Canon Kabushiki Kaisha

Hidejiro Kadowaki

Makoto Takamiya

Shigeki Kato

Yasuhiko Ishida

Ken Tsuchii

Kosuke Yamamoto

Masafumi Wataya

Haruhiko Takahashi

Toshiyuki Yanaka

Ko Ishizuka

Hiroshi Sugiyama

Yasushi Kaneda

Jun Ashiwa

Sakae Horyu

Takayuki Kadoshima

Shinji Ueda

Yasushi Miura

Naoto Kawamura

Takao Aoki

Kou Ishizuka

Naoki Iwami

Yasushi Murayama

Haruhiko Moriguchi

Hisashi Fukushima

Nobuhiko Takekoshi

Masami Izumizaki

Hiroyuki Hagiwara

Naoki Kawamata

Akio Suzuki

Toru Takahashi

Toshiaki Hirosawa

Yoshihiro Takada

Kimio Nakahata

Shunichi Kubo

Kenichi Matsumoto

Akihito Hosaka

Hiroyuki Shiomi

Eiichi Kondo

Tetsuji Tachika

Yasuhide Kurosaki

Kato Shigeki

Akihiro Tomosada

A first beam having high coherence and a second beam having low coherence and having a central wavelength difference from that of the first beam are multiplexed onto the same optical axis. First and second multiplexed beams obtained by beam splitting are emitted at a measurement reflection plane and a reference plane, respectively. The reflected first and second multiplexed beams are multiplexed and interfere with each other. The interference generates a first interference signal that is obtained from the first beams at the interference unit and that relates to information on the distance to the measurement reflection plane and a second interference signal that is obtained from the second beams. The first and second interference signals are used to carry out calculations for determining the position of a measurement origin for the measurement reflection plane.

Absolute position measurement apparatus

A first beam having high coherence and a second beam having low coherence are multiplexed onto the same optical axis. This multiplexed beam is split into first and second multiplexed beams. The first multiplexed beam is directed towards a measurement reflection plane of an object to be measured, and the second multiplexed beam is directed towards a reference plane. The first and second multiplexed beams that are reflected from the measurement reflection plane and the reference plane, respectively, are multiplexed to cause the first beams to interfere with each other and the second beams to interfere with each other. Calculations are carried out to determine a measurement origin on the basis of the first and second interference signals obtained from the first and second beams, respectively.

Interference measuring apparatus having an optical system for dividing a coherent light beam into two light beams, and causing the divided two light beams to pass along discrete optical paths. The light beams are made into linearly polarized light beams orthogonal to each other and given modulation to the phase of the wave front of at least one of them. The wave fronts of the linearly polarized light beams are superposed one upon the others. A light dividing member divides the light beams superposed one upon the other by the optical system into a plurality of light beams. A polarizing plate takes out each light beam with a 45&#xb0; polarized component, and a plurality of light receiving elements individually receive the light beams taken out by the polarizing plate.

Interference measuring apparatus for detecting a plurality of stable phase difference signals

A laser beam is irradiated onto a moving object, and scattered light reflected from the moving object is split into two beams, which are then received through respective spatial filters that are 90&#xb0; out of phase with each other, thereby providing two signals. The signals are processed to determine the movement direction of the moving object.

Movement-direction determination apparatus

Interference measuring apparatus for detecting a plurality of different interference phase signals. The apparatus has a light dividing member for dividing linearly polarized light beams superposed one upon another into a plurality of light beams. The apparatus also includes a light transmitting member with a plurality of light passing portions having different light transmitting properties in conformity with the incidence positions of the plurality of light beams divided by the light dividing member. In addition, the apparatus has a polarizing plate to receive the plurality of light beams that passed through the light transmitting member.

Compact interference measuring apparatus for detecting the magnitude and direction of positional deviation

An optical type encoder includes a light-emitting element, a scale, a light receiving element for detecting light from the scale when a light beam from the light-emitting element is projected onto the scale, an incremental signal resulting from displacement of the scale being obtained by detection by the light receiving element, two or more mark portions for producing an origin signal formed on the scale, and an origin detecting system for detecting the mark portions for producing the origin signal. The rising position or the falling position of at least one pulse signal indicative of the origin is determined by the detection signals of the two or more mark portions for producing the origin signal by the origin detecting system.

Encoder

An interference measuring apparatus has an optical system for dividing a coherent light beam into two light beams, causing the divided two light beams to pass along discrete optical paths and making them into linearly polarized light beams orthogonal to each other and given modulation to the phase of the wave front of at least one of them, and again superposing the wave fronts of the linearly polarized light beams one upon the other, a light dividing member for dividing the light beams superposed one upon the other by the optical system into a plurality of light beams, a rock crystal plate formed with a predetermined level difference in conformity with the incidence positions of the plurality of light beams, a polarizing plate for taking out each light beam transmitted through the rock crystal plate with a 45&deg; polarized component, and a plurality of light receiving elements for individually receiving the light beams taken out by the polarizing plate, a plurality of different interference phase signals being provided by the reception of lights of the light receiving elements.

Optical element used in compact interference measuring apparatus detecting plurality of phase difference signals

An apparatus having a first system for forming a composite light beam of two light beams to be made to interfere with each other, a splitting member for amplitude-splitting the composite light beam into three or more split light beams in the same area, and a second system for obtaining interference light beams of different phases from the plurality of split light beams. Also, an apparatus for effecting information recording on a hard disc drive device comprising an (i) optical system for splitting a light beam into two light beams, causing one of the two light beams to be condensed and reflected by the side of an arm for a recording reading head in the hard disc drive device, and superposing the condensed and reflected light beam on the other light beam to thereby obtain a composite light beam, (ii) a splitting member for amplitude-splitting the composite light beam into three or more split light beams in the same area, (iii) an optical member for obtaining interference light beams of different phases from the plurality of split light beams, (iv) light receiving elements for detecting respective ones of the interference light beams of different phases, (v) a control system for effecting the positioning of the arm on the basis of the result of the detection by each of the light receiving elements, and (vi) a signal writing-in system for writing a signal into a hard disc through the recording reading head each time the arm is positioned.

Interference device, position detecting device, positioning device and information recording apparatus using the same

An apparatus for detecting the relative displacement of a surface to be detected, and an apparatus and method for recording information on a hard disc of a hard disk drive using such a detecting apparatus, the detecting apparatus comprising an interference optical system for condensing a light beam on the surface to be detected, and making the reflected light from the surface to be detected interfere with the condensed light beam to thereby form an interference light beam, light receiving means for receiving the interference light beam and outputting bright and dark signals attributable to the relative displacement of the surface to be detected, and condensed light information supplying means for separating part of the reflected light from the surface to be detected from the optical path until the reflected light arrives at said light receiving means, and utilizing the separated light beam to detect the condensed state of the incident light beam onto the surface to be detected or make the condensed state observable.

Displacement detecting apparatus and information recording apparatus

An interferometer has a semiconductor laser which oscillates in multiple modes, an optical member for providing a beam from the semiconductor laser with a substantial optical path difference between optical paths partially in one beam, and an interference optical system for causing interference, using the beam having traveled via the optical member.

Interferometer which divides light beams into a plurality of beams with different optical paths

An apparatus for detecting the displacement information of an object has a light source, a diffraction grating for diffracting a light beam from the light source so that the light beam diffracted by the diffraction grating is incident on the object, and a photodetector for detecting the light from the object caused upon the incidence of the light beam thereon by the diffraction grating. Information regarding the relative displacement to the object along a predetermined direction is detected on the basis of a light detection signal from the photodetector. The diffraction grating is formed so that the light beam applied to the object may be condensed on the object in a direction in which the relative displacement to the object cannot be detected by the signal from the photodetector.

Displacement information measuring apparatus with hyperbolic diffraction grating

An apparatus for detecting position change information of an object includes a contact member for contacting the object, and a detecting unit for obtaining position change information of the object by detecting a change in force applied from the object to the contact member.

Position detecting apparatus, positioning apparatus, and information

An apparatus records information on a hard disk with a magnetic head arm provided in a hard disk drive. The apparatus comprises an interference measuring system, containing an outgoing portion for a measuring light beam to the arm and a reference light forming portion, for obtaining relative displacement information with respect to the arm by interfering the reference light with reflected light of the measuring light from the arm or a slider belonging to the arm, the interference measuring system having a light beam deflecting member for deflecting the measuring light and thus guiding the measuring light to a lateral surface of the arm or of the slider, a control system for generating a signal for positioning the arm with respect to the hard disk on the basis of the relative displacement information obtained by the interference measuring system, and a signal system for transmitting a signal for recording information on the hard disk to the magnetic head.

Information recording apparatus

A recording apparatus employs a control unit to compensate for any variations in the feed speed of a recording medium. The recording apparatus includes a recording unit for recording an image on a recording medium in accordance with the image data; a speed detection unit for detecting the actual feed speed of the recording medium or of a feed unit for feeding the recording medium; and a control unit for controlling the record timing of the recording unit in accordance with a difference between a reference feed speed and the actual feed speed of the recording medium or feed unit detected by the speed detection unit.

Recording apparatus with compensation for variations in feeding speed

A Doppler velocimeter determines a state of noise generation in a detection signal including a Doppler signal component based on comparison by a preceding/succeeding-signal comparator for comparing the detection signals before and after passing through a band-pass filter for cutting noise adjusted to the frequency of the detection signal, and/or includes a filter circuit for determining passage/interruption of the detection signal after passing through the band-pass filter from a relationship between the count value of a first counter, in which the output of a first frequency multiplier for multiplying the frequency of the detection signal by N is made to be a clock signal and a leading edge in the detection signal is made to be a reset trigger, and a leading edge in the detection signal, and/or includes an error signal generator for generating an error detection signal by detecting a periodic error in the detection signal after passing through the band-pass filter from a relationship between the count value of a second counter, in which the output of a second frequency multiplier for multiplying the frequency of the detection signal by N and a leading edge in the detection signal is made to be a reset trigger, and a leading edge in the detection signal after passing through the band-pass filter, and/or includes a phase comparator for generating a control signal by comparing the phase of the detection signal with the phase of a comparison signal to be compared, an oscillator for controlling the frequency of its output signal in accordance with the control signal from the phase comparator, and a comparison-signal generation unit for generating a comparison signal based on the output of the oscillator. When an error has been detected, a switching unit interrupts the control signal and the phase comparator is reset and stops comparison, and when the error has ended, the switching unit communicates the control signal, the phase comparator starts comparison, and the comparison-signal generation unit generates a comparison signal whose phase coincides with the phase of the detection signal.

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Yokohama, Japan

Hidejiro Kadowaki