JPH0943503A - Image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image pickup device compensating the variation of a flange back due to attachment/detachment of an extender to the optical path by utilizing a wobbling lens. SOLUTION: In an image pickup device forming the image of an object on an image pickup surface by means of a zoom lens comprising a focusing lens group 1 and an extender 6 attachably/detachably mounted in an optical path, this device is provided with a focus detecting means performing focusing operation by moving the focusing lens group 1 by using a signal obtained in an image pickup means 9 at the time of moving a wobbling lens 4 composing the zoom lens, an extender detecting means 15 for detecting whether or not the extender exists in the optical path and a recording part 17 for recording the shifting amount of the origin of the wobbling lens 4 for compensating the change of the shifting amount of a flange back at the time of attaching/ detaching the extender to the optical path; and the position of the origin of the wobbling lens is adjusted based on the shifting amount in the recording part 17 recorded based on a signal from the extender detecting means 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup apparatus, and more particularly, to a focal length of an entire system by inserting / removing a variable power optical system (extender) into / from a part of a relay optical system of a zoom lens having an automatic focus detecting means. It is suitable for a television camera, a video camera, or the like, in which adjustment of the flange back at the time of changing the range of magnification change is favorably performed.

[0002]

2. Description of the Related Art FIGS. 5 and 6 are block diagrams of a main part of a conventional image pickup apparatus in which a variable power optical system (extender) 6 is built in a part of a lens barrel so as to be detachably mounted in an optical path. is there. Of these, FIG. 5 shows a state in which the extender 6 is retracted from the optical path, and FIG. 6 shows a case in which the extender 6 is inserted in the optical path and the focal length range of the entire system is changed.

In the figure, reference numeral 1 is a focusing lens group, and 2 is a variable power lens group, which is a lens group which moves along the optical axis to perform variable power and a lens for correcting an image plane which varies with variable power. Have a group. Reference numeral 3 is a diaphragm device, 4 is a lens group (wobbling lens) that is finely driven in the optical axis direction, 5 is a relay lens, and 6 is a variable power optical system (extender) that is removably arranged on the optical path. The focal length range of is shifted to the longer side. 7 is a movable lens group,
It constitutes a part of the extender 6 and adjusts the back focus of the entire system when the extender 6 is arranged in the optical path. Reference numeral 8 is a relay lens. In the same figure, a zoom lens is constituted by the above-mentioned respective elements 1 to 8.

Reference numeral 9 is an image pickup device, and 10 is a video signal processing circuit, which obtains a video signal based on a signal from the image pickup device 9. Reference numeral 11 denotes a focus lens group drive unit for driving the focus lens group 1, 12 a drive unit for driving the variable power lens group 2, 13 a drive unit for driving the diaphragm 3.
14 is a drive unit for driving the wobbling lens 4, 15 is a detection device for detecting the insertion / removal state of the extender 6,
Reference numeral 16 is an arithmetic unit, and 22 is a recording unit.

Conventionally, when an image pickup apparatus having a zoom lens of this kind is provided with a removable extender, a flange back when the extender is not inserted (FIG. 5) and a flange back when the extender is inserted (FIG. 6) A flange back adjustment portion is provided in a part of the extender so as to match the above (for example, the structure is such that the interval L in FIG. 6 is changed), and the adjustment is performed precisely during assembly.

[0006]

In the zoom lens shown in FIGS. 5 and 6, the extender 6 is inserted in the optical path, and when the focal length range of the entire system is changed, the lens group 7 constituting the extender 6 is moved to the optical axis. It is moved in the direction to adjust the flange back. In general, since the optical sensitivity is high in this portion, it is necessary to sufficiently improve the precision and the adjustment precision of components such as components and lenses in the vicinity.

In general, when the autofocus operation is not performed in such an image pickup apparatus, an allowable amount of error within the depth of focus can be allowed. However, during autofocus, the deviation of the flange back allowed within a certain range is accurately detected by the wobbling lens 4 that slightly moves in the optical axis direction to detect the focus position direction, and the separately provided focusing lens group 1 is forced. It will move so that it will be in focus.

At this time, due to the difference in optical sensitivity of the focusing lens unit 1, when the focal length is long due to zooming, the movement for focusing is small and not so noticeable, but the zoom position is relatively wide angle side. Focusing lens group 1 with a slight flange back shift when the focal length is
Need to move a lot. For this reason, when the extender 6 is inserted, the focusing lens group 1 moves while the same subject is being photographed, which causes a strange movement.

As described above, there is a problem in that, even in the case of a focus shift which has been compromised to some extent in practical use, a conspicuous operation may be caused by the autofocus operation.

According to the present invention, in a zoom lens having a built-in extender, the shift amount (shift amount) of the origin position of the wobbling lens for correcting the shift of the back focus (flange back) when the extender is inserted into and removed from the optical path. ) Is obtained in advance and recorded, and the origin position of the wobbling lens is adjusted by using the shift amount recorded in the recording unit when the extender is inserted / removed to reduce the back focus fluctuation, thereby reducing the focus lens. An object of the present invention is to provide an imaging device that does not move a group.

[0011]

An image pickup apparatus according to the present invention comprises: (1) Imaging in which an object image is formed on a surface of an image pickup means by a zoom lens having a focus lens group and an extender detachably mounted in an optical path. In the apparatus, a focus detection means for moving the focusing lens group to perform a focusing operation by using a signal obtained by the imaging means when the wobbling lens forming the zoom lens is moved, and an optical path of the extender. An extender detecting means for detecting the presence / absence, and a recording unit for recording the shift amount of the origin position of the wobbling lens for correcting the change in the flange back shift amount when the extender is detached from the optical path are provided, The wobbling based on the shift amount recorded in the recording unit based on the signal from the extender detecting means. The feature is that the origin position of the lens is adjusted.

(2) The zoom lens is constructed in an image pickup apparatus for forming an object image on the surface of an image pickup means by a zoom lens having a focus lens group, a variable power lens group, and an extender detachably mounted in the optical path. A focus detection means for moving the focusing lens group to perform a focusing operation using a signal obtained by the imaging means when the wobbling lens is moved, and an extender detection means for detecting the presence or absence of the extender in the optical path. A zoom position detecting means for detecting a zoom position of the variable power lens group, and an origin position of the wobbling lens for correcting a change in a flange back shift amount at each zoom position when the extender is detached from the optical path. A recording unit for recording the shift amount of the zoom position detecting means and the extender. Based on signals from the detecting means it is characterized in that so as to adjust the origin position of the wobbling lens based on the shift amount recorded in the recording unit.

(3) In the image pickup apparatus for forming an object image on the surface of the image pickup means by a zoom lens having a focus lens group, a variable power lens group, an aperture stop, and an extender detachably mounted in the optical path. Using a signal obtained by the image pickup means when the wobbling lens forming the lens is moved, a focus detection means for moving the focusing lens group to perform a focusing operation, and a presence / absence in the optical path of the extender are detected. Extender detection means, zoom position detection means for detecting the zoom position of the variable power lens group, aperture value detection means for detecting the aperture value of the aperture stop, and aperture values when the extender is detached from the optical path and Shift of the origin position of the wobbling lens to correct the change in the flange back shift amount at each zoom position Is provided, and the wobbling lens of the wobbling lens based on the shift amount recorded in the recording unit based on the signals from the zoom position detecting unit, the aperture value detecting unit, and the extender detecting unit. The feature is that the origin position is adjusted.

(4) Wobbling forming a zoom lens in an image pickup apparatus for forming an object image on the surface of an image pickup means by a zoom lens having a focus lens group, an aperture stop, and an extender detachably mounted in the optical path. A focus detection unit that performs a focusing operation by moving the focusing lens group using a signal obtained by the image pickup unit when the lens is moved, an extender detection unit that detects the presence or absence of the extender in the optical path, Aperture value detection means for detecting the aperture value of the aperture diaphragm, and the shift amount of the origin position of the wobbling lens for correcting the change in the flange back shift amount at each aperture value when the extender is attached / detached from the optical path. A recording unit for recording is provided, and based on signals from the aperture value detecting unit and the extender detecting unit. There are is characterized in that so as to adjust the origin position of the wobbling lens based on the shift amount recorded in the recording unit.

[0015]

1 and 2 are schematic views of the essential portions of Embodiment 1 of the present invention. FIG. 1 shows a case where a variable power optical system (extender) 6 is inserted in a part of the optical path of the relay system to shift the focal length range of the entire system to the longer side, and FIG. 2 shows the extender in FIG. 6 shows the case where 6 is retracted from the optical path.

In the figure, 1 is a focusing lens group. The focusing lens group 1 includes a focusing lens driving unit 11 based on a focusing signal from the calculation unit 17.
Is driven on the optical axis by means of which the focusing operation is performed. Reference numeral 2 denotes a variable power lens group, which has a lens group 2a that moves on the optical axis to perform variable power, and a lens group 2b for correcting the image plane that changes with variable power. Reference numeral 3 is an aperture stop. Reference numeral 4 denotes a lens group (wobbling lens) that is minutely driven in the optical axis direction, and is moved in the optical axis direction by the drive unit 14.

In this embodiment, the arithmetic unit 16 obtains the moving direction of the focusing lens group 1 using the signal obtained by the image pickup means 9 when the wobbling lens 4 is moved in the optical axis direction, and inputs it to the drive unit 11. are doing. And drive unit 1
1, the focusing lens group 1 is moved to perform automatic focus detection.

Reference numeral 5 denotes a front lens group relay lens which is fixed during zooming. Reference numeral 6 denotes a variable power optical system (extender) which is removably arranged on the optical path and shifts the focal length range of the entire system to the longer side. A movable lens group 7 constitutes a part of the extender 6 and adjusts the back focus (flange back) of the entire system when the extender 6 is arranged in the optical path. 8 is a rear group relay lens.

In this embodiment, a zoom lens is constituted by the above-mentioned respective elements 1-8. Reference numeral 9 is an image sensor, and 10 is a video signal processing circuit, which obtains a video signal based on a signal from the image sensor 9. 11 is a drive unit for driving the focus lens group 1 in the optical axis direction, 12 is a drive unit for driving the variable power lens group 2, 13 is a drive unit for driving the diaphragm 3, and 14 is a wobbling lens. Drive unit for driving 4
Reference numeral 5 is an extender detecting means for detecting the insertion / removal state of the extender 6 from the optical path. Reference numeral 16 denotes a calculation unit, which performs calculation for controlling various types of drive of the entire zoom lens. A recording unit 17 records the shift amount of the origin position of the wobbling lens for correcting the change in the flange back shift amount when the extender is detached from the optical path.

In this embodiment, it is assumed that the extender 6 is inserted in the optical path from the state shown in FIG. 2 to the state shown in FIG.
At this time, a slight deviation of the flange back remains. Therefore, in the conventional autofocus operation, the focus lens group 1 is moved based on the movement from the calculation unit 16 so that the flange back is corrected in the image forming direction detected by the image pickup device 9 by the minute movement of the wobbling lens 4. I was moving. For this reason, the amount of movement of the focus lens group 1 may change depending on the zoom position and the object distance, which is not preferable for shooting.

On the other hand, in this embodiment, the remaining back focus shift (change in shift amount) due to the presence or absence of the extender 6 is recorded in the recording section 17 during assembly adjustment. Then, it is detected whether or not the extender 6 from the extender detecting means 15 is inserted in the optical path, and the arithmetic unit 1 is operated by a signal from the extender detecting means 15.
6 selects the shift amount recorded in the recording unit 17,
It is input to the drive unit 14. Then, the drive unit 14 moves the wobbling lens 4 on the optical axis based on the signal from the calculation unit 16 to adjust the origin position.

Thus, the change in the shift amount of the back focus due to the insertion / removal of the extender 6 is corrected. After that, the back focus is adjusted with high precision by finely adjusting the lens group 7.

As described above, in this embodiment, the calculating unit 16 is based on the signal from the extender detecting means 15 and the calculating unit 16 is based on the signal.
The amount of movement of the wobbling lens 4 corresponding to the amount of back focus shift is determined from the amount of back focus (flange back) shift recorded in step 1 and the amount of change in back focus (sensitivity) with respect to the amount of movement of the wobbling lens 4. A command is given to the drive unit 14.

Then, the wobbling lens 4 is moved by the drive unit 14 to shift the origin position of the minute movement so that the back focus of the entire optical system is corrected to the state before the extender 6 is inserted. This prevents or significantly reduces the movement of the focus lens group 1 in the optical axis direction when the extender 6 is attached or detached.

FIG. 3 is a schematic view of the essential portions of Embodiment 2 of the present invention. This embodiment is different from Embodiment 1 of FIGS. 1 and 2 in that (A1) zoom position detecting means 18 for detecting the zoom position of the variable power lens group 2 is added. (A2) The recording unit 19 records the shift amount of the origin position of the wobbling lens for correcting the change in the flange back shift amount at each zoom position when the extender is detached from the optical path. (A3) The calculating unit 16 outputs a signal for adjusting the origin position of the wobbling lens based on the shift amount recorded in the recording unit based on the signals from the zoom position detecting unit and the extender detecting unit. You have entered in 14. (A4) The drive unit 14 adjusts the origin position by moving the wobbling lens 4 on the optical axis based on the signal from the calculation unit 16. Are different, and other configurations are the same.

In the present embodiment, when the extender 6 is not used, the calculation unit 16 moves the focus (back focus) based on the zoom position information obtained by the zoom position detection means 18 and the information recorded in the recording unit 19. The amount of movement of the wobbling lens 4 for correcting is calculated, and a command is sent to the drive unit 14 of the wobbling lens 4. As a result, the origin position of the wobbling lens 4 is shifted each time depending on the zooming position.

It is well known that when the extender 6 is inserted, the zoom focus movement is enlarged in proportion to the square of the enlargement magnification. Here, the extender 6 is used.
When a signal indicating that the
Reference numeral 6 calculates a variation amount corresponding to the square of the enlargement magnification of the extender 6 with respect to the zoom focus movement amount recorded in the recording unit 19, and instructs the driving unit 14 of the wobbling lens 4 to move the variation amount. are doing. This makes it possible to correctly correct the focus movement due to zooming whether or not the extender 6 is used.

FIG. 4 is a schematic view of the essential portions of Embodiment 3 of the present invention. This embodiment is different from Embodiment 2 in FIG. 3 in that (B1) the aperture value detecting means 20 for detecting the aperture value of the aperture diaphragm 3 is provided. (B2) The recording unit 21 records the shift amount of the origin position of the wobbling lens for correcting the change of the flange back shift amount at each aperture value and each zoom position when the extender is detached from the optical path. That (B3) The calculation unit 16 determines the origin position of the wobbling lens based on the shift amount recorded in the recording unit based on the signals from the zoom position detection unit, the aperture value detection unit, and the extender detection unit. The signal for adjusting is input to the drive unit 14. (B4) The drive unit 14 adjusts the origin position by moving the wobbling lens 4 on the optical axis based on the signal from the calculation unit 16. Are different, and other configurations are the same.

In this embodiment, the recording unit 21 records the amount of focus shift (shift amount) corresponding to each aperture value for each focal length (zoom position) during assembly adjustment. Based on the zoom position and the diaphragm position during the shooting operation, the calculation unit 16 issues a command to correct the focus shift each time. When the extender 6 is inserted, unlike the case of moving the focus during zooming, there are cases where the extender 6 is enlarged depending on the cause of the focusing defocus, and cases where it is not. Therefore, it is not possible to simply multiply the data when the extender 6 is not used by a certain magnification to perform the correction.

Therefore, in this embodiment, at the time of assembly and adjustment, an appropriate amount of the focusing defocus in the state in which the extender 6 is inserted is also taken in as a data, and is similarly recorded in the recording unit 21 as a data table when the extender 6 is used. are doing. When the extender 6 is inserted in the optical path and a signal for detecting the use state is issued, the arithmetic unit 16 is set to switch the data table when the extender 6 is used to perform the arithmetic operation. Even when the extender 6 is used, the origin position of the wobbling lens 4 is similarly shifted, so that the focusing deviation is properly corrected.

In this embodiment, the zoom position detecting means 18 is not used, and the change in the flange back shift amount at each aperture value when the extender is attached to or detached from the recording unit 22 from the optical path is corrected. The shift amount of the origin position of the wobbling lens is recorded, and the calculation unit 16 calculates the shift amount recorded in the recording unit based on the signals from the aperture value detection unit and the extender detection unit. The origin position of the wobbling lens may be adjusted.

[0032]

As described above, according to the present invention, in a zoom lens having a built-in extender, a wobbling lens for correcting the shift of the back focus (flange back) when the extender is inserted into and removed from the optical path. The displacement amount (shift amount) of the origin position of the wobbling lens is adjusted and recorded in advance, and the origin position of the wobbling lens is adjusted by using the shift amount recorded in the recording unit when the extender is inserted or removed. It is possible to achieve an imaging device in which the focus fluctuation is reduced and the focus lens group is not moved.

Further, according to the image pickup apparatus of the present invention, the optical system and the drive system prepared for the autofocus control are utilized, and for example, the dispersion of the refractive index of the glass constituting the lens, the processing error, the magnification change and the focus. It eliminates the deviation of the flange back (when the extender is not used and when it is used) caused by the processing error of the mechanical parts such as the cam and the adjustment error in the assembly adjustment, and the best image plane for the design is focused. It is possible to match the surface and maximize the performance.

Further, it becomes possible to properly correct the focus shift during zooming and the focus shift due to narrowing by inserting an extender (enlargement), and to provide an image pickup apparatus using a higher performance zoom lens. I am able to Further, during the autofocus operation, it is not necessary to move the focusing lens, which is unnecessary originally, so that it is possible to eliminate a feeling of strangeness during photographing.

Further, as compared with driving the focusing lens group, the wobbling lens, which is much smaller and lighter, is finely moved to correct the focus position, so that it can be driven with extremely small electric power. Yes, it is possible to realize a system with low power consumption.

On the other hand, at the time of assembly and adjustment, it is possible to greatly simplify the flange back-deviation removal and adjustment work which has conventionally been performed depending on the presence or absence of an extender.

[Brief description of drawings]

FIG. 1 is a schematic view of a main part of a first embodiment of the present invention.

FIG. 2 is a schematic view of a main part of the first embodiment of the present invention.

FIG. 3 is a schematic view of the essential portions of Embodiment 2 of the present invention.

FIG. 4 is a schematic view of the essential portions of Embodiment 3 of the present invention.

FIG. 5 is a schematic view of a main part of a conventional imaging device.

FIG. 6 is a schematic view of a main part of a conventional imaging device.

[Explanation of symbols]

 1 Focusing lens group 2 Variable magnification lens group 3 Aperture device 4 Wobbling lens 5 Relay lens 6 Variable magnification optical system (extender) 7 Lens group 8 Relay lens 9 Image sensor 10 Video signal processing circuit 11 Focusing lens drive section 12 Zoom drive section 13 Aperture drive unit 14 Wobbling lens drive unit 15 Extender detection unit 16 Calculation unit 17, 19, 21, 22 Recording unit 18 Zoom position detection unit 20 Aperture position detection unit

Claims (4)

[Claims] 1. A wobbling lens which constitutes the zoom lens is moved in an image pickup apparatus for forming an object image on the surface of an image pickup means by a zoom lens having a focus lens group and an extender detachably attached in the optical path. At this time, using the signal obtained by the image pickup means, a focus detection means for moving the focusing lens group to perform a focusing operation, an extender detection means for detecting the presence or absence of the extender in the optical path, and the extender in the optical path And a recording unit for recording the shift amount of the origin position of the wobbling lens for correcting the change of the flange back shift amount when detached from the recording unit, and recorded in the recording unit based on the signal from the extender detecting means. The origin position of the wobbling lens is adjusted based on the amount of shift that is performed. An imaging device characterized by the above. 2. A zoom lens in an image pickup apparatus for forming an object image on the surface of an image pickup means by a zoom lens having a focus lens group, a variable power lens group, and an extender detachably mounted in the optical path. A focus detection unit that performs a focusing operation by moving the focusing lens group using a signal obtained by the imaging unit when the wobbling lens is moved, an extender detection unit that detects the presence or absence of the extender in the optical path, Zoom position detection means for detecting the zoom position of the variable power lens group, and the origin position of the wobbling lens for correcting the change in the flange back shift amount at each zoom position when the extender is detached from the optical path. A recording unit for recording the shift amount is provided, and the zoom position detecting means and the extender detecting hand are provided. An image pickup apparatus, wherein an origin position of the wobbling lens is adjusted based on a shift amount recorded in the recording unit based on a signal from the stage. 3. An image pickup apparatus for forming an object image on an image pickup means surface by a zoom lens having a focus lens group, a variable power lens group, an aperture stop, and an extender detachably mounted in an optical path. A focus detection unit that moves the focusing lens group to perform a focusing operation by using a signal obtained by the image pickup unit when the wobbling lens that forms the lens is moved, and an extender that detects the presence or absence in the optical path of the extender. Detection means,
Zoom position detecting means for detecting the zoom position of the variable power lens group, aperture value detecting means for detecting the aperture value of the aperture stop,
And a recording unit for recording the shift amount of the origin position of the wobbling lens for correcting the change of the flange back shift amount at each zoom value and each zoom position when the extender is detached from the optical path. The origin position of the wobbling lens is adjusted based on the shift amount recorded in the recording unit based on the signals from the zoom position detection means, the aperture value detection means, and the extender detection means. An imaging device characterized by. 4. A wobbling lens forming a zoom lens in an image pickup apparatus for forming an object image on the surface of an image pickup means by a zoom lens having a focus lens group, an aperture stop, and an extender detachably mounted in the optical path. A focus detection means for moving the focusing lens group to perform a focusing operation using a signal obtained by the image pickup means when the lens is moved, an extender detection means for detecting the presence or absence of the extender in the optical path, and the aperture. Aperture value detection means for detecting the aperture value of the aperture, and recording the shift amount of the origin position of the wobbling lens for correcting the change in the flange back shift amount at each aperture value when the extender is attached / detached from the optical path. And a recording unit provided on the basis of signals from the aperture value detecting unit and the extender detecting unit. An image pickup apparatus, wherein an origin position of the wobbling lens is adjusted based on a shift amount recorded in the recording unit.