JP2002023230A - Camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a camera in which the cost is reduced. SOLUTION: During stroboscopic photographing, prescribed pulses are given to an N-channel MOSFET62 from a digital/analog port D/A of an MPU 40 to recharge a main capacitor 67, to produce a flash by discharging the recharged power. In order to conduct battery checking, the MOSFET62 is given voltage signals that are lower than the pulse voltage and a current flows into a battery 30 according to the resistor value of the MOSFET62 for measuring the remaining power of the battery 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a camera having a strobe device.

[0002]

2. Description of the Related Art In general, a camera is provided with a battery check circuit for measuring the remaining power of a built-in battery for driving a zoom lens, a strobe device, and the like.

FIG. 5 is a diagram showing a battery check circuit of a conventional camera.

A battery check circuit 300 shown in FIG. 5 includes an MPU (Micro) which controls a sequence of a camera.
P-channel MOSFET 3 in which gate G is connected to output port PO of Processor Unit 310
11 are provided. This P-channel MOSFET3
A voltage V _BAT from the + terminal side of a battery (not shown) is applied to the source S 11.

The battery check circuit 300 includes:
A resistor 312 is provided between the gate G and the source S of the P-channel MOSFET 311, and a resistor 313 is provided between the drain D of the P-channel MOSFET 311 and the ground GND on the negative terminal side of the battery. . This resistor 313 has a sufficiently small resistance value to obtain a current required for battery check.

Further, the battery check circuit 300 includes resistors 314 and 31 connected in series between the drain D of the P-channel MOSFET 311 and the ground GND.
5 are provided. The connection point of these resistors 314 and 315 is connected to the analog / digital port A /
D.

In the battery check circuit 300 configured as above, the MPU 31
An “L” level signal is output from the 0 output port PO. Then, the P-channel MOSFET 311 is turned on, whereby the + terminal side of the battery → P-channel MOS
A current flows through a path from the FET 311, the resistor 313, and the ground GND. Then, the battery outputs a voltage V _BAT reduced by a voltage drop determined by the current and the internal impedance of the battery. Output voltage V _BAT
Is divided via the P-channel MOSFET 311 in accordance with the resistance values of the resistors 314 and 315 connected in series. The divided voltage (analog voltage) is a resistor 314,
Analog / MPU 310 connected to the connection point 315
Input to digital port A / D. MPU310
A / D converts the analog voltage input to the analog / digital port A / D to obtain a digital value corresponding to the analog voltage, and measures the remaining power of the battery based on the digital value. Perform a check.

[0008]

In the above-described battery check circuit 300, the P-channel MOSFET 311 is turned on, and a current is caused to flow through the resistor 313 having a relatively small resistance provided as a load for battery check. A battery check is performed. For this reason, a large P-channel MOSFET 311,
It is necessary to use the resistor 313 having a large wattage, and accordingly, the area of the circuit board is large, and thus the cost is increased.

The present invention has been made in view of the above circumstances, and has as its object to provide a camera in which cost is reduced.

[0010]

A camera according to the present invention, which achieves the above objects, boosts and rectifies power from a battery via a boosting transformer, charges a main capacitor, and charges the main capacitor when shooting. A strobe device that emits a flash by discharging electric power, the strobe device includes a switching element that is connected in series to a primary winding of the step-up transformer and that indicates a resistance value according to a control signal. A predetermined pulse is supplied to the switching element when power is stored in the main capacitor, and the switching element has a predetermined resistance value as a battery check control signal for measuring the remaining power of the battery. Control means for giving a control signal indicating the following to the switching element: In a state where the control signal for Terri check is sent, characterized in that a battery check means for measuring the residual power of the battery by determining the voltage of the battery.

In the camera of the present invention, a predetermined pulse is applied to the switching element for flash photography, the main capacitor is charged, the charged power is discharged, and a flash is emitted. Given by the control signal,
Since the current corresponding to the resistance value in the unsaturated region of the switching element is applied to the battery and the remaining power of the battery is measured, as in a conventional camera, a large wattage resistance as a component dedicated to battery check, It is not necessary to provide a large MOSFET to allow current to flow through the resistor. Therefore, the number of components can be reduced and the circuit board area can be reduced, and the cost can be reduced.

Here, the resistance of the switching element is controlled by a voltage value of a control signal. This camera has a memory in which a set value corresponding to a voltage value of a control signal for battery check is stored. It is effective to have the following.

The characteristics of the step-up transformer, switching element and the like constituting the strobe device provided in the camera differ depending on each camera. Therefore, a setting value corresponding to the individual difference of each camera is stored in a memory, and a control signal having a voltage value corresponding to the stored setting value is given to a switching element to perform a battery check. Can be absorbed. Therefore, the remaining power of the battery can be measured with high accuracy.

Further, the switching element is an N-channel MOSFET, and the control means includes:
It is preferable that a voltage signal lower than the voltage of the pulse be given to the gate of the ET as the control signal for battery check. Furthermore, it is also preferable that the switching element is a P-channel MOSFET, and the control means applies a voltage signal higher than the voltage of the pulse to the gate of the MOSFET as a control signal for the battery check. It is an aspect.

As described above, when the switching element is an N-channel MOSFET, a voltage signal lower than the voltage of the pulse is applied to the gate of the N-channel MOSFET.
In the case of a channel MOSFET, when a voltage signal higher than the voltage of the pulse is applied to the gate of the channel MOSFET to measure the remaining power of the battery, the power consumption of the battery can be reduced when performing a battery check.

[0016]

Embodiments of the present invention will be described below.

FIG. 1 is an external perspective view of a camera according to an embodiment of the present invention as viewed obliquely from the front and above.

A camera 10 shown in FIG. 1 is a camera that incorporates an autofocus (AF) device generally called an active type and performs photography on a roll-shaped photographic film. The autofocus device includes a camera 10
Having an AF light projecting window 12 arranged in the upper front part of the
A light projecting unit that emits light for distance measurement from the light projecting window 12 toward the front of the camera 10, and an AF light receiving window 1 disposed on the front surface of the camera 10 at a predetermined distance from the AF light projecting window 12.
The light emitted from the AF light projecting window 12 to the front of the camera 10 and reflected by the subject and returned by the AF light receiving window 1
3 is provided with a light receiving unit that receives the light from the light receiving unit 3 and receives the light to obtain the distance to the subject.

At the center of the front of the camera 10,
Zoom lens barrel 11 having optical zoom lens 11a inside
Is provided.

Further, the camera 10 is provided with a strobe device having a flash part 200 provided on the upper surface of the camera 10. The flash unit 200 emits a flash toward the subject during shooting.

The camera 10 also includes a zoom finder window 14 constituting a zoom finder unit (not shown) and an AE light receiving window 15 for guiding light to a built-in AE sensor for exposure adjustment. further,
A shutter button 18 is provided on the upper surface of the camera 10.

FIG. 2 is an external perspective view of the camera shown in FIG.

On the back of the camera 10, a strobe on / off switch 21, a finder eyepiece window 22, and an optical zoom lens 11a for setting whether or not to emit a flash toward a subject at the time of shooting are provided on the tele side (far side). ) Or a zoom operation lever 23 operated to the wide side (close distance side).

The camera 10 of the present embodiment having the above-described structure includes a battery for driving the optical zoom lens 11a, the flash device, and the like. Hereinafter, a battery check for measuring the remaining power of the battery will be described.

FIG. 3 is a diagram showing a flash device circuit including a battery check circuit of the camera shown in FIG.

FIG. 3 shows a battery 30, an MPU 40, an E
EPROM (Electrically Erasab)
le Programmable Read Only
Memory 50 and a strobe device circuit 60 are shown.

The MPU 40 controls the entire camera 10.

The EEPROM 50 stores the value of a control signal for battery check which will be described later.

The strobe device circuit 60 includes a step-up transformer 6 having one end of a primary winding connected to the + terminal side of the battery 30.
1, an N-channel MOSFET 62 and a Zener diode 63 arranged between the other end of the primary winding thereof and the negative terminal side of the battery 30, a gate of the N-channel MOSFET 62 and a digital / analog port D / A of the MPU 40.
And an N-channel MOSFE
A resistor 65 is provided between the gate of T62 and the negative terminal of the battery 30. N-channel MOSFE
T62 indicates a resistance value according to a control signal described later. This N-channel MOSFET 62 corresponds to the switching element according to the present invention.

The strobe device circuit 60 includes a diode 66 having an anode connected to one end of a secondary winding of the step-up transformer 61, and a diode 66 connected between the cathode of the diode 66 and the other end of the secondary winding. Main capacitor 67 placed
And are provided. Both ends of the main capacitor 67
It is connected to a flash light emitting unit (not shown).

Further, the strobe device circuit 60 includes a primary winding of the step-up transformer 61 and an output port P of the MPU 40.
There are provided resistors 71 and 72 connected in series with O. The connection point between the resistors 71 and 72 is connected to the analog / digital port A / D of the MPU 40.

First, the case where flash photography is performed will be described. In this case, first, the output port PO of the MPU 40 is set to a high impedance state (or “H” level state). As a result, the resistance 7
The current is prevented from flowing through the first and the second 72. Next, the digital / analog port D / A of the MPU 40
Outputs a predetermined pulse. The output predetermined pulse is input to the gate of the N-channel MOSFET 62 via the resistor 64, whereby the N-channel MOSFET
The ET 62 performs a switching operation, and the power from the battery 30 is boosted through the boosting transformer 61, rectified by the diode 66, and the main capacitor 67 is charged. Thereafter, in synchronization with the shutter operation, the power charged in the main capacitor 67 by means not shown is discharged,
A flash is emitted from the flash unit 200 (see FIG. 1).

Next, a battery check for measuring the remaining power of the battery 30 will be described. In this case, first, M
Output port PO of PU 40 is set to the “L” level state. As a result, the voltage divided from the battery 30 according to the resistance values of the resistors 71 and 72 is applied to the analog / digital port A / D of the MPU 40. Then, M
From the digital / analog port D / A of the PU 40, a control signal indicating a predetermined resistance value (on-resistance value) of the N-channel MOSFET 62 for battery check for measuring the remaining power of the battery 30 is output. This control signal is a voltage signal having a DC level lower than the voltage of the predetermined pulse. Thus, the N-channel MOSFE
When the remaining power of the battery 30 is measured by applying a voltage signal lower than the predetermined pulse voltage to the gate of T62, the power consumption of the battery 30 in the battery check can be reduced. Further, characteristics of the step-up transformer 61, the N-channel MOSFET 62, and the like differ depending on each camera. Therefore, in the present embodiment, the EEPROM 50
Setting values corresponding to individual differences between the cameras are stored. The stored setting values are read out by the MPU 40,
By outputting a control signal having a voltage value corresponding to the set value from the digital / analog port D / A, individual differences between cameras can be absorbed. Therefore, battery 3
The residual power of 0 can be measured with high accuracy.

When a control signal having the above voltage value is output from the digital / analog port D / A of the MPU 40, the positive terminal of the battery 30 → the step-up transformer 61 → the N-channel MOSFET 62 → the negative terminal of the battery 30 On the route,
A current flowing through the N-channel MOSFET 62 determined by an on-resistance value corresponding to the voltage value of the control signal flows. Then, a voltage reduced by the voltage drop determined by the current and the internal impedance of the battery 30 is output from the battery 30. The output voltage corresponds to the resistor 7 connected in series.
The voltage is divided according to the resistance values of 1,72. The divided voltage is supplied to the MPU connected to the connection point between the resistors 71 and 72.
It is input to 40 analog / digital ports A / D. The MPU 40 has its analog / digital port A
A / D conversion is performed on the voltage input to / D to obtain a digital value corresponding to the voltage, and the remaining power of the battery 30 is measured based on the digital value to perform a battery check.

The MPU 40 has a function of giving a predetermined pulse from the digital / analog port D / A to the N-channel MOSFET 62 and giving the control signal.
It corresponds to the control means according to the present invention. Further, the series-connected resistors 71 and 72 and the analog / digital port A / D of the MPU 40 correspond to a battery check unit according to the present invention.

In the present embodiment, in flash photography, a predetermined pulse is given from the digital / analog port D / A of the MPU 40 to the N-channel MOSFET 62 to charge the main capacitor 67, discharge the charged power, and emit a flash. In checking the battery, a voltage signal lower than the voltage of the pulse is given to the gate of the N-channel MOSFET 62 to
Current flowing through the battery 30 according to the resistance value of the battery 30
Therefore, unlike a conventional camera, it is not necessary to provide a large wattage resistor as a component dedicated to battery check and a large MOSFET for flowing current through the resistor, unlike a conventional camera. Therefore, the number of components can be reduced and the circuit board area can be reduced, and the cost can be reduced. Also, N-channel MO
Since the remaining power of the battery 30 is measured by giving a voltage signal lower than the voltage of the predetermined pulse to the gate of the SFET, the power consumption of the battery 30 can be suppressed to a low battery check.

In this embodiment, the N-channel MOSF
The description has been given of the example in which the voltage of the battery 30 is measured by supplying a voltage signal lower than the voltage of the predetermined pulse to the gate of the ET.
An OSFET is provided, and a voltage signal higher than the voltage of the predetermined pulse is supplied to the gate of the P-channel MOSFET as a control signal for battery check to measure the remaining power of the battery 30. Power consumption may be reduced.

FIG. 4 is a diagram showing a strobe device circuit different from the strobe device circuit shown in FIG.

The same components as those of the flash device circuit shown in FIG. 3 are denoted by the same reference numerals, and different points will be described.

FIG. 4 shows a battery 30, an MPU 80, an E
EPROM 50 and strobe device circuit 100 are shown.

The MPU 80 is provided with first and second output ports PO1 and PO2 which replace the function of the digital / analog port D / A provided in the MPU 40 described above. These output ports PO1 and PO2 are connected to the gate of an N-channel MOSFET 62 via resistors 91 and 92 constituting the strobe device circuit 100. Note that the resistance value of the resistor 92 is set relatively large as compared with the resistance values of the resistor 65 and the resistor 91. The above-described strobe device circuit 60 shown in FIG.
A predetermined pulse and a voltage signal lower than the voltage of the predetermined pulse are supplied to the N-channel MOSF by the analog port D / A.
The strobe device circuit 100 shown in FIG. 4 applies a predetermined pulse to the N-channel MOSFET 62 through the output port PO1 and sends an “H” level control signal to the N-channel MOSFET 62 through the output port PO2.
This is a configuration provided to the channel MOSFET 62. Less than,
This will be described in detail.

In flash photography, both the output port PO and the second output port PO2 of the MPU 80 are set to a high impedance state. In this state, a predetermined pulse is output from the first output port PO1, whereby the N-channel MOSFET 62 performs a switching operation, and charges for the strobe flash light are stored in the main capacitor 6
7 is stored. Thereafter, a flash is emitted in synchronization with the shutter operation.

On the other hand, when performing a battery check,
Output port PO of MPU 80 is set to the “L” level state, and first output port PO1 is set to the high impedance state. In this state, an “H” level control signal is output from the second output port PO2. The control signal at the “H” level is divided according to the resistance values of the resistors 92 and 65 and input to the gate of the N-channel MOSFET 62. Here, since the resistance value of the resistor 92 is relatively large, the level of the voltage input to the gate of the N-channel MOSFET 62 at the connection point of the resistors 92 and 65 is relatively small. Therefore, the positive terminal side of the battery 30 → the step-up transformer 61 → the N-channel MOSFET 62 → the battery 30
Of the N-channel MOSFET 62
, A current determined by an on-resistance value corresponding to the voltage value flows, and the battery 30 outputs a voltage reduced by a voltage drop determined by the current and the internal impedance of the battery 30. Hereinafter, in the same manner as described with reference to FIG. 3, the voltage divided according to the resistance values of the resistors 71 and 72 is applied to the analog / digital port A / D of the MPU 80 at A / D.
After the D conversion, the remaining power of the battery 30 is measured. In this way, the battery check may be performed.

[0044]

As described above, the camera of the present invention applies a predetermined pulse to the switching element to charge the main capacitor, discharges the charged power, emits a flash, and emits a flash when performing flash photography. Because the switching element gives a control signal indicating a predetermined resistance value to the switching element and measures the remaining power of the battery, like a conventional camera, a large wattage resistance as a part dedicated to battery check, It is not necessary to provide a large-sized MOSFET to allow current to flow through the resistor, so that the number of components can be reduced, the circuit board area can be reduced, and cost can be reduced.

[Brief description of the drawings]

FIG. 1 is an external perspective view of a camera according to an embodiment of the present invention as viewed obliquely from the front and above.

FIG. 2 is an external perspective view of the camera of FIG.

FIG. 3 is a diagram showing a strobe device circuit including a battery check circuit of the camera shown in FIG. 1;

FIG. 4 is a diagram showing a strobe device circuit different from the strobe device circuit shown in FIG. 3;

FIG. 5 is a diagram showing a battery check circuit of a conventional camera.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Camera 11 Zoom lens barrel 11a Optical zoom lens 12 AF projection window 13 AF receiving window 14 Zoom finder window 15 AE receiving window 18 Shutter button 21 Strobe on / off switch 22 Finder eyepiece window 23 Zoom operation lever 30 Battery 40, 80 MPU 50 EEPROM 60,100 Strobe device circuit 61 Step-up transformer 62 N-channel MOSFET 63 Zener diode 64,65,71,72,91,92 Resistance 66 Diode 67 Main capacitor 200 Flash part

Claims (4)

[Claims] 1. A camera equipped with a strobe device for boosting and rectifying power from a battery via a boosting transformer, charging a main capacitor, discharging the power charged in the main capacitor, and emitting a flash when photographing. Wherein the strobe device includes a switching element connected in series to a primary winding of the step-up transformer, the switching element indicating a resistance value according to a control signal; and Control means for giving a predetermined pulse to the switching element at the time, and giving the switching element a control signal indicating a predetermined resistance value to the switching element as a battery check control signal for measuring the remaining power of the battery; In a state where a control signal for battery check is sent to the switching element by the control means, A camera comprising: battery check means for measuring the remaining power of the battery by determining the voltage of the battery. 2. The camera according to claim 1, wherein the switching element has a resistance value controlled by a voltage value of a control signal. The camera has a memory in which a set value corresponding to a voltage value of a control signal for battery check is stored. The camera according to claim 1, further comprising: 3. The switching element is an N-channel MO.
2. The camera according to claim 1, wherein the control unit is configured to apply a voltage signal lower than a voltage of the pulse to the gate of the MOSFET as a control signal for the battery check. 3. . 4. The switching element is a P-channel MO.
2. The camera according to claim 1, wherein the control unit is configured to apply a voltage signal higher than a voltage of the pulse to the gate of the MOSFET as a control signal for the battery check. 3. .