JPS6219144A - Eye examination chart projector - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to an optometric chart projector for projecting an optometric chart for measuring the refractive power of an eye to be examined.

BACKGROUND OF THE INVENTION Conventionally, optometric chart projectors for projecting an optometric chart for measuring the refractive power of an eye to be examined onto a screen or the like have been known. As one configuration example, in order to cope with the case where various types of optometry charts are exchanged during measurement, a rotating disk on which many types of optometry charts are arranged along the circumference is driven to rotate by a driving means such as a motor. , there is one that selectively projects a desired optometry chart.

By the way, in this type of device, when rotating the rotary disk to select a desired optometry chart, needless to say,
The selected optometry chart must be accurately positioned and stopped on the optical axis of the projection system.

Therefore, in the known device, a cam recess for positioning is provided on the circumference of the rotary disk corresponding to the position of each optometry chart, and a microswitch that is activated by tightly engaging the cam recess is used to perform one optometry chart. The rotation of the rotating disk is stopped for each chart. In addition, such a device has different cam parts than the above-mentioned four parts in order to determine the origin reference position of the rotating disk in accordance with a specific one of a large number of optometry charts arranged along the circumferential direction. A cam recess of the same shape is provided, and a microswitch is provided which engages and operates the latter cam portion.

Problems to be Solved by the Invention However, in such conventional devices, positioning is performed by engagement between four cam parts formed along the circumference of a rotating disk and a microswitch. However, there have been problems in that it takes time and effort to mold the rotary disk, and that positioning with high precision requires a strong sense of urgency.

Means for Solving the Problems In order to solve the problems of the prior art, the present invention includes a plurality of chart positioning marks arranged on a rotating disk at positions corresponding to each optometric chart, and a plurality of chart positioning marks arranged on a rotating disc at positions corresponding to each optometric chart. A reference positioning mark is provided at a position corresponding to one of the marks, and a detection means for photoelectrically detecting the position of each of these marks is provided. It is characterized in that the driving means for driving the can be controlled.

When the rotary disk is rotated by operating the action operation switch section and the reference positioning mark is photoelectrically detected by the detection means, the rotary disk stops at the origin position and the desired chart positioning mark is detected by the detection means. When detected, the rotating disk stops at a predetermined position.

Embodiment As shown in FIG. 1, a single rotation disc 1 has a large number of optometry charts 2a, 2b, 2c along the circumferential direction of the outermost part.

2d, . . . are arranged at equal intervals, and these optometry charts 2a, 2b, 2c, 2d, .
is used to measure the refractive power of the eye to be examined. Further, on the inner circumferential portion of the rotating disk 1, each optometric chart 2a, 2b is provided.

2c, 2d, . . . as chart positioning marks at positions corresponding to 2c, 2d, . B4・
...is formed. Here, among the slits, the slit S1 is formed longer than the others, and functions as a reference positioning mark. Here, each slit is obtained by forming a vapor-deposited film of a metal such as chromium on the glass substrate of the rotating disk 1 through a mask in the shape of each slit using a vacuum evaporation method.

Each optometry chart 2a, 2b arranged on a rotating disk l
.

2e, 2d', . A concave mirror 4 is arranged in front of the illumination light source 3, and a second condenser lens 5, 6 is arranged in front of the illumination light source 3. It consists of a projection lens 7.

In addition, a rotating disk 1 is provided at each slit forming portion of the rotating disk 1.
A light emitting unit 8 and a light receiving unit 9 as a first photoelectric detection unit A are provided on both sides of the photoelectric detection unit A. A light emitting part IO and a light receiving part 11 as a second photoelectric detection part B are provided with the rotating disk 1 in between. Note that each light emitting unit 8. IO
are light sources 8a, 10a and condenser lens 8b, respectively.
, 10b, and each light receiving section 9, 11 includes a condenser lens 9a, lla and a light receiving element 9b, llb, respectively.
Slit-shaped aperture stops 9c, ]], c are provided between the condenser lenses 9a, lla of each of the light receiving sections 9, 11 and the rotating disk 1, respectively.

Note that the rotating disk 1 is attached to a mounting plate 12, and is fixed to this mounting plate 12 by a holding plate 13 and fixing bolts 14, and the mounting plate 12 is connected to a pulse motor 15 as a driving means. The flange joint 16 is fixed to a flange joint 16, and the flange joint 16 is supported by a bearing 17. 18 is a presser spring that applies a predetermined pressing force to the presser plate 13.

FIG. 3 shows the circuit configuration for driving the pulse motor 15 connected to the rotating disk 1. The control circuit 19, which forms the central part of the circuit, is configured using, for example, a microcomputer C.
It is composed of PU. This control circuit 19 includes the aforementioned first and second photoelectric detection units A and B, the illumination light source 3,
A drive circuit 20 for driving the pulse motor 15 and an operation switch section 21 are connected to each. Here, the operation switch unit 21 includes a power switch 22 . Light switch 23. Forward rotation switch 24. and reversing switch 25
contains each.

Next, the operation of the optometry chart projector constructed as described above will be explained based on the program shown in FIG. 4. When the program starts running and the power switch 22 is turned on, turn on the light switch 23 (Step 10)
1) Put the illumination light source 3 on standby. Thereafter, the drive circuit 20 is activated and the rotating disk 1 starts rotating in one direction, for example, in the forward direction (step 102). Then, first, the photoelectric detection unit A detects the slit S1 at a certain point, and the reference position of the rotating disk 1 is detected (step 103).
. Subsequently, a rotation stop signal for the rotating disk 1 is supplied to the drive circuit 20 (step 104), and at the same time, the illumination light source 3 is turned on (step 105).

Next, in step 106, the rotation direction of the rotary disk 1 is selected, and if the selection is reverse, the reverse switch 25 is turned on (step 107), and a reverse pulse is supplied to the pulse motor 15, and the rotation is started. The disk 1 is inverted (step 108), but the second photoelectric detection section B is connected to the slit S.
When the position of the slit adjacent to slit 1 is detected, the rotating disk 1 is temporarily stopped (step 110).

When this detected slit position is not a predetermined one,
That is, if the chart corresponding to the detected slit position is not the desired one to be projected, step 111
Then, the reversing switch 25 is turned on and the above-mentioned routine is executed. On the other hand, if the chart is the desired one, the ON operation is stopped to stop the rotating disk 1 (step 106), and measurement is started based on the projected chart corresponding to the stopped position.

Note that if the selection at step 106 is normal rotation,
Although the forward rotation switch 24 is turned on, the following operations (steps 112 to 116) can be explained in the same way as in the case of reverse rotation. In addition, in the above embodiment, the optometry charts are arranged at equal intervals along the circumferential direction.
The optometry charts may be freely arranged at different intervals. In this case as well, it is sufficient to provide chart positioning marks and reference positioning marks corresponding to the positions of the respective optometry charts, and there is no need to make any changes to the control circuit or the like.

As described above, according to the present invention, a chart positioning mark and a reference positioning mark are provided on a rotating disk on which a large number of optometric charts are arranged along the circumferential direction, corresponding to the arrangement position of each optometric chart. Since these are provided and configured to be able to be detected photoelectrically, the troublesome molding and poor detection accuracy of conventional detection means based on mechanical engagement can be dramatically improved.

[Brief explanation of drawings]

FIG. 1 is a plan view of a rotating disk according to an embodiment of the present invention;
FIG. 2 is a layout diagram showing the relationship between the rotating disk shown in FIG. 1 and the detection means, etc., FIG. 3 is a circuit diagram for driving the rotating disk shown in FIG. 1, and FIG. 3 is a flowchart illustrating the operation of the circuit shown in the figure. 1... Rotating disk, 7... Projection lens, 15
...Pulse motor, 19...Control circuit, A...
・First photoelectric detection section, B...Second photoelectric detection section, 2a
, 2b, 2cm optometry chart, Sll s2
1 s3...slit.

Claims (7)

[Claims] (1) a rotating disk on which a plurality of optometry charts are arranged along the circumferential direction; a projection means for projecting the optometry chart; and a drive means for rotationally driving the rotational disk;
In the optometry chart projector having an operation switch section for controlling the driving means, the rotary disc has a plurality of chart positioning marks arranged at positions corresponding to each optometry chart, and a plurality of chart positioning marks arranged on the rotating disc at positions corresponding to each optometry chart. A reference positioning mark is provided at a position corresponding to one of the marks, and a detection means for photoelectrically detecting the position of each mark is provided, and a signal from the detection means is used to detect the drive means. An optometric chart projector characterized by being able to control. (2) The chart positioning mark is formed by a slit-like mark arranged along the circumferential direction of the rotating disk and whose longitudinal direction is the radial direction of the rotating disk. The optometric chart projector according to item 1. (3) The optometry chart projector according to claim 2, wherein the reference positioning mark is formed by one slit-shaped mark whose longitudinal direction is the radial direction of the rotating disk. (4) The optometric chart projector according to claim 3, wherein the chart positioning mark and the reference positioning mark are arranged at different distances from the rotation axis of the rotating disk. (5) The optometric chart projector according to claim 4, wherein the chart positioning mark and the reference positioning mark are each obtained by forming a metal vapor deposition film on the substrate of the rotating disk. . (6) The detection means is composed of two sets of photoelectric detection sections, each including a light emitting section and a light receiving section, which are arranged opposite to each other with the chart positioning mark part and the reference positioning mark part of the rotating disk in between. An optometry chart projector according to claim 4 or 5, characterized in that: (7) The optometric chart projector according to claim 6, wherein the light receiving section is configured to receive light from the light emitting section through a slit-shaped opening.