JP4953660B2 - Photoelectric encoder - Google Patents

Description

  The present invention relates to a photoelectric encoder. In particular, the present invention relates to an improvement in a photoelectric encoder having a telecentric optical system in which a lens and an aperture are inserted between a main scale and a light receiving element.

  As described in Patent Document 1, as shown in FIG. 1, a lens 42 and an aperture 44 serving as a telecentric optical diaphragm are disposed between a main scale 20 and, for example, a light receiving element array 34 constituting a light receiving unit 30. A lens optical system (telecentric optical system) 40 is inserted and the distances a and b between the lens 42 and the scale 21 of the main scale 20 and the light receiving elements 35 on the light receiving element array 34 are adjusted as shown in FIG. Thus, a photoelectric encoder that can set the magnification is considered. In FIG. 1, 10 is a light source, and f is a focal length of the lens 42.

  In the photoelectric encoder using the telecentric optical system 40, an image on the main scale 20 is projected onto the light receiving element array 34 through the lens optical system (42, 44). Here, by arranging the aperture 44 at the focal position of the lens 42, even if the distance (gap) between the main scale 20 and the lens 42 varies, the positional relationship between the lens 42, the aperture 44, and the light receiving element array 34 varies. Otherwise, the magnification fluctuation of the image formed on the light receiving element array 34 can be suppressed. Particularly, when the lens array 46 is used as the lens 42 as shown in FIG. 3 (optical path diagram) and FIG. 4 (perspective view), the lens 42 is reduced in size and the field of view on the scale (FOV) is enlarged. Can do.

JP 2004-264295 A

  However, when a photoelectric encoder is configured with such a lens array 46, as shown in FIGS. 3 and 5, there is a problem that an image is divided and inverted for each lens optical system. It was.

  This problem becomes a big problem particularly in the absolute type that needs to reproduce not only the image pattern but also the accurate shape.

The present invention has been made to solve the above-mentioned conventional problems, and can maintain the pattern and shape of the image without complicating the optical system, and can be used not only for the incremental type but also for the absolute type. and challenge is to provide a possible photoelectric encoder.

The present invention provides a lifting one photoelectric encoder of the optics Les Nzuarei is inserted between the main scale and a light receiving element, the light receiving element interchanged connection array outputs, divided-inverted by the lens array by electrically re-reversed image is obtained by solving the previous SL challenges.

  The lens array is a two-dimensional lens array, and two-dimensional measurement is possible.

  Further, by providing an aperture at the focal position of each lens array, light from the adjacent lens can be blocked.

According to the present invention, it is possible to maintain the pattern and shape of the image without complicating the optical system by electrically re-inverting the image inverted by the lens array , and not only the incremental type. , Ru can also be used in the absolute type.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

In the first reference embodiment, as shown in FIG. 6, in an incremental photoelectric encoder having a lens array 46, the arrangement pitch (referred to as a lens pitch) Pl of each lens constituting the lens array 46 is set to the main scale 20. This is matched with a natural number multiple of the period Ps.

In this reference embodiment, as shown in FIG. 7, be reversed image is divided for each individual lens, because the pattern is guaranteed, as long as used as an incremental type, trouble free.

  Further, as in the modification shown in FIG. 8, the telecentric optical system 40 in which the aperture 44 is disposed at the focal position of each lens constituting the lens array 46 can be used.

Next, the second reference embodiment will be described in detail with reference to FIG. 9 (optical path diagram) and FIG. 10 (perspective view).

This reference embodiment, the same second lens array 48 and lens array 46 (also a first lens array referred to), the focal point is inserted in the opposite direction to come to the focus of the first lens array, the optical system 50.

In this reference embodiment, since the lens array 46 and 48 are the same ones, it can be almost completely inversely corrected by the second lens array 48 aberration exit side of occurring in the first lens array 46 of the entry side Even in the case of using a lens array that is inexpensive but has large aberrations, the aberration can be canceled almost completely and the signal detection efficiency can be greatly improved.

  Further, as in the modification shown in FIGS. 11 and 12, the optical system 50 may be a double-sided telecentric optical system 51 in which the aperture 44 is disposed at the focal position of each lens constituting the lens arrays 46 and 48. it can.

Next, a first embodiment of the present invention will be described in detail with reference to FIG.

  In this embodiment, in an absolute type photoelectric encoder having a lens array 46, the connection of the output of the light receiving element array 34 is exchanged in units of pixels to electrically reinvert the image.

  Further, as in the modification shown in FIG. 14, the telecentric optical system 40 in which the aperture 44 is disposed at the focal position of each lens constituting the lens array 46 can be used.

Next, a second embodiment of the present invention will be described in detail with reference to FIG.

  In this embodiment, in an absolute type photoelectric encoder having an optical system 50 composed of lens arrays 46 and 48, the output of the light receiving element array 34 is switched in units of pixels to electrically reinvert the image. It is a thing.

According to the present invention , an absolute type can be realized without complicating the optical system.

  Further, as in the modification shown in FIG. 16, the optical system 50 can be a double-sided telecentric optical system 51 in which the apertures 44 are arranged at the focal positions of the individual lenses constituting the lens arrays 46 and 48.

Next, a third reference embodiment of the present invention will be described in detail with reference to FIG.

This reference embodiment, the absolute type photoelectric encoder having an optical system 50 composed of lens arrays 46 and 48, out of the first, second lens array 46, 48 and the same third lens array 52 an optical system 50 And the image is optically re-inverted.

  Further, as in the modification shown in FIG. 18, the optical system 50 is a double-sided telecentric optical system 51 in which apertures 44 are arranged at the focal positions of the individual lenses constituting the lens arrays 46 and 48, and the lens array. The aperture 54 can be disposed at the focal position of each lens constituting the lens 52.

Next, the fourth reference embodiment will be described in detail with reference to FIG.

This reference embodiment is an absolute type photoelectric encoder having an optical system 50 composed of lens arrays 46 and 48, and includes an optical system including a third lens array 52 and a fourth lens array 56 having the same configuration as the optical system 50. A system 60 is provided on its exit side to reinvert the image.

In this reference embodiment, since it uses the same optical system at the outlet side and inlet side, it can be shared components.

  Further, as in the modification shown in FIG. 20, the optical system 50 is a double-sided telecentric optical system 51 in which the apertures 44 are arranged at the focal positions of the individual lenses constituting the lens arrays 46 and 48, and the optical system 60. Alternatively, a double telecentric optical system 61 in which an aperture 54 is disposed at the focal position of the individual lenses constituting the lens arrays 52 and 56 may be used.

Next, the fifth reference embodiment will be described in detail with reference to FIG.

This reference embodiment is the same photoelectric encoder as the third reference embodiment shown in FIG. 18, and the focal length f ′ of the third lens array 52 is set to the focal length f of the first and second lens arrays 46, 48. As a result, the total optical length is shortened, and the air gap between the main scale 20 and the entrance lens array 46 is secured, and the size can be reduced.

That is, if the focal length f of the main scale 20 and the distance between the entry-side lens array 46 (equivalent to air gap) = incoming side lens array 46, as in the third reference embodiment, the first to third lens array When the same lens is used, the optical total length L≈8f, whereas in this reference embodiment, the optical total length L ′ = 4f + 4f ′ <8f, and the optical total length can be shortened.

Next, the sixth reference embodiment will be described in detail with reference to FIG.

This reference embodiment is the same photoelectric encoder as the fourth reference embodiment shown in FIG. 20, and the focal lengths f ′ of the third and fourth lens arrays 52 and 56 are set to the first and second lens arrays 46, The total optical length is shortened to be smaller than the focal length f of 48, and miniaturization is possible while ensuring an air gap between the main scale 20 and the entrance lens array 46.

That is, if the focal length f of the main scale 20 and the distance between the entry-side lens array 46 (equivalent to air gap) = incoming side lens array 46, as in the fourth reference embodiment, the first to fourth lens arrays When the same lens is used, the optical total length L≈8f, whereas in this reference embodiment, the optical total length L ′ = 4f + 4f ′ <8f, and the optical total length can be shortened.

Next, the seventh reference embodiment will be described in detail with reference to FIG.

In this reference embodiment, an absolute type photoelectric encoder having an optical system 50 including lens arrays 46 and 48 is provided, and a plurality of small mirrors 70 having the same arrangement pitch as the lenses of the lens arrays 46 and 48 are provided. Optically re-inverted.

  Further, as in the modification shown in FIG. 24, the optical system 50 can be a double-sided telecentric optical system 51 in which the apertures 44 are arranged at the focal positions of the individual lenses constituting the lens arrays 46 and 48.

Next, the eighth reference embodiment will be described in detail with reference to FIG.

In this reference embodiment, in an absolute photoelectric encoder having an optical system 50 composed of lens arrays 46 and 48, a mirror 80 for re-entering the light exiting the lens array 48 on the exit side into the optical system 50; The image is optically re-inverted by including a half mirror 82 for taking out light that has passed through the optical system 50 twice in the direction of the light receiving element array 34.

  Further, as in the modification shown in FIG. 26, the optical system 50 can be a double-sided telecentric optical system 51 in which the aperture 44 is disposed at the focal position of each lens constituting the lens arrays 46 and 48.

Note that all of the above embodiments can be applied not only to the absolute type but also to the incremental type.

  The present invention can be applied to both an index grating and a light receiving element that are separated, and a light receiving element array in which both are integrated. Furthermore, the present invention can be applied not only to a transmission type encoder but also to a reflection type encoder.

The perspective view which shows the principal part structure of the photoelectric encoder using a telecentric optical system Same top view Optical path diagram showing conventional problems Same perspective view Same top view Optical path diagram showing a main configuration of a first reference embodiment The figure which shows the principle of the 1st reference form The figure which shows the modification of 1st reference form Optical path diagram showing a configuration of a main part of the second referential embodiment Same perspective view The figure which shows the modification of 2nd reference form Same perspective view FIG. 1 is an optical path diagram showing the main configuration of the first embodiment of the present invention. The figure which shows the modification of 1st Embodiment. Optical path diagram showing the configuration of the main part of the second embodiment of the present invention. The figure which shows the modification of 2nd Embodiment. Optical path diagram showing main configuration of third reference embodiment The figure which shows the modification of 3rd reference form Optical path diagram showing main configuration of fourth reference embodiment The figure which shows the modification of 4th reference form Optical path diagram showing main configuration of fifth reference embodiment Optical path diagram showing main configuration of sixth reference embodiment Optical path diagram showing main configuration of seventh reference embodiment The figure which shows the modification of 7th reference form Optical path diagram showing main configuration of eighth reference embodiment The figure which shows the modification of 8th reference form

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Light source 20 ... Main scale 30 ... Light-receiving part 31 ... Light-receiving surface 34 ... Light-receiving element array 40 ... Telecentric optical system 44, 54 ... Aperture 46, 48, 52, 56 ... Lens array 50, 60 ... Optical system 51, 61 ... Telecentric optical system on both sides 70 ... Small mirror 80 ... Mirror 82 ... Half mirror

Claims (3)

In a photoelectric encoder having an optical system Les Nzuarei is inserted between the main scale and a light receiving element,
The light receiving element interchanged connection of the output of the array, photoelectric encoder is characterized in that electrically re invert the split-inverted image by the previous sharp Nzuarei. The photoelectric encoder according to claim 1, further comprising an aperture at a focal position of at least one of the lenses constituting the lens array. The photoelectric encoder according to claim 1 or 2, wherein the lens array is a two-dimensional lens array.

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