JPH0476509A - Image pickup device - Google Patents

Abstract

PURPOSE:To complete an additional function so as to attain high performance and to accomplish the mutual sharability of parts by fixedly arranging a front lens system and an image-formation system and constituting a variable power system and an image-formation element so that they may move on an optical axis by a driving means. CONSTITUTION:An optical system is constituted of the front lens system 30 consisting of a convex lens system, a zoom system(variable power system) 31 consisting of a concave lens system, the image-formation system 32 consisting of convex lenses 32a, 32b and 32c. The short distance on a telephoto side is made closer without eclipsing an oblique light beam from the system 32b to the outside of the system 32c, which occurs because the distance between the systems 32b and 32c becomes longer than a specified value, and a focusing position is rapidly corrected even when the focusing position is varied at the time of zooming, then the high performance is attained even in a device provided with the additional function. As to the moving range of an image pickup element 34, furthermore, the moving range [I] is from >=1m object distance to an infinity area, the moving range [II] is from <=5m object distance to a macro area, and the moving range [III] is from the macro area to the infinity area, and ordinarily it is preferentially limited to the range [I] in an arithmetic circuit 43, thereby obtaining rapid response to focusing.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an autofocus imaging device with a zoom function.

(Prior art) Fig. 6 is a schematic block diagram of a conventional imaging device having an autofocus function, and the optical system includes a front lens system 1 consisting of a convex lens system, a zoom system 2 consisting of a concave lens system, and a convex lens system 3a.
, 3b, and 3c.

Imaging light A from the subject is incident on the imaging device (CCD) 5 from the optical system via the low-pass filter 4, converted into an electrical signal by a photoelectric conversion surface in the imaging device 5, and the signal is amplified by an amplifier 6. The signal is supplied to a camera circuit (not shown).

On the other hand, the output signal from the amplifier 6 is supplied to a detector (DET>9) via a gain controller circuit (GCΔ) 7 and a bandpass filter (BPF) 8.

Then, the detector 9 obtains a focal voltage corresponding to a predetermined high-frequency component of the bandpass filter 8, and when the object is just focused, the maximum focal voltage is obtained.

This focal voltage is digitized by an A/D (analog-to-digital) converter 11 and supplied to an arithmetic circuit 12, which converts the focal voltage and the image forming system 3 from rotary encoders 13 and 14. A predetermined calculation is performed using the position information of the convex lens system 3C and the position information of the zoom system 2 to calculate the moving distance of the convex lens system 3C, and the motor 16 is driven by a predetermined control signal to bring the convex lens system 3b into just focus on the optical axis. move to position.

Furthermore, when a zoom operation is performed, the zoom system 2
7, the convex lens system 3G is moved on the optical axis and the focal length changes again, so a predetermined calculation is performed based on the above two positional information and the convex lens system 3G is moved to the just-focus position again.

(Problems to be Solved by the Invention) In the imaging device having the above-mentioned configuration, the convex lens system 3C of the imaging lens system 3 is moved in the optical axis direction in order to achieve just focus, so the convex lens system 3b and the convex lens system 3C are When they are separated by more than a predetermined distance, the oblique ray of the imaging light A from the convex lens system 3b is vignetted outward in the optical axis direction,
A part of the important imaging light A is missing.

In order to prevent this, it is possible to increase the diameter of the convex lens system 3C, but today there is a demand for imaging devices with additional functions such as a zoom function, so it is necessary to prepare a zoom lens system, etc. Considering the reduction in size and weight of the entire device, the other lens systems cannot be made very large.

Moreover, in order to achieve high magnification, it is necessary to move the convex lens system 3b and the convex lens system 3C of the imaging system 3 in the direction of increasing separation, which further causes the problem of vignetting of the imaging light A. It also becomes necessary to quickly correct changes in focal length due to zooming.

In addition, since the focusing method uses a configuration in which the optical system of the convex lens 3C is moved, when moving, the shift on the optical axis of the convex lens system 3C due to changes in lens position and mechanical errors, sagging, etc. are significantly affected by aberrations. This makes it difficult to improve performance.

Furthermore, these image carriers 5 use CCDs (Charge Coupled Devices), and dust can enter the Jl image device and adhere to the important image pickup device, impairing its function. There were concerns that it would decline.

Furthermore, the optical system and the 1811 element generally correspond in size, and if they do not correspond to each other, they cannot be shared, resulting in poor utilization efficiency.

The present invention has been made in view of the above points, and its purpose is to provide an imaging device with enhanced additional functions, improved performance, and mutual commonality of parts. .

(Means to solve the problem) As a means to achieve the above purpose, the following (1) ~
The present invention aims to provide the imaging device described in (6).

That is, the imaging device of the present invention includes: (1) an optical system in which at least a front lens system including a convex lens system, a variable power system including a concave lens system, and an imaging system including a convex lens system are sequentially arranged on the optical axis; It is equipped with an image sensor that photoelectrically converts the imaging light from the optical system, and supplies a signal based on the electric signal photoelectrically converted in the M image element and position information of the optical system to a performance means to change the magnification. In an imaging device that performs focusing at the time of focusing, the front lens system and the imaging system are fixedly arranged, and the variable power system and the imaging element are moved on the optical axis by a driving means, and at the time of focusing, A signal based on the photoelectrically converted electric signal is supplied to the calculation means to generate a control signal, and the control signal is supplied to the drive means to move the image sensor to a focusing position on the optical axis. , when the variable magnification system is moved, a control signal generated in the calculation means based on positional information related to the focal length of the variable magnification system and position information of the imaging element, which are sequentially supplied, is sent to the driving means. An imaging apparatus, characterized in that the imaging device corrects the in-focus position of the imaging element by supplying a signal to the imaging device.

(2) In the apparatus described in (1) above, the imaging device has a configuration in which a distance-dependent optical filter or a lens system is fixedly disposed on the same holding member at a predetermined interval on the front side on the optical axis of the imaging device.

(3) In the apparatus described in (1) above, the imaging device is configured such that the moving range of the imaging element in the optical axis direction can be switched by a switching means.

(4) In the apparatus described in (3) above, the imaging device is configured such that movement of the image sensor on the optical axis is restricted at a position closer than a predetermined distance to the optical system of the subject.

(5) In an imaging device that performs focusing by focusing imaging light from a lens system onto a solid-state image sensor, an optical element is arranged on the front side on the optical axis of the solid-state image sensor, and cooperation with this optical element is provided. An imaging device characterized in that the front side of the solid-state image device has a sealed structure.

(6) In an imaging device that performs focusing by focusing imaging light from an imaging system on an imaging element, there is a gap between the imaging element and the imaging element on the optical axis, which is outside the direction of the optical axis of the imaging light. 1. An imaging device comprising a fixing means for fixedly arranging a lens system that is expanded or contracted in one direction at a predetermined interval.

(Function) The device according to claim (1) has a structure in which the front lens system and the imaging system of the optical system are fixedly arranged, and the variable power system and the image sensor are moved, but the image capturing system is also configured to move when the variable power system is moved. The structure is such that the element is moved to the in-focus position to prevent the occurrence of vignetting of oblique rays of imaging light and to correct the in-focus position when changing the magnification.

The apparatus according to claim (2) is the apparatus according to claim (1), in which the image sensor and the distance-dependent optical low-pass filter or the lens system are held by the same holding member and held at a constant interval with respect to the image sensor. .

The apparatus according to claim (3) is the apparatus according to claim (1), in which the moving range of the image sensor in the optical axis direction is switched in multiple stages to increase the focusing speed.

The apparatus according to claim (4) is the apparatus according to claim (3), in which the movement of the image sensor is restricted when the subject approaches the optical system more than a predetermined value to prevent the optical system itself from being reflected in the image. prevent it.

In the device according to claim (5), an optical member is provided on the front side on the optical axis of the solid-state image sensor, and in cooperation with this member, the solid-state image sensor is made into a sealed structure to prevent dust from adhering to the element. The apparatus according to claim (6) is characterized in that a lens system for expanding or contracting the imaging light outward is provided on the front side on the optical axis between the imaging system and the I-image element by a fixing means. In this way, a lens system that is compatible with a different image sensor is shared.

(Embodiment) FIG. 1 is a schematic block system diagram showing an embodiment of an imaging device according to the present invention.

A detailed explanation will be given below according to this embodiment.

In the figure, the optical system is composed of a front lens system 30 consisting of a convex lens system, a zoom system (variable magnification system) 31 consisting of a concave lens system, and an imaging system 32 consisting of convex lens systems 32a, 32b, and 32c.

Imaging light A from the object passes through the optical system, passes through a crystal low-pass filter 33 for removing optical beats, and forms an image on an image carrier (solid-state image sensor) 34, where photoelectric conversion is performed within the IIl element 34. and this output signal is sent to amplifier 3
The output of the amplifier 36 is supplied to a video circuit 37 via a bandpass filter (BPF) 3, where it is subjected to predetermined signal processing to become a signal compliant with a video signal.
8 and a predetermined high frequency component is extracted.

This output signal is the gain control amplifier (GGA) 3
9, and if the focal voltage becomes low here, the voltage is amplified and supplied to the next stage area sensing circuit 41.

The area sensing circuit 41 extracts and detects the imaging area, and outputs it as a focal voltage to an A/D (analog-digital) converter 42 at the next stage.

This A/D converter 42 supplies digitized focal voltage information to an arithmetic circuit 43 .

This arithmetic circuit 43 is simultaneously supplied with position information of the image sensor 34 from a position sensor 44 and also supplied with position information related to the focal length of the zoom lens system 31 from another position sensor 46 .

The arithmetic circuit 43 samples the focal voltage from the A/D converter 42 as the image carrier 34 moves in the optical axis direction every field from the start of focusing.
The focal voltages for each field are sequentially digitized and supplied, and a differential voltage is calculated by sequentially comparing the levels of the focal voltages for each field, and the level and sign change of this differential voltage are detected and output from the position sensors 44 and 46. A focus position is calculated based on the position information of , a control signal is generated, and this control signal is supplied to a drive circuit 47 to drive a motor 48 to move the image sensor 34 to the focus position.

FIG. 2 is a diagram showing the general relationship between the position of the image sensor and the focal length when the zoom lens system 2 focuses on an object at the same distance. It is shown that the position changes.

The rate of change in the imaging position due to zooming varies depending on the distance to the subject, and the rate of change in the imaging position is large, forming a two-dimensional curve.

Therefore, when zooming, +
It becomes necessary to move the a-image element 34 to correct the imaging position. In the apparatus of this embodiment as well, zoom correction is performed in light of this two-dimensional curve.

In the figure, for example, now the focal length fa and the subject distance 2Tr1. The position of the image sensor 34 is set to
Set to state a.

When the zoom switch 49 is operated in the wide direction from this state, a control signal is supplied from the arithmetic circuit 43 to the drive circuit 50, and the motor 51 moves the zoom lens system 31 in the X direction on the optical axis to the position of the focal length fa'. At the same time, the arithmetic circuit 43 is supplied with the position information of the image sensor 34 from the position sensor 44 and the focal length information from the position sensor 46. From these, the object distance is calculated, and the relationship curve shown in the figure is calculated in advance. The corrected position of the image sensor 34 determined by Place @
The configuration is such that it is moved to xa'.

Therefore, according to this embodiment, the front lens system 30 and the imaging lens system 3
2 is not moved, but the zoom system 31 and the image sensor 34 are moved, so the distance between the convex lens system 32b and the convex lens system 32c of this imaging system increases beyond a predetermined value, and the convex lens system The oblique rays from 32b pass through the convex lens system 32c.
The focus position can be quickly corrected even when the focus position changes during zooming, and the focus position can be quickly corrected even when the focus position changes during zooming. High performance can be achieved.

In addition, since the optical system is not moved as a focusing method, there are no inconveniences such as changes in the lens position that occur when the optical system is moved, deviations on the optical axis of the lens system due to mechanical errors, and bending. It becomes.

Furthermore, the movement range of the image sensor 34 is set into three categories from movement range [I] to [I[II] as shown in FIG. Macro area from range [n] below 577L,
The moving range [I[[] ranges from macro to infinity, and is configured to be switched to each range as desired.

The focal range of the imaging device according to this embodiment is configured to be able to focus to infinity even on the telephoto side, but when the contrast is low, the entire area may be scanned, and in this case, it takes time to detect the focal voltage. This results in poor focusing responsiveness.

Therefore, conventionally, focusing on the fact that there are many images of objects that are separated by approximately 17 FL or more when imaging on the telephoto side, the movement range is limited to [II] in the arithmetic circuit 43 and this limited area is provided for quick focusing response.

Furthermore, when photographing an area from 5 m or less to macro, the switch 45a is turned on, thereby turning on the arithmetic circuit 43.
A control signal is generated within which the movement range of the image carrier 34 is limited to the movement range [II], thereby limiting the movement of the image pickup element 34 and increasing the responsiveness of focusing within this range.

If you are not concerned about the responsiveness of focusing, if switching etc. is troublesome, or if you are unsure of the distance of the subject to be photographed, turn on the switch 45b and the arithmetic circuit 43 will change the movement of the III element 34. A control signal extending to the range [II[] is generated and supplied to the drive circuit 47.

Furthermore, if the subject distance approaches 10JIII or less in the macro areas of the movement #jJ ranges [II] and [I[[], the front outer periphery of the lens of the front lens system 30 or the scene inside the lens will enter the imaging screen. It becomes something to behold.

Therefore, consideration was given to this point, and the arithmetic circuit 43
, the object distance is calculated based on the position information from the position sensors 44 and 46, and when the object distance becomes 10 am or less, a control signal is generated to limit the movement of the ML carrier 34 in the Y direction on the optical axis. is generated.

FIG. 3 is a schematic partial view showing the holding mechanism 52 for the crystal low-pass filter and the edge element 34. The crystal low-pass filter 33 and the m-image element 34 are respectively housed in the housing section 53, and the holding plates 54 and 55 are viewed from the outside. are held by the screws 5 and 5.
6a to 56d, and this housing part 53 is fixed by a support member 57 through long holes 60a, 60b and screws 70a, 7.
It is fixed by 0b.

This elongated hole is for adjusting the position of the accommodating portion 53 in the optical axis direction.

This support member 57 is connected to a gear (not shown), and this gear is meshed with a gear connected to the motor 48 side.
When moved to the focusing position on the optical axis, the III element 34
and the crystal low-pass filter 33 are moved together.

Therefore, the incident surface side of the imaging light A of the imaging device 34 is completely sealed by the crystal low-pass filter 33 and the inner wall 53a of the accommodating portion 53, and dust can be prevented from adhering to the imaging device 34. , the function of the image carrier element 34 is not deteriorated.

Furthermore, when a distance-dependent optical low-pass filter such as a phase grating low-pass filter or a lens array low-pass filter is attached instead of the crystal low-pass filter 33, the distance from the II image element 34 is always kept constant.
Even if the image sensor 34 is configured to move as in the embodiment, it can be attached.

FIG. 4 shows another embodiment of the holding mechanism 52, in which the holding mechanism 58
The image carrier element 34 is attached to one end side of the accommodating portion 59 by a screw 61a.
, 61b, and a sliding clamp plate 63 is installed inside the housing section 59 on the front side of the image sensor 34, and is always biased in the X direction by coil springs 64a and 64b.

A crystal low-pass filter 33 is interposed on the front side (X direction) of this sliding clamping plate 63, and this crystal O-bus filter 33 is clamped and fixed by a sliding clamping plate 66.

67a and 67b are grooves cut out to the end of the housing portion 59 and formed in the optical axis direction, and screws 68a.

68b is a groove width that allows liquid to pass through.

When installing this crystal low-pass filter 33 inside, first loosen the screws 67a and 67b and slide the sliding clamp plate 66 in the X direction to remove it. The sliding clamping plate 66 is fitted again, and this clamping sliding plate 66 is attached to the coil spring 64a.
, 64b in the Y direction to sandwich the crystal low-pass filter 33, and screw the screw 68a into M8i\ in that state.

The structure is such that the crystal low-pass filter 33 is fixed by sandwiching the inner and outer surfaces of the accommodating portion 59 by the accommodating portion 68b.

Further, according to this embodiment, it is also possible to accommodate the phase grating filter or the lens array optical low-pass filter, and in that case, the distance to the image sensor 34 can be adjusted by sliding it against the coil springs 64a and 64b. This can be done by sliding the plate 63.

FIG. 5 shows a state in which a concave lens 69 is attached in this second embodiment. Generally, there is a correspondence between the sizes of the optical system and the image sensor. For example, for a 1/3 inch optical system, An image sensor of a size corresponding to this is required.
Even if a 1/2-inch image carrier is provided in this optical system, the
Therefore, the amount of information corresponding to the phantom image element of /2 inch cannot be obtained.

Therefore, in such a case, it is sufficient to attach the concave lens 19 to enlarge the imaging optical path.

On the other hand, if the optical system is compatible with a larger size, a convex lens may be attached in place of the concave lens 19 to sandwich the imaging optical path.

Therefore, there is a mutual correspondence relationship and mutual sharing can be achieved. In particular, according to this second embodiment, the sliding clamp plate 6
3, and when fixing and holding an optical element that affects the phase or optical path direction of the imaging light A, such as a phase optical filter or a lens system, on the front side, the distance to the imaging device 34 can be adjusted. This is particularly suitable.

It goes without saying that a dustproof effect can be obtained in this second embodiment as well, and if a filter and lens system are not attached, a dustproof glass may be attached.

(Effects of the Invention) As described above, in the apparatus of claim (1), at least the front lens system consisting of a convex lens system, the variable power system consisting of a concave lens system, and the imaging system consisting of a convex lens system are sequentially arranged on the optical axis. An array of optical systems and a photoelectric converter 1 for photoelectrically converting the imaging light from this optical system.
111 ml element, and supplies a signal based on an electrical signal photoelectrically converted within the image carrier element and position information of the optical system to a calculation means to perform focusing during zooming. The lens system and the imaging system are fixedly arranged, and the variable magnification system and the imaging element are moved on the optical axis by a driving means, and when focusing, a signal based on the photoelectrically converted electric signal is transmitted. A control signal is supplied to the calculation means to generate a control signal, and the control signal is supplied to the drive means to move the image sensor to a focus position on the optical axis, while sequentially supplying the control signal when the variable magnification system is moved. A control signal generated in the arithmetic means based on the positional information of the focal length of the variable magnification system and the positional information of the imaging element is supplied to the driving means to focus the imaging element. Since the imaging device is characterized by position correction, it is possible to prevent the occurrence of vignetting of the imaging light, eliminate factors that adversely affect aberrations due to changes in lens position, and make the entire device smaller. High performance can be achieved by supporting additional functions.

In the apparatus according to claim (2), in the apparatus according to claim (1), the distance-dependent optical low-pass filter or the lens system is held at a predetermined interval on the front side on the optical axis of the image element Ii by the same holding member. Since the imaging device is configured to be fixedly arranged, it is suitable for holding an optical element that affects the phase or optical path direction of the Jl image light without changing the distance to the image carrier.

In the apparatus according to claim (3), in the apparatus according to claim (1), the moving range of the image carrier element in the optical axis direction can be switched by the switching means, so that the focusing speed can be changed. This makes it possible to speed up the process and provide multifunctionality.

In the apparatus according to claim (4), in the apparatus according to claim (3), the image pickup device is configured such that movement of the image pickup element on the optical axis is restricted at a position closer than a predetermined distance to the optical system of the subject. Therefore, during close-up photography, the outer periphery or the inside of the lens system does not get into the image and make the image difficult to see.

In the apparatus according to claim (5), in the imaging device that performs focusing by focusing imaging light from an imaging system onto a solid-state image sensor, an optical element is arranged on the front side on the optical axis of the solid-state image sensor. However, since the imaging device is characterized in that the front side of the solid-state Ii image element has a sealed structure in cooperation with this optical element, dust etc. do not adhere to the solid-state image sensor.
The functions of the solid-state image device etc. are not deteriorated.

In the apparatus of claim (6), in the II imaging device that performs focusing by focusing imaging light from an imaging system on an imaging element, the above-mentioned Since the imaging device is characterized by being provided with a fixing means for fixedly arranging a lens system that expands or contracts the imaging light outward in the optical axis direction at a predetermined interval, the optical system and the imaging device are They can be shared even if their sizes do not correspond to each other, which has the effect of increasing the value of use.

[Brief explanation of the drawing]

Fig. 1 is a schematic block system diagram showing one embodiment of the device of the present invention, Fig. 2 is a diagram explaining the principle at the time of zooming, and Figs. 3 to 5 are each embodiment of the holding mechanism of the image carrying element of the present invention. Figure 6 showing
The figure is a schematic block diagram of a conventional imaging device. 30... Front lens system, 31... Zoom system, 32... Imaging system, 32a, 32b, 32C''-convex lens system, 33.
...Crystal low-pass filter, 34...Image sensor, 43
...Arithmetic circuit, 44.46...Position sensor, 45a
, 45b...Switch, 48.51-...Motor, 5
2.58... Holding mechanism, 63.66... Sliding clamp plate, 69... Concave lens. Patent Applicant: Victor Japan Co., Ltd. Figure 2 Figure 4

Claims (6)

[Claims] (1) An optical system in which at least a front lens system consisting of a convex lens system, a variable power system consisting of a concave lens system, and an imaging system consisting of a convex lens system are sequentially arranged on the optical axis, and the imaging light from this optical system is an imaging device that performs focusing during zooming by supplying a signal based on the photoelectrically converted electric signal and position information of the optical system to a calculation means, the front lens system and The imaging system is fixedly arranged, and the variable magnification system and the imaging element are moved on the optical axis by a driving means, and when focusing, the calculation means converts a signal based on the photoelectrically converted electric signal into a signal based on the photoelectrically converted electric signal. and generates a control signal, and supplies this control signal to the driving means to move the image pickup element to a focusing position on the optical axis, while at the same time, when the variable magnification system moves, the A control signal generated in the arithmetic means based on positional information related to the focal length of the variable magnification system and positional information of the imaging element is supplied to the driving means to correct the focal position of the imaging element. An imaging device characterized by: (2) The imaging device according to claim 1, wherein a distance-dependent optical low-pass filter or a lens system is fixedly disposed on the same holding member at a predetermined interval on the front side on the optical axis of the imaging device. (3) The imaging device according to claim (1), wherein the moving range of the imaging element in the optical axis direction can be switched by a switching means. (4) The imaging device according to claim (3), wherein movement of the imaging device on the optical axis is restricted at a position closer than a predetermined distance to the optical system of the subject. (5) In an imaging device that performs focusing by focusing imaging light from a lens system onto a solid-state image element, an optical element is disposed on the front side on the optical axis of the solid-state image element, and cooperation with this optical element is provided. An imaging device characterized in that the front side of the solid-state imaging device has a sealed structure. (6) In an imaging device that performs focusing by focusing imaging light from an imaging system on an imaging element, there is a gap between the imaging system and the imaging element on the optical axis, which is outside the direction of the optical axis of the imaging light. 1. An imaging device comprising a fixing means for fixedly arranging a lens system that is expanded or contracted in one direction at a predetermined interval.