Canon Kabushiki Kaisha

Yasuhiko Ishida

Makoto Takamiya

Hidejiro Kadowaki

Hiroshi Sugiyama

Jun Ashiwa

Shigeki Kato

Shinji Ueda

Ken Tsuchii

Kosuke Yamamoto

Masafumi Wataya

Toshiyuki Yanaka

Haruhiko Takahashi

Naoki Kawamata

An angular division apparatus for circumferentially dividing a rotating object into a plurality of areas by using Doppler pulses includes an optical head for applying a beam emitted from a light source unit to a rotating object and detecting Doppler pulses based on a shift of the frequency of the light scattered from the rotating object, and a counting unit for counting the Doppler pulses output from the optical head to determine the number of pulses for one revolution of the rotating object. The number of Doppler pulses for one revolution is divided by a division number for dividing the rotating object into a plurality of areas in the angular direction. The rotating object is divided into a plurality of areas in the angular direction thereof by using the number of Doppler pulses per divided area.

Apparatus for detecting rotational displacement information of a

A velocimeter includes a light source for irradiating light onto an object to be measured, a light-receiving element for receiving scattered light from the object and outputting a light-receiving signal upon receiving the scattered light, a signal processing circuit for obtaining velocity information of the object to be measured by performing signal processing of the light-receiving signal output from the light-receiving element, a bandpass filter arranged in the signal processing circuit and having a function of passing frequency components near the frequency of the light-receiving signal to be obtained when the object to be measured is in a still state, and a switch arranged in the signal processing circuit to activate the bandpass filter substantially in the signal processing circuit when the moving velocity of the object to be measured is low.

Velocimeter, signal processing method, and driving system using the same

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.

Doppler velocimeter and various kinds of apparatuses for signal

This invention has as its object to provide a frequency tracking method, a frequency control apparatus (tracking apparatus) using this method, and a Doppler velocity meter using the same, which easily and quickly allow the center frequency of a band pass filter to coincide with the frequency of an input signal even when an input signal suffers from a large level drift. A tracking method for a center frequency of a band-pass filter relates to a method including the deviation information detection step of detecting deviation information of the frequency of a signal to be input to the band-pass filter or a signal output from the band-pass filter with respect to the center frequency of the band-pass filter, the deviation information detection step including at least the step of detecting the deviation direction, and the changing step of changing the center frequency of the band-pass filter on the basis of a detection result in the detection step of detecting the deviation information including the deviation direction, thereby adjusting the center frequency of the band-pass filter to coincide with the frequency of a signal to be filtered through the band-pass filter.

Frequency tracking method and apparatus, and Doppler velocity meter

In an apparatus wherein a recording medium is conveyed by a conveying system with the front surface of the recording medium opposed to recording heads and information is recorded on the recording medium by liquid droplet jet, a first speed meter is provided on the back side of the recording medium and further, a second speed meter for detecting liquid droplet jet speed together with the first speed meter is provided at a predetermined location, whereby the recording position is adjusted. The first and second speed meters may preferably be optical Doppler velocimeters which will not cause any speed detection error with fluctuation of the wavelength of a light source.

Information recording apparatus

A Doppler velocimeter includes an illuminating system for projecting a light beam for measurement onto an object to be measured at a predetermined working distance, and a light-receiving system for receiving light from the object illuminated with the light beam by the illuminating system. Information relating to a speed of the object is detected by a Doppler shift of the light received by the light-receiving system. The Doppler velocimeter further includes a changing device for changing the working distance of the illuminating system.

Doppler velocimeter

A position information detection apparatus includes a first detection system for radiating two collimated light beams onto an object to be measured at a predetermined crossing angle to form interference fringes at a predetermined interval, and detecting scattered light emanating from the object to be measured by the interference fringes at the predetermined interval, a second detection system for radiating two light beams onto the object to be measured at a predetermined crossing angle to form interference fringes having a gradient with each other in an opposing direction to the object to be measured, and detecting scattered light emanating from the object to be measured by the interference fringes having the gradient, and a detection unit for comparing output signals from the first and second detection systems, and detecting relative position information, along the opposing direction of the first and second detection systems, of the object to be measured.

Doppler velocimeter and position information detection apparatus for use

A doppler velocimeter determines the velocity of an object moving through a beam intersection area by using a doppler frequency obtained by detecting light from the beam intersecting area. The doppler velocimeter includes: a light source; a diffraction grating for diffracting light received from the light source; first and second lens systems for transmitting diffracted light from the diffraction grating to irradiate a portion of a movable object to be examined, the first and second lens systems having the same focal length F; and a detector device for receiving light from the portion of the object irradiated with the light which has been transmitted through the first and second lens systems and for obtaining a doppler signal used for velocity determination. The interval between the first and second lens systems is twice as long as the focal length F. Spherical aberration caused by a portion of the first lens system through which the diffracted light travels is offset by spherical aberration caused by a portion of the second lens system through which the diffracted light travels. This simple construction achieves equidistant interference fringes over the beam intersection area.

Displacement information detecting apparatus and doppler velocimeter

An apparatus for detecting velocity of an object, includes a light source for generating light having a wavelength .lambda., a light-transmission block for receiving the light from the light source, and guiding the light onto the object, and a photosensor for detecting the light from the object on which the light from the light-transmission block is incident. The light-transmission block is integrally constituted by a diffraction grating for diffracting the light from the light source to produce two diffraction lights, and an optical element for causing the two diffraction lights from the diffraction grating to be incident onto the object at a predetermined incident angle. The diffraction grating and the optical element are arranged so as to have substantially constant sin.theta./.lambda. independently of a change in wavelength .lambda. of the light from the light source where .theta. is the incident angle of each diffraction light onto the object. A velocity of the object is detected through detection by the photosensor.

Displacement information detection apparatus

An apparatus for detecting the velocity information of an object comprises a light source; optical system for irradiating beam from the light source, which is provided with a first lens or lens group and a second lens or lens group having an identical focal distance which are arranged apart from each other substantially two times such focal distance along the direction of the optical axis, to irradiate the beam onto the measuring object through the first and second lenses or lens group, and the optical system being arranged so as to make the value of sin .theta./.lambda. substantially constant where .theta. is the incident angle of the beam irradiated onto the measuring object and .lambda. is the wavelength of the beam; and detector for detecting the scattering rays of light from the measuring object irradiated by the above-mentioned optical system to detect the velocity information of the measuring object. With the constituents thus arranged, the apparatus is capable of effectively preventing the deviation of the intersecting position of the beams irradiated on the measuring object to perform a high-precision detection of the velocity information at all times.

Doppler velocimeter having a diffraction grating and dual lens groups

An apparatus for detecting the speed information of an object comprises a light source device, a frequency shifting device for shifting the frequency of a light flux from the light source device, a light-flux dividing device for dividing a light-flux whose frequency is divided by the frequency shifting device, one of the divided light fluxes divided by the light-flux dividing device being projected onto an object to be measured and the other light flux being projected in a direction other than that of the one of the light fluxes, a first detection device for detecting light from the object to be measured to which the one of the light fluxes is projected, the light detected by the first detection device having undergone a Doppler shift proportional to the speed of the object to be measured, a second detection device for detecting the other light flux, and a speed information detection device for detecting the speed information of the object to be measured on the basis of the comparison between the detection results of the first and second detection devices.

A Doppler velocity meter has a radiation source for emitting a radiation beam the wavelength of which fluctuates, such as a laser; an optical system for directing the radiation beam to an object at an incident angle .theta. and a detector for detecting scattered beam generated from the object by directing the radiation beam. The optical system has a diffraction grating which serves to change the incident angle .theta. in accordance with a change in the wavelength .lambda. of the radiation beam in such a manner as to maintain the value of sin .theta./.lambda. substantially constant. The velocity meter can accurately detect the velocity of movement of the object regardless of any change in the wavelength .lambda., because the diffraction grating serves to substantially compensate for any change in the frequency of the scattered beam caused by the change in the wavelength.

Doppler velocity meter

An apparatus for detecting the velocity information of an object comprises the irradiation optical system for performing the irradiation of beam to the predetermined position on an object to be measured; the photodetector for detecting the light from the irradiated object by the irradiation optical system, the velocity information being obtained by the detection; the detector for detecting the irradiating state for detecting the deviation of the irradiating position of the beam on the object to be measured; and the adjuster for adjusting the irradiating state of the beam on the object based on the detection result of the detector for detecting the irradiating state. With such constituents as above, the apparatus is capable of dealing with the fluctuation of the lightning to obtain a high-precision detection of the velocity information at a high speed.

This invention is characterized in that a light beam from a light source is made to enter a diffraction grating and .+-. nth-order (n=1,2, . . . ) diffracted lights from the diffraction grating are made to enter a moving object at an angle substantially equal to the angle of intersection of the angles of diffraction of the two diffracted lights from the diffraction grating. As a result, the two diffracted lights are converged by a lens system provided between the diffraction grating and the light source on the moving object and intersect with each other. Scattered light subjected to Doppler shift by the moving object is detected by photodetector thereby detecting the velocity information of the moving object.

Growing community of inventors

Tokyo, Japan

Yasuhiko Ishida