JPH0629894B2 - Automatic focus adjustment device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic focusing device that can be used in an optical system of a video camera.

2. Description of the Related Art Conventionally, this type of automatic focusing apparatus is constructed as shown in FIG. 6 or 7. In FIG. 6, light that has passed through a taking lens system 4 including a focusing lens group 1, a zoom lens group 2, a master lens group 3 and the like is an optical path length changing lens 5 and an optical filter as an optical low pass filter. 6 is used to form an image on the solid-state image sensor 7. The optical path length changing lens 5 is held via a thin annular metal plate 8, and annular piezoelectric elements 9a and 9b bonded to both surfaces of the metal plate 8 are driven by a signal from an oscillator 10. Then, the optical path length changing lens 5 vibrates in the direction of the optical axis (A) of the taking lens system 4 by a minute amount, and the optical path length of the light traveling to the solid-state image sensor 7 repeats a slight change. The configuration of the fine movement device is described in detail in Japanese Patent Application Laid-Open No. 60-179710 filed by the present applicant.

An amplifier 11 amplifies the output signal obtained by the solid-state image pickup device 7, and a frequency detector 12 detects a high-frequency signal including a vibration frequency component of the piezoelectric elements 9a and 9b. The phase detector 13 compares the phase of the signal detected by the frequency detector 12 with the phase of the output signal of the oscillator 10, and the control unit 14 detects the direction of defocus, and the solid-state image sensor 7 The focusing lens group 1 is moved to the optical axis by the motor 15 so that the output voltage reaches the peak value.
Focusing is done by moving in the direction of (A).

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

In the apparatus shown in FIG. 6, the solid-state image sensor 7 is fixed and the optical path length varying lens 5 vibrates.
As shown in FIG. 7, there is a structure in which the solid-state imaging device 7 is held by a metal plate 8 having piezoelectric elements 9a and 9b bonded on both sides. In FIG. 7, the same reference numerals are given to those having the same operation as in FIG.

In the case of the device shown in FIG. 7, conventionally, the optical filter 6 and the solid-state image pickup device 7 are different holders 16 and 17 as shown in FIG.
Are attached to the lens barrel 18 at positions separated from each other. Here, in the holder 17, the outer peripheral portion of the metal plate 8 is sandwiched between the holder 17 and the ring 21 screwed into the inner peripheral portion. On the other hand, the tip 19a of the movable side holder 19 is inserted into the hole formed in the center of the metal plate 8, and this tip
The movable side holder 19 is held by sandwiching the circumferential portion of the annular metal plate 8 between the ring 20 screwed into 19a and the movable side holder 19. And this movable holder
A solid-state image sensor 7 is attached to 19.

Problems to be Solved by the Invention In order to reduce the size and weight of the video camera in the conventional configuration as shown in FIGS. 7 and 8, as shown in FIG. 9, the optical filter 6 and the solid-state image sensor are used. It is effective to reduce the size and weight of the optical filter 6 by shortening the interval (l) from the optical filter 6 so that the optical filter 6 enters the optical path at a position near the image plane of the solid-state image sensor 7. However, in the conventional configuration in which the optical filter 6 and the solid-state image sensor 7 are attached to the separate holders 16 and 17, the holder 16 and the holder 17 are the ninth.
As shown in the figure, the above-mentioned interval (l) cannot be sufficiently shortened by making contact.

Further, even if the interval (l) can be shortened, the piezoelectric elements 9a,
The movable holder 19 that is driven by 9b and vibrates in the direction of the optical axis (A) contacts the optical filter 6 to prevent normal vibration of the solid-state imaging device 7.

In addition, there is a conventional optical filter 6 and a solid-state image pickup device 7 integrally held as shown in FIG. 10 (for example, Japanese Patent Laid-Open No. 60-207107). this is,
Rear part of the holder with the solid-state image sensor 7 attached with screws 22
23 is attached to the holder front part 25 with screws 24a and 24b, the optical filter 6 is inserted from the side opposite to the holder rear part 23 attachment side of the holder front part 25, and the holder front part 25 is attached with screws 26a and 26b. The optical filter 6 is sandwiched between the holding plate 27 to be attached and the protrusion 28 of the holder front part 25, but the solid-state image sensor 7 is attached to the holder 29 composed of the holder rear part 23 and the holder front part 25 and the optical filter. Since 6 is attached separately, there is a problem that the number of assembling steps increases.

The present invention relates to an image pickup apparatus for vibrating a solid-state image sensor to perform automatic focusing, in which the distance between the optical filter and the solid-state image sensor can be shortened without disturbing normal vibration of the solid-state image sensor, and the optical filter can be manufactured with a small number of steps. It is an object of the present invention to provide an automatic focus adjusting device capable of assembling an integral part of a solid-state image sensor and Further, deterioration of the focusing control occurs when the focusing control is performed based on the video signal due to the deterioration of the element due to the temperature rise of the solid-state imaging device and the change of the video signal accompanying this deterioration. It is an object of the present invention to provide an automatic focus adjustment device that can improve deterioration of focusing control.

Means for Solving the Problems An automatic focusing apparatus according to the present invention holds an optical filter disposed between a taking lens system and a solid-state image pickup device integrally with the solid-state image pickup device, and the optical filter and the solid-state image pickup device. A vibrating means for vibrating the element in the optical axis direction of the photographing lens system by an electric signal, and a focus configured to detect the shift of the focus by the output signal of the solid-state image sensor and move the lens of the photographing lens system to focus. Means, a portion of the signal means for integrally holding the solid-state image sensor and the optical filter, a movable side holder having a through hole formed in the optical axis direction, and one end side of the through hole of the movable side holder. The solid-state imaging device is brought into contact with the projection formed inward and the surface opposite to the light-receiving surface of the solid-state imaging device, which is locked to cover the opening of the through hole at the other end of the movable-side holder. To release the heat of A member
An optical element which is interposed between the solid-state image sensor and the optical filter, and which is composed of an annular elastic body which is inserted into the through hole of the movable holder together with the solid-state image sensor and the optical filter, and which is mounted on the protrusion. It is characterized in that an annular elastic body is interposed between the filter and the solid-state image pickup device so that the solid-state image pickup device is pressed against the holding member attached to the movable side holder.

Operation According to this configuration, since the optical filter and the solid-state image sensor are integrated, the optical filter vibrates in the same direction as the solid-state image sensor by driving the vibrating device and does not interfere with the vibration of the solid-state image sensor. The distance between the solid-state image pickup devices can be minimized. Furthermore, since the optical filter is sandwiched between the end surface of the solid-state image sensor and the protrusion of the movable-side holder, by fixing the movable-side holder solid-state image sensor, not only the solid-state image sensor but also the optical filter can be fixed to the movable-side holder. The solid-state image sensor is biased by an annular elastic body interposed between the optical filter and the solid-state image sensor and positioned so as not to move, and the solid-state image sensor is pressed against the holding member by the annular elastic body. As a result, the heat of the solid-state imaging device is radiated well through the pressing member.

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

The output signal of the solid-state image sensor 7 is amplified by the amplifier 11, and the high frequency component is extracted by the frequency detector 12. Here, the oscillator 10 oscillates at, for example, 15 Hz, and the high frequency component which is the output of the frequency detector 12 is a waveform modulated at 15 Hz. The oscillation frequency of 15 Hz 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 output of the frequency detector 12 and the output of the oscillator 10 in phase by the phase comparator 13, information on whether the subject is currently in front of or behind the subject is obtained, and based on that, the control unit 14 , The direction of movement of the focusing lens group 1 is determined via the motor 15. Then, a control operation is performed to detect that the result of the phase comparison is in focus at the lens position where the vibration of the solid-state image sensor 7 outputs plus or minus.

FIG. 1 is a vertical cross-sectional view of the main part in one embodiment of the present invention. In FIG. 1, the solid-state imaging device 7 is a movable holder.
It is attached to 30 with screws 31a and 31b. Movable side holder 30
As shown in FIGS. 2 to 4, a through hole 32 is formed along the direction of the optical axis (A), and an annular protrusion 33 is formed at the end of the through hole 32 on the object side. The through-hole 32 is formed in order from the protrusion 33 toward the opposite side to which the solid-state imaging device 7 is mounted, and has a larger diameter than the first accommodating part (a) and the first accommodating part (a). The second housing portion (b) and the third housing portion (c) following the second housing portion (b).

The movable holder 30 has a holder 34 with an annular metal plate 8 having annular piezoelectric elements 9a and 9b attached on both sides.
Is attached to. 35 is a ring screwed onto the outer periphery of the movable side holder 30.
The inner peripheral portion of the metal plate 8 is sandwiched between and. Reference numeral 36 denotes a ring screwed into the inner peripheral portion of the holder 34, and the ring 36 and the holder 34 sandwich the outer peripheral portion of the metal plate 8.

As shown in FIGS. 1 and 5, the assembling procedure is performed by inserting the optical filter 6 into the first accommodating portion (a) from the mounting side of the solid-state imaging device 7 of the movable side holder 30, and then the first accommodating portion (a). An annular rubber packing 38 is placed on the stepped portion 37 at the connection between the portion (a) and the second accommodating portion (b).

Here, the depth L ₁ of the first accommodating portion (a) in the direction of the optical axis (A) is slightly shallower than the thickness L ₂ of the optical filter 6, and the depth L ₁ of the second accommodating portion (b) ( Depth L _{3 in} direction A) is rubber packing 38
Is formed to be shallower than the thickness L ₄ before the assembling.

As described above, the solid-state image sensor 7 is placed in the third accommodation portion (c) of the through hole 32 in which the optical filter 6 and the rubber packing 38 are inserted.
Insert the end face 39 part of the
40 and printed wiring board 41 soldered to this connection pin 40
When the holding plate 42 that is sandwiched by and that also functions as a radiator of the solid-state image pickup device 7 is attached to the end face of the movable side holder 30 with screws 31a and 31b, the rubber packing 38 is stepped at the end face 39 of the solid-state image pickup device 7. The optical filter 6 is elastically deformed by being pressed against the 37 and the optical filter 6, and the optical filter 6 is sandwiched between the annular protrusion 33 of the movable side holder 30 and the end face 39 of the solid-state image sensor 7 via the rubber packing 38 without any gap.

With this configuration, the posture of the optical filter 6 in the movable side holder 30 can be stably maintained only by attaching the solid-state image sensor 7 to the movable side holder 30 with screws 31a and 31b, and the solid-state image sensor 7 is driven by the piezoelectric elements 9a and 9b. Image sensor 7
And the optical filter 6 vibrate together in the direction of the optical axis (A). Further, the solid-state image pickup device 7 is pressed against the holding plate 42 by the rubber packing 38, and the heat of the solid-state image pickup device 7 is radiated well through the holding plate 42, so that the temperature rise of the solid-state image pickup device is suppressed and the focusing control is performed. Can be improved.

In the above embodiment, the optical filter 6 and the solid-state image sensor 7 are vibrated by the vibrating device 43 that vibrates in the direction of the optical axis (A) of the taking lens system 4.
As the vibration device 43, the combination of the magnetic plate and the coil facing the magnetic plate is used as the vibration device 43, while the metal plate 8 and the piezoelectric elements 9a and 9b are described as an example. The configuration in which one of the coils is coupled to the image sensor and the optical filter, or the configuration in which one of the permanent magnet and the coil is coupled to the image sensor and the optical filter by combining the permanent magnet and the coil can be similarly used.

As described above, according to the present invention, the optical filter and the solid-state image sensor are integrally provided, and the optical filter and the solid-state image sensor are vibrated in the optical axis direction of the photographing lens system by the vibrating device. Even if the solid-state image sensor and the solid-state image sensor are brought sufficiently close to each other, the normal vibration of the solid-state image sensor is not disturbed, and the optical filter can be placed near the coupling surface of the solid-state image sensor. Compared to the one on the movable side that vibrates the solid-state image sensor,
The same function can be obtained with a small optical filter, which can contribute to downsizing and weight saving of a video camera or the like.

Furthermore, since the optical filter is sandwiched between the end surface of the solid-state image sensor and the protrusion of the movable-side holder, the solid-state image sensor and the optical filter are integrated with a small number of steps for fixing the solid-state image sensor to the movable-side holder. Can be held in.
Further, the solid-state image pickup element is biased by an annular elastic body interposed between the optical filter and the solid-state image pickup element and positioned so as not to move, and the solid-state image pickup element is further fixed to the pressing member by the annular elastic body. By being pressed, the heat of the solid-state image sensor is radiated well through the pressing member, and the temperature rise of the solid-state image sensor can be suppressed and the deterioration of focusing control can be improved.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of an embodiment of an automatic focusing apparatus according to the present invention during assembly of a mounting portion of a solid-state image sensor,
1 is an enlarged plan view of the holder in FIG. 1 viewed from the mounting side of the solid-state image sensor, FIG. 3 is a sectional view taken along the line XX 'in FIG. 2, and FIG. FIG. 5 is an enlarged plan view seen from the side, FIG. 5 is an exploded perspective view of an integrated portion of an optical filter and a solid-state image sensor, and FIG. 6 is a conventional automatic focus adjustment that vibrates an optical path length changing lens to change the optical path length. FIG. 7 is a configuration diagram of the apparatus, FIG. 7 is a configuration diagram of a conventional automatic focusing device that vibrates a solid-state image sensor to change the optical path length, and FIG. 8 is a vertical cross-sectional view of a mounting portion of the solid-state image sensor in FIG. FIG. 9 is a vertical sectional view when the optical filter of FIG. 8 is brought close to the solid-state image sensor side, and FIG. 10 is a vertical sectional view of a conventional example in which the optical filter and the solid-state image sensor are integrally held. 4 ... Photographing lens system, 6 ... Optical filter, 7 ... Solid-state imaging device, 30 ... Movable side holder, 31a, 31b ... Screw, 32 ... Through hole, 33 ... Projection part, 34 ... Holder, 37 ... Step part, 38 ... Rubber packing [annular elastic body], 39 ... End surface of solid-state imaging device 7, 42
... pressing plate, 43 ... vibrating device, (A) ... optical axis, (a) ... 1st accommodation part, (b) ... 2nd accommodation part, (c) ... 3rd accommodation part.

Claims (1)

[Claims] 1. An optical filter (6) disposed between a taking lens system and a solid-state image sensor (7) is integrally held with the solid-state image sensor (7), and the optical filter (6) and the solid-state image sensor are held together. A vibrating means for vibrating the element (7) in the optical axis direction of the photographing lens system by an electric signal, and a deviation of the focus from the output signal of the solid-state image sensor (7) are detected, and the lens of the photographing lens system is moved to move the focus. Focusing means configured to match, the portion of the vibrating means that integrally holds the solid-state image sensor (7) and the optical filter (6), a through hole (32) is formed in the optical axis direction. The movable side holder (30), a protrusion (33) formed inward at one end side of the through hole (32) of the movable side holder (30), and the other end side of the movable side holder (30) A retainer that is locked to cover the opening of the through hole (32) and contacts the surface of the solid-state image sensor (7) opposite to the light-receiving surface to radiate the heat generated by the solid-state image sensor (7). Material (42)
And is inserted between the solid-state imaging device (7) and the optical filter (6) and inserted into the through hole (32) of the movable side holder (30) together with the solid-state imaging device (7) and the optical filter (6). Annular elastic body
(38), the solid-state imaging by inserting an annular elastic body (38) between the optical filter (6) mounted on the protrusion (33) and the solid-state imaging device (7). An automatic focus adjusting device configured to press the element (7) against a holding member (42) attached to the movable side holder (30).