JPS6378115A - Automatic focus adjustor - Google Patents

Abstract

PURPOSE:To arrange an optical filter nearby the image formation position of a solid-state image pickup element and to contrive to reduce the pize of a video camera, etc. by interposing an annular elastic body between the end surface of the solid-state image pickup element and the optical filter and clamping the optical filter by the end surface of the solid-state image pickup element and the projection part of a movable-side holder. CONSTITUTION:When a pressure plate 42 which operates even as the heat radiator of the solid-state image pickup element 7 is fitted to the end surface of the movable-side holder 30 with screws 31a and 31b, a rubber packing 38 is pressed against a step part 37 and the optical filter 6 by the end surface 39 of the solid-state image pickup element 7 to deform elastically, and the optical filter 6 is clamped through the rubber packing 38 by the annular projection 33 of the movable-side holder 30 and the end surface 39 of the solid-state image pickup element 7. Thus, the solid-state image pickup element 7 is only fitted to the movable-side holder 30 with screws 31a and 31b to hold the attitude of the optical filter 6 on the movable-side holder 30 stably, and piezoelectric elements 9a and 9b are driven to vibrate the solid-state image pickup element 7 and optical filter 6 integrally in directions of the optical axis A.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an automatic focus adjustment device that can be used in the optical system of a video camera.

2. Description of the Related Art Conventionally, this type of automatic focus adjustment device has been constructed as shown in FIG. 6 or 7. In FIG. 6, light that has passed through a photographing lens system 4 consisting of a focusing lens group 1, a zoom lens group 2, a master lens group 3, etc. is filtered through an optical path length varying lens 5 and an optical low-pass filter. The solid-state image sensor 7 is configured to form an image via the solid-state image sensor 6. The optical path length varying lens 5 is held via a thin annular metal plate 8, and annular piezoelectric elements 9a are bonded to both sides of the metal plate 8.

9b is driven by a signal from the oscillator 10, the optical path length varying lens 5 vibrates by a small amount in the direction of the optical axis (A) of the photographic lens system 4, and the optical path length of the light heading toward the solid-state image sensor 7 is slightly changed. The structure of the above-mentioned fine movement device, which repeats small changes, is detailed in Japanese Patent Application Laid-open No. 179710/1989 filed by the present applicant.

The output signal obtained by the solid-state image sensor 7 is amplified by the amplifier 11, and the frequency detector 12 amplifies the output signal from the piezoelectric element 9a.

A high frequency signal containing a vibration frequency component of 9b is detected.

The phase of the signal detected by the frequency detector 12 and the phase of the output signal of the oscillator 10 are compared by the phase comparator 13, and the control unit 14 polarizes the direction of focus shift and outputs the output of the solid-state image sensor 7. Focusing is achieved by moving the focusing lens group 1 in the direction of the optical axis (A) using a motor 15 so that the voltage reaches its peak value.

The operating principle of the control system for driving the focusing lens 1 based on the output signal of the solid-state image sensor 7 is detailed in Japanese Patent Laid-Open No. 60-42723 filed by the present applicant.

In the device shown in FIG. 6, the solid-state image sensor 7 was fixed and the optical path length varying lens 5 was vibrating, but in addition to this,
As shown in FIG. 7, a piezoelectric element 9a.

There is a structure in which the solid-state image sensor 7 is held by a metal plate 8 with 9b bonded to both sides. In FIG. 7, parts having the same functions as those in FIG. 6 are given the same reference numerals.

In the case of the apparatus shown in FIG. 7, conventionally, the optical filter 6 and the solid-state image sensor 7 are placed in separate holders 16 and 16, respectively, as shown in FIG.
They are attached to the lens barrel 18 at mutually distant positions via 17. In the holder 17, the outer periphery of the metal plate 8 is held between the holder 17 and a ring 21 screwed into the inner periphery.

On the other hand, the tip 19a of the movable holder 19 is inserted into the hole drilled in the center of the metal plate 8, and the ring 20 screwed into the tip 19a and the movable holder 19 form a ring around the circumference of the metal plate 8. The movable side holder 19 is held by pinching the parts. And this movable side holder 1
A solid-state image sensor 7 is attached to 9.

Problems to be Solved by the Invention How to reduce the size and weight of a video camera with the conventional configuration shown in FIGS. 7 and 8.

As shown in FIG. 9, the distance between the optical filter 6 and the solid-state imaging device 7 is shortened so that the optical filter 6 enters the optical path at a position near the imaging plane of the solid-state imaging device 7. Although it is effective to reduce the size and weight of the optical filter 6 and the solid-state image sensor 7 in separate holders 16.
In the conventional structure in which the holder 16 and the holder 17 are attached to each other as shown in FIG. 9, the holder 16 and the holder 17 come into contact with each other as shown in FIG.

Moreover, even if the interval (vertical) can be shortened, the piezoelectric elements 9a,
The movable holder 19, which is being driven by the holder 9b and vibrating in the direction of the optical axis (A), comes into contact with the optical filter 6 and prevents normal vibration of the solid-state image sensor 7.

In addition, there is a conventional system in which the optical filter 6 and the solid-state image sensor 7 are held together as shown in FIG.
. In this case, the holder rear part 23 to which the solid-state image sensor 7 is attached is attached with screws 22 to the holder front part 25 with screws 24a and 24b, and the holder rear part 23 of the holder front part 25 is attached from the opposite side. After inserting the optical filter 6, the optical filter 6 is held between the holding plate 27 attached to the holder front part 25 with screws 26a and 26b and the protrusion 28 of the holder front part 25, but the holder rear part 23
Since the mounting of the solid-state image sensor 7 and the mounting of the optical filter 6 to the holder 29 consisting of the holder front portion 25 and the holder front portion 25 are performed separately, there is a problem in that the number of assembly steps increases.

The present invention provides an imaging device that performs automatic focusing by vibrating a solid-state image sensor, in which the distance between the optical filter and the solid-state image sensor can be shortened without interfering with the normal vibration of the solid-state image sensor, and the optical filter can be filtered with less man-hours. An object of the present invention is to provide an automatic focusing device that can be assembled into an integral part with a solid-state image sensor and a solid-state image sensor.

Means for Solving the Problems The automatic focus adjustment device of the present invention includes an optical filter disposed between a photographing lens system and a solid-state image sensor, which is integrated with the solid-state image sensor, and a combination of the optical filter and the solid-state image sensor. A vibrating device is provided to vibrate the lens in the optical axis direction of the photographic lens system using an electric signal, and the lens of the photographic lens system is moved to adjust the focus by detecting a shift in focus using an output signal from a solid-state image sensor. , and a movable holder is provided in which a through hole in the optical axis direction is formed for a portion that holds the solid-state image sensor and the optical filter together, and the portion that holds the solid-state image sensor and the optical filter together is provided with a movable side holder in which a through hole is formed in the direction of the optical axis, and the movable side holder is provided with a movable side holder that faces inward toward one end of the through hole. The optical filter is placed on the protrusion formed by the through hole, and an annular elastic body is interposed between the optical filter and the end surface of the solid-state image sensor attached to the opening of the other end flange of the through hole. The optical filter is configured such that the optical filter is held between the other end surface of the solid-state image sensor and the protrusion of the movable holder.

According to this configuration, since the optical filter and the solid-state image sensor are integrated, the optical filter is vibrated in the same direction as the solid-state image sensor by the driving of the vibration device.

The distance between the optical filter and the solid-state image sensor can be made the shortest without disturbing the vibration of the solid-state image sensor.

Furthermore, since the optical filter is sandwiched between the end face of the solid-state image sensor and the protrusion of the movable holder, by fixing the solid-state image sensor to the movable holder, not only the solid-state image sensor but also the optical filter can be fixed to the movable holder. .

EXAMPLE An example of the present invention will be described below with reference to FIGS. 1 to 5. The photographing lens system and the electric circuit for controlling its focus are the same as those shown in FIG. 7, but the focus control operation will be explained in detail here.

The output signal of the solid-state image sensor 7 is amplified by an amplifier 11, and its high frequency component is extracted by a frequency detector 12.

Here, the oscillator 10 oscillates at, for example, 15Hz,
The high frequency component that is the output of the frequency detector 12 is 15)
This is a waveform modulated by 1z. 1 of this oscillation frequency
5Hz is not limited to this value as long as the image obtained from the output signal of the solid-state image sensor 7 does not appear unnatural to the human eye.
By comparing the phases of the output of the oscillator 10 and the output of the oscillator 10 with the phase comparator 13, information as to whether the front or rear of the subject is currently in focus is obtained, and based on the motion, the controller 14. The direction of movement of the focusing lens #1 is determined via the motor 15. Then, a control operation is performed to detect that the result of the phase comparison is focused at the lens position where the solid-state image pickup device 7 vibrates to output plus or minus.

FIG. 1 is a vertical cross-sectional view of essential parts in an embodiment of the present invention. In FIG. 1, the solid-state image sensor 7 is attached to the movable holder 30 with screws 31a and 31b. As shown in FIGS. 2 to 4, the movable side holder 30 is aligned with the optical axis (A
), and an annular protrusion 33 is formed at the end of the through hole 32 on the subject side. in order toward the opposite side to which the first housing part (a) is attached.
and a second accommodating part (a) having a larger diameter than the first accommodating part (a).
b) and a third accommodating part (c) following the second accommodating part (b).
).

The movable side holder 30 is an annular piezoelectric element 9a.

9b is attached to the holder 34 via an annular metal plate 8 attached to both sides. 35 is a ring that is screwed into the outer periphery of the movable side holder 30;
The inner periphery of the metal plate 8 is held between the movable holder 30 and the movable holder 30 . 36 is a ring that is screwed into the inner circumferential portion of the holder 34, and the ring 36 and the holder 34 connect the metal plate 8.
The outer periphery of the

As shown in FIGS. 1 and 5, the assembly procedure is to install the solid-state image sensor 7 of the movable holder 30 by inserting the optical filter 6 into the first housing part (a) from the side, and then inserting the optical filter 6 into the first housing part (a). An annular rubber backing 38 is placed on the stepped portion 37 at the connection point between the accommodating portion (a) and the second accommodating portion (b).

Here, the depth Ll of the first housing part (,) in the optical axis (A) direction is slightly shallower than the thickness L2 of the optical filter 6, and the optical axis (A) of the second housing part (b) is slightly shallower than the thickness L2 of the optical filter 6. The depth in the direction of is formed to be shallower than the thickness L4 of the rubber backing 38 before assembly.

As described above, the end surface 39 of the solid-state image sensor 7 is inserted into the third accommodating part (c) of the through hole 32 into which the optical filter 6 and the rubber backing 38 are inserted, and the connection pin of the solid-state image sensor 7 is inserted. 40 and the printed wiring board 41 soldered to the connecting pins 40, the holding plate 42, which also acts as a heat sink for the solid-state image sensor 7, is fixed by screws 31a and 31b.
When attached to the end face of the movable side holder 30, the rubber backing 38 is pressed against the step portion 37 and the optical filter 6 by the end face 39 of the solid-state image sensor 7 and is elastically deformed, and the optical filter 6 is movable via the rubber backing 38. side holder 3
The annular protrusion 33 of 0 and the end surface 39 of the solid-state image sensor 7 are sandwiched without any gap.

With this configuration, simply attaching the solid-state image sensor 7 to the movable holder 30 with the screws 31a and 31b is enough.
The posture of the optical filter 6 in the movable holder 30 is held stably, and the solid-state image sensor 7 and the optical filter 6 vibrate together in the direction of the optical axis (A) by driving the piezoelectric elements 9a and 9b.

In the above embodiment, the metal plate 8 and the piezoelectric element 9a are used as the vibration device 43 that vibrates the optical filter 6 and the solid-state image sensor 7 in the direction of the optical axis (A) of the photographic lens system 4.

9b was used as an example, but the vibration device ffi! 43 is a combination of a magnetic plate and a coil facing it, with one of the magnetic plate and coil coupled to an image sensor and an optical filter, and a combination of a permanent magnet and a coil. A structure in which one side of the coil is coupled to an image sensor and an optical filter can also be used in the same way.

Effects of the Invention As described above, according to the present invention, an optical filter and a solid-state image sensor are provided integrally, and the optical filter and solid-state image sensor are vibrated in the optical axis direction of the photographing lens system by a vibration device. Even if the solid-state image sensor is brought close enough to the solid-state image sensor, normal vibration of the solid-state image sensor will not be disturbed, and the optical filter can be placed close to the imaging plane of the solid-state image sensor. Compared to a fixed side and a movable side that vibrates the solid-state image sensor, the same function can be obtained with a smaller optical filter, contributing to the miniaturization and weight reduction of video cameras and the like.

Furthermore, since the optical filter is sandwiched between the end face of the solid-state image sensor and the protrusion of the movable holder, the solid-state image sensor and the optical filter can be integrated into a single unit with a small amount of man-hours required for fixing the solid-state image sensor to the movable holder. It is something that can be maintained.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view showing the installation of a solid-state image sensor in an embodiment of the automatic focusing device of the present invention, while the parts are being assembled;
The figure shows an enlarged plan view of the holder shown in Fig. 1 with the solid-state image sensing device mounted from the side, Fig. 3 is a sectional view taken along line x-x' in Fig. 2, and Fig. 4 shows the holder shown in Fig. 1. Fig. 5 is an exploded perspective view of the integral part of the optical filter and solid-state image sensor, and Fig. 6 is a conventional automatic method that changes the optical path length by vibrating the lens for changing the optical path length. A configuration diagram of a focus adjustment device, FIG. 7 is a configuration diagram of a conventional automatic focus adjustment device that vibrates a solid-state image sensor to vary the optical path length, and FIG. 9 is a vertical sectional view when the optical filter shown in FIG. 8 is brought close to the solid-state image sensor, and FIG. 10 is a vertical sectional view of a conventional example in which the optical filter and the solid-state image sensor are held together. It is a diagram. 4...Photographing lens system, 6...Optical filter, 7...
・Solid-state image sensor, 30...Movable side holder, 31a
, 31b...screw, 32...through hole, 33...
Projection, 34...Holder, 37...Step, 38...
・Rubber backing [annular elastic body], 39... End face of solid-state image sensor 7, 42... Holding plate, 43... Vibration device!
, (A)... Optical axis, (a)... First housing part, (b
)...Second accommodating part, (c)...Third accommodating part. Agent Yoshihiro Morimoto Figure 4 Figure 3 Figure 2 Figure 8 Figure D

Claims (1)

[Claims] 1. An optical filter disposed between the photographic lens system and the solid-state image sensor is held integrally with the solid-state image sensor, and the optical filter and the solid-state image sensor are vibrated in the optical axis direction of the photographic lens system using an electrical signal. a vibrating device configured to detect a focus shift based on an output signal of a solid-state image sensor and move a lens of the photographing lens system to focus the image, and hold the solid-state image sensor and the optical filter together. A movable holder is provided in which a through hole in the optical axis direction is formed, and the optical filter is mounted on a protrusion formed inward at one end of the through hole of the movable holder. and an annular elastic body is interposed between the end face of the solid-state image sensor attached to the opening on the other end side of the through hole and the optical filter, so that the end face of the solid-state image sensor and the movable holder are An automatic focusing device configured to sandwich the optical filter with the protrusion.