Abstract:
A flasher type fish sonar includes an ultrasonic vibrator transmitting and receiving ultrasonic waves in water, a transmitting circuit supplying oscillating signals to the ultrasonic vibrator, a receiving circuit amplifying reflected signals received by the ultrasonic vibrator, an A/D converter converting the reflected signals to digital signals, an input circuit receiving the digital signals from the A/D converter through a control circuit, a flasher display including a rotary disk having a rotated luminous body and a display board having a window displaying luminosity of the luminous body in response to the digital signals from the input circuit through brushes and slip rings, and a constant current circuit in the input circuit which eliminates changes of electric current flowing to the luminous body due to contact resistance between the slip rings and the brushes.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a flasher type fish sonar in which a circular board having a luminous body is rotated in a window of a display board. 
     In a prior flasher type fish sonar, a circular window is formed in the periphery of a display board provided with the front of a case, a luminous body mounted on a rotary disk is arranged opposite to the window, and the rotary disk is rotated by a motor. Brushes  8  are attached to slip rings provided with the rotary shaft of the rotary disk, an input circuit is connected to the brushes and a flasher display is constituted by these elements. A transmitting-receiving circuit is connected to the input circuit. When a signal from the transmitting-receiving circuit is input from the input circuit to the luminous body through the brushes and the slip rings, a part A becomes a starting point showing the surface of the sea, fishes are shown by parts B and C and the bottom of the sea is shown by a part D. 
     In the transmitting-receiving circuit, when output signals are input from a control circuit to a transmitting circuit, oscillating signals are input from the transmitting circuit to an ultrasonic transducer, and ultrasonic signals are emitted to the sea. When reflected signals from the sea are received by the ultrasonic transducer, the reflected signals are amplified by a receiving circuit, the amplified reflected signals are converted to digital signals in an analogue to digital converter, and the digital signals are input from the control circuit to a base of a transistor through a resistor of the input circuit of the flasher display. The base of the transistor is connected to the ground through a resistor. An emitter of the transistor is connected to the ground, a collector of the transistor is connected to the anode of the luminous body through a resistor, one of the brushes and the slip rings, and the cathode of the luminous body is connected to a direct current electric power source through the slip rings and the other of the brushes. 
     In the flasher type fish sonar, because the direct current electric power connected to the luminous body in the flasher display is constituted by a constant voltage circuit, when the digital signals from the control circuit are input to the base of the transistor of the input circuit of the flasher display, the electric current from the direct current electric power source flows to the luminous body through the other of the brushes and the slip rings and flows from the luminous body to the ground connected to the emitter from the collector of the transistor through the slip rings and the one of the brushes. Thus the electric current flowing to the luminous body is changed and the luminosity of the luminous body is changed when the contact resistance between the slip rings and the brushes is changed. When the change in the luminosity of the luminous body becomes high, a detection of fish is incorrectly viewed as the bottom of the sea. 
     SUMMARY OF THE INVENTION 
     It is, therefore, the primary object of the present invention to provide a flasher type fish sonar in which a constant current is input to a luminous body for eliminating a change of contact resistance between slip rings and brushes. 
     It is another object of the present invention to provide a flasher type fish sonar in which a constant current is connected to a luminous body for inputting constant current always. 
     In order to accomplish the above and other objects, the present invention comprises an ultrasonic vibrator for transmitting ultrasonic waves in the water and for receiving reflected signals in the water, a transmitting circuit for supplying oscillating signals to the ultrasonic vibrator, a receiving circuit for amplifying reflected signals received by the ultrasonic vibrator, an analogue to digital converter for converting the reflected signals to digital signals, an input circuit for inputting the digital signals from the analogue to digital converter by the control circuit, a flasher display consisting of a rotary disk having a luminous body mounted on a rotary disk rotating by a motor and a display board having a window displaying luminosity of the luminous body by inputting the digital signals from the input circuit through brushes connected to the input circuit and slip rings mounted on a rotary shaft of the rotary disk, the slip rings contacting the brushes, and a constant current circuit constituted in the input circuit, whereby changes of electric current flowing to the luminous body due to the contact resistance between the slip rings and the brushes is eliminated by the constant electric current from the constant current circuit. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a front view of the flasher display of a flasher type fish sonar in the prior art. 
     FIG. 2 shows a side sectional view of a flasher display in FIG.  1 . 
     FIG. 3 shows a block diagram of the flasher type fish sonar in FIG.  1 . 
     FIG. 4 shows a block diagram of the flasher type fish sonar of an embodiment in the present invention. 
     FIG. 5 shows a block diagram of the flasher type fish sonar of another embodiment in the present invention. 
     FIG. 6 shows a block diagram of the flasher type fish sonar of another embodiment in the present invention. 
     FIG. 7 shows a flasher display in another embodiment of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In a prior flasher type fish sonar, as shown in FIGS. 1 and 2, a circular window  2  is formed in the periphery of a display board  3  provided with the front of a case  1 , a luminous body  5  mounted on a rotary disk  4  is arranged opposite to the window  2 , and the rotary disk  4  is constituted to be rotated by a motor  6 . Brushes  8  are attached to slip rings  7  attached to the rotary shaft of the rotary disk  4 , and an input circuit  9  is connected to the brushes  8 . A flasher display  10  is constituted by these elements. A transmitting-receiving circuit  11  is connected to the input circuit  9 . When a signal from the transmitting-receiving circuit  11  is input from the input circuit  9  to the luminous body  5  through the brushes  8  and the slip rings  7 , a part A becomes a starting point showing the surface of the sea, fishes are shown by parts B and C and the bottom of the sea is shown by a part D. 
     As shown in FIG. 3, in the transmitting-receiving circuit  11 , when output signals are input from a control circuit  12  to a transmitting circuit  13 , oscillating signals are input from the transmitting circuit  13  to an ultrasonic transducer  14 , and ultrasonic signals are emitted to the sea. When reflected signals from the sea are received by the ultrasonic transducer  14 , the reflected signals are amplified by a receiving circuit  15 , the amplified reflected signals are converted to digital signals in an analogue to digital converter  16 , and the digital signals are input from the control circuit  12  to a base of a transistor Tr 1  through a resistor R 1  of the input circuit  9  of the flasher display  10 . The base of the transistor Tr 1  is connected to the ground through a resistor R 2 , an emitter of the transistor Tr 1  is connected to the ground, a collector of the transistor Tr 1  is connected to the anode of the luminous body  5  through a resistor R 3 , one of the brushes  8  and the slip-rings  7 , and the cathode of the luminous body  5  is connected to a direct current electric power source  17  through the slip-rings  7  and the other of the brushes  8 . 
     In the flasher type fish sonar, because the direct current electric power  17  connected to the luminous body  5  in the flasher display  10  is constituted by a constant voltage circuit, when the digital signals from the control circuit  12  are input to the base of the transistor Tr 1  of the input circuit  9  of the flasher display  10 , the electric current from the direct current electric power source  17  flows to the luminous body  5  through the other of the brushes  8  and the slip-rings  7  and flows from the luminous body  5  to the ground connected to the emitter from the collector of the transistor Tr 1  through the slip-rings  7  and the one of the brushes  8 . Thus the electric current flowing to the luminous body  5  is changed and the luminosity of the luminous body  5  is changed when the contact resistance between the slip-rings  7  and the brushes  8  is changed. When the change in the luminosity of the luminous body  5  becomes high, a detection of fish is incorrectly viewed as the bottom of the sea. 
     In FIG. 4,  5  designates a luminous body,  11  a transmitting-receiving circuit,  12  a control circuit,  13  a transmitting circuit,  14  an ultrasonic vibrator,  15  a receiving circuit,  16  an analogue to digital convertor,  17  a first direct current electric power source, R 1  a first resistor, R 2  a second resistor, and Tr 1  a first transistor, and these constitutions are the same as those in the prior art and the explanation of these constitutions is omitted. In the embodiment, a resistor R 4  is connected between the emitter of the first transistor Tr 1  and the ground, a collector of a second transistor Tr 2  is connected to the base of the first transistor Tr 1  and the first resister R 1 , the base of the second transistor Tr 2  is connected through the second resistor R 2  to the output terminal of control circuit  12  in the transmitting-receiving circuit  11 , the emitter of the second transistor Tr 2  is connected to the plus terminal of a second direct current electric power source  18 , the minus terminal of the second direct current electric power source  18  is connected to the ground, a third resistor R 3  is connected between the emitter and base of the second transistor Tr 2 , and a constant current circuit is constituted by these constitutions. 
     In the flasher type fish sonar in the embodiment of the invention, when the reverse signals of the digital signals are input from the control circuit  12  of the transmitting-receiving circuit  11  to the base of the second transistor Tr 2  and the electric current flows into the second transistor Tr 2 , the constant voltage subtracted by the putting-on voltage between the emitter-collector of the second transistor Tr 2  from the voltage of the direct current electric power source  18  is generated at the first resistor R 1  connected to the base of the first transistor Tr 1 , and thus the constant voltage is so generated at the fourth resistor R 4  connected to the emitter of the first transistor Tr 1  such that a constant current from the first direct current electric power source  17  flows between the collector and the emitter of the first transistor Tr 1 . Thus, the constant current flows to the luminous body  5 , and the change of the electric current due to the change of the contact resistance between the slip rings  7  and the brushes  8  is eliminated. Then, even if the contact resistance is changed, the constant current always flows to the luminous body  5 , and the luminosity of the luminous body  5  is not changed. 
     FIG. 5 shows another embodiment of the flasher type fish sonar in the present invention,  10  designates a flasher display,  11  a transmitting-receiving circuit,  12  a control circuit,  13  a transmitting circuit,  14  an ultrasonic vibrator,  15  a receiving circuit,  16  an analogue to digital converter,  17  a first direct current electric power source, R 1  a first resistor, R 2  a second resistor, R 3  a third resistor, R 4  a fourth resistor, Tr 1  a first transistor, and  18  a second direct current electric power source, and these constitutions are the same as those in the above embodiment and the explanation of these constitutions is omitted. In the embodiment, the luminous body is constituted by four red color luminous diodes  5   a ,  5   b ,  5   c  and  5   d . Since the red color luminous diodes  5   a ,  5   b ,  5   c  and  5   d  have small forward voltages, the two luminous diodes  5   a  and  5   b  and  5   c  and  5   d  are respectively connected in series and these two series resistor circuits are connected in parallel. 
     The change of the luminosity of the luminous diodes  5   a ,  5   b ,  5   c  and  5   d  due to the change of the contact resistance of the slip rings  7  and the brushes  8  is eliminated by the above embodiment. 
     FIG. 6 shows another embodiment of the flasher type fish sonar in the present invention,  10  designates a flasher display,  11  a transmitting-receiving circuit,  12  a control circuit,  13  a transmitting circuit,  14  an ultrasonic vibrator,  15  a receiving circuit,  16  an analogue to digital converter,  17  a first direct current electric power source, R 1  a first resistor, R 2  a second resistor, R 3  a third resistor, Tr 1  a first transistor, Tr 2  a second transistor, and  18  a second direct current electric power source, and these constitutions are the same as those in the above embodiment and the explanation of these constitutions is omitted. In the embodiment, the luminous body  5  is constituted by four green color luminous diodes  5   a ,  5   b ,  5   c  and  5   d . Since the green color luminous diodes  5   a ,  5   b ,  5   c  and  5   d  have large forward voltages, the four luminous diodes  5   a ,  5   b ,  5   c  and  5   d  are connected in parallel. 
     The change of the luminosity of the luminous diodes  5   a ,  5   b ,  5   c  and  5   d  due to the change of the contact resistance of the slip rings  7  and the brushes  8  is eliminated by the above embodiment. 
     FIG. 7 shows another embodiment of the flasher type fish sonar in the present invention,  10  designates a flasher display,  11  a transmitting-receiving circuit,  12  a control circuit,  13  a transmitting circuit,  14  an ultrasonic vibrator,  15  a receiving circuit,  16  an analogue to digital converter,  17  a first direct current electric power source, R 1  a first resistor, R 2  a second resistor, R 3  a third resistor, Tr 1  a first transistor, and Tr 2  a second transistor, and these constitutions are the same as those in the prior art and the explanation of these constitutions is omitted. In the embodiment, a zener diode Zn is connected instead of the second direct current electric power source  18 . 
     In this embodiment, the zener diode Zn acts the same as the second direct current electric power source  18 . 
     In the above embodiments, though the first and second transistors Tr 1  and Tr 2  are used as a constant electric current circuit, another constant electric current circuit may by used. 
     As stated above, in the flasher type fish sonar of the present invention, because a constant electric current from the second direct current electric power source flows between the emitter and collector of the second transistor, whereby a constant voltage is generated by the fourth resistor connected to the emitter of the first transistor, therefore, a constant electric current from the first direct current electric power source is flowed between the collector and emitter of the first transistor, the change of the electric current due to the change of the contact resistance of the slip rings and brushes is omitted, even if the contact resistance in the slip rings and brushes is changed, the constant electric current flows in the luminous body, and the luminosity of the luminous body is not changed.