Photoelectric encoder
A kind of encoder and photoelectric technology, which is applied in the direction of instruments, conversion sensor output, measuring devices, etc., can solve the problems such as the low response rate of the encoder that cannot be ignored, and achieve the effect of suppressing the increase of the number and preventing the increase of the junction capacitance
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no. 1 Embodiment approach
[0049] FIG. 1 is a diagram showing a schematic configuration of a photoelectric encoder 1 according to the first embodiment. The present embodiment takes the structure of a photodetector chip included in the light receiving unit as a main feature, and as a prerequisite for its understanding, the photoelectric encoder 1 will be described. First, the structure of the encoder 1 is explained. The encoder 1 is composed of a light emitting diode (LED (light emitting diode)) 3, a scale 5 and a light receiving portion 7 arranged in an order adjacent thereto.
[0050] The light emitting diode 3 is an example of a light source, and irradiates the scale 5 with light L from the diode 3. The scale 5 includes a long transparent substrate 9 made of a transparent material such as glass. Figure 1 shows a part of it. The optical lattice 11 is formed on the surface of the transparent substrate 9 opposite to the surface facing the light emitting diode 3 side. The optical lattice 11 includes a plurali...
no. 2 Embodiment approach
[0073] The second embodiment will be described with a focus on the difference from the first embodiment. 7 is a plan view schematically showing the arrangement relationship between one light receiving surface and the calibration grid 33 in the central part 29 of the PD array formed on the light receiving chip 15 of the photoelectric encoder of the second embodiment. Fig. 8 is a plan view of the structure shown in Fig. 7 viewed from the VIII(a)-VIII(b) section.
[0074] In the second embodiment, the light shielding portion 35 of the calibration grid 33 serves as a part of the wiring connected to the photodiode 23. This will be explained in detail below. The light shielding portion 35 is a conductive metal such as aluminum. The four light shielding portions 35 and the wiring 47 arranged on the light receiving surface 25 are located in the same layer. They are formed simultaneously by patterning. The two light-shielding parts 35-1 in the center of the light-shielding part 35 are conn...
no. 3 Embodiment approach
[0079] The third embodiment will be described with a focus on differences from the first embodiment. 9 is a plan view schematically showing the photodiode array of the light receiving chip 15 of the third embodiment viewed from the optical grid side. In this figure, the illustration of the calibration grid is omitted. FIG. 10 is a partial plan view of the light receiving chip 15 of the third embodiment. In this figure, the positional relationship between the light receiving surface 25 and the light transmitting portion 40 of the calibration grid is shown. The grid arranged in front of the light receiving element is called the calibration grid.
[0080] As shown in FIG. 9, the light receiving surfaces 25 of the plurality of PDs 23 are arranged in two dimensions on the xy surface facing each other with the optical grid. In other words, a plurality of PD23 are arranged in an array. It can also be said that the plurality of PDs 23 are arranged in an array in the x direction (that is, ...
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