GB2180705A

GB2180705A - Switching arrangements for power distribution

Info

Publication number: GB2180705A
Application number: GB08523052A
Authority: GB
Inventors: Laurence Atkinson
Original assignee: KEYHARBOUR Ltd
Current assignee: KEYHARBOUR Ltd
Priority date: 1985-09-18
Filing date: 1985-09-18
Publication date: 1987-04-01
Also published as: GB8523052D0

Abstract

A power pack for flash photography includes two groups 4, 6 of charge storage units 4A to 4E 4E and 6A to 6E). A first bus 40 connects all the output terminals of the storage units of group 4 in parallel to a bank 8 of lamp-receiving sockets 30. A second bus 42 is connected to another socket bank 10. A switching device 2 selectively switches the charge storage units of the second group 6 between the two buses (40, 42) so as to vary the power distribution supplied to the two socket banks 8, 10. Unit 6E is permanently connected to bus 42. A control unit 16 varies the voltage level to which all the storage units are commonly charged. The pack is such that both the quantity of power and the ratio with which it is distributed between the lamps plugged into the socket banks can be readily adjusted as required. <IMAGE>

Description

SPECIFICATION Switching arrangements The present invention relates to switching arrange ments for example for a power pack for powering an array of photographic flash lamps.

Previously proposed power packs comprise a plurality of charge storage units, each arranged to store an electrical charge and a switching unit for selectively connecting the outputs of the storage units in parallelsothatdifferentamountsofpower can be discharged through an array of photographic lamps.

Where different amounts of power are to be discharged through different lamps, use is made of a resistive or selective network to reduce the amount of power supplied to particular lamps. Such an arrangement has little flexibility and is wasteful of power.

It is an object of the invention to provide an improved switching arrangement and power pack.

According to the present invention there is provided a switching arrangementforswitching power fromtwo groups of storage units betweenfirstand second connector banks each capable of being coupled to two or more lamps,the arrangement comprising first and second conductors respectively connected to the first and second banks, the first con ductor connecting the outputs of the storage units of one group in parallel, and a switch device operableto selectively switch the output terminals ofthe storage units ofthe other groupto one of said first and second conductors, the switch device in each setting thereof connecting the output terminals of the storage units ofthe second group not connected to the second conductor, in parallel with those storage units of said first group.

According to the present invention there isfurther provided a power packforflash photography,the power pack comprising first and second banks of connectors, each bank being connectable with two or more flash lamps, first and second groups of storage units each arranged to store an electric charge, first and second buses, the first bus connecting all the output terminals of the storage units of the first group in parallel to the first bank, and a multiposition switching device arranged in each position to couple different numbers of the output terminals of the storage units ofthe second group to the second bus and the output terminals ofthe remaining storage units of the second group to the first bus in parallel with the output terminals of the storage units ofthefirst group.

Apower packembodying the invention will now be described, byway of example, with reference to the accompanying diagrammatic drawings in which: Figure lisa block diagram of the power pack; and Figure2 is a circuit diagram of one form of charging circuit for capacitor banks.

The power pack shown in Figure 1 is arranged to distribute the power from ten charge storage units 4Ato 4E and 6Ato 6E between two socket banks 8 and 10 each having two sockets 30 and 32 respectively.

Each storage unit4Ato 4E and 6Ato 6Ecomprises a bank of electrical capacitors which is held charged through a charging unit 12. The charging unit 12 is supplied with powerfrom a source 18through avoltage control unit 16. Avariable knob 24 of thevoltage control unit 12 can be rotated to varvthevoltage supplied to the charging units from full voltage to zero. Thus the power stored by each charging unit is determined by the setting of the control knob 24.

As shown the charging units are arranged in two groups4and 6. The outputterminals of the storage units of group 4 are permanently connected in parallel by a bus 40 coupled to the socket bank 8. The output terminals of the storage units of group 6 are selectively connectable by means of change-over switches 6Ato 6E to the bus 40 orto a bus 42which is coupled to the socket bank 10. A switching unit 2 controls the operation of the switches 20Ato 20D and 20F; the storage unit 6E being permanently connected to the bus 42.

The switching unit 2 has a control knob with five different settings representing five different distributions of power to the two socket banks. The five different settings respectively provide a division of the total power stored by all the storage units 4Ato 4Eand6Ato6E between the two socket banks 8 and 10 as follows: 50%-50%, 60%-40%, 70%-30%, 80%- 20%, 90%-I 0%.

In the position shown in Figure 1 the distribution of power is 50%-50% and with this setting all ofthe storage units 6Ato 6E are connected in parallel to the bus 42 and the switch 20F is closed to connectthetwo buses 40 and 42 in parallel.

For the setting 60%-40% the switching unit 12 causes the switch 20F to open and the switch 20Ato change over so that the output of storage unit 6A is disconnected from the bus 42 and instead connected to the bus 40.

For the setting 70%-30% the switching unit 2 causes the two switches 20A and 20B to change over so that the outputs of the two storage units 6A and 6B are disconnected from the bus 42 and instead connected to the bus 40.

Forthetwo othersettingsthe positionsofthe switches 20A to 20D will be apparent.

In operation when a photographer wishes to illum- inate a scene with an array of flash lamps he must decide how much light is needed. Based on this decision he can readilyworkout how much electrical power is required to produce the required level of illumination and so the knob 24 is adjusted accord ingly. Adjustment of the knob 24 will set the charging voltage of the storage units and therefore the total power stored.

Thephotographerwill norm ally have two or more flash lamps that he wishes to use and will position them forexampleto provide required highlights of the subject. One flash lamp is plugged into the bank 10 and the other lamp is plugged into the bank8. By adjustment of the knob 22 the photographer can adjust the ratio of power supplied to the two flash lamps.

Thus by and large the photographer can experiment using different ratios to achieve the required highlighting without adjusting the overall powerstored for producing each flash.

Where the photographer has more than two flash lamps and when two of them have similar electrical characteristics, then those two can be plugged into different sockets 30 of the same socket bank. When the lamps are triggered the power supplied to each of the lamps connected to the sockets 30 will be equally divided between them.

Thus when the setting 50%-50% is used all ofthe lamps connected to the sockets 30 and 32 will receive equal amounts of power. For example the two lamps in the sockets 30 will each receive 33-1/3% of the total power, while the lamp connected to the socket 32 will also receive 33-1/3% of the power.

With the setting of 60%-40% the two lamps in the socket 30 will each receive 30% of the powerwhile the lamp connected to the socket 32 will receive 40% of the power.

It will be appreciated that a multitude of different divisions of power can be achieved by varying the setting of the knob 22 ofthe switching unit and the sockets into which the available lamps are plugged.

In a modification the switch 20F may be omitted.

It will further be appreciated that with the arrangement all the available power is discharged into the lamps and little or none is wasted as in the prior artto reduce the power supplied to a particular lamp.

The switching unit 2 and the associated switches 20Ato 20D and 20Fcan be in the form of complex multi-rotary switch or comprise an equival ent semi- conductor switching circuit.

Each storage unit is preferably in the form of a bank of capacitors which are charged by a semiconductor charging circuit, an example ofwhich is illustrated in the circuit diagram of Figure 2.

Itwill be appreciated that other suitable charging circuits as will be apparent to the skilled addressee can be used instead.

Also while the arrangement described includes two groups offive switching units the numberof switching units in each group can be varied as required.

Claims

1. A switching arrangement for switching power from two groups of storage units between first and second connector banks each capable of being coupled to two or more lamps, the arrangement comprising first and second conductors respectively connected to the first and second banks, the first con ductor connecting the outputs of the storage units of one group in parallel, and a switch device operable to selectively switch the outputterminals of the storage units of the other group to one of said first and second conductors, the switch device in each setting thereof connecting the output terminals of the storage units of the second group not connected to the second conductor, in parallel with those storage units of said first group.

2. Apowerpackforflash photography,thepower pack comprising first and second banks of connectors, each bank being connectable with two or more flash lamps, first and second groups ofstorage units each arranged to store an electric charge, first and second buses, the first bus connecting all the output terminals of the storage units ofthefirst group in parallel to the first bank, and a multiposition switching device arranged in each position to couple different numbers ofthe output terminals of the storage units of the second groupto the second bus and the output terminals of the remaining storage units of the second group to the first bus in parallel with the output terminals of the storage units of the first group.

3. A power pack according to Claim 2 wherein the storage units in the first and second groups are equal in number.

4. A power pack according to Claim 2 orto Claim 3 including charging means for charging each storage unit to a predetermined voltage level, and control means for varying said predetermined voltage level.

5. A power pack according to any one of Claims 2 to 4wherein said switching device comprises a rotary switching device.

6. A power pack according to any one of Claims 2 to 4wherein said switching device comprises a semiconductor switching circuit.

7. A power pack according to any one of Claims 2 to 6wherein the switching device is such that the ratio of power supplied to the two connector banks is variable from 50%-50% to 90%-10%.

8. A power packforflash photography substantially as hereinbefore described with reference to the accompanying drawings.