JPH028229Y2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field The present invention relates to an improvement of a switching shutter for a light wave distance meter.

A light wave distance meter uses a light transmission optical system to emit light from a light emitting element such as an LED that is modulated at a certain specified frequency toward a reflector such as a corner cube placed at a measurement point. The light returned from the reflector is imaged onto a light receiving element using a light receiving optical system, then converted into an electrical signal, and the distance is measured by measuring the phase difference between the phase at the time of modulation and the phase at the time of light reception. It is something.

The present invention has made it possible to practically measure long distances and obtain stable distance values at short distances with a simple configuration consisting of an improved switching shutter. It is something.

Prior Art and its Problems The conventional technology will be explained in detail with reference to FIGS. The emitted modulated light is reflected and returned by a reflector 5 such as a corner cube placed at the measurement point.
The light passes through the other side of the transmitting/receiving lens 4, passes through the transmitting/receiving split prism 3, and is focused on the light receiving section 2. (still,
The light passing through the optical path 6 in this manner will be referred to as measurement light hereinafter. ) On the other hand, the light that is output from the light emitting section 1 and reaches the light receiving section 2 via the optical path 7 in order to correct error factors in the measurement electronic circuit section is called correction light, and switching between the correction light and the measurement light is performed by emitting light. This is performed by a disc-shaped switching shutter 8 provided on the front surface of the section 1, and a sixth plate is provided on the plate surface of the switching shutter 8.
As shown in FIG. The light is alternately switched to measurement light and correction light as shown in FIGS. 6a and 6b.

Further, in front of the light receiving section 2, a light amount adjuster 9 is provided, which has two tracks, a correction light track and a measurement light track, each having a concentration gradient, in order to equalize the received light intensities of the correction light and the measurement light. The light amount adjuster 9 is rotated by a motor 9a etc.
The motor 9a and the like are controlled by an electronic circuit (not shown) depending on the relative intensities of the correction light and measurement light.

Here, providing the light amount adjuster 9 with two tracks, a correction optical track and a measurement optical track, is a conventional technique that enables measurement over long distances and stabilizes measurement at short distances. FIG. 7 shows the density gradient of the track of a light amount adjuster according to the prior art. Track A in FIG. 7 is a measurement optical track, and track B is a correction optical track. That is, at short distances, for example, use the part shown in Fig. 7 to equalize the received light intensity at a large amount of light.
Measurements can be made by obtaining stable distance measurement values and, at long distances, by aligning the received light intensity with the amount of measurement light using, for example, the method shown in FIG.

However, such a configuration requires a light attenuator with two concentration gradients in the same member, which is difficult to manufacture even if it is constructed using a density filter or a light aperture. At the same time, the place where this light amount adjuster can be placed is limited, and since the two optical paths are set separately on two adjacent tracks, the track width is narrow, making it difficult to adjust its position and eccentricity. It was hot.

Purpose The purpose of the present invention is to solve these problems in view of the difficulties in manufacturing and adjusting the conventional technology, and to obtain a practical distance measurement value that is stable at short distances and for long distances. The object of the present invention is to provide a switching shutter that enables distance measurement.

Configuration In order to achieve the above object, the present invention provides a switching shutter which is used in a light wave distance meter and switches between the distance measuring optical path and the reference optical path, in which a plurality of correction light apertures are provided in the switching shutter, and each of these apertures is provided. In order to differentiate the amounts of light passing through the correction light apertures, a light amount attenuation member is selectively provided in each of the correction light apertures.

Configuration of Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

FIG. 1 shows a first embodiment of the present invention, and the plate surface of the switching shutter 8 is provided with arbitrary angular intervals, similar to the conventional switching shutter (shown in FIG. 6c). Arc-shaped measurement light slit 11
A correction light slit 12 is provided, but the difference from conventional switching shutters is that, for example, a light amount is provided at a position facing the correction light slit 12 to provide a difference in the amount of light passing through the correction light slit 12. A further correction light slit 13 equipped with a density filter as an attenuation member is provided.

Effects of the Embodiment By using the switching shutter shown in FIG.
1 and a correction light slit 12, and when the measurement light becomes small due to a long distance, the measurement light slit 11 and the correction light slit 13 equipped with a light quantity attenuation member may be used.

Incidentally, the switching of the slits as described above can be easily performed by using a pulse motor or the like as the drive motor 10 and directly controlling it with a microcomputer.
It can also be easily achieved by those skilled in the art by using a solenoid or the like.

FIG. 4 shows a light quantity adjuster using the switching shutter according to the present invention, which is particularly simple and can be arranged freely, as only the measuring light track A is required.
Although there is a difference between the conventional example and the present invention in the attenuation density entering the correction optical path between stepless and two steps, this does not pose a practical problem.

In the first embodiment, the slits are provided at 90° intervals, but depending on the relationship with the drive system, the slits may be provided at any angle.

FIG. 2 shows a case where a net-like light amount attenuation member is used instead of the density filter as the light amount attenuation member in the first embodiment shown in FIG. 1. In addition, it is also possible to use an optical diaphragm, such as one that reduces the measurement light slit width, as a light attenuation member for making the amounts of light passing through each correction light aperture different from each other.

In addition, in order to make the attenuation concentration entering the correction optical path more multi-level, for example, as shown in Fig. 3, measuring light slits are placed at two locations and correction light slits are placed at three locations, and a drive motor that can switch at these angles is adopted. Three-stage switching is now possible, and this indicates that the same can be said for more stages.

That is, in FIG. 3, a light quantity attenuation member having a density different from that of the correction light slits 12 and 13 is attached to the additional correction light slit 15, and distance measurement is performed using the measurement light slit 14 and the correction light slit 15. I can do it.

Effects As described above, according to the present invention, by simply improving the switching shutter used for other purposes, the light amount adjuster only needs a measuring light track, which simplifies manufacturing and reduces the need for the light amount adjuster. The arrangement is flexible, the arrangement and track width can be adjusted easily, and while it is possible to measure long distances, it is also possible to obtain stable distance measurement values at short distances, and its practicality is extremely high. .

[Brief explanation of the drawing]

FIG. 1 is a front view showing one embodiment of the switching shutter for a light wave distance meter according to the present invention, and FIG. 2 is a front view showing another embodiment of the switching shutter for a light wave distance meter according to the present invention. FIG. 3 is a front view showing still another embodiment of the switching shutter for a light-wave distance meter according to the present invention, and FIG. 4 is a front view of a light amount adjuster when the switching shutter for a light-wave distance meter according to the present invention is used. figure,
Fig. 5 is a schematic diagram showing the configuration of a general light wave distance meter, Fig. 6 a and b are sectional views showing the mechanism of a conventional switching shutter, Fig. 6 c is a front view of a conventional switching shutter, and Fig. 6 c is a front view of a conventional switching shutter. FIG. 7 is a front view of a light amount regulator when a conventional switching shutter is used. 8... Switching shutter, 11, 14... Measuring light slit, 12, 13, 15... Correction light slit.

Claims (1)

[Claims for Utility Model Registration] 1. Switching to switch the optical path from the light-emitting element to the light-receiving element to a distance measuring optical path that is reflected by a reflector placed at a measurement point and then reaches the light-receiving element, and a reference optical path that leads directly to the light-receiving element. In a light wave distance meter that is equipped with a shutter and measures the distance to a measurement point from the phase difference between the distance measurement light and the reference light that pass through the distance measurement optical path and the reference optical path, the switching shutter is provided with a plurality of correction light apertures. A switching shutter for a light wave rangefinder, characterized in that a light amount attenuation member is selectively provided in each of the correction light apertures in order to differentiate the amount of light passing through each of the correction light apertures. 2. A switching shutter for a light wave distance meter according to claim 1, wherein the light amount attenuation member is a density filter. 3. A switching shutter for a light wave distance meter according to claim 1, wherein the light quantity attenuation member is a net-like member. 4. A switching shutter for a light wave distance meter according to claim 1, wherein the light amount attenuation member is an optical diaphragm.