached to the camera body 10 side, or it may be attached to both the camera body 10 and the lens barrel 14 to correct focus shift due to thermal expansion and thermal contraction based on respective temperature changes. Shooting lens 1
2 and / or the CCD 16 may be moved.

[0023]

As described above, according to the fixed focus camera of the present invention, the thermal expansion of the camera body and the lens barrel,
When a focus shift occurs due to thermal contraction, the image pickup device or the photographing lens is moved by the driving unit in the photographing optical axis direction, so that the focus shift can be corrected.

Further, according to the present invention, the image pickup element or the photographing lens is moved by the amount for correcting the focus shift amount based on the temperature information from the temperature sensor. Therefore, the focus shift is automatically corrected. You can

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of a fixed focus camera according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a main part of a fixed focus camera according to a second embodiment of the present invention.

FIG. 3 is a sectional view of a main part of a fixed focus camera according to a third embodiment of the present invention.

FIG. 4 is a sectional view of a main part of a fixed-focus camera according to a fourth embodiment of the present invention.

[Explanation of symbols]

 10 ... Camera body 12 ... Photographing lens 14 ... Lens barrel 16 ... CCD 18 ... Optical axis 32 ... Piezoelectric element 36 ... Piezoelectric element drive circuit 38 ... CPU 40 ... Temperature sensor 42 ... Stepping motor 52 ... Motor driver

Claims (4)

[Claims] 1. A fixed focus camera in which a lens barrel holding a photographing lens is fixed to a camera body to which an image pickup device is attached, and a subject is picked up by the image pickup device via the photographing lens. A fixed-focus camera, characterized in that the element is supported so as to be movable back and forth in the shooting optical axis direction with respect to the camera body, and drive means is provided for moving the imaging element in the shooting optical axis direction. 2. A temperature sensor for detecting the temperature of the camera body and / or the lens barrel is attached to the camera body and / or the lens barrel, and the driving means is provided with temperature information from the temperature sensor. Camera body based on
Alternatively, the fixed focus camera according to claim 1, wherein the fixed focus camera is controlled so as to move the image pickup device by an amount that corrects a focus shift due to thermal expansion and contraction of the lens barrel. 3. A fixed focus camera in which a lens barrel holding a photographing lens is fixed to a camera body to which an image pickup device is attached, and a subject is imaged by the image pickup device via the photographing lens. A fixed focus camera, characterized in that a lens is supported so as to be movable back and forth with respect to the lens barrel in the photographing optical axis direction, and a driving means for moving the photographing lens in the photographing optical axis direction is provided. 4. A temperature sensor for detecting the temperature of the camera body and / or the lens barrel is attached to the camera body and / or the lens barrel, and the driving means is provided with temperature information from the temperature sensor. Camera body based on
4. The fixed focus camera according to claim 3, wherein the fixed focus camera is controlled so that the photographing lens is moved by an amount that corrects a focus shift due to thermal expansion and contraction of the lens barrel.