GB2295736A

GB2295736A - Battery chargers for wireless microphones

Info

Publication number: GB2295736A
Application number: GB9513857A
Authority: GB
Inventors: Masaaki Tokimi; Terou Taira
Original assignee: Nikkodo Co Ltd; UNITRON CORP
Current assignee: Nikkodo Co Ltd; UNITRON CORP
Priority date: 1994-11-30
Filing date: 1995-07-07
Publication date: 1996-06-05
Also published as: TW341734B; MY132012A; CN1123964A; JP2759764B2; KR960019902A; GB9513857D0; JPH08163784A

Abstract

The charger comprises a recess 12 for receiving a lower-end portion of the microphone 16. A circuit board 34 has electrodes 36 and 38 connected to plungers 30 and 32 which project into the recess 12 urged by a respective coil spring 44 and 40. A d.c. supply of charging current is fed to the plungers 30, 32 via a connector 56 so that the microphone battery 18 is charged when electrodes 20, 22 on the microphone engage the spring biassed plungers 30, 32. When the microphone is removed from the charger a spring biassed insulating sleeve 42 covers the plunger 30. <IMAGE>

Description

TITLE Battery Chargers DESCRIPTION The invention relates to a charger suitable for a storage battery in a wireless microphone. The charger design is such that it may be used in a karaoke device or for other commercial purposes involving frequent use.

Background Art One example of a conventional charger has two microphone electrodes at the lower-end surface of the wireless microphone, a recess into which the lower-end portion of the wireless microphone is fitted in the charger, and at the bottom of this recess electrodes or plungers facing the microphone electrodes. There is also a switch activated by the dead weight of the wireless microphone.

When the wireless microphone is inserted, the switch is turned on, and a charging voltage is applied across the electrodes or plungers at the bottom of the recess.

There is also a charger in which there is at the bottom of the recess a cover which moves under the dead weight of a wireless microphone. The electrodes or plungers are covered when the cover is in a raised position, but project when the cover moves down. Charging is effected through the establishment of contact between the electrodes of the wireless microphone and electrodes or plungers of the charger when the microphone is inserted.

The Invention The invention provides a charger suitable for a storage battery in a wireless microphone comprising a recess for a lower-end portion of the microphone, a circuit board having electrodes connected to plungers for contacting microphone electrodes, the plungers each projecting and being urged into the recess by a coil spring, an insulating tube fitting on an outer end portion of one or both of the plungers in a manner permitting relative movement along the plunger, and a coil spring having a force weaker than that urging the associated plunger urging the tube into the recess.

A wireless microphone having a battery suitable for charging is capable of fitting into the recess, and has electrodes for contacting the charger electrodes through which the battery may be charged. One of the microphone electrodes may be in the centre of the lower-end portion of the microphone, and the other may be annular and centre on the said one electrode.

Drawings Fig. 1 is a longitudinal section through a battery charger according to the invention in a state prior to insertion of the lower end of a wireless microphone; Fig. 2 is a corresponding section in a state when the lower end of the wireless microphone has been inserted; and Fig. 3 is a perspective view of the external appearance of the assembly when the wireless microphone is inserted in the charger.

As shown in the drawings, a wireless microphone charger 10 is formed in the general shape of a beer barrel with an upwardly opening recess 12. In Fig. 3, chargers 10 fit in and are carried by a microphone stand 14, on which there are rings supported by a post and arms above the chargers. The lower ends of wireless microphones 16, whose grip portions are generally cylindrical, are passed through the rings and their bottom ends are inserted into the recesses 12 of the chargers 10. Nickel-cadmium or similar chargeable storage batteries 18 in the wireless microphones 16 can be so charged.

In Figs. 1 and 2, there can be seen the lower end of the microphone 16, a first microphone electrode 20 in the centre, and on the periphery of a circle around this centre, another microphone electrode 22. The microphone electrodes 20 and 22 each connect to a flexible circuit board 24 inside the microphone 16, and make up a circuit configuration permitting a storage battery 18 to be charged. Infrared LEDs 26,26, driven by a carrier wave modulated by voice signals radiate signals in the form of infrared rays. The portion of the case enclosing the LEDs 26 comprises a smoky semitransparent body which does not attentuate infrared rays but does attenuate visible light rays.

The recess 12 is of a shape which permits smooth insertion of the microphone 16 and allows little positional displacement in relation thereto once the microphone has been inserted. Plungers 30 and 32 are respectively installed in a manner permitting upward and downward movement in the centre of the bottom surface of the recess 12, and in locations which correspond to the microphone electrode 20 and the circle of the annular microphone electrode 22. Enlarged portions 30a and 32a are formed at intermediate parts of these plungers 30 and 32. Below the plungers 30 and 32, there is a circuit board 34 containing electrodes 36 and 38 which face the plungers 30 and 32.

The upper-end portion of the plunger 32 in correspondence to the annular microphone electrode 22 projects a set length from the bottom surface of the recess 12. The upward projection of the plunger 32 is limited by the enlarged portion 32a. A first coil spring 40 is compressed between the enlarged portion 32a and the electrode 38.

On the upper-end portion of the plunger 30, an insulating tube 42 is fitted in a manner permitting relative upward and downward movment. A tubular expanded portion 42a is formed at a lower-end portion of this insulating tube 42, and because of the step at this expanded portion, the upper-end portion projects a set length from the bottom of the recess 12, and its upward protrusion is limited. A second coil spring 44 is compressed between the enlarged portion 30a and the electrode 36. A third coil spring 46 is compressed between the tubular expanded portion 42a and the expanded portion 30a.The force of this third coil spring 46 is weaker than that of the second coil spring 1414. Thus when there is no downward force on the plunger 30 and insulating tube 142, the plunger 30 is raised to a height such that it does not contact the electrode 36, and its upper-end portion projects a set length from the bottom of the recess 12. The upper-end portion of the insulating tube 42 projects further than the plunger 30 from the bottom of the recess 12, so the upper-end portion of the plunger 30 is covered by the outwardly projecting insulating tube 42. The force of the third coil spring 46 is for example less than or equal to 30 g so that the insulating tube 42 is not moved downward counter to its force by weight of a coin. The first and second coil springs 40 and 44 are made of good electrical conductors, and they may have the same force.

The casing of the charger 10 is divided into a top and bottom. In the top half, there is a guide 50 for the installation of the plungers 30 and 32 below the bottom of the recess 12, a member 52 for fixing the circuit board 34 by means of screws, and a member 54 for fixing the lower half of the casing, with the circuit board sandwiched in-between, by means of screws.

On the circuit board 34, a connector 56 for DC voltage power supply, obtained by conversion of a commercial power supply by an AC adapter (not shown), is directed towards the exterior of the casing. The DC voltage is processed by the circuit on the board 34 and applied to the electrodes 36 and 38. An LED 58 for display purposes is assembled on the circuit board 34, and the circuit is made such that the magnitude of charging current is detected, while the LED 58 lights up during charging. The light of this LED 58 can be seen from outside the casing via a light guide 60.

When the wireless microphone 16 is not in position, the two plungers 30 and 32 project from the bottom of the recess 12, and the plunger 30 in the centre is covered by the insulating tube 42. There can be no short-circuit acci/dent due to a coin for example falling in, since the force of the third coil spring 46 prevents the insulating tube 42 from being moved down by the weight of a coin.

When the wireless microphone 16 is positioned in the charger 10, the weight of the microphone 16 being about 300 g, the insulating tube 42 is moved down counter to the force of the third coil spring 46, and the top end of the plunger 30 comes into contact with the electrode 20.

Also, the top end of the other plunger 32 comes into contact with the annular electrode 22. Further, the weight of the microphone 16 comprises the first and second coil springs 40 and 44, and the bottom ends of the plungers 30 and 32 come into contact with the electrodes 36 and 38. Charging voltage is thereby imposed on the electrodes 20 and 22, going from the electrodes 36 and 38 and via the plungers 30 and 32. It is not essential that the plungers 30 and 32 contact the electrodes 36 and 38; voltage may be supplied from the electrodes 36 and 38 to the plungers 30 and 32 via the first and second coil springs 40 and 44.If the force of the first and second coil springs is set so that the plungers 30 and 32 do not contact the substrate electrodes 36 and 38 when the wireless microphone 16 is inserted, the impact on insertion of the microphone 16 is absorbed by the first and second coil springs 40 and 44, and damage to the circuit board 34 is prevented.

Although upward movement of the plunger 32 is restricted by the enlarged portion 32a, alternatively one end of the first coil spring 40 may be fixed to the lower-end portion of the plunger 32, and its other end to the circuit board 34, so that upward protrusion of the plunger 32 is limited by the natural length of the first coil spring 40. Upward protrusion of the other plunger 30, also, may be similarly limited by the natural length of the second coil spring 44. For the insulating tube 42, upward protrusion of the insulating tube 42 may be limited by the natural length of the third coil spring 46 by fixing one end of the third coil spring 46 to the insulating tube 42, and fixing its other end to the other plunger 30. An insulating tube 42 and a third coil spring 46 may be provided for the other plunger 32.

Claims

1. A charger suitable for a storage battery in a wireless microphone comprising a recess for a lower-end portion of the microphone, a circuit board having electrodes connected to plungers for contacting microphone electrodes, the plungers each projecting and being urged into the recess by a coil spring, an insulating tube fitting on an outer end portion of one or both of the plungers in a manner permitting relative movement along the plunger, and a coil spring having a force weaker than that urging the associated plunger urging the tube into the recess.

2. A charger according to claim 1 in which one or both of the plungers has an enlarged intermediate portion restricting movement into the recess.

3. A charger according to claim 1 in which the lower end of one or both of the plungers is fixed to a lower end of its associated coil spring to limit projection of the plunger into the recess.

14. A charger according to any preceding claim in which the insulating tube or tubes has or have an enlarged portion restricting movement into the recess.

5. A charger according to any of claims 1 to 3 in which one end of the insulating tube is fixed to its associated coil spring to limit projection of the tube into the recess.

6. A charger according to any preceding claim in which one of the plungers is in the centre of the recess.

7. A charger substantially as herein described with reference to the drawings.

8. A charger according to any preceding claim together with a microphone or microphones capable of fitting into the recess or recesses and having electrodes through which a battery may be charged.