JPH0627654B2 - A device that optically detects the position and speed of a moving object - Google Patents

Description

The present invention relates to a moving body or rotating body detecting device used for a speed or position control motor or the like, and is particularly suitable for optical detection. Shape, manufacturing method, and apparatus.

[Conventional technology]

Conventionally known methods for detecting the position and speed of a moving body are roughly classified into a method using a magnetic encoder and a method using an optical encoder. The present invention relates to optical encoder methods.

The optical encoder method is composed of a light emitting / receiving unit and a measuring disk. A thin SUS material is used for the measuring disc, and it is generally manufactured by precision press punching or etching, and the one described in Japanese Utility Model Laid-Open No. 63-33409 corresponds to this.

[Problems to be Solved by the Invention]

Also in the above-mentioned conventional technique, when the slit width and the pitch of the disc for measuring the rotation angle are wide (large), press punching is easy, mass productivity is high, and there is no problem in cost. However, if the slit width and pitch of the disk are too narrow, a highly accurate precision press die is required, and if it is too tight, it is inevitable to rely on chemical etching, and mass productivity is extremely reduced.

Therefore, of course, there was a problem that the cost was high.

The object of the present invention is to optimize the rotational angle measuring disc by establishing a product shape and a manufacturing method for plasticizing the disc for rotation angle measurement, and at the same time to give the slit part a lens effect to obtain an inexpensive and highly precise disc. To provide a simple rotation angle measuring device.

[Means for Solving the Problems]

The above objectives are to make the material of the measuring disc cheap plastic, to automate the molding, to improve the pitch accuracy by giving the slit part a lens effect, and to clarify the transmission of light and the blocking of light. It is achieved by doing.

As one specific configuration, it comprises a light projector, a light receiver optically opposed to the light projector, and a movable body placed movably in an optical path emitted from the light projector, and the movable body alternates with the movable body. A light-transmitting portion that transmits light and a light-shielding portion that blocks light are provided, and the light transmitted through the light-transmitting portion is received by the light receiver,
In the one that detects the position and speed of the moving body by the output signal from this light receiver, the moving body is made of plastic, and its both surfaces (entrance / emission surface) or a curved surface with a regular pitch on either one of the surfaces, Alternately form a plane that is sufficiently narrower than this curved surface, and receive the light collected by this curved surface section at the light receiver,
This is converted into an electric signal, and the position and speed of the moving body is optically detected, which is characterized in that the light is shielded by the plane portion.

[Action]

First, the material of the measuring disk, which is the moving body, is made of plastic material (acrylic, etc.) instead of SUS material, and the disk and the mounting boss are integrated. If the material is transparent,
A film is formed for the purpose of shielding light, and a slit for transmission is provided in the case of an opaque material.

Further, the light input / output surface is not limited to a flat surface, but is formed into a shape suitable for converging the incident light at a desired position, whereby the measurement accuracy of the rotation angle can be improved.

In order to improve the precision of the shape of the disc, we adopted pressure forming, which is premised on low pressure and low strain preforming.

This molding method is suitable for precision molding because the distance that the material flows at the time of high pressure pressurization is short and it is radial with respect to the rotating shaft.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 to 13. The present invention is applicable to both rotating and linear moving bodies, but in the embodiments, an example of rotation will be described for convenience.

First, FIG. 1 shows an embodiment of a disk for measuring a rotation angle according to the present invention, which is used for measuring a rotation angle of a motor for controlling speed and position.

Boss 1 and flange 2 for mounting on the motor shaft
Are integrally molded. The flange 2 is formed with an elongated lens portion 8 having a convex surface arranged radially according to the measurement level. The lens unit 8 has a light source 3 which is irradiated over a plurality of lenses, and a light receiving unit 5 which detects the light of the light collecting unit 4 is arranged on the emission side.

The light source 3 with which the lens portion 8 is irradiated is condensed according to the shape of the lens portion 8 and becomes a multi-condensing line shape, and the light receiving portion 5 detects the light and controls the rotation speed and position of the motor.

FIG. 2 shows an enlarged view of the lens unit 8.

The light source 3 is condensed by passing through the incident surface 6 of the lens unit 8 and the emission surface 7 and forms a linear focus (condensing unit 4). In order to make each lens independent on the emission surface 7. There is a slit, and there is a light shielding portion 9 for preventing the transmission of light.The light receiving portion 5 sequentially detects the light collecting portion 4.

The embodiment of FIG. 3 shows the shape of the lens portion 8 when the light source 3 is parallel light or near parallel light. In this case, the incident surface 6 is a flat surface, and the convex shape of the exit surface 7 causes the condensing portion 4
Then, the light receiving section 5 performs detection. Also in this case, there is a slit on the exit surface 7 side for making each lens independent, and there is a light shielding portion 9 for preventing the transmission of light.

In the embodiment shown in FIG. 4, light-shielding paint is applied to grooves formed at equal intervals in a radial pattern on the upper surface or the lower surface of a transparent disk with integrally formed bosses 1, or the groove is applied to the groove. This is an example in which a reflective film is generated and the light shielding portions 9 and the transmission portions 10 are alternately provided to obtain an optical slit. The light shielding portion 9
When is provided on the side of the emission surface 7, the light is shielded sharply and the detection accuracy can be improved.

In the embodiment shown in FIG. 5, a reflective film is formed on the upper surface or the lower surface of a transparent disk with integrally formed bosses 1 at equal intervals radially.
This is an example in which an optical slit is obtained by forming the irregular reflection film 11 and alternately providing the light shielding portions 9 and the transmission portions 10.
Similarly to the above, when the light shielding portion 9 and the irregular reflection portion 11 are provided on the emission surface 7 side, the light shielding becomes sharp, and the detection accuracy can be improved.

The embodiment shown in FIG. 6 shows the shape of the lens portion 8 using the parallel light or the light source 3 close to the parallel light. The incident surface 6 is a flat surface, grooves are provided at equal intervals in a radial pattern, and the exit surface 7 serves as a convex lens surface to collect light and obtain the light collecting portion 4. The light receiving unit 5 detects the light collecting unit 4. With this shape, the width (D) of the light shielding portion is equal to or wider than the groove width (d) between the lower surface lenses, so that uniform parallel light can be obtained.

In the embodiment of FIG. 7, one side of the rotary disc (flange 2) is
Triangular planes with acute-angled ridges were formed at equal intervals.

The light source 3 projected from the light projecting unit 12 is
It is detected by the light receiving unit 5 at a certain point. At other points and in the low reflection portion, the light source 3 does not enter the light receiving portion 5. In the above description, the high reflection portion 13 and the low reflection portion 14 may be both high reflection surfaces, not an absolute condition.

The embodiment shown in FIG. 8 is a method of applying light-shielding paint to the flange 2. A paint residue 16 is provided between the end surface of the boss 1 and the flange 2, and the light-shielding paint 15 is dripped into the recess. At this time, since the flange 2 is kept rotating, the dropped light-shielding paint 15 flows into the light-shielding portion 9 by centrifugal force, and the application is completed.

The embodiment of FIG. 9 shows the shapes of the light-shielding portion 9 and the transmitting portion 10. In order to easily and accurately process the mold pieces when molding the measurement disk,
The shape of the transmissive portion 10 is parallel to the normal line of the disc.

Even when the piece is machined by surface polishing or the like, the running direction of the grindstone is simple, and high-precision machining is easy. However,
The shape of the light shield 9 is fan-shaped.

The example of FIG. 10 shows a method for forming a measuring disk. First, a low-pressure preformed blank is supplied into a mold and compression molded. In this method, there is no trace of the gate (material inflow), the material flow 17 is radial from the axial center, and the back direction and internal strain in the material are uniform.

The embodiment shown in FIG. 11 is an example in which a measuring disk is molded by using a light-shielding material 18, and slits 19 for allowing light to pass through are radially provided at equal intervals.

In the embodiment shown in FIG. 12, the light collecting portion 4 and the light receiving portion 5 of the measuring disk are used.
This is an example in which the distance between the lens unit 8 and the light receiving unit 5 is adjusted for the purpose of adjusting the detection sensitivity of. In this case, the light source 3, the entrance surface 6, the exit surface 7, and the light blocking portion 9 are the same.

In the embodiment of FIG. 13, by providing an appropriate diffraction grating 20 on the surface of the flange 2, diffracted light of the light source 3 is generated, and multi-orders such as diffracted 0th order light 21 and diffracted ± first order light 22 are generated. This is an example in which a minute rotation angle is detected and counted by detecting light.

In the embodiment of FIG. 14, the light receiving portion 5 is provided in the flange 2 where the light shielding portion 9 and the light transmitting portion 10 alternately pass, and the plurality of light receiving element patterns 23 accurately formed therein. . By sequentially detecting the light transmitted through the transmissive portion 10 or condensed, it is possible to make fine counting or to increase the pitch of the transmissive portion. In this example, since the light receiving element pattern 23 is shifted by δ, the resolution (minimum detection pitch) is δ.

〔The invention's effect〕

As described above, according to the present invention, firstly, the movable body is made of plastic, and a curved surface is formed on both sides (entrance / emission surface) or one of the surfaces by regular pitches, and the width is sufficiently wider than this curved surface. Narrow flat surfaces are alternately formed, and the light collected by this curved surface is received by the photoreceiver, converted into an electrical signal, and shielded by the flat surface, so accurate detection and resolution can be improved. Moreover, since the plastic does not require ultra-precision machining such as etching, the machining is extremely simple.

Furthermore, since the coating material is applied to the groove portion (flat surface portion), the boundary between the transmitting portion and the light shielding portion can be clearly distinguished, the light can be accurately detected without interference, and the malfunction can be prevented.

[Brief description of drawings]

FIG. 1 is a perspective view of a measuring disk according to an embodiment of the present invention, and FIG.
The figure is an enlarged perspective view of the same lens portion, FIG. 3 is the same side view, and FIG.
5 and 5 are the same plan view and sectional side view, FIG. 6 is the same side view, FIG. 7 is the same side view, FIG. 8 is the same perspective view, FIG. 9 is the same plan view, and FIG. , FIG. 11 is the same perspective view, FIG. 12 is the same side view, FIG. 13 is the same side view, and FIG. 14 is the same plan view. 1 ... Boss, 2 ... Flange, 3 ... Light source, 4 ... Condensing section, 5 ... Light receiving section, 6 ... Injection surface, 7 ... Exit surface, 8 ...
… Lens section, 9 …… Light blocking section, 10 …… Transparent section, 11 ……
Diffuse reflection part, 12 ... Projection part, 13 ... High reflection part, 14 ...
… Low reflection part, 15 …… Shading paint, 16 …… Paint stay, 1
7 ... Material flow, 18 ... Shading material, 19 ... Slit, 20 ... Diffraction grating, 21 ... Diffraction zero-order light, 22 ...
Diffraction ± first-order light, 23 ... Light receiving element pattern.

Front page continuation (72) Inventor Tsutomu Fujimoto 1-1-1, Higashi-Taga-cho, Hitachi-shi, Ibaraki Hitachi Ltd. Taga factory (56) References: 57-26008 (JP, U) JP 49-534 (JP, B1) Japanese Patent Publication Sho 51-3191 (JP, B1)

Claims (1)

[Claims] 1. An apparatus for optically detecting the position and speed of a moving body, which has a light projector 12, a light receiver 5, and a moving body movably placed between the light projector 12 and the light receiver 5. The movable body is provided with a large number of lens portions 8 and is made of plastic, the incident surface 6 of the lens portion 8 is formed in a flat shape, and the emission surface 7 is formed in a convex lens surface shape. And a groove-shaped light-shielding portion 9 having a groove width (D) on the exit surface side and a groove width (D) on the incident surface side are provided between the adjacent lens portions 8 (D). ) ≧ (d), which is a device for optically detecting the position and speed of a moving body.