JPS584398B2 - encoder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an encoder in which a light emitting element and a light receiving element are arranged on the outer peripheral surface of a code wheel.

Generally, measuring instruments and the like display their measured values on a numerical wheel type display.

On the other hand, an automatic weighing method has been developed in which the weighing value from a nearby measuring device is electrically read from a remote location instead of visually.

The number wheel type display used in this automatic weighing system is required to be able to output the displayed digits of each number wheel as an electrical signal.

For this reason, in conventional numeric wheel type displays, for example, a multi-contact changeover switch that is linked to each numeric wheel is provided, and the switch switches the resistance value or voltage, etc., and the resistance value or voltage value is detected. The displayed numbers are readable.

However, in such a numeric wheel type display, the multi-contact changeover switch acts as a load, so a large torque is required to advance the numeric wheel, which causes a problem of negative errors in the micrometering range.

Additionally, the reliability of the switching contacts in the multi-contact switch was low, making it difficult to guarantee performance over time.

On the other hand, as a means for detecting the rotational position of the rotating body, a light emitting element is arranged on one side of a code disk having an optical code pattern, and a plurality of light receiving elements are arranged on the other side to receive light passing through the code pattern of the code disk. It is conceivable that an encoder is provided to obtain a code signal representing the rotational position of the code disk from the light-receiving element, and the code disk is rotated in synchronization with a rotating body.

According to this means, no particular load is applied to the rotating body, and aging does not pose any particular problem.

Therefore, it is conceivable to use such means to read the rotational position of the number wheel, that is, the displayed number, but since the number wheel type display device has a number wheel with many digits, the above-mentioned code disk is not suitable. It is difficult to provide each number wheel with an encoder, which requires a light emitting element and a light receiving element to be arranged on both sides, in other words, it requires a large space, and has not been put to practical use.

This invention was made in view of these circumstances, and it is sufficient to arrange a light emitting element and a light receiving element around the outer periphery of a code wheel corresponding to a code disk, and no special space is required in the axial direction of the code wheel. In this way, a large number of code wheels can be arranged adjacent to each other in the axial direction like the number wheels of a number wheel type display, and an encoder suitable for reading the numbers displayed on the number wheel is provided.

Embodiments of the present invention will be described below with reference to the drawings.

In the figure, reference numeral 11 denotes a fixed shaft, and this fixed shaft 11 rotatably supports the code wheel 12 and non-rotatably supports the light shielding frame 13.

The code wheel 12 is a cylindrical code wheel made of a light-transmitting synthetic resin, such as a transparent synthetic resin, located at the center of one side of a light-shielding plate 14 made of a non-light-transmitting synthetic resin, for example, a black synthetic resin. The main body 15 is integrally immersed.

The light shielding plate 14 has a gear portion 16 formed on its outer periphery, which meshes with a carry pinion of the numeric wheel type display.

Further, the light shielding plate 14 has a cylindrical protrusion 17 embedded in the code wheel body 15 at the center of one side thereof, and protrudes radially from the circumferential surface of the protrusion 17, and the protruding end is attached to the code wheel body 15. A light-shielding wall 1 that exactly matches the outer peripheral surface
8a, 18b, 18c, and 18d are provided protrudingly.

These light-shielding walls 18a, 18b, 18c, and 18d are located within the virtual lines 0, 1, 2, 3, 4, 5, 67, 8, and 9 that divide the code wheel body 15 into 10 equal parts, as shown in FIG. It is located on lines 2, 4, 6.9.

Therefore, on the outer circumferential surface of the code wheel main body 15, as shown in FIG.
An optical code pattern 21 is formed which includes a light-shielding part 19 where the end faces of 8c and 18d are located and a light-transmitting part 20 where the end face is not located.

The light-shielding frame 13 is made of a non-light-transmitting synthetic resin, for example, a black synthetic resin, and has a fitting recess 22 formed in the center of one side thereof, and the code wheel body is inserted into the fitting recess 22. 15 are rotatably fitted.

The light shielding frame 13 has a light projecting window 24 and light receiving windows 25a, 25b in a peripheral wall portion 23 surrounding the outer peripheral surface of the code wheel main body 15.
, 25c, and 25d are provided.

The light projection window 24 is located on the outer peripheral surface of the code wheel body 15 on the edge side, that is, even if the code wheel body 15 rotates, the light shielding portion 1
It is provided at an axial position facing only the light-transmitting portion 20 without facing the light-transmitting portion 9 .

The light receiving windows 25a, 25b, 25c, and 25d are formed on the outer peripheral surface of the code wheel body 15 on the light shielding plate 14 side, that is, when the code wheel 15 rotates, the light shielding part 19 and the light transmitting part 2
0 and is provided at an axial position selectively opposite to 0.

Furthermore, the light projection window 24 is provided at a position in the circumferential direction that coincides with the imaginary line 5 in a state where the number wheel interlocking with the light shielding plate 14 through the pinion is externally displaying the display number "0". , the light receiving windows 25a, 25b, 25c, and 25d are distributed and provided at positions in the circumferential direction that coincide with the virtual lines 8, 6, and 4.2, respectively.

With such a configuration, the code wheel main body 15 diffusely reflects the light that enters the interior from the transparent portion 20 on the outer circumferential surface, and radiates it to the outside from the fully transparent portion 20 on the outer circumferential surface. The light emitted by the light emitting diode 26 from the light projection window 24 into the code wheel main body 15 through the transparent portion 20 on the outer circumference thereof is radiated to the outside from the entire transparent portion 20 on the outer circumference of the code wheel 15.

Therefore, each phototransistor 27a, 27b, 2
7c, 27d, light receiving windows 25a, 25b loaded with it
, 25c, and 25d face the transparent portion 20, light from the light emitting diode 26 enters through the code wheel body 15.

By the way, since the code wheel main body 15 moves clockwise in FIG. 2 in conjunction with the number wheel, each light receiving window 2
5a, 25b, 25c, and 25d selectively face the light-shielding portion 19 and the light-transmitting portion 20 on the outer periphery of the code wheel body 15 in response to changes in the displayed numbers on the number wheel.

Therefore, as shown in the electric circuit in FIG. 4, if the light from the light emitting diode 26 is made to enter the phototransistors 27a, 27b, 27c, and 27d through the code wheel body 15, the displayed number on the number wheel, in other words, the Each phototransistor 27a, 27b, 27c,
27d selectively receives or does not receive light,
producing a change in its output level.

Therefore, each output A of each phototransistor 27a, 27b, 27c, 27d in response to a change in the number displayed on the number wheel,
If the output level changes of B, C, and D are tabulated with the logic level "0" when light is received and the logic level "1" when no light is received, the following output table is obtained.

Therefore, as is clear from this output table, by combining the outputs of the phototransistors 27a, 27b, 27c, and 27d, different code signals can be obtained for the numbers "0" to "9" displayed on the number wheel. Can be done.

In other words, it is capable of outputting a code signal representing the displayed number on the number wheel.

Moreover, such a code signal can be converted into a normal decimal signal indicating "0" to "9" or a binary coded decimal signal by using a logic conversion circuit 28 as shown in FIG. It can be easily converted.

Therefore, if the light emitting diode 26 is made to emit light and the code signals output from the phototransistors 27a, 27b, 27c, and 27d are detected, the numbers displayed on the number wheels can be easily read.

Moreover, since the configuration is such that the light emitting diode 26 and the phototransistors 27a, 27bt27c27d are arranged around the outer periphery of the code foil main body 15 via the light shielding frame 13, the arrangement space for the light emitting diode and phototransistor is taken up by the code wheel. Since it is not necessary to provide it on both sides of the main body 15, that is, the code wheel 12,
Since a plurality of code wheels 12 can be arranged adjacent to each other in the axial direction, it is suitable for reading the displayed numbers on each number wheel of a number wheel type display having a plurality of number wheels adjacent to each other in the axial direction.

Note that the above explanation was about reading the display position of the number wheel on a number wheel type display, but it is not limited to this and can also be used to read the rotational position of other rotating bodies, such as the rotation of the pointer on a pointer scale type display. It can also be applied to position reading, etc.

Further, in the above embodiment, a single light emitting element is provided at a different axial position from the light receiving element, but for example, two light emitting elements may be provided, at least one of which always faces the transparent part of the outer peripheral surface of the code wheel. If this is done, the light receiving element may be provided in the same axial position as the light receiving element.

Furthermore, in the embodiment described above, a plurality of light receiving elements are arranged at different positions in the circumferential direction around the outer periphery of the code wheel. In other words, the light-emitting elements and the light-receiving elements may be arranged in the axial direction with their circumferential positions aligned, as shown by dotted circles 26, 27a, 27b, 27c, and 27d in the figure.

[Brief explanation of drawings]

Fig. 1 is a vertical sectional view showing an embodiment of the present invention, Fig. 2 is a sectional view taken along the line ■-■ in Fig. 1, Fig. 3 is a developed view of the code pattern portion of the same embodiment, and Fig. 4 is a FIG. 5 is a circuit diagram showing an example of a logic conversion circuit for converting a code signal according to the same embodiment, and FIG. 6 is a developed diagram showing another example of the code pattern. 0 to 9...Virtual line, 11...Fixed axis,
12... Code wheel, 13... Light blocking frame, 14... Light blocking plate, 15... Code wheel body, 17... Protrusion, 18a-18
d... Light-shielding wall, 19... Light-shielding sound 20
......Transparent part, 21... Code pattern, 22... Fitting recess, 23... Peripheral wall,
24... Floodlight window, 25a-25d...
Light receiving window, 26... Light emitting element, 27a to 27d.
·····Light receiving element.

Claims (1)

[Claims] 1. An optical code pattern consisting of a light-transmitting part and a light-blocking part is formed on the outer circumferential surface, and light incident from a part of the light-transmitting part is diffusely reflected internally to form a completely transparent part. A code wheel that emits light to the outside from the code wheel, a light shielding frame fixedly provided around the outer periphery of the code wheel, a light emitting window and a plurality of light receiving windows provided in the light shielding frame, and a light transmitting window that emits light from the light transmitting window into the code wheel. a light emitting element that emits light through a transparent portion on the outer peripheral surface of the code wheel; and a light emitting element that receives light emitted from the transparent portion of the outer peripheral surface of the code wheel through the light receiving window, and 1. An encoder comprising a plurality of light receiving elements that output a code signal representing a rotational position. 2. The encoder according to claim 1, characterized in that the code wheel rotates in synchronization with the number wheels of a number wheel type display so that the numbers displayed on the number wheel can be read.