GB2194355A

GB2194355A - Exposure meter of illuminating equipment

Info

Publication number: GB2194355A
Application number: GB08717614A
Authority: GB
Inventors: Jean-Francois Bernhard
Original assignee: Bron Elektronik AG
Current assignee: Bron Elektronik AG
Priority date: 1986-08-26
Filing date: 1987-07-24
Publication date: 1988-03-02
Anticipated expiration: 2007-07-24
Also published as: DE3628879A1; GB8717614D0; FR2603390A1; FR2603390B1; JPS63184025A; GB2194355B; JPH07122591B2

Abstract

The exposure meter of the invention is particularly suitable for photographic illuminating equipment such as flash-light units, or studio lights. It has a remote control setting device (30-32, 7, 12, 16), by which the quantity of light to be emitted can be adjusted. Setting buttons (30-32) can actuate an encoder (12). to which a device (16) for emitting coded remote control signals is connected. The output of the illuminating equipment scan be adjusted by the control signal emitting device (16) in a remotely controlled manner via infra-red transmitting diodes (4), so that the user does not need to alter his measuring position for trial measurements and adjustments of the lights. <IMAGE>

Description

SPECIFICATION Exposure meter of illuminating equipment The invention relates to an exposure meter for illuminating equipment in particular photographic illuminating equipment.

Exposure meters are known in which flashlight units can be tripped for a trial measurement by way of a remote control arrangement. The photographer can then ascertain whether the setting of the flash-light units is correct for emitting an adequate quantity of light. If the result of the trial measurement is that the output of the flash-light units must be altered, then the photographer must adjust the flash-light units by hand to the desired output stage. In this case, above all he must leave the measuring position. There is consequently a risk in the case of several successive trial measurements, the measuring cell of the exposure meter does not occupy the same position in each case during measurment, so that under certain circumstances the flash-light units are incorrectly set.Moreover, this method of adjustment is time-consuming, in particular if the output of the flash-light units must be altered more frequently.

It is the object of the invention to construct the exposure meter of this type so that there is no necessity for the user to leave his measuring position for adjusting the output of the illuminating equipment.

The invention provides an exposure meter for illuminating equipment, comprising a casing which comprises at least one display for exposure values and is provided with at least one tripping device for a trial measurement, by which the illuminating device can be tripped in a remotely controlled manner for the trial measurement, and with at least one measuring cell, which is connected in a lightmeasuring circuit, and comprising a remote control setting device by which the quantity of light to be emitted by the illuminating equipment can be adjusted, which remote control setting device comprises at least one setting button, by which an encoder can be actuated, to which encoder a device for emitting coded remote control signals is connected.

The exposure meter according to the invention is provided with the remote control setting device, which can be actuated by the setting button. Remote control signals coded in a corresponding manner by way of the device are emitted by the encoder, by which the output at the illuminating device or devices is adjusted by the desired extent according to the coding. Therefore, after a trial measurement, the user of the exposure meter according to the invention is immediately able, and without leaving his measuring position, to vary the setting of the illumination equipment by way of the setting button, and then to carry out a renewed trial measurement for checking the newly set values.Since the user is always located at the same position, the measuring cell of the exposure meter always occupies substantially the same position, so that in the case of several successive trial measurements, measurement results which are troube-free and can be properly compared with each other are achieved.

The invention will be described in detail with reference to one embodiment illustrated in the drawings, in which: Figure 1 shows an exposure meter according to the invention in elevation.

Figure 2 shows a circuit of the exposure meter of fig 1.

The exposure meter has a casing 1, in the front side of which a measuring cell 2, a display 3, infra-red transmitting diodes 4, and several buttons 5 for operating the various measuring functions of the exposure meter, are provided. Located on one side wall of the casing 1 is a measuring button 6, by which the measurement can be initiated. Measuring buttons 6 may also be located on the front side of the casing 1.

With the exposure meter, the photographer may adjust, in a remotely controlled manner, the output of the illuminating device to be controlled, which in the embodiment comprises flash-light units. First of ail, by pressing the measuring button 6, the infra-red transmitting diodes 4 are actuated, which emit a corresponding remote control signal. The flash-light units to be controlled are actuated by this. The flash-light emitted by the latter is monitored by the measuring cell 2 and evaluated by way of the circuit still to be described, in Figure 2. An aperture value corresponding to the flash energy then appears in the display 3. If the photographer decides to alter the amount of flash-light, then he can do this by depressing corresponding buttons on the exposure meter, without having to leave his measuring position.Consequently the measuring cell 2 is always located at the same point, so that correct and comparable conditions are produced in the case of successive trial measurements. Consequently an optimum and rapid adjustment of the flash-iight units to the respective illumination conditions is possible. The remote control signals are transmitted in the embodiment as infra-red pulses; however, they may also be transmitted by radio or by wire.

The circuit of the exposure meter located in the casing 1 has a microprocessor 7 (Figure 2) with an external programme memory 8. An address memory 9 is connected to the latter by way of the data bus 10. The circuit also has an oscillator 11 connected to the microprocessor 7, a keyboard encoder 12 and a keyboard 13. The display 3 is connected by way of a display driver 14 to the SDA (Serial Data) and SCL (Serial Clock) connections of the microprocessor 7. Apart from being con nected by way of the data bus 10, the address memory 9 is also connected to the ALE (Address Latch Enable) connection of the microprocessor 7. The programme memory 8 is connected by way of the address bus 15 to the micro-processor 7. Furthermore, the programme memory 8 is connected to the PSE (Programme Store Enable) connection of the microprocessor 7.

The infra-red transmitting diodes 4 are located in an infra-red transmitting stage 16, which is connected by way of a transistor 17, a resistor 18 and a NOT-gate 19 to the connection P1 of the microprocessor 7. The measuring cell 2 is connected in a light-measuring circuit 20, which comprises a switch 21 connected to the connection P3 of the microprocessor 7. The measuring cell 2 is connected to one input of an integrator 22, whereof the other input is connected to earth. The output 23 of the integrator 22 is connected to one input 24 of a comparator 25, the other input 26 of which receives the signal from a voltage divider 27. The output 28 of the comparator 25 is connected to the connection P2 of the microprocessor 7.

The programme stored in the programme memory 8 controls the microprocessor 7. On actuating the measuring button 6, a signal is produced at the connection P1 of the microprocessor 7, which actuates the infra-red transmitting diodes 4. The infra-red light emitted by them actuates the corresponding flash-light units. Directly thereafter, the integrator 22 short-circuited in the inoperative condition is cleared. The measuring cell 2 in the light-measuring circuit 20 receives the flashlight emitted by the flash-light units and produces a pulse corresponding to the quantity of light measured, which pulse arrives at the input of the integrator 22. At its output 23, a voltage proportional to the quantity of light measured by the measuring cell builds up.

After the expiration of the measuring time, the switch 21 is again ciosed by way of the connection P3 of the microprocessor 7, due to which the integrator 22 discharges by way of a resistor 29. The measuring duration is fixed in the programme memory 8. The voltage divider 27 fixes the voltage level up to which the integrator 22 may discharge. The duration of the discharge up to this fixed level defined by the voltage divider 27 thus depends on the voltage present at the output 23 of the integrator and thus on the quantity of light measured by the measuring cell 2. The discharge time is measured by the comparator 25, at whose output 28 a pulse appears, whereof the duration is a measurement of the quantity of light measured. The microprocessor 7 measures this pulse length at the connection P2 and from this calculates the quantity of light received by the measuring cell 2.The value of the quantity of light ascertained is then displayed in the display 3 by way of the display driver 14. The photographer may thus ascertain from the indication of the display 3 whether the flash-light units are producing the quantity of light necessary for the respective photograph.

If the photographer decides to alter the quantity of flash-light on tie basis of this measurement, then he may adjust the output at the flash-light units, without having to leave his measuring position. If the output of the flash-light unit is to be increased, then the buttons 30 and 31 are depressed simultaneously. On the contrary, if the output of the flash-light units is to be reduced, the buttons 30 and 32 are depressed simultaneously. The microprocessor 7 receives a corresponding command by way of the keyboard encoder 12. A coded signal is then emitted by way of the connection P1 and the transmitting stage 16, by which signal the output of the flashlight unit or units is increased or reduced, depending on which of the buttons 31 or 32 has been depressed.The exposure meter is constructed so that with each depression of the buttons 30, 31 or 30, 32, the flash energy to the flash-light units is varied by adjusting the output by one stage respectively.

Thus, if the flash energy is to be reduced for example by three stages, then the photographer must actuate the button 32 three times in succession. The size of the individual stages can be chosen freely; for example it may amount to one tenth of a stop or one third of a stop. With the buttons 5 (Figure 1) it is possible to display the new output values in the display 3, so that it is simple for the photographer to check whether the flash-light units are set correctly. After setting the flashlight units, the photographer may carry out a renewed measurement, in that he depresses the measuring button 6 in the manner described and actuates the flash-light units for a trial measurement.If the value of the quantity of light displayed in the display 3 should still not yet correspond to the photographer's wishes, then in the manner described, the flash-light unit or units can be re-set and checked by a trial measurement. Since there is no need for the photographer to move away from his measuring position during the trial measurement and the adjustment of the flashlight units, the measuring cell 2 is always located approximately at the same point during successive trial measurements, so that an optimum and rapid setting of the flash-light units is possible.

The flash-light units are equipped with corresponding decoders, so that the coded signals emitted by the transmitting diodes 4 can be decoded in a corresponding manner for adjusting the output.

The afore-described exposure meter is also suitable for controlling other illuminating equipment, such as studio lights. If the remote control signals are transmitted by radio or by wire, then the transmitting device 16 is naturally constructed in a corresponding manner.

Claims

1. An exposure meter for illuminating equipment, comprising a casing which comprises at least one display for exposure values and is provided with at least one tripping device for a trial measurement, by which the illuminating device can be tripped in a remotely controlled manner for the trial measurement, and with at least one measuring cell, which is connected in a light-measuring circuit, and comprising a remote control setting device by which the quantity of light to be emitted by the illuminating equipment can be adjusted, which remote control setting device comprises at least one setting button, by which an encoder can be actuated, to which encoder a device for emitting coded remote control signals is connected.

2. An exposure meter according to Claim 1, wherein the encoder is connected by way of a microprocessor to the control signal emitting device.

3. An exposure meter according to Claim 1 or claim 2, wherein the control signal emitting device is an infra-red transmitting stage.

4. An exposure meter according to Claim 1 or claim 2 wherein said control signal emitting device is a radio signal transmitting stage.

5. An exposure meter according to Claim 3 or claim 4, wherein the transmitting stage comprises at least one transmitting diode.

6. An exposure meter according to Claim 2 or any claim dependent thereon wherein the light-measuring circuit comprises an integrator and a comparator connected in series, whereof the output is connected to the microprocessor.

7. An exposure meter according to Claim 6, wherein connected to an input of the integrator is a switch, whereof the break period can be controlled by the microprocessor.

8. An exposure meter according to Claim 6 or claim 7, wherein the integrator is connected to an input of the comparator and a voltage divider is connected to another input thereof.

9. An exposure meter according to anyone of Claims 1 to 8, wherein the remote control setting device is located in the casing.

10. An exposure meter for illuminating equipment substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.