Abstract: In a color sonar system especially suitable for displaying fish echo signals, high and low frequency echo image signals are displayed utilizing colors corresponding to the echo signal strength, when the signal strength differences between the simultaneously received high and low frequency echo image signals are within a preset level range, when the differences between the high and low frequency echo image signals are outside the preset level range, the selected high frequency or low frequency echo image signals are displayed utilizing colors indicative of the differences in signal strength between the corresponding high frequency and low frequency echo signals.

Abstract: Ultrasonic waves are reflected on or passed through a sample by a focusing ultrasonic transmitting element and a focusing ultrasonic receiving element or a focusing ultrasonic transmitting-receiving element, and two signals are produced by operating the ultrasonic waves or by changing conditions and are displayed as one image on a color cathode ray tube by changing the color.

Abstract: A display system for fish sonar displays two ultrasonic echo signals of different frequencies from the left side to the central portion and from the central portion to the right side on the screen of a cathode ray tube. After the two ultrasonic echo signals are displayed on the entire screen of the cathode ray tube, the old echo signals are eliminated and the display is refreshed with new echo signals so that a picture of a school of small fish which is displayed by ultrasonic echo signals of high frequency can be compared with a horizontally adjacent picture of a large fish simultaneously displayed by ultrasonic echo signals of low frequency on a single cathode ray tube screen.

Abstract: A focusing ultrasonic transducer element comprising an ultrasonic propagating medium and an ultrasonic transmitting and receiving transducer. The ultrasonic propagating medium is provided with a convex spherical or cylindrical portion in one end and a concave spherical or cylindrical portion in the other end.

Abstract: An ultrasonic transmitting element and an ultrasonic receiving element are arranged in a sample liquid in opposition to each other. Either the ultrasonic transmitting element or the ultrasonic receiving element is finely vibrated, and the difference between the velocities of sound in the sample liquid and another sample in the sample liquid is displayed on a CRT.

Abstract: An ultrasonic microscope is provided wherein a sample placed in a medium is irradiated with a focused ultrasonic wave from a focusing ultrasonic transmitting element and the focused ultrasonic wave is detected by a focusing ultrasonic receiving element. The sample (or the focusing transmitting element and the focusing ultrasonic receiving element) is moved within the X-Y plane, and either the focusing transmitting element or the focusing ultrasonic receiving element is vibrated toward the sample along the beam axis.

Abstract: A fish sonar is capable of detecting ultrasonic waves from a desired direction by shaping the waveforms of the outputs of a pair of vibrators spaced apart by a certain distance, and detecting a delay of the output from one of the vibrators with respect to that of the other of the vibrators so as to detect the direction of the ultrasonic waves coming to the pair of vibrators and to delay the output of the other of the vibrators with respect to the output of one of the vibrators.

Abstract: A recording unit is disclosed which comprises a single hard wire member bent in the form of a coil, one end of which is a recording or current collecting end and the other end of which is a hook end. The coil support of an adapter supports the coil portion of the wire member. The hook end is hooked on one of the hook end supports of the arms extending from the adapter. The recording needle and the current needle are placed on their respective supports.

Abstract: A scanning circuit consisting of a plurality of time delay circuits and a plurality of holding circuits at least equal in number to the delay circuits is provided for a fish detecting sonar. In response to the input pulse applied to the input terminal of the first stage delay circuit in synchronism with the sound pulse propagated, the delay circuits are triggered to reproduce the input pulses which are sequentially delayed by a time interval equal to the pulse width of the input pulse, and the output pulses from the delay circuits are held only by the holding circuits to which are applied the recording or echo signals. The output pulses held by the holding circuits are picked up by a brush, which slides over the contacts connected to the output terminals, respectively, of the holding circuits, and applied to a recording pen or stylus for recording. The above arrangement permits the recording or display even when the speed of the brush is relatively slow.

Abstract: A fish detection sonar is provided wherein a receiver has a display device comprising a rotary disk having a display element mounted thereupon, and a scale disk disposed coaxially of and in opposed relation with the rotary disk; the ultrasonic signal transmitted from a transmitter into the sea is immediately received by the receiver so that the display element may be turned on or energized in response to the level of the received signal, thereby displaying the surface of the sea; and the receiver receives the ultrasonic sound reflected by the targets so that the display element may be turned on in response to the level of the reflected signal; a color display device wherein a plurality of display elements capable of emitting light in different colors when energized are mounted upon the rotary disk, and the ultrasonic signals received by the receiver are divided into a plurality of groups depending upon the levels of the received signals, each level being assigned to each of the display elements, so that the t