JP3596988B2 - megaphone - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electric circuit of a megaphone, and particularly to an electric circuit of a megaphone which can be used in a place of concern.
[0002]
[Prior art]
In 1979, the Ministry of Labor, Industrial Safety Research Institute issued “Industrial Safety Research Institute Technical Guidelines”, “Factory Electrical Equipment Explosion Protection Guidelines” (gas vapor explosion protection 1979), or JIS C0930, etc. It is defined as an explosion-proof construction in which, in the event of a gas explosion, the container withstands the explosion pressure and prevents the propagation of fire to an external explosive atmosphere. The "internal pressure explosion-proof structure" sends or seals a protective gas inside the container and keeps the pressure higher than the pressure on the outer periphery of the container, so that the surrounding explosive atmosphere does not enter the inside of the container during energization It is defined as an explosion-proof structure. The “safety-enhanced explosion-proof structure” is designed to prevent electrical sparks, electrical equipment that does not generate high-temperature parts, and electrical, mechanical and It is defined as an explosion-proof structure with a higher degree of safety in terms of temperature. In the "intrinsically safe explosion-proof structure", in a normal state and an assumed abnormal state, an electric spark generated in an electric circuit does not ignite a predetermined test gas under specified test conditions, and ignites an explosive atmosphere due to high temperature. It is defined as an explosion-proof structure that does not have to be subject to fire. The “oil-filled explosion-proof structure” refers to an explosion-proof structure in which the portion that generates an electric spark in the container is contained in oil so that there is no danger of igniting the explosive atmosphere present on the oil surface and outside the container. , Is defined. In addition, the special explosion-proof construction is an explosion-proof construction that can prevent ignition of explosive atmospheres by methods other than the explosion-proof construction, internal pressure explosion-proof construction, safety-enhanced explosion-proof construction, intrinsically safe explosion-proof construction, and oil-filled explosion-proof construction. Structure is defined as
[0003]
Furthermore, in the fifth edition of the explosion-proof structure of electric equipment, a rated voltage of 1.2 V and a rating of "new factory electrical equipment explosion-proof guidelines"("Gas vapor explosion-proof 1985") issued by the "Industrial Safety Research Institute Technical Guidelines" issued by the Ministry of Labor in 1985 It is described that the explosion-proof structure of the electric device is not applied to electric devices and electric components that do not exceed the current of 0.1 A, the electric energy of 20 μJ, or the rated power of 25 mW.
[0004]
The megaphone operates using a battery as a power source. The megaphone is used for instructions, instructions, guidance, broadcasting, etc., at the operation of plants, equipment, and equipment, at construction sites, accident sites, and in danger areas and places of concern such as those around them. In such cases, large output is required. It is also desirable that the value be below the rated value of the applicable range of the explosion-proof structure of electric equipment. In order to obtain a high-power megaphone, a plurality of batteries are connected in series to operate the amplifier at a high voltage, and a power switch turns ON / OFF the high voltage.
[0005]
[Problems to be solved by the invention]
In order to obtain a large output megaphone, the amplifier is operated at a high voltage, and a power switch must turn on and off the high voltage. Since the amplifier uses components with transient characteristics such as capacitors and coils, sparks may be generated when the power switch is turned on and off, and it may become an ignition source in an explosive atmosphere. Could not be used in caution places.
[0006]
To solve these problems, megaphones are equipped with explosion-proof construction, internal pressure explosion-proof construction, increased safety explosion-proof construction, intrinsically safe explosion-proof construction, oil-filled explosion-proof construction, and special explosion-proof construction. Megaphones with a rated value that is less than the applicable range of the explosion-proof structure of equipment can be considered, but such megaphones are supposed to be complex, large, heavy, and expensive. Has not been commercialized and has no proposal. The present invention constitutes an electric circuit having a rated value or less of the applicable range of the explosion-proof structure of the electric device, and can be used in places requiring attention.
[0007]
Hazardous areas are classified as follows: In the "Guidelines for Explosion-proof Plant Electrical Equipment" of the "Technical Guideline for Industrial Safety Research Institute" published by the Ministry of Labor in 1979, the "Class 0 place" usually has a hazardous atmosphere. In the state of the above, "a type 1 place" refers to a place that exists continuously or for a long time, and a "type 2 place" refers to a place where a dangerous atmosphere may be generated in a normal state. Is defined as a place where a dangerous atmosphere may be generated in an abnormal state. If the frequency of occurrence of earthquakes and other unexpected accidents is extremely low, and the amount of explosive gas leakage is large and exceeds the scope of explosion-proof measures for electrical equipment, do not include the abnormal conditions in two places. It is defined as a place of concern.
[0008]
[Means for Solving the Problems]
Claim 1 of the present invention comprises a semiconductor switch for opening and closing a connection between a megaphone power supply terminal for supplying power to a megaphone amplifier and a power supply line of the amplifier , and a control transistor for controlling on / off operation of the semiconductor switch. , the control transistor, at a lower voltage than the megaphone power terminals, controlled by megaphone switch connected between the voltage control power source terminal and said control transistor close to the rated value of the coverage of the explosion-proof electrical equipment Thus, the semiconductor switch is controlled, and the configuration solves the problem.
[0009]
According to a second aspect of the present invention, the megaphone power terminal is derived from a megaphone battery in which a plurality of batteries are connected in series, and the control power terminal is derived from a first battery of the megaphone battery. To achieve the above object.
[0010]
According to a third aspect of the present invention, the semiconductor switch comprises a power MOS-FET, a source is connected to the megaphone power supply terminal, a drain is connected to a power supply line of the amplifier, and a gate is connected to a collector of the control transistor. The base of the control transistor is connected to the control power supply terminal via a megaphone switch, thereby achieving the above object.
[0011]
A semiconductor switch for opening and closing a connection between a megaphone power supply terminal for supplying power to a megaphone amplifier and a power supply line of the amplifier , and a control transistor for controlling on / off operation of the semiconductor switch the provided, the control transistor, at a lower voltage than the megaphone power supply terminal, a megaphone switch connected between the control power supply terminal and the control transistor of the voltage close to the rated value of the coverage of the explosion-proof electrical equipment By controlling the semiconductor switch, the switching element for the power line of the amplifier can be constituted by a semiconductor element like a semiconductor switch and a control transistor, and there is no mechanical contact opening / closing. Is no longer generated. In addition, the megaphone switch is connected between the control power supply terminal and the control transistor, which has a lower voltage than the megaphone power supply terminal and is close to the rated value of the applicable range of the explosion-proof structure of electrical equipment, and opens and closes between these terminals. It is sufficient to open and close the circuit described above, and it is possible to approach the rated value of the applicable range of the explosion-proof structure of the electric device.
[0012]
According to a second aspect of the present invention, in the first aspect, the megaphone power terminal is derived from a megaphone battery in which a plurality of batteries are connected in series, and the control power terminal is a first megaphone battery of the megaphone battery. Since the control transistor is operated at the voltage of one battery (1.5 V) by deriving from the battery, it should be close to the rated voltage (1.2 V) of the applicable range of the explosion-proof structure of the electric equipment. Can be. Therefore, a "safety explosion-proof structure" or an "intrinsically safe explosion-proof structure" can be provided.
[0013]
In a third aspect of the present invention, in the first aspect, the semiconductor switch comprises a power MOS-FET, a source is connected to the megaphone power supply terminal, a drain is connected to a power supply line of the amplifier, and a gate is connected to the power supply line of the amplifier. Since the control transistor is connected to the collector of the control transistor, and the base of the control transistor is connected to the control power supply terminal via the megaphone switch, the semiconductor switch can be controlled by the control transistor. Is operated by a megaphone switch that switches a low-voltage control power supply terminal. Therefore, the megaphone switch may be turned on and off at a low voltage, and is close to the rated voltage (1.2 V) of the applicable range of the explosion-proof structure of the electric device. be able to. Therefore, a "safety explosion-proof structure" or an "intrinsically safe explosion-proof structure" can be provided.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1A is a side view showing a state in which a battery cover is removed, and FIG. 1B is a rear view showing an amplifier to which a horn mouse 1 and a handle 3 are attached. It is separated into four parts: a case 2, a battery cover 4 for storing six megaphone dry batteries, and a microphone cover 5.
[0015]
The horn mouse 1 houses a magnetic circuit including a ring-shaped permanent magnet 11, a yoke 12, and a plate 13 therein as shown in FIG. The voice coil is inserted into a magnetic gap formed between the voice coil and the voice coil. The upper end of the voice coil is coupled to the dome-shaped diaphragm 14, and the voice signal input to the voice coil works with the magnetic circuit to be converted into vibration of the diaphragm 14. An equalizer 15, a throat 16, reflectors 17 and 18 are attached in front of the diaphragm 14, and sound is emitted from an opening at the tip of the horn mouse 1. The reflector 18 is screwed to the horn mouse 1 with a screw 19, and the screw 19 is screwed into the amplifier case 2 to connect the horn mouse 1 and the amplifier case 2. When the horn mouse 1 and the amplifier case 2 are connected, the rear outer periphery of the magnetic circuit is mounted so as to be covered with a waterproof packing 6 made of rubber and a flexible resin, and the gap between the horn mouse 1 and the amplifier case 2 is filled to provide airtightness. It has a waterproof structure.
[0016]
Inside the amplifier case 2, an amplifier waterproof case 22 and a volume switch box 25 are housed. The amplifier waterproof case 22 incorporates a printed wiring board 21 on which electrical components (not shown) such as an LSI, an IC, a resistor, and a capacitor, which constitute the amplifier, are mounted, and the like. The volume switch box 25 incorporates a volume 23 and a power switch 24 of a megaphone (the switch 24 is preferably a waterproof type), and is screwed to the amplifier waterproof case 22.
[0017]
The power switch 24 is mounted on the vertical part of the mounting bracket 30, and the volume 23 is fixed to the horizontal part by passing the rotating shaft through the hole of the volume switch waterproof packing 9. The mounting bracket 30 to which the power switch 24, the volume 23, and the packing 9 are mounted is housed inside the volume switch box 25, and the packing 9 is mounted on the amplifier waterproof case 22 by tightening together with the volume switch box 25. The volume switch waterproof packing 9 prevents sparks from leaking from the amplifier waterproof case 22 and the volume switch box 25, and also performs waterproofing. The volume switch box 25 has a hole through which the rotating shaft 27 of the volume 23 projects, and an O-ring 29 is fitted between the rotating shaft 27 and the volume switch box 25 to prevent spark leakage and waterproof. Have been. A rotary knob 28 is attached to the rotary shaft 27, and a part of the rotary knob 28 faces the rear side of the handle 3. Further, a projection 9a is formed on a portion of the volume switch waterproof packing 9 facing the actuator 31 of the power switch 24, and faces the operation plate 33 of the switch knob 32, a part of which protrudes forward of the handle 3. ing. Therefore, the volume 23 can be operated by the rotary knob 28, and the power switch 24 can be operated by the switch knob 32.
[0018]
A circular rear opening 40 is formed behind the battery cover 4, and the microphone cover 5 that houses the microphone units 51a and 51b is fitted into the rear opening 40. The microphone unit 51a is a main condenser microphone, and receives a voice input. The microphone unit 51b is a sub-condenser microphone, and receives noise around the megaphone to cancel noise. In particular, it is effective in preventing howling caused by an audio signal generated from a megaphone. A waterproof packing 39 is inserted around the inside of the rear opening 40 to prevent sparks from leaking from between the battery cover 4 and the microphone cover 5 and to provide waterproofing.
[0019]
The details of the waterproof packing 39 will be described below with reference to a sectional view before assembling of FIG. 3A, a sectional view after assembling of FIG. 3B, and a sectional view of the waterproof packing 39 of FIG. explain. The rear surface of the rear opening 40 of the battery cover 4 is chamfered by the thickness of the waterproof packing 39 to form a step 4a. The thickness of the waterproof packing 39 is about half to １ ／ of the thickness of the battery cover 4. As a result, the rear surface of the battery cover 4 is flush with the waterproof packing, and the appearance is improved. The waterproof packing 39 is formed in a ring shape in conformity with the shape of the rear opening 40, and its outer peripheral side is in contact with three inner peripheral edges of the rear opening 40 so as to be in close contact with the inner surface 39a, the outer surface 39b, and the outer peripheral surface 39c. It is formed in a U-shape. An inner protrusion 39d, an outer protrusion 39e, and an inner recess 39f are formed on the inner peripheral side so as to be in close contact with the microphone cover 5. The distance S1 between the inner protrusion 39d and the outer protrusion 39e is preferably larger than the distance S2 between the inner surface 39a and the outer surface 39b.
[0020]
As shown in FIG. 3A, the waterproof packing 39 is fitted in the rear opening 40 before assembly, the battery cover 4 is put on the microphone cover 5, the microphone cover 5 is projected from the rear opening 40, and the outer peripheral projection 58 is formed. And the waterproof packing 39 is inserted until the waterproof packing 39 is completely adhered to the outer peripheral surface of the microphone cover 5. The waterproof packing 39 has three surfaces, an inner surface 39a, an outer surface 39b, and an outer surface 39c, on the outer peripheral side, which are in close contact with the inner peripheral edge of the rear opening 40 at three surfaces. Since the two surfaces of the portion 39e are in contact with the outer peripheral surface of the microphone cover 5 on the two surfaces, and the inner peripheral concave portion 39f is attracted to the outer peripheral surface of the microphone cover 5, the dimensional accuracy of the battery cover 4, the microphone cover 5, and the waterproof packing 39 are improved. Absorbing the positioning accuracy of each part, making surface contact possible, high waterproof effect.
[0021]
The microphone cover 5 having the above-described structure is combined with a battery case in which an upper battery case 41 and a lower battery case 42 are fixed and integrated with six screws 43 with six screws 44, and the microphone cover 5 and the battery cover 4 are combined. Are integrated. A battery case configured by combining the upper battery case 41 and the lower battery case 42 is composed of a central tubular portion A and a battery terminal support portion B of the upper battery case 41, and is radiated at equal intervals around the central tubular portion A. Six C-cells 50 are stored. The lower battery case 42 is provided with a hole through which a negative electrode terminal plate 45 that contacts the negative electrode of the C-cell battery, and the rear portion of the negative electrode terminal plate 45 is screwed to a wiring land on the battery circuit board 38 by a nut 45a. . The circuit board for battery 38 is formed with circuit wiring for connecting the negative electrode of the first battery and the positive electrode of the second battery.
[0022]
Further, as shown in FIG. 4, a positive electrode terminal plate 46 that is in contact with the positive electrode of the single cell 50 is attached to the battery terminal support portion B on the upper part 41 of the battery case. The battery terminal plate 46 is bent in a U-shape in cross section so that one end portion is wound around a side edge of the battery terminal support portion, and is attached with screws 47a and screws 47b. The other end of the battery terminal plate 46 is extended to the central cylindrical portion A, and a lead wire connecting the positive electrode of the first battery and the negative electrode of the second battery through the inside of the central cylindrical portion A at this extended end. Connected to. The other end of the lead wire is connected to the circuit wiring of the battery circuit board 38, and all six batteries are connected in series. If the circuit wiring of the battery circuit board is changed, it can be connected in parallel or series-parallel as appropriate.
[0023]
The battery terminal support portion B includes a battery terminal tightening screw 47a. By tightening the battery terminal tightening screw 47a, the positive electrode terminal plate 46 advances as shown in FIG. 4A, the positive electrode terminal plate 46 is retracted as shown in FIG. Therefore, when removing or replacing the battery, the screw 47a is rewound to retract the positive electrode terminal plate 46 as shown in FIG. 4A, and the battery is removed or replaced. After the insertion, the screw is tightened as shown in FIG. 4B to advance the battery terminal plate 46, and the battery 50 is pressed against the negative terminal plate 45 under the battery case 42, so that the megaphone vibrates or tilts when the megaphone is used. The battery 50 is not separated from the battery terminal plate 46 even if it is pressed, thereby preventing a spark from being generated. The microphone case 5 and the battery case lower 42 integrated with the battery case upper 41 in this manner are fixed to the amplifier case 2 with six screws 48 with the waterproof packing 8 interposed therebetween. The waterproof packing 8 prevents sparks from leaking from between the battery cover 4 and the lower battery case 42 and provides waterproofing, and also prevents sparks from leaking from between the amplifier case 2 and the lower battery case 42. , And waterproof.
[0024]
Finally, the battery cover 4 is fitted, and the microphone cover 5 is made to protrude from the rear opening 40 of the battery cover. As shown in FIG. The battery is inserted until it is completely adhered, and the internal screw 49 formed in the front opening of the battery cover 4 is screwed into the outer peripheral screw of the lower battery case 42.
[0025]
As shown in FIG. 5, the megaphone circuit of the present invention includes a microphone circuit 110, a microphone amplifier 111, a preamplifier 112, a main amplifier 113, a whistle oscillation circuit 115, a megaphone power supply control circuit 116, a whistle power supply control circuit 117, and a battery. And a switch circuit 118. The microphone circuit 110 is configured by connecting the main microphone 51a and the sub microphone 51b shown in FIG. The outputs of the main microphone 51a and the sub microphone 51b are supplied to a microphone amplifier 111 composed of transistors 122 and 123 via a variable resistor 121 for adjusting the volume constituted by the volume 23. The audio signal amplified by the microphone amplifier 111 is supplied to a main amplifier 113 composed of transistors 125 and 126 via a coupling transformer 127 via a preamplifier 112 composed of a transistor 124, and is output from a speaker 114.
[0026]
On the other hand, the whistle circuit controls the whistle power supply control circuit 117 by the whistle switch 131. When the power control circuit for whistle 117 is turned on, the first oscillation circuit 136 including the transistors 134 and 135 and the second oscillation circuit 139 including the transistors 137 and 138 constituting the whistle oscillation circuit 115 start operating, and the whistle signal Occurs. The whistle signal is supplied to the preamplifier 112, amplified by the main amplifier 113, and an alarm sound is generated from the speaker 114.
[0027]
The megaphone power supply control circuit 116 of the present invention includes a P-channel power MOS-FET 141 and a PNP-type control transistor 142. The power switch 24 is operated by a trigger-type switch knob 32 provided at the handle 30 in FIG. Then, when the megaphone switch 143 is turned ON / OFF, the control transistor 142 changes to the ON or OFF state, whereby the power MOS-FET 141 is controlled to the ON or OFF state. Here, the semiconductor switch composed of the power MOS-FET 141 opens and closes a connection between a megaphone power terminal (9 V) derived from a megaphone battery in which a plurality of batteries (six in this embodiment) are connected in series and a power line of the amplifier. The ON / OFF of the control transistor 142 is controlled by the voltage of a control power supply terminal (1.5 V) derived from the first battery of the megaphone battery.
[0028]
That is, the positive potential of the megaphone battery in which six batteries are connected in series is connected to the source of the power MOS-FET 141 as the megaphone power terminal 146, and the drain is connected to the power lines of the amplifiers 111, 112, and 113, more specifically, of the amplifier 113. It is directly connected to the power supply line, and further connected to the power supply lines of the amplifiers 111 and 112 via a resistor. The gate is connected to the collector of the control transistor 142, and the emitter is connected to the ground potential. The base is connected via a megaphone switch 143 to a control power supply terminal 148 that is the lowest potential of the megaphone battery. Accordingly, when the megaphone switch 143 is turned on, a base current flows through the control transistor 142, the control transistor 142 is turned on, and an on-current flows through the resistor 145 between the collector and the megaphone power supply terminal. Therefore, the power MOS-FET 141 is turned on, and a power supply current is supplied to the amplifiers 111, 112, and 113. When the megaphone switch 143 is operated to the off state, the base current of the control transistor 142 disappears and the state is turned off, so that the power MOS-FET 141 is turned off and the power lines of the amplifiers 111, 112, and 113 are turned off.
[0029]
The P-channel power MOS-FET 133 and the control PNP transistor 132 of the whistle power supply control circuit 117 are configured similarly to the megaphone power supply control circuit 116. When the whistle switches 131 and 131a are turned on, the megaphone power supply It operates similarly to the control circuit 116.
[0030]
As described above, since the megaphone switch 143 and the whistle switch 131 of the present invention only switch the voltage (1.5 V) for one battery, they are defined by the new factory electrical equipment explosion-proof guidelines (gas explosion-proof 1985). It approaches the rated values of 1.2 V, rated current 0.1 A, electric energy 20 μJ, or rated power 25 mW, which improves the safety.
[0031]
According to the present invention , the power supply control circuit for the megaphone is constituted by a semiconductor element, and the opening and closing of mechanical contacts is eliminated, so that no spark is generated. The megaphone switch is connected between the control power supply terminal and the control transistor, which has a lower voltage than the megaphone power supply terminal and is close to the rated value of the applicable range of the explosion-proof structure of electrical equipment. It can be close to the rated value of the applicable range of the explosion-proof structure. Further, the present invention includes a control power supply terminal having a voltage lower than that of the megaphone power supply terminal, and the control power supply terminal has a voltage of one battery (1.5 V). Value (1.2 V). Further, according to the present invention, the power MOS-FET can be controlled by the control transistor by connecting the power MOS-FET and the control transistor, and the control transistor is operated by a megaphone switch that switches a low-voltage control power supply terminal. Therefore, the megaphone switch can be opened and closed at a low voltage, and can be close to the rated value (1.2 V) of the applicable range of the explosion-proof structure of electric equipment.
[0032]
In the present invention, since the megaphone battery is pressed against the negative electrode terminal plate by the battery terminal tightening screw, the use of the megaphone prevents the megaphone from tilting or vibrating even if the megaphone tilts or vibrates. Therefore, it is possible to prevent a gap from being generated between the positive electrode or the negative electrode of the megaphone battery and the battery terminal plate, and to prevent generation of a spark.
[0033]
With the above-described structure, the megaphone of the present invention can be used in a place of concern without increasing the size and weight of the conventional megaphone.
[Brief description of the drawings]
FIG. 1A is a side view of a megaphone of the present invention with a battery cover removed, and FIG. 1B is a rear view.
FIG. 2 is a sectional view taken along the line ZZ 'of FIG. 1 (b).
FIG. 3 is a cross-sectional view of a battery cover and a microphone cover.
FIG. 4 is a sectional view of a battery and a positive electrode terminal plate portion.
FIG. 5 is an electric circuit diagram of the megaphone of the present invention.
[Explanation of symbols]
1 Horn Mouse 2 Amplifier Case 3 Handle 4 Battery Cover 5 Microphone Cover 6 Waterproof Packing 7 Pressure Adjustment Packing 8 Waterproof Packing 9 Volume Switch Waterproof Packing 22 Amplifier Waterproof Case 25 Volume Switch Box 29 O-Ring 37 Distribution Hole 39 Waterproof Packing 41 Battery Upper case 42 Lower battery case 45 Negative terminal plate 46 Positive terminal plate 47 Battery terminal plate tightening screw 50 Battery for megaphone A Central cylinder B Battery terminal support plate 111 Microphone amplifier 112 Preamplifier 113 Main amplifier 115 Whistle oscillator 116 Power control for megaphone Circuit 117 Power control circuit for whistle 118 Battery and switch circuit 141 Power MOS-FET
142 control transistor 143 megaphone switch 145 resistor 146 megaphone power terminal 148 control power terminal

Claims (3)

A semiconductor switch for opening and closing the connection between the power supply line of the megaphone power supply terminal and the amplifier for supplying power to megaphone amplifier includes a control transistor which controls the on-off operation of the semiconductor switch, the control transistor, the The semiconductor switch is controlled by a megaphone switch connected between the control power supply terminal and the control transistor, which is lower in voltage than the megaphone power supply terminal and is close to the rated value of the applicable range of the explosion-proof structure of electric equipment. Megaphone characterized by doing. 2. The megaphone power supply terminal according to claim 1, wherein the megaphone power supply terminal is derived from a megaphone battery in which a plurality of batteries are connected in series, and the control power supply terminal is derived from a first battery of the megaphone battery. megaphone. The semiconductor switch includes a power MOS-FET, a source connected to the megaphone power supply terminal, a drain connected to a power supply line of the amplifier , a gate connected to a collector of the control transistor, and a base of the control transistor. 2. A megaphone according to claim 1, wherein said megaphone is connected to said control power supply terminal via a megaphone switch.

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