Abstract: Improvements in a treatment chair whose backrest frame is designed to be tiltable with respect to the seat frame of the chair by use of a roller rotating within a guide groove are disclosed. In the disclosed embodiments all utilize an arc segment portion groove. As a result, the top portion of the backrest frame holds substantially the same peripheral speed throughout travels with raising and lowering of the backrest frame and the patient resting against the backrest frame is thereby free from any uncomfortable feeling due to preceptible changes in peripheral speed during the rise and fall movement of the frame.

Abstract: According to this invention, useless exposure of a human being to X-ray is avoided and X-ray film is economically used by providing the X-ray generator of a dental X-ray apparatus with an X-ray intercepting means by which the size of the opening or slit for X-ray beams flow is easily controlled. The X-ray apparatus comprises an X-ray generator, an X-ray film, an arm for supporting the X-ray generator and the X-ray film in such a manner that the X-ray generator faces the X-ray film. When the arm is rotated at a predetermined angle around the X-ray film thereby causing the X-ray generator to be rotated proportionally, the X-ray generator emits X-ray beams through the vertically elongated slit disposed in the X-ray generator's head.

Abstract: The disclosure relates to a system of automatically controlling the distance between two members placed in a relatively variable relation with each other with respect to distance on a straight line. One of the two members is provided with a transmitter capable of generating an ultrasonic pulse excellent both in directivity and in damping characteristics, and the other is provided with a receiver with the same in characteristics as the transmitter and which is disposed in an opposed relation with respect to the transmitter. The distance between the two members is automatically controlled by causing an ultrasonic pulse to be transmitted and received respectively by the transmitter and the receiver.

Abstract: The disclosure relates to a system for aerially transmitting an ultrasonic view of a vibration mode, small in angle of direction, in a clear state and to a transmitter and a receiver used in the system. According to the system, an ultrasonic pulse can be used for distance measurement, control and other signal means even at relatively short distance.

Abstract: A dental treatment system comprising a treatment chair seat, a backrest mounted tiltably thereto, and a headrest characterized in that the device includes a unit box assembly adapted to be stored inside or underside the backrest and to be drawn out therefrom. The unit box assembly having a variety of instruments housed therein is designed such that the instruments may be positioned in the space on the shoulder of the backrest or on the side of the headrest or on both of the shoulder and the side because of the construction of the assembly that, when the box assembly is stored in the backrest, it may be interlocked with the tilting of the backrest and, when drawn out therefrom, may be freely moved, stopped, vertically and bilaterally rotated and stopped independently of tilting the backrest to thereby facilitate handling of the instruments and to save additional space for separate arrangement of instruments.

Abstract: A method of apparatus for making X-ray photographs of a jaw structure which makes it possible to obtain clear and distinct images of the dental arch without superimposition of neighboring teeth and further to equalize the enlargement ratio of images to be made on the film no matter which spots of the teeth may be taken at the time of X-ray photographing.