JPS61231516A - Focus adjusting device of image reader - Google Patents

Abstract

PURPOSE:To make focus adjustments with high accuracy by supporting a base which is guided in directions of an optical axis by a couple of guide members for focus adjustments by the guide members at three points and pressing it against one guide member by an energizing member. CONSTITUTION:When a motor 18 for focus adjustment is driven after a slider 15 is moved in the direction of the optical axis for optical variable power a guide (driving) shaft 21 rotates to move forth and back the base 27 through support parts 27a and 27b in the direction of the optical axis, and the distance of a solid-state image pickup element 10 to a reduction optical system 9 is varied to make a focus adjustment. At this time, the base 27 is supported on the guide (driving) shaft 21 at two points and on a guide shaft 22 at one point, i.e. three points in total, so there is no play. The base while pressed axially by a coil spring 34 is pressed radially by coil springs 33 and 33, so a back-lash occurs to neither female screws of the support parts 27a and 27b nor the external screw of the guide (driving) shaft 21.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a focus adjustment device suitable for an image reading device.

(Prior Art) Generally, as shown in FIG. 9, an image reading device illuminates a document placed on a document table glass 2 of a cabinet 1 with an illumination lamp 5 using a reflector 3.4. mirror 6.7
．． 8 to a reduction optical system 9, and the optical system 9 forms an image on a solid-state image sensor 10, and the solid-state image sensor 10 scans the original using a mirror scan method, an original platen scan method, or an original conveyance method. (reads the information and converts it into an electrical signal).

By the way, when variable-magnification reading is performed using an image reading device such as the one described above, it is necessary to perform the variable-magnification process optically, since deterioration in image quality cannot be avoided with electrical variable-magnification processing.

In the case of optical magnification processing, it is sufficient to change the conjugate length of the optical path, but at the same time, it is necessary to change the distance between the reduction optical system 9 and the solid-state image sensor 10 to adjust the focus. .

At this time, the depth of focus of the reduction optical system 9 is very shallow, about ±0.01 aperture, so if a normal focus adjustment device is used,
Due to rattling (backlash of screws, etc.), it was difficult to adjust the focus to an appropriate position.

(Object of the Invention) The present invention has been made in view of the above-mentioned conventional problems, and provides a focus adjustment device that enables highly accurate focus adjustment without rattling in an image reading device. The purpose is to provide

(Structure of the Invention) For this reason, the present invention provides a pair of guide members that support a base of a solid-state image sensor that is opposed to a reduction optical system and guide it in the optical axis direction, and that a pair of guide members are provided on one side of the base. is provided with a support part that is supported at two points on one guide member, and a support part that is supported at one point on the other guide member is provided on the other side of the base. A biasing member is provided to press and bias one of the guide members.

(Embodiments) Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Note that the parts having the same structure and function as those of the conventional device shown in FIG. 9 are given the same reference numerals, and the explanation thereof will be omitted.

As shown in FIG. 8, the reduction optical system 9 and the solid-state image sensor 10
is attached to a slider 15, and by moving the slider 15 in the optical axis direction using a guide rail and a drive mechanism (both not shown), the conjugate length of the optical path is changed,
Optical magnification processing is performed.

The slider 15 has a bottom plate 1 as shown in FIG.
A front substrate 17 on which a reduction optical system 9 is attached in alignment with the optical axis F is provided at the front of the bottom plate 16, and a rear substrate 19 is provided at the rear of the bottom plate 16 on which a focusing motor 18 is attached.

Between the front substrate 17 of the slider 15 and the bracket 20 erected on the bottom plate 16, there are a pair of left and right guide (drive) shafts 21 and an idle shaft 22 (see FIG. 2).

(see FIG. 3) are respectively supported by bearing members 23 and 24, one guide (drive) pongee 21 is formed with a male thread, and the guide (drive) pongee 21 is connected to the motor 18. ing.

On the other hand, the solid-state image sensor 10 has screws 25. ....

25 and is attached to the holding 7 frame 26 in a position adjustable manner;
A base 27 is fixed to the lower part of the holding frame 26.

As shown in detail in FIGS. 2 and 3, one side of the base 27 is provided with support parts 27m and 27b that are supported by the guide (drive) pongee 21 at two points in the front and rear directions. There is.

The support parts 27a, 27b are formed with female threads on the inner half, and the female threads are supported by being screwed into the male threads of the id (driving) pongee 21.

On the other side of the base 27, the lower surface 27c is connected to the guide pongee 22.
Support g27 that is held against and supported at substantially one point
It acts as e.

Therefore, the base 27 is connected to the guide (drive) shaft 21 and the guide shaft 21.
2, it will be stably supported at three points.

A presser spring 28 is attached to a screw 35 on the lower surface 27c of the base 27.
By pressing the pressing spring 28 against the lower surface of the id pongee 22, the base 27 is pressed against the upper surface of the id pongee 22 so that the lower surface 21c7yt of the base 27 does not float upward.

On the lower surface 27c of the base 27, on both sides of the pressing spring 28,
Movable levers 31.31 are each mounted to be movably guided in the width direction by guide pins 29.30, and the movable levers 31, 311i have roller bearings 32.32 that can come into contact with the inner surface of the id pongee 22. and the moving lever 31.31 is provided with the moving lever 31.31.
31a, 31a and id pin 30.30
The coil springs 33, 33 stretched between the guy V
Tsumugi is biased in the 22 direction, and the roller bearing 32°32
comes into contact with the id pongee 22, and the base 27 is urged in the direction of the guide (driving) pongee 21 by the reaction force, and the support parts 27a, 27b
The female thread is pressed against the male thread of the guide (drive) shaft 21 from the radial direction.

A guide (drive) is used to open the base 27 and the front board 17.
The coil spring 34 (see FIG. 1) wound around the pongee 21 is compressed, the base 27 is biased toward the rear board 19, and the female screws of the support parts 27a and 27b are connected to the guide (drive) pongee. It is pressed and biased from the axial direction by the male thread No. 21.

With the above configuration, when the focus adjustment motor 18 is driven after the slider 15 is moved in the optical axis direction to perform optical magnification processing, the guide (drive) shaft 21 is rotated. The base 27 is moved back and forth in the optical axis direction via the supports 27a and 27b, and the distance of the solid-state image sensor 10 with respect to the reduction optical system 9 is changed to perform focus adjustment.

At this time, the base 27 is set at two points by the guide (driving) pongee 21.
Since it is supported by one point of Ido Tsumugi 22, a total of three points, no rattling occurs.

Furthermore, since the base 27 is axially biased by the coil spring 34 and radially biased by the coil springs 33, 33, the female threads of the supports 27a, 27b and the guide ( Drive) No backlash occurs between the male thread of the pongee 21.

Therefore, the solid-state image sensor 10 does not shake or tilt, and does not deviate from the depth of focus not only on the optical axis but also at both ends of the screen, so that focus adjustment can be performed with high precision.

FIGS. 4 and 5 show other embodiments, and the configuration that differs from the embodiment shown in FIGS. 2 and 3 is that the support part 27 on one side of the substrate
A, 27b are formed with female threads around the entire circumference, and the female threads are supported by being screwed into the guide (drive) pongee 21, and the pressing spring 28 is omitted, and a guide is provided on the other side of the board 27. Support part 27 having a horizontally elongated hole 27d that fits into the shaft 22
e is provided.

If the horizontally elongated hole 27d of the support portion 27e is configured to fit into the idle shaft 22, the base 27 is the support portion 27a.

Since it is supported at two points by 27b and supported at one point by the support portion 27e, it is supported more stably at three points.

In addition, the horizontally elongated hole 27d of the support portion 27e allows the ID port 21 to be
, 22 can be made parallel, and installation of the id pongee 21 and 22 becomes easier.

FIGS. 6 and 7 show still another embodiment, and the difference from the embodiment shown in FIGS. 2 and 3 is that the supporting parts 27a and 27b on one side of the base 27 have female threads around the entire circumference. The female thread is supported by being screwed into the id (drive) pongee 21, and only one moving lever 31 is provided in the center of the base 27, and two moving levers are provided on both sides of the moving lever 31. Book pressing springs 28, 28 are provided.

In each of the above embodiments, if the guide (drive) pongee 21 is a guide shaft without a male thread, the accuracy of the back and forth movement of the base 27 is further improved. In this case, a screw shaft may be provided separately, or the base 27 may be moved back and forth using a cam or the like.

(Effects of the Invention) According to the present invention, the base that is guided in the optical axis direction by a pair of guide members for focus adjustment is supported at three points by the guide members, and one of the guide members is supported by the biasing member. When pressed and energized, there is no wobbling, and the focus is adjusted with high precision without deviating from the depth of focus not only on the optical axis but also at both ends of the screen. will be able to do it.

[Brief explanation of the drawing]

FIG. 1 is a side view of the focus adjustment device according to the present invention, FIG. 2 is a front view of the base, FIG. 3 is a bottom view of FIG. 2, and FIG. 4 is a front view of the base of another embodiment. 5 is a bottom view of FIG. 4, FIG. 6 is a front view of the base of another embodiment, FIG. 7 is a bottom view of FIG. 6,
FIG. 8 is a side view of an image reading device incorporating the focusing muscle device of FIG. 1, and FIG. 9 is a side view of a conventional image reading device. 9... Reduction optical system, 10... Solid-state image sensor, 15.
...Slider, 21...Guide (drive) shaft, 22.
・・Guide shaft, 27 ・・・Base, 27a, 27b, 2
7e-Support part, 33.34... Coil spring. Patent applicant: Minolta Camera Co., Ltd. Agent: Patent attorney: Two idiots, Figure 2, Figure 3, Figure 4, Figure 5

Claims (1)

[Claims] (1) A pair of guide members are provided on one side of the base to support the base of the solid-state image sensor that is opposed to the reduction optical system and guide it in the optical axis direction. A support part supported at two points is provided, and a support part supported at one point on the other guide member is provided on the other side of the base, and the base is pressed against one guide member. A focus adjustment device for an image reading device, characterized in that a biasing member for biasing is provided.