Tokyo Kogaku Kikai Kabushiki Kaisha

Kigaku Kikai Kabushiki Kaisha

Taketoshi Ishihara

Yasuo Kato

Ikuo Kitao

Yoshinori Oana

Mitsugu Aoki

Shinji Wada

Shinzi Wada

Yoshikazu Konishi

Yosiaki Watanabe

Yuji Sugahara

A visual acuity testing apparatus is herein disclosed which comprises a test chart displayer having a display surface pointing to an upward direction; a first reflector, for downwardly reflecting a light beam from the test chart displayer, disposed above the displayer; and a second reflector for reflecting the light beam, reflected by the first reflector, towards eyes to be tested. Said test chart displayer and the first reflector for reflecting and propagating the light beam from the displayer are contained in a leg of a table and the second reflector for reflecting the light beam from the first reflector towards the eyes to be tested is supported by a supporting arm of the table.

Visual acuity testing apparatus

A refractory power measuring device for measuring the refractory power of the human eye or a lens. The device includes a target projecting optical system having two optical elements which are movable along the optical axis of the system independently from each other. The device can measure simultaneously the refractory powers along two astigmatic axes.

Refractory power measuring device

Eye refractmeter using infrared rays in which the target projecting optical system includes an aperture disc having a semicircular apertures disposed within a circle corresponding to the pupil of the patient's eye with chord portions thereof opposed to each other with a spacing therebetween. The observing optical system includes a disc having a slot located at a position corresponding to the space between the apertures. The apertures and the slots are located in conjugate with the patient's pupil with respect to the objective lens.

Eye refractmeters using infrared rays

A vision testing instrument has a projecting optical system for projecting a test chart to produce an aerial image. In the optical system, there is provided a focusing reflector for producing a chart image at a far point. A second focusing reflector is provided so that it can be retractably inserted into the projecting optical path for producing a chart image at a near point.

Vision testing instrument

An apparatus for detecting astigmatic axes and measuring refractive powers such as the lens of a human eye. A disc has a first group of slits oriented in one direction and a second group of slits oriented perpendicular thereto. Each slit has a deflecting means with a direction of deflection perpendicular to the lengthwise direction of its slits for measuring the refractive power. The apparatus also has astigmatic axis detecting target means which can be used immediately prior to the refraction so that the refraction on each astigmatic axis can be measured before conditions change in the eye.

Apparatus for detecting astigmatic axes and measuring refractive powers

An eye refractmeter comprising a target projecting optical system for projecting an image of a target means through a pupil of a patient's eye to produce a target image on a retina of the eye, an observing optical system including objective lens means for observing the target image through the pupil, and a sighting optical system for observing light reflected at the cornea of the eye to determine that the objective lens means is appropriately spaced from the patient's eye, means being provided in the projecting optical system so that the image of the target means is projected by an infrared ray, half-transparent optical means for passing therethrough one of the light bundles along the observing and sighting optical systems and reflecting the other of the bundles, means for directing both of the light bundles passing through the observing and sighting optical systems to a single image pick-up tube, the half-transparent optical means having a reflecting rate such that more than 50% of the light along the observing optical system and less than 50% of the light along the sighting optical system are directed to the image pick-up tube.

Eye refractmeter

Ophthalmometer comprising a chart projecting optical system for projecting a Landolt type inspection chart and a lens means for locating a corrective lens in the projecting light path. A manually operated switch is provided for actuation by a patient. A mark is presented and moved around the projected chart image for the purpose of having the patient actuate the switch when the mark is at a position corresponding to the slit of the chart. When the switch is actuated at a correct time, the chart advanced by one step but when the switch is actuated at an incorrect timing the lens of next larger dioptral valve is placed in the projecting light path.

Ophthalmometer

Lens diopter measuring device includes a first and a second diopter scales which have the same but oppositely directed graduations. Correct identification of the diopters of an astigmatic lens can be obtained by bringing the second scale to zero reading at the first focus position and then adjusting the device to the second focus position.

Method and device for measuring diopters of astigmatic lenses

Ophthalmic examination chart projector including a rotatable chart carrying disc and a mask plate which are co-axial with each other. A light source and a projecting lens assembly are provided for projecting one of the charts on the disc and one of the mask openings onto a screen. An index tube is rotatably mounted in the projecting optical path and carrying a colored filter on the inner periphery thereof. Thus, an astigmatic index can be projected on the peripheral portion of the astigmatic examination chart. The chart carrying disc, the mask plate and the astigmatic index tube can be controlled by knobs all provided on the front panel of the projector.

Growing community of inventors

Tokyo, Japan

Taketoshi Ishihara