JP3417706B2 - Camera battery check device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery check device for a camera, which is suitable for checking the capacity (battery life) of a power supply battery of the camera.

[0002]

2. Description of the Related Art Conventionally, when checking the capacity of a battery such as a manganese battery or an alkaline battery, a dummy load having a constant resistance value is connected to these batteries to allow a current to flow, and after a specified time has passed, a dummy is loaded. A battery check device was used to measure the voltage appearing across the terminals of the load. Then, the size of the battery capacity is determined based on the level of this voltage.

However, a battery that has not been used for a long time, such as a new battery, may have a high internal resistance due to oxidation of internal substances. Therefore, if a current is flown in this state, a voltage drop occurs due to the internal resistance itself, the voltage appearing outside the battery is lowered, and a phenomenon that only a value below the specified voltage can be measured occurs.

Such an internal resistance is removed (activated) as a current is continuously passed through the battery. After being activated in this way, the voltage generated outside the battery also exhibits a value corresponding to the original capacity. Then, as the usage amount of the battery further increases, the voltage generated outside the battery corresponding to the decrease in the capacity also decreases.

Therefore, if the voltage generated between the dummy load terminals is simply measured, if the measured voltage is equal to or lower than the specified voltage, is the capacity sufficient but not activated? In the first place, it is impossible to judge whether the capacity is insufficient. for that reason,
Prior to making voltage measurements, it is necessary to connect a load to the battery and activate the battery.

In this case, in order to reduce the number of circuit components of the battery checking device as a whole, it is conceivable that the circuit components of the camera incorporating the battery checking device may also be used as a dummy load for voltage measurement. However, if current is passed from the power supply battery to this circuit component, the original function of this circuit component will be unnecessarily exhibited. Therefore, it cannot be simply used for both purposes. This is the first in the past
Is the problem.

Further, even if the battery is activated prior to the voltage measurement, it is necessary to measure the voltage for the first time after loading a completely new battery into the camera, or the minimum capacity required for operating the camera. If you leave the camera for a long time after using the battery until immediately before and measure the voltage when you use the camera again, compared to the case where you use the camera regularly with the same battery installed, It takes time to activate. Therefore, when the determination reference voltage used for the determination of the voltage during the use of the camera is applied as it is when the determination of the voltage is first executed after the power is turned on to the camera, the battery has sufficient capacity. However, the measured voltage may not reach the judgment reference value due to insufficient activation. However, in particular, a completely new battery
Since the measured voltage does not reach the judgment reference value, it is unreasonable to judge that the capacity is not sufficient. This is the second problem in the related art.

[0008]

In view of the above-mentioned first problem of the prior art, the first object of the present invention is to load a circuit component having a separate original function into a load for supplying a current for activating a battery. It is an object of the present invention to provide a battery check device for a camera that does not unnecessarily exert the original function of this circuit component when the battery is activated, even if it is also used as.

A second object of the present invention is to solve the above-mentioned second problem in the prior art, and in the first voltage judgment performed after turning on the power of the camera, the voltage of the battery having a sufficient capacity is determined. It is judged that the judgment reference voltage has not been reached,
It is an object of the present invention to provide a battery check device for a camera that will not be mistaken for its insufficient capacity.

[0010]

The present invention adopts the following means in order to solve the above problems. That is, the first aspect of the camera battery check device according to the present invention is
In order to solve the first problem, a battery for a camera that connects a circuit component having a separate original function and a battery to form a closed circuit for battery check and measures the voltage generated between the terminals of the circuit component. A check device, wherein switch means for intermittently connecting the battery and the circuit component to form a battery check closed circuit, and the circuit component connected to the battery by the switch means Voltage measuring means for measuring voltage, and prior to the measurement of the voltage by the voltage measuring means, at a time interval from connecting the circuit component to the battery until the circuit component produces the original function, And a control means for connecting and disconnecting the switch means (claim 1).
Corresponding to).

In order to solve the second problem, the following structure may be added to the above structure.
That is, the control means causes the voltage measuring means to repeatedly measure the voltage, and compares the voltage measured by the voltage measuring means with a predetermined reference voltage for the first time after operating the camera. When measuring the voltage, the predetermined reference voltage of the comparing means is set to a relatively low first voltage value, and when measuring the voltage thereafter, the predetermined reference voltage is set to a relatively high second voltage. When the measured voltage is lower than the predetermined reference voltage as a result of comparison by the reference voltage setting means for setting a value and the comparing means, the voltage state of the battery is determined as the first state and the measurement is performed. When the voltage reaches the predetermined reference voltage, the battery is further configured to include a determining unit that determines the voltage state of the battery as the second state (claim). Corresponding to 2). Further, the control means causes the voltage measurement means to repeatedly measure the voltage, and compares the voltage measured by the voltage measurement means with a predetermined reference voltage, and the first time after operating the camera. When measuring the voltage, the predetermined reference voltage of the comparing means is set to a relatively low first voltage value, and when measuring the voltage thereafter, the predetermined reference voltage is set to a relatively high second voltage. A reference voltage setting means for setting a value and a warning means for giving a warning when the measured voltage is lower than the predetermined reference voltage as a result of the comparison by the comparing means are further provided (claim 4). Correspondence). Further, the control means causes the voltage measurement means to repeatedly measure the voltage, and compares the voltage measured by the voltage measurement means with a predetermined reference voltage, and the first time after operating the camera. When measuring the voltage, the predetermined reference voltage of the comparing means is set to a relatively low first voltage value, and when measuring the voltage thereafter, the predetermined reference voltage is set to a relatively high second voltage. A reference voltage setting means for setting a value and a photographing means for enabling photographing only when the measured voltage reaches the predetermined reference voltage as a result of comparison by the comparison means are further provided ( (Corresponding to claim 5).

[0012]

Embodiments of the present invention will be described below with reference to the drawings. Before giving a detailed description of each embodiment, the concept of each constituent element of the present invention will be described. (Circuit Component) The circuit component in the present invention is a resistor because the battery is a DC power source. However, this resistance may include reactance.

For example, a lamp such as an incandescent lamp can be used as a circuit component having an original function separately (corresponding to claim 7). In such a lamp, it takes time for the filament temperature to rise, in addition to the effect of the transient current, before it is visually recognized that the lamp is lit after the current starts to flow. Therefore, it is possible to take a long time to flow the current for activating the battery. As for this lamp,
A red-eye prevention lamp used for stroboscopic photography can be used (corresponding to claim 8). (Switch Means) The switch means may be a switch having a mechanical contact or a transistor switch, as long as it has a function of interrupting a current flowing through a circuit component. (Voltage Measuring Means) The voltage measuring means may directly measure the terminal voltage of the circuit component, or may convert it into another unit and measure it. For example, the measuring means is composed of an integrating circuit composed of a resistor and a capacitor connected in parallel to the circuit component, and a time measuring means for measuring the time until the voltage generated between the terminals of the capacitor reaches a predetermined value. You may. In this case, the voltage generated between the terminals of the circuit component can be indirectly measured based on the length of the measured time (corresponding to claim 6). (Control Unit) The control unit repeats the interruption of the current at a time interval from when the current starts flowing through the circuit component to when the circuit component performs its original function, prior to the voltage measurement (corresponding to claim 1). Further, the control means repeatedly measures the voltage by the voltage measuring means (corresponding to claims 2, 4 and 5). (Determination Means) The second state determined by the discrimination means is a voltage state corresponding to the case where the battery has a capacity necessary to drive the camera, and the first state is that the battery is the camera. May be in a voltage state corresponding to the case where the capacitor does not have the capacity necessary to drive (corresponding to claim 3). (Warning Means) The warning means may visually warn,
You may give an audible warning. For example, a light emitting element, particularly a light emitting diode, may be provided in the viewfinder of the camera to emit light.

[0014]

First Embodiment A first embodiment of the present invention will be described below with reference to the drawings. This embodiment shows an example in which the battery check device for a camera according to the present invention is mounted on a compact camera with a built-in strobe (hereinafter, simply referred to as "camera"). <Appearance of Camera> FIG. 2 is a perspective view showing the appearance of the camera 1. As is apparent from FIG. 2, on the front surface of the camera 1, there are a photographing lens 2, a stroboscopic light emitting window 3, a red-eye prevention lamp 4, a distance measuring window 8, a photometric window 9, and a viewfinder window 1.
0 is provided. Among these, the red-eye prevention lamp 4 is a lamp that closes the iris of the person to be photographed by turning on the light immediately before strobe light emission in order to prevent the subject's red-eye phenomenon during stroboscopic photography.

Further, on the upper surface of the camera 1 (the upper surface in FIG. 2), there are provided a main switch 6 for turning on the power to the circuits inside the camera, and a shutter button 5. Further, inside the camera 1, an AA alkaline battery or a manganese battery (hereinafter, simply referred to as “battery”) 7 is provided.
The book is built in so that it can be replaced. <Structure of automatic exposure control circuit of internal circuit of camera>
It is an internal circuit of the camera 1 described above. The microcontroller 11 in FIG. 1 is a microcomputer for controlling the entire camera 1. The microcontroller 11 has a function as a switch device, a voltage measuring device (time measuring device), a control device, a reference voltage setting device, a discriminating device, a photographing device, and a warning device.

The negative electrode of the power source 7 is connected to the GND port of the microcontroller 11 and is supplied with the ground potential. Hereinafter, the portion connected to the GND port and supplied with the ground potential will be referred to as GND.

A regulator 17 is connected to the positive electrode of the battery 7 via a diode D1 connected in the forward direction. The regulator 17 is a constant voltage circuit that supplies a power supply voltage (VDD) to the VDD port of the microcontroller 11. Here, the power supply voltage (VDD)
Is 2V. Note that V of the microcontroller 11
A capacitor C2 to which the power supply voltage (VDD) from the regulator 17 is applied is connected between the DD port and GND. This capacitor C2 is connected to the power supply voltage (VD
It is for backup of D). That is, the voltage of the battery 7 falls below the operating voltage of the regulator 17, and the regulator 1
When the power supply voltage (VDD) of 7 to 2 V is no longer output, the accumulated charge is discharged to guarantee the operation of the microcontroller 11. The diode D1 is for preventing reverse current flow when the capacitor C2 is discharged.

On the other hand, the above-mentioned red-eye prevention lamp 4 is connected to the positive electrode of the battery 7. The red-eye prevention lamp 4 as a circuit component having the original function separately serves as a load used as a dummy load when measuring the voltage of the battery 7.
It is a load for passing a current that activates the battery 7. The resistance value is almost the same as the load of the entire camera.
It is 2Ω. The other end of the red-eye prevention lamp 4 and the GN
A switching transistor 16 as switching means is connected in series with D. The base of the switching transistor 16 is connected to the LMPOUT port of the microcontroller 11 and is ON / OFF controlled by the microcontroller 11.

Further, the series resistances R2 and R1 connected to the P101 port of the microcontroller 11 are connected to the battery 7 side terminal of the red-eye prevention lamp 4. The resistance value of the resistor R2 is sufficiently smaller than the resistance value of the resistor R1. Connection point A of these resistors R2 and R1
And GND between these resistors R1 and R2, a capacitor C forming an integrating circuit as a voltage measuring means.
1 is connected. The positive terminal of the capacitor C1 is also connected to the P102 port of the microcontroller 11.

Both electrodes of the battery 7 are connected to the V of the strobe circuit 12.
It is also connected between the BATT port and the GND port to supply power to this strobe circuit 12. The CHEN port of the strobe circuit 12 is connected to the CHEN port of the microcontroller 11 and receives a charge start signal from the microcontroller 11. The RLS port of the strobe circuit 12 is connected to the microcontroller 11
Connected to the RLS port of the microcontroller 11
Send a charge complete signal to. Further, the STRG port of the strobe circuit 12 is the STR of the microcontroller 11.
It is connected to the G port and receives a strobe trigger signal from the microcontroller 11.

The slot board circuit 12 is composed of a strobe light emitter arranged in the strobe window 3, a booster circuit, a charging capacitor, etc. (all not shown). When the strobe circuit 12 receives the charge start signal, the VBA
A large amount of current is passed from the TT port into the strobe circuit 12 to generate a high voltage for charging the charging capacitor. In this way, the strobe circuit 12 flows a large amount of current during charging, and therefore also functions as a load for activating the battery 7. Specifically, this strobe circuit exhibits a minimum resistance value of about 0.8Ω between the VBATT port and the GND port at the start of charging. Therefore,
The strobe circuit 12 can pass about 5.25 times the load current as compared with the red-eye prevention lamp 4. However, the strobe circuit 12 transmits a charging completion signal when the charging capacitor is in the charging completed state, and the microcontroller 11 receiving the signal sends CHEN = H,
Disconnect the current from the VBATT port. Therefore, thereafter, the strobe circuit 12 does not function as a load for activating the battery 7 until recharging is performed. That is, the strobe circuit 12 is used as the load for the purpose of activating the battery 7.
Although it is effective to utilize the battery, the battery may not be surely activated in the configuration in which the strobe circuit 12 is simply connected. For this reason, as will be described later, in the present embodiment, the activation operation by the red-eye prevention lamp 4 is also performed independently of the activation operation by the strobe circuit 12 connection. And the strobe circuit 12
When the strobe trigger signal is received, the strobe light emitting device emits strobe light.

The P1 port of the microcontroller 11 is a photometric circuit 1 for photometrically measuring the subject brightness through the photometric window 9.
3 to receive photometric data from the photometric circuit 13.

Similarly, P2 of the microcontroller 11
The port is connected to a distance measuring circuit 14 that measures a subject distance through the distance measuring window 8 and receives distance measuring data by the distance measuring circuit 14.

Similarly, P3 of the microcontroller 11
The port is connected to a shutter drive circuit 15 for driving a shutter and a focusing lens in the taking lens 2, and sends an operation signal to the shutter drive circuit 15.

Similarly, P4 of the microcontroller 11
The port is connected to a winding motor drive circuit 20 for driving a motor for winding the film,
An operation signal is transmitted to the winding motor drive circuit 20.

A light emitting diode LED as a warning means provided in the finder window 10 is connected between the P5 port of the microcontroller 11 and the GND, and the blinking control is possible by the P5 port.

The main switch 16 is connected to the MAIN port of the microcontroller 11, and the state of the main switch 16 is input. Similarly, a photometric switch 18 is connected to the SWS port, and a release switch 19 is connected to the SWR port, and their states are input. This photometric switch 18 is used for the shutter button 5
The release switch 19 corresponds to the second stage of the shutter button 5.

FIG. 3 shows an integrating circuit (resistor R
1, R2, and capacitor C1) in detail. VBATT in FIG. 3 is the positive electrode of the battery 7 and the red-eye prevention lamp 4
It is the potential that appears between and. This VBATT is battery 7
Of the red-eye prevention lamp 4 and the presence or absence of a current flowing in the red-eye prevention lamp 4. Since the battery 7 is formed by connecting two AA batteries in series, if the battery 7 is new and almost no current flows, VBATT = 3 (V).

The P101 port of the microcontroller 11 is an input / output port, and as shown in FIG.
The H state of outputting VDD (2V) and the state of the input mode are switched. Here, when the P101 port is viewed from the outside in the input mode, it is in a high impedance state. Similarly, the P102 port is also an input / output port, and switches the L state for outputting the ground potential, the H state for outputting VDD (2V), and the input mode state, as shown in FIG. The terminal voltage of the capacitor C1 is read from P102 in the input mode. <Process Flow in Microcontroller> Next,
The processing executed inside the microcontroller 11 to which the electronic components are connected as described above will be described based on the time chart of FIG. 4 and the flowcharts of FIGS. 5 and 6.

The automatic exposure control process shown in FIG.
It starts when the battery is stored inside, when the main switch 6 is turned on in the standby state, and so on. Then, first, in step S101, the variable “BC_LEVE” is set.
The value of L "is set to n1 (corresponding to the reference voltage setting means). This variable" BC_LEVEL "corresponds to the judgment reference voltage (first voltage value) in the battery check (S107, S202) described later. This is the value used as the value.

As will be described later, in step S101, first, the judgment reference value is set to a value lower than the normally used judgment reference value. When the battery is stored or when the main switch is turned on, the battery is significantly inactive, and the voltage that the battery originally has is not enough if it passes the processing such as red-eye lamp driving for battery activation described later once. Often does not reach the value.

The battery check process is executed in advance as a guideline of whether or not the operation is possible when performing some kind of operation process, and is frequently called in the sequence of the entire camera. In the above case, if no processing is performed,
Suddenly, "the battery is judged unsuitable", and the operation of the camera is stopped without performing the activation operation.

In order to avoid such an inconvenience, in step S101, a process of temporarily lowering the judgment reference value is performed,
The operation is connected to the activation process by driving the strobe circuit 12 and the red-eye prevention lamp 4 later.

Next, the state of the main switch 6 is checked (step S102), and if it is OFF, the state of the camera is set to the standby state. The standby state is a state in which only the minimum current capable of recognizing the state of the main switch 16 is supplied to the microcontroller 11 while maintaining the memory state of the memory in the microcontroller 11.

On the other hand, it is turned on in step S102.
If it is determined to be true, the flash charge control process of step S103 is executed. FIG. 6 shows a subroutine of this strobe charge control processing. In the first step S201 after entering this subroutine, the state of the CHEN port is checked. If CHEN = H (no charge start signal), the process proceeds to step S202, and CHEN = L.
If (charging start signal is being output), the process proceeds to step S.
Proceed to 204. Here, the CHEN port is in the H output state in the initial state. Therefore, when this strobe charge control subroutine is first entered after the start, the battery check process must be performed (step S202) before the load current is supplied to the strobe circuit 12.
Is executed.

Battery check processing (step S20)
When 2) is completed, in step S203, charging of the strobe circuit 12 is started (corresponding to the control means). That is, the load current from the battery 7 is the strobe circuit 12
Begins to be washed away. Therefore, even if the inactivation of the battery 7 is incomplete, the activation is completed by this load current. When the process of step S203 is completed, the strobe charge control process subroutine is terminated and the process returns.

On the other hand, in step S204, it is checked from the state of the RLS port whether or not the charging of the strobe circuit 12 is completed. Then, if RLS = H (not completed), the subroutine of this strobe charge control process is finished and returns. If RLS = L (completed), the CHEN port is in the H output state (no charge start signal).
To stop strobe charging (step S20)
5). Then, this subroutine is ended and the process returns.

In the main routine of FIG. 5 to which the processing is returned, in step S104 following step S103, the value of the variable "BC_LEVEL" is set to n2 (corresponding to the reference voltage setting means). This value n2 is larger than the value n1 set in step S101. Therefore, in the battery check (steps S107 and S202) executed after the second time, the judgment reference voltage corresponding to n2 is always used.

In the next step S105, the state of the photometric switch 18 is checked. If it is OFF, the process is returned to step S102, and if it is ON, the process is step S.
Proceed to 106.

In step S106, step S204
Regardless of the check result in step 2, the CHEN port is set to the H output state (no charging start signal) and the strobe charging is temporarily stopped. This is to ensure the voltage required for various controls associated with shooting.

In the next step S107, step S2
Similar to 02, the battery check process is executed. This is to confirm whether or not the capacity necessary for properly performing shooting remains in the battery 7.

Battery check processing (step S10)
Upon completion of 7), photometry is performed in step S108. That is, the output of the photometric circuit 13 is read. In the next step S109, the distance measuring circuit 14 is activated to read the distance measuring data of the subject.

In the next step S110, the state of the photometric switch 18 is reconfirmed. If the photometric switch 18 is off, the process returns to step S102, but on.
If so, the state of the release switch 19 is checked in step S111. This release switch 1
If 9 is still OFF, the process proceeds to step S110.
Return to.

On the other hand, the release switch 19 is turned off.
If the result is N, the process proceeds to step S112. In this step S112, the shutter drive circuit 15
Is started, and the film is exposed at a predetermined aperture value, shutter speed, and focus position based on the photometric data obtained in step S108 and the distance measurement data obtained in step S109.

When the exposure of the film is completed, in the next step S113, the winding motor drive circuit 20 is activated to wind the film by one frame. Next step S
At 114, the process waits until the finger is released from the shutter button 5 and both the photometric switch 18 and the release switch 19 are turned off. When both are turned off, the process proceeds to step S.
Return to 102.

FIG. 7 shows steps S107 and 6 of FIG.
The subroutine of the battery check process executed in step S202 is shown. In the first step S301 after entering this subroutine, red-eye prevention lamp pulse output processing is executed. This red-eye prevention lamp pulse output processing is processing for causing a load current to flow in a pulsed manner via the red-eye prevention lamp 4 in order to activate the battery 7 before actually measuring VBATT. When the battery check processing subroutine is entered from step S202 for the first time after the start, the battery 7 is activated only by this red-eye prevention lamp pulse output processing, and VBATT is measured.

FIG. 8 is a flowchart showing a subroutine of this red-eye prevention lamp pulse output processing. In the first step S401 after entering this subroutine, a count value n indicating the number of times the pulsed output is repeated is set to n =
Set to 1.

Next, the processing enters a loop of steps S402 to S407. In the first step S402 after entering this loop, the switching transistor 1
6 is turned on, and a current is passed through the red-eye prevention lamp 4 (corresponding to the control means). Then, as it stands by for 10 mS (step S403), the switching transistor 16 is turned off.
F This 10 mS is shorter than the time from when the electric current starts to flow to the red-eye prevention lamp 4 to when the red-eye prevention lamp 4 is actually recognized to be lit by the naked eye. Table 1
Will be described with reference to. This table 1 shows that the red-eye prevention lamp 4 is actually turned on after the switching transistor 16 is turned on.
The time it takes for the naked eye to recognize that the
The values are experimentally obtained and shown for each TT.

[0049]

[Table 1]

When the resistance value of the red-eye grid lamp 4 is 4.2Ω (when the wattage of the red-eye prevention lamp 4 is 1.5 W), for example, VBATT = 1.7 [V], from Table 1, About 2 from ON of switching transistor 16
After 9 ms, the filament heats up, and it can be visually identified that the red-eye prevention lamp 4 is turned on. Therefore, if only the current is supplied for 10 ms, it is possible to avoid unnecessary lighting of the red-eye prevention lamp 4 while using the red-eye prevention lamp 4 as a load for supplying the current for activating the battery 7. Of.

In step S404, which is executed immediately after completion of step S403, the switching transistor is turned off to stop the current flow to the red-eye prevention lamp 4 (corresponding to the control means). Even if the battery is new and active, connecting the red-eye prevention lamp load
Since VBATT = is about 2.2 [V], the lighting of the red-eye prevention lamp 4 is not confirmed.

In the next step S405, another 20 ms
Wait for a while. This is to cool the filament of the red-eye prevention lamp 4. In the next step S406, it is checked whether or not the number (n) of executions of the loop processing (pulse output) of steps S402 to S406 has reached eight. If it is less than 8 times, the count value n is incremented by 1 in step S407 and then the process returns to step S402, and if it is the 8th time, this red-eye prevention lamp pulse output processing subroutine is returned. Number of times this pulse output was executed (n = 8)
Can be any other number, but can be activated to some extent by setting it to 8 (times). Further, the number of pulse outputs may be changed depending on the environmental temperature, for example.

In the battery check process of FIG. 7, which is returned from the red-eye prevention lamp pulse output process subroutine, step S302 is next executed. In step S302, the P101 port is set to the input mode,
The P102 port is set to the L output state.

In the next step S303, the switching transistor 16 is turned on and a current is supplied to the red-eye prevention lamp 4. In step S304, which is executed immediately after execution of step S303, the time constants of the resistor R1 and the capacitor C1 are measured. Specifically, the terminal voltage of the capacitor C1 is set to the reference value Vc after the P102 port is set to the input mode.
The time (T1) to reach
ATT is measured (corresponding to voltage measuring means (time measuring means)).

That is, when the P102 port is set to the input mode, VB in the state in which current is flowing through the red-eye prevention lamp 4 (first load: dummy load) in the capacitor C1.
Electric charges are accumulated according to the time constant determined by ATT and the value of the resistor R1 and the value of the capacitor C1. At this time, since P101 is still in the input mode, the influence of the current flowing through the resistor R2 can be ignored. This relationship is expressed by the following equation (1).

[0056]

[Equation 1]

However, in this embodiment, the capacitor C
The value of 1 is 0.022 μF, and the value of the resistor R1 is 510
It is kΩ. As is clear from the equation (1), the time (T1) changes according to the value of VBATT. Therefore,
The value of VBATT can be indirectly known by measuring the time (T1). When the measurement of T1 is completed, the P102 port is immediately set to the L output state to clear the charge accumulated in the capacitor C1.

The reference value Vc is T1 within the time (see Table 1) from when the switching transistor 16 is turned on until it is visually recognized that the red-eye prevention lamp 4 is actually turned on. Is calculated and set as. That is, if the reference value Vc is set to 1.5 V or less, T1 = 24 ms in the equation (1) even when the VBATT determination reference voltage is 1.7 V.
(1) It is possible to prevent the red-eye prevention lamp 4 from turning on during measurement. However, when VBATT greatly falls below the judgment reference voltage, T1 may exceed the lighting point of the red-eye prevention lamp 4 in calculation. However, in such a case, the time until it can be recognized that the red-eye lamp 4 is turned on when the state of VBATT is equal to the reference value Vc is set to be within the maximum measurement time of T1. When it reaches, the switching transistor 16 is turned off.
Then, the measurement of T1 may be stopped. As described above, in the present embodiment, Vc = 1 / 2VDD = 1V, that is, Vc is set using the threshold level of the port. T1 when Vc = 1 [V] in Expression (1)
The calculated values of are shown in Table 1.

In step S305, which is executed immediately after execution of step S304, the switching transistor 16 is turned off. Therefore, as described above, it is prevented that the red-eye prevention lamp 4 is lit by the naked eye.

In the next step S306, the P101 port is set to the H output state. This state can be regarded as a state in which a constant voltage source that outputs VDD (2 V) as the reference voltage is connected to the end of the port 101.

In the next step S307, the resistors R1 and R
2. Measure the time constant of the capacitor C1. In particular,
Capacitor C1 after P102 port is in input mode
The time (T2) until the terminal voltage of V reaches Vc is measured.

That is, when the P102 port is set to the input mode, VBATT and VDD in the state where no current is flowing through the red-eye prevention lamp 4 (dummy load), the combined resistance of the resistors R1 and R2, and the capacitor C1. The charge is accumulated according to the time constant determined by the value of the capacitor C1. This relationship is expressed by the following equation (2).
Represented by

[0063]

[Equation 2]

By the way, as described above, the value of R2 is R
It is set to be sufficiently smaller than 1. Therefore, the part of R2 / (R1 + R2) · VBATT in the equation (2) can be approximated to zero. That is, VBA for T2
The effect of TT can be ignored. for that reason,
An almost constant reference time (T2) can be obtained regardless of the value of VBATT. Immediately after the measurement of T2 is completed, the P102 port is set to the H output state. This is to prevent the voltage from the battery 7 from being applied to the microcontroller 11 to cause the latch-up phenomenon.

In the next step S308, the measured T
Calculation based on 1, T2 is performed. That is, T with respect to T2
The ratio of 1 (T1 / T2) is calculated. Next step S309
Then, based on the calculation result obtained in step S308,
The result of the battery check is judged (corresponding to the comparing means and the judging means). Specifically, it is checked whether or not the following formula (3) is satisfied.

T1 / T2 ≧ a (3) However, the value of a is set according to the value of the variable “BC_LEVEL”. This equation (3) is T2 which is a substantially constant value.
The content is to identify the length of T1 on the basis of. When T1 / T2 becomes a or more, VB
It is determined that the ATT has not reached the determination reference voltage.

By the way, as is clear from the equation (1),
When VBATT is low, the value of T1 is large. Therefore, if the value of a is set relatively large, VB
Even if ATT is relatively low, the condition of Expression (3) is not satisfied (that is, VBATT reaches the judgment reference voltage).
Can be certified as On the contrary, if the value of a is set relatively small, it is determined that the condition of Expression (3) is not satisfied unless VBATT is relatively high (that is, VBATT reaches the judgment reference voltage). It will not be done. Thus, setting the value of a in equation (3) to a relatively large value is equivalent to lowering the determination reference voltage, and setting the value of a to a relatively small value is equivalent to increasing the determination reference voltage. become. Therefore, in this embodiment, for example, BC_
When LEVEL = n1, a = 10 is set, and BC_
When LEVEL = n2, a = 6 is set. Therefore, when the battery check process is started from step S202 for the first time after the start, the judgment reference voltage is lowered (first voltage value) to check VBATT, and the battery check after the second time is performed. In the process, the judgment reference voltage is increased (second voltage value) to check VBATT.

As a result of the check in step S309, when T1 / T2 is equal to or larger than a, it cannot be determined that the capacity of the battery 7 is sufficient, so that the process waits for 20 ms in step S310. This is because if heat remains in the filament of the red-eye prevention lamp 4, the time required for relighting will be shortened, so prepare for the T1 measurement (step S304) in the next battery check,
This is for cooling the filament of the red-eye prevention lamp 4. Then, after the lapse of 20 ms, the process proceeds to step S31.
Proceed to 1.

In step S311, the photometric switch 18
Check the status of. Then, the photometric switch 18 turns O
As long as it is N, in step S312, the light emitting diode LED provided in the finder is blinked to continue to warn the photographer (corresponding to the warning means). If the photometric switch 18 is turned off during that time, the process returns to step S102. In this case, as long as the main switch 16 is ON, the process returns to this battery check process through steps S103 and 202, and step S3
The activation of the battery 7 in 01 and the comparison check in step S309 are performed.

As a result, the battery 7 is activated and VBAT is activated.
When it is determined in step S309 that T has reached the determination reference voltage and T1 / T2 has become less than a, this battery check subroutine is terminated and the original step (step S202 in FIG. 6, or in FIG. 5) is terminated. Step S10
Return to 7) (corresponding to the photographing means). <Operation of Embodiment> FIG. 9 shows the state of changes in the current (load current) flowing out from the battery 7 and VBATT in the camera 1 of the present embodiment configured as described above. FIG. 9 shows an example in which the main switch 16 is turned on from the standby state and then the photometric switch 18 is turned on.

First, when the main switch is turned on, the first red-eye prevention lamp pulse output is executed without passing a current through the strobe circuit 12 (steps S103, S).
202, S301, S402 to S405). The pulse width in this pulse output, that is, the length of the period during which the current is passed through the red-eye prevention lamp 4 is from when the current is passed through the red-eye prevention lamp 4 until it can be visually recognized that the red-eye prevention lamp 4 is actually turned on. It is set shorter than the time.
Therefore, even though the circuit component (red-eye prevention lamp 4) having another original function (light emission for red-eye prevention) is also used as a load for activating the battery 7, its original function is maintained. It is prevented from exerting it in vain. That is, it is possible to prevent the red-eye prevention lamp 4 from emitting light without being originally necessary to make it look bad.

When this red-eye prevention lamp pulse output is executed, even if the battery 7 has a sufficient capacity but is inactive, it is activated to some extent and VBA at the time of load connection.
The value of TT increases. At this time, if this battery 7 has been used before, but if it is in a state where it has been consumed for a small amount of time and then left for a short period of time, shooting with this single red-eye prevention lamp pulse output The value of VBATT that indicates the minimum amount of capacity remaining that can be done properly (ie,
VBA higher than the original judgment reference voltage corresponding to n2)
It comes to show TT. On the other hand, if a completely new battery 7 is in use, or if it is left for a while with the minimum capacity that allows proper shooting, red eye It is possible that VBATT may not reach the voltage corresponding to n2 only with the preventive lamp pulse output. However, if VBATT at the time of load connection rises to a certain extent as a result of one red-eye prevention lamp pulse output, it can be estimated that sufficient capacity remains in this battery 7.

Therefore, in the battery check (steps S302 to S309) executed immediately after this, a voltage lower than the original determination reference voltage (voltage corresponding to n1).
Is used as a determination reference voltage to check the capacity of the battery 7. If the value of this n1 is activated by continuously applying a current to the load, VBATT will be the original judgment reference voltage (n
A voltage corresponding to the minimum VBATT that can be predicted to reach (a voltage corresponding to 2). Therefore, when a new battery 7 is loaded, it is possible to avoid the inconvenience that it is determined that the battery 7 does not have a sufficient capacity and the photographing operation becomes impossible.

This battery check is performed based on the value immediately before the rise of VBATT.
Therefore, in the example of FIG. 9, VBATT when the load is connected is n1.
The judgment reference voltage corresponding to is exceeded. Therefore, it is determined that the battery is likely to have sufficient capacity,
Subsequent operations are possible. On the other hand, if VBATT does not reach the voltage value corresponding to n1, it can be determined that there is almost no possibility of sufficient capacity. Therefore, in that case, a warning is given and photographing cannot be performed (steps S311 and S312).

In the battery check, specifically, T1 based on VBATT is measured during the period when current is flowing through the red-eye prevention lamp 4, and T2 based on VDD is measured during the period when current is not flowing through the red-eye prevention lamp 4. Measure. At this time, the length of the period in which current is passed through the red-eye prevention lamp 4 is
The time is set to be shorter than the time from when a current is started to flow through the red-eye prevention lamp 4 until it can be visually recognized that the red-eye prevention lamp 4 is actually turned on. Therefore, the number of circuit components is reduced by using the circuit component (red-eye prevention lamp 4) having another original function (light emission for red-eye prevention) as a dummy load used when measuring the capacity of the battery 7. Nevertheless, the current flowing through this circuit component (red-eye prevention lamp 4) is stopped before this circuit component (red-eye prevention lamp 4) exhibits its original function. Therefore, this circuit component (red-eye prevention lamp 4) can be prevented from unnecessarily exhibiting its unique use.
That is, it is possible to prevent the red-eye prevention lamp 4 from emitting light without being originally necessary to make it look bad.

When the strobe circuit 12 is charged immediately after the battery check (step S203 to step S205, or S106), a larger current than the current value at the red-eye prevention lamp pulse output flows from the battery 7 to the strobe circuit 12. . Therefore, even if VBATT reaches the judgment reference voltage corresponding to n1 but does not reach the judgment reference voltage corresponding to n2 as a result of the first red-eye prevention lamp pulse output, the battery 7 is It can be surely activated. The example in FIG. 9 shows that VBATT exceeds the voltage corresponding to n2 as a result of the reliable activation of the battery 7. In this way, once the battery 7
When is completely activated, the value of VBATT when the load is connected to the battery 7 thereafter becomes substantially constant if the value of the load is constant.

When the photometry switch 18 is turned on in this state, the second red-eye prevention lamp pulse output and the battery check are executed, and the photographing is possible only when it is judged by this battery check that the remaining capacity is sufficient. (Steps S309 and S107 to 114). In this second battery check, it is assumed that the battery 7 has been completely activated by charging the strobe circuit, and the original determination reference voltage corresponding to the value of n2 is used.
The capacity of the battery 7 is checked. In the example of FIG. 9, since VBATT when the load is connected exceeds the determination reference voltage corresponding to n2, it is determined that the battery has a sufficient capacity, and shooting is possible. On the other hand, if BVATT has not reached the voltage value corresponding to n2, it can be determined that the capacity is insufficient. Therefore, in that case, a warning is given and the photographing becomes impossible (steps S311 and S3).
12).

Thereafter, unless the photometry switch 18 is turned on but the release switch is kept off, charging of the battery circuit 12, red-eye prevention lamp pulse output, and battery check are repeatedly executed. The determination reference voltage used for the battery check at this time is always a relatively high original voltage corresponding to n2.

[0079]

According to the battery check device for a camera of the present invention configured as described above, even when a circuit component having another original function is also used as a load for supplying a current for activating the battery, It is possible to prevent the original function of the circuit component from being unnecessarily exhibited when the battery is activated.

Further, the control means controls the voltage measurement means to repeatedly measure the voltage, and the comparator means for comparing the measured voltage by the voltage measurement means with a predetermined reference voltage, and after the camera is operated. When the voltage is measured for the first time, the predetermined reference voltage of the comparing means is set to a relatively low first voltage value, and when measuring the voltage thereafter, the predetermined reference voltage is set to a relatively high second voltage value. By including a reference voltage setting means,
In the first voltage judgment performed after turning on the power of the camera, it may be judged that the voltage of the battery with sufficient capacity has not reached the judgment reference voltage, and it may be erroneously recognized that the capacity is not sufficient. To be prevented.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an internal circuit of a camera equipped with a battery check device for a camera according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing the appearance of the camera shown in FIG.

FIG. 3 is a detailed diagram of the integrating circuit in FIG.

FIG. 4 is a time chart showing signal states of P101 port, P102 port, and LMPOUT port in FIG.

5 is a flowchart showing the contents of control processing executed in the microcontroller of FIG.

FIG. 6 is a flowchart showing the contents of a strobe charge control processing subroutine executed in step S103 of FIG.

7 is a flowchart showing the contents of a battery check processing subroutine executed in step S107 of FIG. 5 or step S202 of FIG.

8 is a flowchart showing the contents of a red-eye prevention lamp pulse output processing subroutine executed in step S301 of FIG.

FIG. 9 is a time chart showing the states of the current and terminal voltage flowing through the red-eye prevention lamp.

[Explanation of symbols]

1 camera 4 Red-eye prevention lamp 7 batteries 11 Micro controller 16 switching transistors R1 resistance R2 resistance C1 capacitor LED light emitting diode

Claims (8)

(57) [Claims] 1. A battery check device for a camera, which connects a circuit component having a separate original function and a battery to form a closed circuit for battery check and measures a voltage generated between terminals of the circuit component. Switch means for intermittently connecting the battery and the circuit component to form a closed circuit for battery check, and a voltage for measuring the voltage in a state where the circuit component is connected to the battery by the switch means. Prior to the measurement of the voltage by the voltage measuring means and the voltage measuring means, the switching means is turned on and off at a time interval from the connection of the circuit component to the battery to the generation of the original function of the circuit component. A battery check device for a camera, comprising: a control means for performing the operation. 2. The control means causes the voltage measuring means to repeatedly measure the voltage, and activates the camera by comparing means for comparing the voltage measured by the voltage measuring means with a predetermined reference voltage. In the first measurement of the voltage, the predetermined reference voltage of the comparison means is set to a relatively low first voltage value, and in the subsequent measurement of the voltage, the predetermined reference voltage is set to a relatively high first voltage value. Two
With reference voltage setting means for setting the voltage value of, and as a result of the comparison by the comparing means, when the measured voltage is lower than the predetermined reference voltage, while determining the voltage state of the battery as the first state, The battery of the camera according to claim 1, further comprising: a determining unit that determines a voltage state of the battery as a second state when the measured voltage reaches the predetermined reference voltage. Checking device. 3. The second state is a voltage state corresponding to a case where the battery has a capacity necessary to drive the camera, and the first state is a state where the battery drives the camera. 3. The battery check device for a camera according to claim 2, wherein the battery is in a voltage state corresponding to a case where the battery does not have a required capacity. 4. The control means causes the voltage measuring means to repeatedly measure the voltage, and activates a camera and a comparing means for comparing the voltage measured by the voltage measuring means with a predetermined reference voltage. In the first measurement of the voltage, the predetermined reference voltage of the comparison means is set to a relatively low first voltage value, and in the subsequent measurement of the voltage, the predetermined reference voltage is set to a relatively high first voltage value. Two
A reference voltage setting means for setting a voltage value of, and a warning means for giving a warning when the measured voltage is lower than the predetermined reference voltage as a result of the comparison by the comparing means,
The battery check device for a camera according to claim 1, further comprising: 5. The control means repeats the measurement of the voltage by the voltage measuring means, and activates the camera by comparing means for comparing the voltage measured by the voltage measuring means with a predetermined reference voltage. In the first measurement of the voltage, the predetermined reference voltage of the comparison means is set to a relatively low first voltage value, and in the subsequent measurement of the voltage, the predetermined reference voltage is set to a relatively high first voltage value. Two
Further comprising: a reference voltage setting means for setting the voltage value of 1 and a photographing means capable of photographing only when the measured voltage reaches the predetermined reference voltage as a result of the comparison by the comparing means. The battery check device for a camera according to claim 1, wherein the battery check device is for a camera. 6. The time for measuring the time required for the voltage measuring means to reach a predetermined value for the voltage generated between the integrating circuit including a resistor and a capacitor connected in parallel to the circuit component and the terminal of the capacitor. 2. A measuring unit, which measures the voltage generated between the terminals of the circuit component based on the length of the measured time.
The battery check device according to any one of 2, 4, and 5. Wherein said circuit component is a lamp, the switching means, claims, characterized in that the lamp from the start of the flow of the current to the lamp is intermittently the current time interval until the lights The battery check device according to any one of 1, 3, 4 and 5. 8. The battery check device according to claim 7, wherein the lamp is a red-eye preventing lamp, and the switch means also functions as a lighting switch of the red-eye preventing lamp.