Canon Kabushiki Kaisha

Yasuyuki Ishikawa

Yoshimi Kohayakawa

Isao Matsumura

Shigeo Maruyama

Reiji Hirano

Takashi Masuda

Toshio Sakane

An ophthalmic apparatus has an objective optical system opposed to an eye to be examined. First and second photodetectors are provided on the substantially conjugate plane of the iris of the eye to be examined with respect to the objective optical system when the operating distance to the eye to be examined is appropriate. The photodetectors detect the image of the iris of the eye to be examined and the image of the pupil of the eye to be examined, respectively, and a detecting device compares the output of the first and second photodectors and detects the state of alignment with the eye to be examined.

Ophthalmic apparatus

An eye refractive power measuring apparatus having a unit for projecting a plurality of index images onto the fundus of an eye to be examined, a unit for detecting the eye fundus reflected light beams of the index images correspondingly to each measuring meridian direction, a unit for operating the refractive power of the eye on the basis of the output of the detecting means, a unit for moving a fixation target for fixing the eye to be examined thereto or the projection system thereof in the direction of the optic axis, and a unit for controlling the movement speed of the fixation target or the projection system thereof on the basis of the degree of variation in the result of the measurement of the operated refractive power of the eye which results from the movement.

Eye refractive power measuring apparatus

An ophthalmic instrument for effecting eye measurement with an eye-measuring target mark projected onto an eye to be examined, includes a photodetector provided at a position optically conjugate with the position of the corneal reflection image of the eye-measuring target mark to thereby determine the quality of the accuracy of alignment with the eye to be examined.

Ophthalmic instrument

An eye examining instrument comprises examining means disposed to project an examining light to and receive the light from the eye of a person to be examined; a casing for encasing said examining means; a beam splitter disposed on the outside of said casing for directing the examining light to the eye to be examined, said beam splitter having sufficient width to allow both eyes of the person to be examined to see a fixation object and being directly opposed to the eye to be examined; and a cover connected with said casing for preventing any undesirable light from coming into said beam splitter.

Eye examining instrument

An eye-refractometer includes an objective optic having a first optical path, an apertured mirror for dividing the first optical path into a second optical path and a third optical path, a mask disposed in the second optical path and having linear marks orientated in at least three directions, a radiation source for illuminating the mask, a mask disposed in the third optical path and having liner detecting areas orientated in at least three directions and photocells arranged behind the respective areas. Improvements in this eye-refractometer comprise an apertured plate disposed between the apertured mirror and one of above said masks and an annular apertured plate disposed between said apertured mirror and the other mask. Another improvement is found in that the length of the linear detecting area is shorter than the length of optimum focused images of the linear marks.

Auto eye-refractometer

In an apparatus having a ray generator for directing measuring rays through a first optical path, a light-receiving portion for receiving the measuring rays reflected by the eye fundus through a second optical path, and a uniting device for uniting the first and second optical paths to form a third optical path, and also having movable lens groups in each of the first and second optical paths or a movable lens group in the third optical path, and wherein the movable lens groups or group is moved along the optical path to measure the refractive power of the eye from signals corresponding to the positions of the movable lens groups or group and the signal of the light-receiving portion, the movable lens groups or group is made into an afocal system to prevent the dimensions of the pupil from being varied and a collimator for collimating the principal rays is fixedly disposed on that side of the movable lens groups or group which is adjacent to the eye to be examined.

Apparatus for measuring the refractive power of the eye

An automatic eye-refractometer includes a projector for projecting a test pattern onto the fundus of an eye to be examined, a photo-electric device disposed to receive an image of the test pattern reflected upon the fundus of the eye, a calculator for calculating the refractive power of the eye using outputs from the photo-electric device and a processor for processing the results of the calculation into digital video signals. The eye-refractometer is further provided with a video camera for image picking up the front part of the eye through an objective lens of the projector to produce video signals and a video display device for displaying on a screen a picture produced from the video signals. With the measuring apparatus, the examiner can observe the image of the front part of the eye to be examined and can properly arrange the eye and the objective lens to each other while watching the picture displayed on the screen. By putting the digital signals into the video display device from the processor there are also displayed on the screen numerals, characters or other symbols informing of the refractive power of the examined eye.

Automatic eye-refractometer

An eye refractometer is provided with a projection optical system for projecting test beams forming test patterns such that the central ray of each test beam passes through the pupil of the eye to be inspected while being spaced apart from the optic axis in order to form test patterns corresponding to three meridians forming 60.degree. with each, a focusing lens disposed in the projection optical system and movable only in one direction during one measurement, and a beam detecting device for detecting the reflected images of the test patterns by the retina of the eye and generating electrical signals corresponding to the three meridians.

Eye refractometer

An apparatus for driving a reel-to-reel system in which the tape web such as magnetic sound tape for a player-recorder and film strip for a cine camera is wound onto one reel from another is provided with means forming part of a motion transmitting mechanism for imparting constantly changing driving torque to the reel driving means during the reeling operation. The driving torque control mechanism is provided with a movable member responsive to an insertion and a removal of a tape cassette into and from a cassette chamber and arranged to move it into and out of operative relationship with the motion transmitting mechanism respectively.

Growing community of inventors

Kawaguchi, Japan

Yasuyuki Ishikawa