JPH04366822A - Battery check circuit for camera - Google Patents

Abstract

PURPOSE:To excellently perform various driving including the light emission of an auxiliary light source by a battery even when the auxiliary light source is provided. CONSTITUTION:The battery check circuit of the camera wherein the auxiliary lamp 7 is incorporated so as to prevent a red-eye phenomenon checks a battery voltage when a dummy current is supplied to, for example, a shutter driving pulse motor in normal operation. When a red-eye phenomenon preventive mode is selected, the battery voltage at the time of supplying dummy currents to a film winding motor and a zoom motor in addition to a driving part is checked to check the battery with a decision level higher than a level in the normal operation.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery check circuit for a camera, and more particularly to a battery check circuit for a camera provided with an auxiliary light source separate from a strobe light source to prevent red-eye.

0002

[Prior Art] A battery is used as a driving source for various types of cameras.
The capacity has been checked to ensure that basic operations such as strobe photography and film winding can be carried out smoothly.

[0003] Incidentally, when photographing with a camera using a strobe light, the so-called red-eye phenomenon, in which the eyes of a subject such as a person appear red, has traditionally been a problem, but recently measures have been taken to reduce and prevent this red-eye phenomenon. In other words, the red-eye phenomenon is a phenomenon in which when a strobe is used on a human or animal, the strobe light enters the eyeball through the pupil, and this light is reflected from the blood vessels in the eyeball, causing the eye to appear red. Therefore, conventionally, in order to prevent the above-mentioned red eye, a weak light is emitted in advance (pre-flash) to reduce the diameter of the subject's pupil before the actual shooting.
This is done to reduce the incidence of strobe light into the pupil.

[0004] When performing the above-mentioned pre-emission using a lamp built into the camera, a method has been proposed in which one strobe light source (lamp) such as a xenon tube is used to emit light using two types of capacitors; In order to facilitate discharge control, a method has been proposed in which an auxiliary light source is provided separately from the strobe light source. According to this, the auxiliary light source causes pre-emission of light in synchronization with the shooting button, and after the pupil diameter of the subject is reduced, the main light emission is performed using the strobe light source.

[0005]

[Problem to be Solved by the Invention] However, in cameras using the above-mentioned auxiliary light source, the power required to operate the auxiliary light source is greater than the power of other drive units, and conventional battery checks are insufficient. There is. In other words, a lamp with a relatively large luminous flux of irradiation light is used as the auxiliary light source, and it takes about 1 second for the pupil to react when preventing red eye.
A power greater than that of other drive units (e.g. 600mA)
degree) is required. For example, in the case of a strobe light source, the light emitting power is large, but the capacitor is charged once and this charged power is used to cause the xenon tube to emit light. Therefore, an auxiliary light source requires a large amount of power even when compared to a strobe light source.

On the other hand, the battery check level setting of a camera is usually set to the lowest possible level so that many pictures can be taken while the functions and performance of the camera are satisfied. Therefore, under these circumstances, when the above-mentioned auxiliary light source is built into the camera, there may be cases where the auxiliary light source is unable to obtain the amount of light emitted to prevent red-eye, and even though the auxiliary light source is able to emit light, , which may cause problems in subsequent driving. For example, even if the battery is determined to be good after a battery check, basic operations such as firing an auxiliary light source, firing a strobe during exposure, and winding the film after taking pictures may not be possible.

The present invention has been made in view of the above-mentioned problems, and its object is to provide a camera that can perform various drives including light emission of the auxiliary light source using a battery even when an auxiliary light source is provided. The purpose is to provide a battery check circuit.

[0008]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a battery check circuit for a camera with a built-in auxiliary light source in order to prevent the red-eye phenomenon. The battery voltage is checked when current is applied, and when the red-eye prevention mode is selected, the battery voltage is checked when dummy current is applied to other drive units in addition to the above-mentioned predetermined drive unit. shall be.

[0009]

[Operation] According to the above configuration, for example, the pulse motor for driving the shutter is put in the brake state and a dummy current is generated, and a normal battery check is performed in this state, but the red-eye prevention mode is selected. In this case, for example, in addition to the pulse motor, the film winding motor and the zoom motor are braked to generate a new dummy current. Therefore, in the red-eye prevention mode, a larger dummy current is applied than in normal times for checking.
A substantially higher level battery check is performed.

0010

[Embodiment] Fig. 1 shows the configuration of a battery check circuit for a camera according to an embodiment, and Fig. 2 shows an external appearance of a camera according to an embodiment. A lens barrel 3 having a photographic lens 2 is disposed on the front surface of the camera 1 so as to be movable forward and backward. A finder 4, an autofocus (AF) light emitting section 5a, an AF light receiving section 5b, and a strobe light emitting section 6 with a built-in xenon tube are provided on the front surface of the camera body 1, and the lens barrel 3 and the strobe light emitting section are also provided. An auxiliary light source (lamp) 7 is disposed between the two.

A shutter button 8 and a strobe mode switching button 9 are provided on the top surface of the camera body 1, and the shutter button 8 performs a photographing operation as described later with a two-stage switch (S1, S2). Further, the strobe mode switching button 9 has a configuration in which a knob slides within a groove, and is configured to switch between red-eye prevention red-eye prevention mode, low-brightness automatic flash mode,
It is possible to switch between forced flash modes such as daytime synchronization.

In FIG. 1(a), a CPU (central processing unit) 11 that controls the entire camera operation is provided with an auxiliary lamp 7 via a switching transistor 12, and a battery is connected to the other side of the auxiliary lamp 7. (Battery - e.g. 6V) 13 is connected. Further, the strobe mode switching button 9 is connected to the CPU 11 so as to input its selection signal, and although not shown, an autofocus (AF) section, a shutter control section, a strobe control section, an automatic exposure (AE) ) units etc. are also under general control by the CPU 11.

A check start transistor 14 is provided for starting a battery check, and the positive terminal of the battery 13 is connected to the emitter terminal of this transistor 14, and the base terminal is connected to the A terminal of the CPU 11. Ru. Further, resistors R1 and R2 are connected in series between the collector terminal of the transistor 14 and the ground.
are connected, and a divided voltage output of the battery voltage is taken out from the connection point between the resistor R1 and the resistor R2. Furthermore, a comparator 16 for determining the battery level is provided, the positive input terminal of which is supplied with the partial voltage at the connection point between the resistors R1 and R2, and the negative input terminal of which is supplied with a comparison standard (reference) voltage Vref. The output terminal of the comparator 16 is connected to the B terminal of the CPU 11.

On the other hand, a first driver circuit 18 for driving a shutter driving pulse motor 19 is connected to the CPU 11, and a second driver circuit 20 for driving a film winding motor 21 and a zoom motor 22 is also connected to the CPU 11. There is. Figure (b) shows a detailed circuit configuration inside the second driver circuit 20, and the circuit shown in the figure is composed of transistors TR1 to TR6 sandwiching the film winding motor 21 and the zoom motor 22, respectively. becomes an H-bridge circuit, and these transistors TR1
~TR6 is turned on and off by a logic circuit 23 to which the base terminal is connected.

Therefore, when the logic circuit 23 turns on the transistors TR1 and TR5, the film winding motor 21 is driven to rotate, and the transistor TR
By turning on transistors TR2 and TR6, the zoom motor 22 can be rotationally driven, and transistors TR1 to TR6 can be turned on.
TR3 is turned off and transistors TR4 to TR6
The brake can be set by turning on the brake. In this braking state, transistor TR
In order to lower the saturation voltage between the collector and emitter of 4 to TR6, a base current of about 30 to 50 mA is supplied per transistor, and in this case, a dummy current of about 90 to 150 mA is passed through three transistors TR. be able to. Further, the first driver circuit 18 has a similar configuration, and when the first driver circuit 18 is in a braking state, a dummy current of about 60 to 100 mA can flow.

According to such a check circuit, the CPU
When the A terminal of 11 is set to Low level, the check start transistor 14 is turned on, and the voltage of the battery 13 is applied to the series resistors R1 to R2. At the same time, under normal conditions, the first driver circuit 18 puts the shutter driving pulse motor 19 in a braking state and causes a dummy current of about 60 to 100 mA to flow, and the battery voltage is checked by this drop. In other words, the partial voltage of the battery voltage dropped by the dummy current is applied to the comparator 16.
is supplied to the positive input terminal of the comparator 16, and the reference voltage V
compared to ref. If the partial voltage of the battery voltage is higher than the reference voltage Vref, it is determined that the capacity (power) is sufficient, and the comparator 16 outputs a high voltage.
The level output is input to the B terminal of the CPU 11, and if it is lower than the reference voltage Vref, it is determined that the capacity is insufficient, and a low level output is supplied from the comparator 16.

On the other hand, when the red-eye prevention mode is selected, the CPU 11 operates the shutter driving pulse motor 19.
In addition, the second driver circuit 20 brakes the film winding motor 21 and the zoom motor 22 to further flow a dummy current of 90 mA to 150 mA. Therefore, the voltage of the battery 13 is lowered by a dummy current larger than normal, and checked by the divided voltage output of this battery voltage.

The embodiment has the above configuration, and its operation will be explained below based on FIG. 3. In FIG. 3, first, in step 101, the first stage switch S of the shutter button 8 is
1 is turned on, in step 102 the CPU 1 is turned on.
1 turns on the check start transistor 14, and in step 103 the first driver circuit 18 puts the shutter drive pulse motor 19 in a braking state. In the next step 104, it is determined whether or not the strobe mode switching button 9 is set to the red-eye prevention mode.
”, the process moves to step 107, but when it is “Y”, the process moves to the next step 105, where the second driver circuit 20 turns off the transistors TR1 to TR3, and at step 106, the process moves to the next step 105 to turn off the transistors TR4 to TR6.
1 is turned on, and the film winding motor 21 and the zoom motor 22 are put into the brake state. Therefore, under normal conditions, a dummy current is applied to the shutter drive pulse motor 19, and in the red-eye prevention mode, a high judgment level is applied by adding dummy currents to the film winding motor 21 and zoom motor 22 to the above dummy current. A battery check will be performed.

In this step 107, it is determined whether the output of the comparator 16 (B terminal input of the CPU 11) is High, and when it is "N", the battery capacity is insufficient. Therefore, the process moves to step 108 to turn off the transistor 14, and step 1
At 09, the transistor TR4 in the second driver circuit 20
~TR6 is turned off, and in the next step 110, processing for battery exhaustion (display processing, etc.) is performed. On the other hand, when "Y" in step 107, the battery capacity is sufficient, so in step 111 the transistor 14 is turned off, and in step 112 the transistors TR4 to TR6 in the second driver circuit 20 are turned off.
After turning off, in step 113, photometry and distance measurement processing for focus control and exposure control is performed.

In the next step 114, it is determined whether the second stage switch S2 (release switch) of the shutter button 8 is turned on, and if it is "Y", step 1 is executed.
The process moves to step 15, where it is further determined whether or not the red-eye prevention mode is in effect, and if "N", the process moves to step 117, where focus control and exposure control are performed. If "Y" in step 115, the red-eye prevention mode is in effect, so the auxiliary lamp 7 is turned on for about 1 second in step 116, and the process moves to step 117.In step 117, focus control and exposure control are controlled. After the strobe light is emitted and the photographing is completed, the film is advanced. In this way, when the red-eye prevention mode is set, by increasing the dummy current and performing a battery check at a high level, it is possible to not only emit light from the auxiliary lamp 7 but also maintain its subsequent operation in good condition. It will be possible.

In the above embodiment, the film winding motor 21 and the zoom motor 22 are operated in the red-eye prevention mode.
Although a dummy current is applied to both of the motors 21 and 22, the present invention is not limited to this. For example, a dummy current may be applied to either one of the motors 21 and 22, and the motors are operated in a normal state and when a red-eye prevention mode is selected. It is also possible to use a combination of drive motors different from those in the above embodiment.

Further, in the embodiment, the auxiliary lamp 7 is used to prevent red-eye, but this auxiliary lamp 7 can also be used to emit auxiliary light in a low brightness state, for example, in passive autofocus control. It is.

[0023]

[Effects of the Invention] As explained above, according to the present invention,
Normally, when checking the battery, the battery voltage is checked when a dummy current is passed through the specified drive part.
When the red-eye prevention mode is selected, the battery voltage is checked when dummy current is sent to other drive parts in addition to the above-determined drive part, so even if an auxiliary light source is built-in, red-eye prevention can be avoided. It is possible to perform pre-emission for the purpose well, and also to reliably carry out subsequent camera drives such as strobe emission and film winding.

[Brief explanation of drawings]

FIG. 1 is a circuit block diagram showing the configuration of a camera battery check circuit according to an embodiment of the present invention, and FIG.
1 is an overall view, and FIG. 2B is a diagram showing a second driver circuit.

FIG. 2 is a perspective view showing the external configuration of the camera of the embodiment.

FIG. 3 is a flowchart showing the operation of the embodiment.

[Explanation of symbols]

7... Auxiliary light source (lamp), 9... Strobe mode switching button, 11...
CPU, 13...Battery, 14...Check start transistor, 16
... Comparator, 18 ... First driver circuit, 19 ... Shutter drive pulse motor, 20
... second driver circuit, 21 ... film winding motor, 22 ...
Zoom motor, TR1 to TR6...Transistor, R1,
R2...Resistance.

Claims (1)

[Claims] [Claim 1] In a battery check circuit for a camera with a built-in auxiliary light source to prevent red-eye phenomenon,
Under normal conditions, the battery voltage is checked when a dummy current is passed to a predetermined drive section, and when red-eye prevention mode is selected, the battery voltage is checked when a dummy current is passed to other drive sections in addition to the above predetermined drive section. A camera battery check circuit characterized by checking the following.