JPH0731361B2 - Focus holding device such as micro reader - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention automatically sets a focused state (called a focused state) in a microreader, a microreader printer or the like (referred to as a microreader). A device for holding.

(Prior Art) Conventionally, in a micro reader or the like, focus adjustment was manually performed each time.

(Problems to be Solved by the Invention) However, in recent years, as the magnification of microfilm has increased,
In addition, since a zoomable lens has been developed, high-precision focusing has become necessary, and even if the focus is adjusted once, it is likely to get out of focus and the focus is adjusted manually each time. There is a problem that the work is complicated and time-consuming.

On the other hand, various autofocus devices have been proposed for cameras, video cameras, etc., but in the case of a micro reader, etc., an extremely high standard is required because the numerical aperture is small on the image side, and therefore it is extremely complicated. It becomes expensive, and there is a problem that there is a limit to the space in which the optical system of the automatic focusing device can be arranged.

In view of the above problems, the present invention provides a micro reader or the like which, once adjusted to the in-focus state, automatically keeps the in-focus state thereafter to save the effort of focus adjustment, and has a simple structure and can be implemented at low cost. An object is to provide a focus holding device.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a lens for projecting an image, a distance measuring unit for detecting a distance to a microfilm, and a distance measuring device linked with the movement of the lens. An interlocking mechanism for moving the unit, a storage unit for storing the output signal of the distance measuring unit at the time of focusing, a driving unit for adjusting the lens position, a signal from the storage unit and a signal from the distance measuring unit. In comparison, it has a control circuit for controlling the driving means.

(Operation) In the above configuration of the present invention, the distance measuring unit moves in conjunction with the lens for projecting an image by the interlocking mechanism, so that the positional relationship between the distance measuring unit and the microfilm used for projection is the same. Since the distance is maintained, the distance measuring unit can properly measure the distance between the projection lens and the microfilm at any time without any special manual operation of the projection lens, no matter how the position of the projection lens is adjusted. Can be kept automatically.

In such a state, when the projection lens is manually adjusted to the in-focus state, an output signal relating to the distance between the projection lens and the microfilm from the distance measuring unit at this time is stored by the storage means, By the function of the control means, the output signal from the distance measuring section at that time is compared with the stored signal and the drive means for adjusting the position of the projection lens is controlled. The position of the projection lens is changed, the holding state of the microfilm changes when the microfilm is moved for searching, etc., or the microfilm is replaced with a different thickness. Even if there is, by adjusting the position of the lens so that the output signal from the distance measuring unit at that time and the stored signal always match, Can continue automatically maintains the in-focus position between.

In addition, focus adjustment is performed by moving only the projection lens and distance measuring unit that are interlocked by the interlocking mechanism, and there are fewer moving parts than when moving as a whole with the projection lens and distance measuring unit held together. can do. Further, compared to the case where the focus state is maintained only by the distance measurement information from the distance measurement unit that works in conjunction with the lens and the focus state is determined on the projection image plane, the configuration of the optical system and signal processing is increased. Since it is simplified, it is small and inexpensive.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. 1 to 7.

First, the overall structure of the microreader printer 1 will be described with reference to FIG. 3. The light from the light source 2 is projected on the microfilm 3, and the image thereof is the lens unit 4, the first mirror 5, the reader second mirror 6, and the reader. The image is projected on the screen 8 via the third system mirror 7. The reader system second mirror 6 is displaced so as to be out of the optical path system, and the image is projected onto the photoconductor 11 via the printer system second mirror 9 and the printer system third mirror 10, and the microfilm 3 It is configured to print images.

The lens unit 4 is configured to adjust the position of a projection lens that projects an image via a cam or the like (not shown) by rotating the focus gear 4a,
As shown in FIGS. 1 and 4, it is supported by a lens holder 12. A drive pinion 14 mounted on a drive motor 15 via an intermediate gear 13 is meshed with the focus gear 4a. Further, the focus gear 4a
Is configured to be meshed with the moving gear 16b of the distance measuring device 16 and to move the measuring unit 16a which constitutes the distance measuring unit of the distance measuring device 16 in conjunction with the movement of the lens unit 4.

Here, the moving gear 16b forms an interlocking mechanism that moves the measuring unit 16a in conjunction with the movement of the projection lens of the lens unit 4 in this embodiment (hereinafter referred to as the movement of the lens unit 4). As a result, the measuring unit 16a is interlocked with the movement of the lens unit 4 by the moving gear 16b, and the measuring unit 16a has the same positional relationship as the lens unit 4 with respect to the microfilm 3 used for projection. Four
No matter how the position is adjusted or how the position is changed, the measuring unit 16a is positioned at a position corresponding to the distance between the lens unit 4 and the microfilm 3 at that time without any special manual operation. Automatically kept.

The distance measuring device 16 is configured to detect the distance to the microfilm 3 by the measuring part 16a, and its output signal is inputted to the control circuit 17 as shown in FIG. Storage means 18 is connected to the circuit 17. The output signal of the control circuit 17 is input to the drive circuit 19 of the drive motor 15. The control circuit 17 and the storage means 18
Is composed of a one-chip microcomputer 20.

When the focusing end button (not shown) is pressed, the control circuit 17 stores the output signal from the distance measuring device 16 at that time.
The signal input from the distance measuring device 16 is compared with the signal stored therein, and the distance between the lens and the microfilm 3 is changed so that the input signal does not match the stored signal. In this case, by outputting a control signal to the drive circuit 19 to operate the drive motor 15 and rotate the focus gear 4a of the lens unit 4 to adjust the lens position, the lens in the in-focus state is obtained. The distance between the micro film 3 and the micro film 3 is held, and the input signal and the memory signal are matched.

As shown in FIGS. 4 and 5, the distance measuring device 16 is configured such that the measuring unit 16a can adjust the position in the arrow A direction by the feed screw mechanism 21 in conjunction with the rotation of the focus gear 4a. ing. As shown in FIG. 6, the measuring unit 16a projects light from a light emitting source 22 such as an LED onto the microfilm 3 via a light projecting lens 23 and detects the reflected light via a light receiving lens 24 for position detection. The position detecting element 25 is configured to be incident on the element 25, and the output signal of the position detecting element 25 is changed according to the light receiving position. Therefore, when the distance L between the lenses 23 and 24 and the microfilm 3 changes, the light receiving position of the position detecting element 25 changes, and the output signal from the position detecting element 25 changes. As shown in FIG. 7, this output signal is converted into a position signal proportional to the distance L between the lenses 23 and 24 and the microfilm 3 by the position signal generation circuit 26, and is converted via the A / D converter 27. It is configured to output to the microcomputer 20.

Next, the operation will be described. First, a manual operation button (not shown) is pressed to release the automatic control state, and the focus gear 4a is manually operated so that the image of the microfilm 3 is projected on the screen 8 in a focused state. Then, when a focusing end button (not shown) is pressed, the previous storage means is reset, and then the distance measuring device corresponding to the distance between the lens and the microfilm 3 in the focused state.
The output signal from 16 is stored in the storage means 18. And
Thereafter, the output signal from the distance measuring device 16 is compared with the signal stored in the storage means 18, and if they do not match, a control signal is output from the control device 17 to the drive circuit 19 to drive the drive motor 15. The focus gear 4a is actuated to rotate, and the distance between the lens and the microfilm 3 in the focused state is automatically maintained.

When the lens is replaced, the manual operation button is pressed again to bring the lens into the in-focus state manually, and then the in-focus end button is pressed to keep the in-focus state.

The present invention is also effective for maintaining focus in an overhead projector in which the screen position is often not constant.

(Effect of the Invention) According to the focus holding device such as the micro reader of the present invention, the distance measuring unit moves in conjunction with the lens for projecting an image, so that the positional relationship between the distance measuring unit and the microfilm is projected. The positional relationship between the lens and the microfilm is kept the same, and no matter how the projection lens is adjusted, the distance between the projection lens and the microfilm can be properly adjusted without any special manual operation. It is possible to automatically maintain the state in which distance measurement is possible, and the output signal from the distance measurement unit that is stored when the lens is manually adjusted to the in-focus state and the output signal from the distance measurement unit at that time. The lens position is adjusted so that it always matches, and the lens is automatically held at the focus position with the manually adjusted micro film. The focus state with the film does not go mad and becomes a problem, the holding state of the microfilm changes when the microfilm is moved for searching, etc.,
This is convenient because it eliminates the need to readjust the in-focus state, including the case where the microfilm is replaced with one having a different thickness.

In addition, focus adjustment is performed by moving only the projection lens and distance measuring unit that are interlocked by the interlocking mechanism, so compared to the case where the projection lens and distance measuring unit are integrally held and moved as a whole In addition, compared to the case where the focus state is maintained only by the distance measurement information from the distance measurement unit linked with the lens and the focus state is determined on the projection image plane, Since the configuration of the signal processing is simplified, it can be made small and inexpensive.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a main part of an embodiment of the present invention, FIG. 2 is a control block diagram thereof, FIG. 3 is a side view showing an overall schematic configuration of a microreader printer, and FIG. 4 is a front view thereof. , Fifth
FIG. 6 is a schematic configuration diagram of the distance measuring device, FIG. 6 is an explanatory diagram of the measurement principle of the distance measuring device, and FIG. 7 is a control block diagram of the distance measuring device. 1 ... Micro reader printer 3 ... Micro film 4 ... Lens unit 15 ... Drive motor (driving means) 16 ... Distance measuring device 16a ... Measuring unit (distance measuring unit) 16b ... Moving gear (interlocking mechanism) 17 ... Control circuit 18 ... Storage means 19 ... Drive circuit (drive means)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akika Hamada 2-30 Azuchi-cho, Higashi-ku, Osaka-shi, Osaka, Osaka, Osaka International Building Minolta Camera Co., Ltd. (72) Kazuyuki Yoshida Azuchi-cho, Higashi-ku, Osaka-shi, Osaka 2-30, Osaka Osaka Building Minolta Camera Co., Ltd. (56) References JP 62-262811 (JP, A) JP 59-172619 (JP, A)

Claims (1)

[Claims] 1. A lens for projecting an image, a distance measuring unit for detecting a distance to a microfilm, an interlocking mechanism for moving the distance measuring unit in association with movement of the lens, and the distance measuring unit at the time of focusing. And a drive unit for adjusting the lens position, and a control circuit for comparing the signal from the storage unit with the signal from the distance measuring unit to control the drive unit. A focus holding device such as a micro reader.