Mitutoyo Corporation

Mitutoyo Mfg. Co., Ltd.

Mitytoyo Corporation

Seiji Sakagami

Souji Ichikawa

Hideki Oka

Naoyoshi Terao

Toru Yaku

Hiroaki Kawada

Hiroatsu Mori

Mikiya Teraguchi

Shingo Nihommori

Hitoshi Sakamoto

Jynichi Iida

Shigeru Nagashima

An absolute linear encoder includes a plurality of absolute scales aligned in the detection direction with absolute calibrations, a plurality of detectors for detecting the calibrations on the absolute scales, absolute position data generating portions of each scale for generating absolute position data of each detector, and a calculator for outputting an absolute position over the whole length of connected whole absolute scales adding the absolute position data of each detector and the distance between the detectors. The detectors are fixed at such intervals as to simultaneously detect the calibrations of the two absolute scales adjoining in a scale connecting section. Thus, the long absolute linear encoder which is easy to use is realized at low costs.

Absolute linear encoder

A linear scale attachment device for holding and securely attaching a linear scale on an object to be measured is disclosed. The device includes an aluminum base formed with a holding groove having a larger opening than the width of a linear scale that is fitted in this groove, and a retainer for preventing the linear scale fitted in the holding groove from falling off. The base is permanently attached to the object at one location in the lengthwise direction, and resiliently attached at one or more other locations such as to be pressed in the X and Y directions using a cantilever plate spring. While using an aluminum base, the attachment device allows easy attachment and maintenance of the scale and relieves the effect of thermal stress caused by a difference in the thermal expansion coefficient between the aluminum base and the object.

Linear scale attachment device and attachment method

An optical encoder comprises a main scale ( ) having scale gratings ( ) formed thereon with a certain angular pitch along a measurement axis (x ) that describes a circular arc. It also comprises a detection bead ( ) having photoreceptive optical gratings ( ) formed thereon. The detection head is arranged relatively movable along the measurement axis (x ), opposing to the main scale ( ). The photoreceptive optical gratings ( ) on the detection head ( ) have transparent and opaque portions alternately arranged with a certain distance pitch along a straight, grating arrangement axis (x ).

Optical encoder

In an optical encoder using a collimated lighting system, an index scale is inclined toward a main scale by a predetermined value. With this arrangement, a component of variation in the detection signal due to variations in the grating gap can be offset or integrated to be removed from a geometric image of the first grating in the detection signal, whereby the dependence of an S/N ratio of the detection signal on the grating gap can be avoided.

Diffraction-type optical encoder with improved detection signal

In a reflection type encoder having a main scale and an index scale with first and second gratings, respectively, and using a diffusing light source, diffused rays from a point light source are focused by a condensing lens to produce a secondary point light source positioned on a plane defined by the second gratings of the index scale. With this arrangement, a collimator lens can be dispensed with, so that the encoder can be rendered compact in size. Furthermore, the respective elements can be easily supported and positioned.

Diffraction type optical encoder with improved detection signal

In a diffraction type optical displacement encoder using a diffractive light source and having a main scale grating and an index scale grating, a light-receiving element receives two rays satisfying a relationship concerning the lengths of light paths at the rays between the light source and the index scale grating, and the width of the light receiving element, wherein the difference between the path length of each ray is approximately equal to an integral multiple of the square of the pitch of the main scale grating divided by the wavelength of the light source, and the width of the light receiving element, measured as the distance between the impingement points of the two rays at the index scale, is integrally related to the difference in ray path lengths and the angle of the impinging rays due to an offsetting of the light-receiving element. In a second aspect of the invention, two light-receiving elements receive two rays satisfying a similar relationship, and a sum of outputs of the respective light-receiving elements is made to be a detection signal. Or, in an optical encoder using a collimated lighting system, an index scale is leaned (inclined) toward a main scale by a predetermined value. With any one of these arrangements, a component of variation in the detection signal due to a geometric image can be offset or integrated to be removed, whereby the dependence of an S/N ratio of the detection signal on the grating gap can be avoided. Furthermore, in a reflection type encoder using a diffusive light source, diffused rays from a point light source is focused by a condensing lens to produce a secondary point light source and this secondary point light source is positioned in a plane where second gratings corresponding to an index scale are formed. With this arrangement, a collimator lens can be dispensed with, so that the encoder can be rendered compact in size. Furthermore, the respective elements can be easily supported and positioned.

In a linear scale type displacement measuring instrument including: a case fixed to one of relatively movable members; a main scale; a carriage; index scales and a detector; the carriage and the other of the relatively movable members are connected to each other through a connecting mechanism, one end of which is connected to the carriage, the other end of which is connected to the other of the relatively movable members in a location where a section standard length of the main scale is maintained as it is when the main scale is straight, i.e. within the neutral planes of the case as a whole including the main scale mounted, and capable of permitting the carriage to change the posture thereof such that the index scales can be held in a state of perpendicularly intersecting the normal line of the surface of a warp of the main scale.

Linear scale type displacement measuring instrument

In a seal device in a displacement measuring instrument, comprising a hollow case fixed to one member, a connecting rod for imparting a displacement of the other member to a displacement detecting mechanism housed in the hollow case through the opening and seal members disposed at opposite sides of the opening, for shielding a penetrating portion of said connecting rod, to enhance the drip-proof performance, a difference is given between the positions of the forward ends of lip members constituting said seal members, whereby the forward end of the lip member disposed at one side where liquid drops are generated is projected farther than the forward end of the lip member disposed at the other side, and/or a liquid receiving groove extending along the opening is provided at least at one side of the inner surface of the hollow case, liquid drain holes are formed in the bottoms of the liquid receiving grooves, filters for excluding dust intruding from outside are provided in the liquid drain holes, and/or liquid breaking means for precluding a liquid flow intruding from outside of the hollow case are provided on the outer peripheral surface of the connecting rod.

Seal device in displacement measuring instrument

A measuring instrument for measuring the contour of the outer surface of a workpiece. This measuring instrument is of such an arrangement that the tip end of a stylus solidly secured at one end of an arm adapted for rotational movement is brought into contact with the outer surface of the workpiece by a slight pressing force, the arm in this condition is moved in the axial direction thereof, and the displacement of the stylus tracing the irregularities of the outer surface of the workpiece to vertically move due to the abovedescribed movement is converted into the rotational movement of the arm, which is measured by measuring means such as a differential transformer, whereby the contour of the outer surface of the workpiece is measured from the vertical movement of the stylus and the axial (or horizontal) movement of the arm. The arm of the measuring instrument of this type has a dual construction adapted to be held in place by means of springs, wherein a mechanism for detecting the relative movement between these dual arms is provided, whereby a force exceeding a predetermined value applied to the stylus is detected, so that the breakage of the stylus, damages of the object to be measured and the like can be prevented.

Contour measuring instrument

A dust excluding device for a linear scale type measuring instrument which comprises; flexible shield members disposed at opposite sides of an opening formed in a hollow casing along a line of movement of a movable member and having the forward ends thereof being brought into abutting contact with each other; and a neck adapted to locally push open the abutting contact portions of the shield members, for imparting a displacement of the movable member at the outside of said hollow casing to the interior of said hollow casing through said opening; characterized in that the end portions of said neck in the moving directions thereof are each formed into a letter `V` shape, the tip of which obliquely recedes from inside to outside of said hollow casing.

Growing community of inventors

Kawasaki, Japan

Seiji Sakagami