JPH07333698A - Power supply voltage detector for camera - Google Patents

Abstract

PURPOSE:To reduce the generation of a collision noise between mechanical members and the distortion of members by preliminarily and stepwise increasing/ decreasing a current before/after a motor is energized at the time of checking a battery. CONSTITUTION:A shutter is composed of shutter blades 11 and 12, the aperture for exposing 13 of a shutter base plate, a shutter opening/closing lever 14, a motor rotary disk 15 rotated by a shutter driving motor, etc., and when the shutter driving motor is energized so as to rotate in the closing direction of the shutter, the shutter blades 11 and 12 are rotated a little by the backlash of the engaging part, among the motor rotary disk 15 and the shutter blades 11 and 12 and collide against blade stopping bosses 19 and 20, so that the collision noise occurs. At this time, the energization by PWM drive is attained before and after the checking of the battery, that is, the current at the time of energizing the motor is increased/decreased stepwise to reduce impact imparted to the shutter blades 11 and 12 at the time of checking the battery and the occurrence of the collision noise and the distortion of the member as well.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply voltage detection device for a camera, and more particularly to a device for detecting the power supply voltage while a motor is being energized for performing various operations of the camera.

[0002]

2. Description of the Related Art Conventionally, when checking the voltage of the battery power supply of this type of camera, it is necessary to take the internal resistance of the battery into consideration in order to improve the detection accuracy. The battery voltage is detected in this state. Then, in this case, as a load, a dedicated load resistor is not provided, and a predetermined motor mounted in the camera is used, and the voltage applied to both ends of the motor is detected while the motor is energized. By the way, when detecting the power supply voltage of the camera in this way, it is necessary to be careful not to inadvertently operate by energizing the load.If the load is a motor, properly select the type of motor and its energizing direction. It is necessary to make a selection, and when the motor is a shutter drive motor, it is known to energize in the shutter closing direction (for example, Japanese Patent Laid-Open No. 61-
(See Japanese Patent No. 249033).

[0003]

However, in such a conventional device, due to the mechanical (mechanical) play, a collision noise is generated between the mechanical members when the motor is energized for checking the battery. In addition, if a member driven by a motor such as a shutter is vulnerable to impact,
Due to the increase in the number of times of energization, the member may be distorted, and if it is further advanced, it may be damaged.

The present invention has been made in order to solve the above-mentioned problems, and by gradually increasing or decreasing the current when the motor is energized at the time of checking the battery, the generation of collision noise between mechanical members and the member It is an object of the present invention to provide a power supply voltage detection device for a camera, which can reduce the distortion of the.

[0005]

To achieve this object, the present invention provides a motor for performing various operations of a camera,
A power supply for supplying electric power to the motor, drive means for connecting the motor as a load of the power supply and giving a drive signal for driving the motor in a direction other than a direction for performing various operations of the camera; In a power supply voltage detection device for a camera provided with a voltage detection means for detecting a voltage applied to the motor during energization to the motor, the drive means increases the current stepwise at the start of energization to the motor,
The current is gradually reduced at the end of energization.

[0006]

According to the power supply voltage detection device for a camera having the above structure, when the power supply voltage for the camera is detected, the motor is energized so as to drive the motor in a direction other than the direction in which various operations of the camera are performed. Then, the voltage applied to the motor is detected during the energization of the motor. Before and after that, that is, when the energization of the motor is started, the current is increased stepwise, and when the energization is ended, the current is decreased stepwise. By controlling the current flowing through the motor in this way, collisions and distortions between mechanical members can be alleviated.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to the drawings. 1 is a perspective view of the camera, and FIG.
FIG. 3 is a block diagram of an internal circuit of the camera. In these figures, the camera includes a main switch SM that activates the camera operation, a release button (photometry / distance measurement switch S1, release switch S2), a zoom switch button (zoom-out switch SZ1, zoom-in switch SZ2), a back cover opening / closing switch. It has various switches such as SR, and is also provided with a microprocessor (hereinafter referred to as a control circuit) 1 including an integrated circuit (IC) for controlling the entire camera.
The control circuit 1 has a built-in CPU and RAM, and the various switches and liquid crystal display (LC
D) 2, flash circuit 3, auto focus (AF) circuit 4,
An automatic exposure (AE) circuit 5, a DC / DC converter 6 for generating a high voltage, an EEPROM 7 for storing various data, a motor driver 8 for driving various motors, etc. are connected. A shutter drive motor M1, a film feeding motor M2, and a zoom motor M3 are connected to the motor driver 8.

The shutter drive motor M1 drives the shutter blades of the shutter, and the film feeding motor M2 winds up the film to a predetermined position where the film can be taken when the film is filled in the camera, and one frame is taken. Each film is wound one frame at a time, and when the film is taken to the last frame, the film is rewound.
The zoom motor M3 drives the zoom lens barrel to change the focal length of the zoom lens for zoom photography. The LCD 2 is a display that displays shooting information and the operating state of the camera. The flash circuit 3 is a light emission control circuit of a flash device that illuminates a subject when the light amount is insufficient during shooting. The AF circuit 4 is a circuit that measures the distance to the subject, and the AE circuit 5 is a circuit that measures the luminance of the subject. The DC / DC converter 6 is a circuit that boosts the voltage of a battery (battery) that is a power source to a predetermined voltage at which various circuits of the camera can operate. E
The EPROM 7 is a memory that stores information such as the current number of film frames and various adjustment values that must be stored even when the circuit power cannot be supplied at all when the battery of the power supply is replaced.

When the main switch SM is operated, the main switch SM is switched to an operating state if the camera is in a non-operating state, and a non-operating state if the camera is in an operating state. Each time you switch, the operating state of the camera switches. When the camera is in operation, the DC / DC converter 6 is driven to boost the voltage of the battery and apply a predetermined voltage to the control circuit 1. The release button S1 is a switch for activating a series of shooting operations of distance measurement, photometry, shutter drive, flash emission, and one frame winding. The zoom-out switch SZ1 and the zoom-in switch SZ2 are seesaw type switches. When the switch is pushed to one side, the zoom-out switch SZ1 is turned on, and when the switch is pushed to the other side, the zoom-in switch SZ2 is turned on. When the zoom-out switch SZ1 is on, the zoom lens barrel is driven to the one with a long focal length, and when the zoom-in switch SZ2 is on, the zoom lens barrel is driven to the one with a short focal length. Back lid open / close switch SR
Is turned on when the back lid of the camera is open and turned off when the back lid is closed, and the control circuit 1 can determine the open / closed state of the back lid by the state of the back lid open / close switch SR.

Next, the camera control sequence by the CPU of the control circuit 1 will be described with reference to FIGS. FIG. 3 is a flowchart of the reset routine.
When the battery is loaded into the camera, the CPU clears all RAM (# 30) and outputs a high level to the input / output port (# 31). Then, read the status of all switches, RA
The data is stored in M (# 32), and the predetermined data stored in the EEPROM 7 necessary for executing the camera sequence is downloaded to the RAM (# 35). Then, EE
The value of a specific address of PROM 7 (the address where the data for determining whether the initial data has been written is stored, specifically address 67) is read into the accumulator built in the CPU (# 36). Since the unwritten data in the EEPROM 7 is generally FF (Hexa: hexadecimal number), it is determined whether the value of the accumulator is FF (H) (# 3
7), if FF (H), it is determined that the initial data is not written in the EEPROM 7, and it is determined that the data in the EEPROM 7 is abnormal (# 38). If the initial data is not written in the EEPROM 7, normal camera operation is not executed. Stop.

The value of the accumulator is FF in the judgment of # 37.
If not (H), the process proceeds to # 39, and the adjustment sequence of the shutter / photoreflector (the photoreflector is referred to as PR in the drawing) for detecting the open / closed state of the shutter is executed in # 39 to # 42. The photo reflector has a light emitting element and a light receiving element, and the configuration thereof is shown in FIG. 7 described later. The reason for adjusting this shutter / photo reflector is that the shutter / photo reflector is set so that the output at the initial position is at a high level, but the output voltage changes depending on the level of the power supply voltage, etc. Sometimes
This is because it is necessary to determine a level for high judgment at this initial position. In this adjustment sequence,
The state where the signal from the shutter / photo reflector is read is selected (# 39), and when the shutter is closed, a high level is output from the shutter / photo reflector, so the voltage of the shutter / photo reflector at this time is changed. It is A / D converted (# 40) and input to the CPU.
Then, based on the A / D converted value, the comparator 6
5 (FIG. 7 which will be described later) calculates the REF level serving as the reference voltage (# 41), and the calculated result is stored in the EEPROM 7
(# 42).

Then, in # 43 to # 46, the zoom motor
A photo interrupter (hereinafter, referred to as a zoom interrupter, a photo interrupter is referred to as PI in the drawing) is adjusted. The state of reading the signal from the zoom-in interrupter is selected (# 43), the zoom motor is rotated, and the motor is turned off after a fixed time. When the motor is turned off, the motor rotates at a relatively slow speed due to inertia, so at this time,
The number of rotations of the motor is detected by the photo interrupter. By performing A / D conversion of the output signal from the photo interrupter a certain number of times (# 44) and performing sampling, it is possible to perform sampling with higher accuracy than when performing sampling while energizing the motor. In this way, a series of sequences such as energizing the motor for a certain period of time, turning off the motor, and sampling for a certain number of times are repeated a plurality of times to sample the output signal from the photo interrupter, and after A / D conversion, input to the CPU. Then, the REF level serving as the reference voltage output to the comparator 65 (FIG. 7 described later) is calculated based on the sampling value (# 4
5), write the calculated result to the EEPROM (# 4
6) The shutter / photo reflector and zoom / interrupter adjustment processing ends.

The comparator 65 for converting the output from the shutter photoreflector and the zoom interrupter into a digital signal is common, and the reference value of the comparator 65 and the shutter photoreflector signal and the zoom interrupter signal are controlled for each control target. By switching,
A single comparator 65 can convert a plurality of shutter photoreflector signals or zoom interrupter signals into digital signals. After # 46 above, drive the zoom lens barrel to return to the initial position (# 4
7) After that, the CPU enters a standby state (# 48). It should be noted that in the above embodiment, in step # 38, the EEPROM 7
When the initial data has not been written, the sequence is stopped, but it is also possible to perform processing such as displaying an error on the display member or sounding a warning sound.

Here, the shutter / photoreflector adjustment will be described with reference to FIGS. FIG. 7 shows a block diagram of a waveform shaping circuit for a shutter photo reflector and a zoom interrupter. In the figure, VCC
Is the circuit voltage, PR is the shutter / photo reflector, PI
Is a zoom interrupter. Shutter / photo reflector PR and zoom / interrupter PI are each PR
Connected to the / PI selector 61, this PR / PI
Selector 61 allows shutter / photo reflector PR
The current IPI is selected to be supplied to the zoom interrupter PI and the zoom interrupter PI. This current IPI is converted into the voltage VPI by flowing through the resistor 62 whose one end is grounded. The reference voltage VREF is the same as the reference voltage VPI and is the A / D circuit 63.
In A / D conversion and send to CPU for processing
Is determined by D / A converting the data from the D / A circuit 64. This voltage VPI and reference voltage VR
It is input to the comparator 65 and compared with EF, and a pulse signal is output from the comparator 65. 8 is V
A PI waveform and a pulse waveform are shown. The voltage VPI is the reference voltage V
When it is higher than REF, the pulse output becomes H, while when the voltage VPI is lower than the reference voltage VREF, the pulse output becomes L. The H / L settings may be reversed. Further, in the above, the output of the D / A circuit 64 is used as the reference voltage VREF, but a variable resistor may be used, or several kinds of voltages may be set in advance and an appropriate voltage may be selected from them. You may

Next, the main sequence of the camera by the CPU of the control circuit 1 will be described with reference to FIG. In the main sequence of the camera, first, check the state of each NG flag after the end of each sequence (# 50).
If the flag is not set, the process proceeds to # 53 to execute each process. If the NG flag is set, the content is written to the EEPROM 7 (# 5
1) After clearing the NG flag (# 52), H is output to the CPU port (# 72), and a standby state, that is, a hold state is entered (# 73). From the hold state, the main switch SM is turned on to start the operation, and the process proceeds to # 53.

At # 53, the main switch SM is turned off.
If it is turned on, the zoom lens barrel is driven so that the zoom lens reaches the wide position (# 54), and then the process returns to # 50. If the main switch is not turned on in # 53, it is determined whether or not the main switch SM is turned off from on (# 5
5) If turned off, the zoom lens barrel is returned to the retracted position (# 56), the process proceeds to # 72, and then the CPU enters the hold state. The main switch SM goes to 0 at # 55.
If it is not FF, it is judged whether or not the rewind switch is turned on (# 57). If it is turned on, the rewind sequence is executed (# 58), and the process returns to # 50.

If the rewind switch is not turned on in # 57, it is detected whether the back cover opening / closing switch SR has changed from the open state to the closed state (# 59). Is performed (# 60). If the result of the battery check is OK, an initial load sequence described later is executed (# 61), and the process returns to # 50. If the back cover open / close switch SR has not changed, it is detected whether or not the release button S1 is turned on (# 62). If it is turned on, a battery check is performed (# 63). If the result of the battery check is OK, A release sequence described later is executed (# 64), and the process returns to # 50. If the release button S1 is not turned on in # 62, the zoom-in switch SZ2 is turned on.
If it is turned on (# 65), it is detected whether or not it is turned on.
A battery check is performed (# 66), and if the result of the battery check is OK, a zoom-in sequence is performed (#
67), and returns to # 50.

At # 65, the zoom-in switch SZ2 is turned on.
If not, it is detected whether or not the zoom-out switch SZ1 is turned on (# 68). If it is turned on, a battery check is performed (# 69). If the result of the battery check is OK, the zoom-out sequence is executed. (# 7
0), return to # 50. Zoom out switch S with # 68
If Z1 is not turned on, auto power off (APO)
Detects whether the timer has timed out (# 71),
If the time is not over, the process returns to # 53 and the above operation is repeated, while if the time is over, the CPU enters the hold state (# 72). The above is the main sequence of the camera.

Next, the release sequence of the camera will be described with reference to FIGS. First, the distance to the subject is measured (# 1), and the AF zone value is calculated from the obtained distance measurement data. Then measure the brightness of the subject (#
2) From the obtained photometric data, it is determined whether the automatic exposure (AE) release or the flashmatic (FM) release. For AE release, the control EV value is calculated, and for FM release, the control EV value and AV value are calculated. Thereafter, in order to perform shutter control based on the control EV value and AV value obtained in # 2, shutter control data is calculated and obtained (#
3). Next, it is checked from the distance measurement result of # 1 whether or not the camera is in the short-distance lock state (# 4), and if it is in the short-distance lock state, the release sequence is ended (# 2).
9). If the short-distance lock state does not occur, it is determined whether the AE release or the FM release according to the result of # 2 (# 5).
If it is an AE release, move to # 7. FM release #
Proceed to step 6 to monitor the voltage of the main capacitor to check whether flash firing is possible (#
6), the voltage of the main capacitor is at a light emission level (L1
If it is equal to or higher than the level), flash light emission is possible, so the process proceeds to step # 7. If it is below the light-emission possible level, a sufficient voltage for flash emission cannot be obtained, so release is prohibited (# 29).

In # 7, it is determined whether or not self release is performed. If self release, the process proceeds to # 10, and if normal release, the process proceeds to # 8. In steps # 8 and # 9, the release switch S2 is waited for being turned on, and if it is turned on, the process proceeds to step # 10. When the photometry / distance measurement switch S1 is turned off, the release sequence ends (# 29). In # 10,
It is determined whether or not it is self release, and if it is self release, self-counting is started (# 11), and then it is determined whether or not the main switch SM is turned off (# 1).
2) If it is turned off, the release sequence is ended (# 29). If the main switch SM remains ON,
Wait for the self-counter to overflow (# 13
YES), the process proceeds to # 14. If the release is not self-release in # 10 above, that is, the release is normal, then # 1
Go to 4. In # 14, it is determined whether or not it is the FM release, and if it is not the FM release, the process proceeds to # 17. In the case of the FM release, the red-eye reduction mode that reduces the phenomenon that the eyes appear red due to flash photography in a dark place It is determined whether or not (# 15), and if it is not the red-eye reduction mode, # 1
Move to 7. In the red-eye reduction mode, the red-eye reduction lamp is irradiated for a certain period of time (# 16), and the process proceeds to # 17.

In # 17, the lens is driven to perform the focusing operation based on the distance measurement result obtained in # 1. After focusing, it is determined whether or not focusing is normally performed (# 18), and if a focusing abnormality occurs, the release sequence ends (# 29). If there is no focusing abnormality, shutter control is performed based on the shutter control data calculated in # 3 to open / close the shutter (# 19), and then the lens driven in # 17 is reset to the initial position (# 20). The shutter control will be described later. After the processing of # 20, it is determined whether the current release is the FM release or the AE release (# 21), and A
If it is E release, the process proceeds to # 25, and if it is FM release, whether or not the normal flash operation is performed is performed by monitoring the voltage of the main capacitor (# 22, # 2
3) Then, if the voltage of the main capacitor is lower than the L1 level, the process proceeds to # 25, and if it is equal to or higher than the L1 level, F
Since the main capacitor is not discharged even after the M-release, it is determined that the flash trigger has not been normally applied, the FM trigger NG flag is set (# 24), and the process proceeds to # 25.

In # 25, the state of the back cover is monitored, and if the back cover is closed, a data imprinting signal is output to imprint the data on the film (# 26). Then, the presence or absence of the film is discriminated. If there is no film (# 27), the release sequence is ended (# 29), and if there is a film, one frame of film is wound up (# 28), and then this sequence is ended (# 29). If the back cover is open in # 25, the process proceeds to # 27 without processing # 26.

Next, the structure for driving the shutter in this embodiment will be described with reference to FIG. The shutter has its blades opened and closed by a motor M1 to obtain a desired exposure amount. Although not shown, the control circuit 1 also functions as a shutter control signal generating means, and detects the power supply voltage Vp for driving the motor, and controls the opening and closing of the shutter according to the detected voltage. Control signal, that is, shutter drive motor control signal MCON
1 and MCON2 are output by changing the duty of pulse width modulation (PWM). A control signal consisting of H (high) and L (low) is given to the motor driver 8 and its output controls conduction of the transistors Tr1 to Tr4 to control the motor M.
1 is driven, and the shutter blades are opened and closed by this motor M1. The relationship between the control signals MCON1 and MCON2, the transistors Tr1 to Tr4, and the shutter opening / closing operation is as shown in the table below.

[0024]

[Table 1]

Next, with reference to FIGS. 10 and 11, the reason why the PWM control as described above produces an effect equivalent to that of using a constant current circuit will be described. Figure 1
0 indicates the signal waveform of PWM control, and in the figure, PW
When the L period of the control signal for M control is t, 1 cycle is T, and the fundamental frequency is f (Hz), T = 1 / f (s) Duty: (t / T) × 100 (%) When a pulse is output and the fundamental frequency is fixed,
By changing the duty, it is possible to change the current flowing in the motor M1 (referred to as shutter current). Therefore, if an appropriate duty is determined for each condition, a constant current can be passed through the motor M1. FIG. 11 shows a timing chart of shutter control. M when the shutter is open
PWM control of the CON1 signal makes the shutter current constant when the shutter is energized. MCON when shutter is closed
By performing PWM control of the two signals, the shutter current when the shutter is closed can be made constant.

Next, how to determine an appropriate duty of the shutter current will be described. FIG. 12 is a graph showing the dependency of the voltage value and the duty upon energization so that the time until the shutter is fully opened and fully closed is 3 ms. As can be seen from this graph, in order to open and close the shutter stably, the duty must be changed according to the voltage Vp. As a method thereof, at the time of shutter adjustment, a duty value at a predetermined voltage of at least one point (for example, Vp = 6V and Vp = 4V) is found and stored. Then, when actually driving, the current voltage (Vp) level is detected, the optimum duty value is calculated from the linear approximation formula of the stored value, and the shutter is driven with the duty value. Good. Of course, the more adjustment points stored in memory, the more optimal the duty value can be obtained. Although the duty value is calculated by linear approximation in this embodiment, it may be calculated by the original characteristic curve.

The shutter characteristic changes not only with the power supply voltage as described above but also with the ambient temperature. FIG. 13 shows changes in the optimum duty value with respect to changes in ambient temperature. Such temperature dependence is stored in advance and the current ambient temperature is detected when actually driving,
The duty value calculated as described above is corrected. For example, the calculated duty is 77% and the detected temperature is 40 ° C.
At this time, the optimum duty value is 77 + 1 = 78 (%). In the case of the present embodiment, the control circuit 1 needs to be configured so that an ambient temperature detection signal is input from a temperature detection sensor (not shown). Although the duty is calculated by using the power supply voltage Vp as the voltage and the absolute temperature as the temperature, it is also possible to use the result at the time of battery check or the relative temperature between the adjustment and the actual driving. If further accuracy is required for the duty ratio, the change in the shutter characteristics due to the camera attitude such as vertical or horizontal shooting may be detected and corrected by detecting the camera attitude.

Next, the shutter drive processing at the time of the long shutter release (for example, the shutter speed is 1 second or more) will be described. While it is necessary to constantly supply current to the shutter drive motor M1 while the shutter open state is maintained, if the state is continued, the temperature rise of the shutter drive motor M1 becomes large. FIG. 14 is a graph showing the relationship between the energization time and temperature of the shutter drive motor M1. As can be seen from the figure, if the shutter open state is maintained for a long time and is repeated continuously, the shutter drive motor M1 may be burned out. Therefore, compared to when driving from the fully closed state to the fully open state, by utilizing the shutter characteristics that can hold the fully open state with a small shutter current, by reducing the shutter current only when the fully open state is maintained, without impairing the opening / closing performance of the shutter, It is possible to reduce the temperature rise of the motor M1 during the long-time release. Further, it also reduces the current consumption at the time of a long-time release.

FIG. 15 is a diagram showing shutter drive motor control signals MCON1 and MCON2 by PWM and shutter opening / closing waveforms. PW from fully closed shutter to fully open
The M drive is performed with the optimum duty obtained in advance (the optimum duty is 78% in this example). After sufficient time has passed for the shutter blades to reach the predetermined aperture, the PW
The duty of the M drive is switched to the minimum required holding duty for holding the shutter open state (in this example, the holding duty is 55%). Also, the operation of the shutter blades is monitored to detect that the shutter has reached a predetermined opening,
If you switch to the holding duty at that timing,
Further, the switching can be performed with high accuracy.

Next, how to determine the holding duty will be described with reference to FIG. FIG. 16 is a graph showing the dependency of the voltage value Vp and the holding duty when the shutter drive motor M1 is energized. As can be seen from this graph, it is necessary to calculate the holding duty as well as the optimum duty by linear approximation or a characteristic curve in order to find a value that allows the minimum shutter current to reliably hold the shutter open state. In addition, when the accuracy of the holding duty is required, it is necessary to correct the holding duty according to the detected ambient temperature and the shutter attitude, as in the optimum duty.

In this embodiment, in order to easily calculate the holding duty, the duty of a predetermined ratio of the optimum duty (obtained experimentally) is set as the holding duty. For example, when the optimum duty is 78%, the predetermined ratio is set to 0.
7, the holding duty is 78% × 0.7 = 54.
It will be 6%. It should be noted that if an optimum ratio is found and stored in memory during shutter adjustment, a more accurate holding duty can be obtained. Further, a value obtained by subtracting a predetermined amount from the optimum duty may be set as the holding duty according to the shutter opening / closing characteristics.

Next, a concrete method of the battery check processed in # 60, # 63, etc. of FIG. 4 described above will be described. In order to improve the detection accuracy, the battery check method usually detects the voltage applied across the load while the load (motor or the like) is energized and uses the voltage value. As described above, it is necessary to pay attention so that the load is not energized for the battery check so that the careless operation is not performed. That is, when the load is a motor, it is necessary to properly select the type of motor and the energization direction thereof. For example, in the case of a shutter drive motor, power is supplied in the direction in which the shutter is closed. However, due to mechanical (mechanical) play, collision noise occurs between mechanical members when the motor is energized, and if a member driven by the motor, such as a shutter, is vulnerable to impact, energization is performed. As the number of times increases, the member may be distorted, and if it is further advanced, it may be damaged.
Therefore, in this embodiment, by gradually increasing or decreasing the current when the motor is energized at the time of checking the battery, generation of collision noise between mechanical members and reduction of distortion between members are attempted. The details will be described below.

17 (a) and 17 (b) respectively show the states of the shutter when the shutter drive motor M1 is turned off and when the battery is checked in the closing direction.
The shutter includes shutter blades 11 and 12, an opening 13 for exposing the shutter base plate, a shutter opening / closing lever 14, and a motor rotating plate 1 rotated by a shutter drive motor M1.
The shutter blades 11 and 12 are rotatably supported by pins 16 and 17 that are planted on the shutter base plate, and the pin 18 of the shutter opening / closing lever 14 slides in the cam holes of the shutter blades 11 and 12. It is fitted freely. In addition, blade stop bosses 19 and 20 projecting from the shutter base plate
Serves as a rotation stopper for closing the shutter blades 11 and 12.

In the above structure, the shutter drive motor M
When 1 is energized so as to rotate in the shutter closing direction, the shutter blades 11 and 12 slightly rotate due to the play of the engaging portion between the motor rotating plate 15 and the shutter blades 11 and 12 (the rotation direction is indicated by an arrow). ), Blade stop bosses 19, 20
A collision sound is generated. Further, FIG. 18 shows a shutter drive motor control signal MCON1, based on the conventional drive method.
FIG. 3 is a diagram showing MCON 2 and motor operation amount. As shown in the diagram, since the shutter blades 11 and 12 are weak against impact, they are distorted when they collide with the blade stopper bosses 19 and 20.

FIG. 19 shows shutter drive motor control signals MCON1 and MCO in the case of the PWM drive system according to this embodiment.
It is a figure which shows N2 and a motor operating amount. The shutter drive motor control signal is output from the control circuit 1 (FIGS. 2 and 9). As shown in FIG. 19, in the present embodiment, before and after the battery check, preliminary energization by PWM driving is performed, that is, the current at the time of energizing the motor is increased / decreased step by step to check the battery. The impact on the shutter blades is reduced, and the collision noise and distortion of the members are reduced. The control signal MCON1 is "H",
When the MCON2 is "L", the shutter closing direction drive is performed, and when the control signal MCON2 is 100% "L", the voltage across the motor is detected to perform the battery check.

Further, in the present embodiment, the shutter current is shown to be controlled in three steps, but if the number of steps is further increased, the shock becomes even smaller. In addition, the number of stages of the above-described preliminary energization can be easily increased by adopting the PWM driving method. In addition to the shutter drive motor, the load that is energized to increase the detection accuracy during the battery check may be, for example, a photographic lens drive motor, and in this case, energization during the battery check is performed by the photographic lens. Perform with the drive motor stopped at the stroke end.

[0037]

As is apparent from the above description, according to the power supply voltage detecting device for a camera of the present invention, the current is stepwise increased / decreased before and after the motor is energized at the time of checking the battery. Therefore, it is possible to reduce the occurrence of the collision noise between the mechanical members and the distortion between the members. When performing the stepwise increase / decrease control of this preliminary energization, by using the pulse width modulation (PWM) drive method,
It is possible to increase the number of steps easily.

[Brief description of drawings]

FIG. 1 is a perspective view of a camera according to an embodiment of the present invention.

FIG. 2 is a block diagram of a control circuit of the camera and peripheral circuits thereof.

FIG. 3 is a flowchart of a camera reset routine.

FIG. 4 is a flowchart of a main sequence of the camera.

FIG. 5 is a flowchart of a release sequence of the camera.

FIG. 6 is a flowchart of a release sequence of the camera.

FIG. 7 is a block diagram of a waveform shaping circuit of a photo reflector and a photo interrupter.

8A is a waveform diagram of a voltage VPI, and FIG. 8B is a waveform diagram of a pulse signal.

FIG. 9 is a configuration diagram of a shutter driving device of the present embodiment.

FIG. 10 is a diagram showing a control signal waveform of PWM control.

FIG. 11 is a time chart of shutter control.

FIG. 12A is a diagram showing a voltage dependency when a shutter is energized and FIG. 12B is a diagram showing a voltage dependency when a shutter is energized.

FIG. 13 is a diagram showing temperature dependence when the shutter is energized.

FIG. 14 is a diagram showing a relationship between energization time and temperature of a shutter drive motor.

FIG. 15 is a diagram showing a shutter drive motor control signal and a shutter opening / closing waveform by PWM.

FIG. 16 is a diagram showing the dependency of the voltage value and the holding duty when the shutter drive motor is energized.

FIG. 17 (a) shows that the power supply to the shutter drive motor is turned off.
FIG. 7B is a diagram showing the state of the shutter at the time, and FIG. 7B is a diagram showing the state of the shutter at the time of energizing in the closing direction during the battery check.

FIG. 18 is a diagram showing a shutter drive motor control signal and a motor operation amount according to a conventional drive method.

FIG. 19 is a diagram showing a shutter drive motor control signal and a motor operation amount according to the PWM drive system of the present embodiment.

[Explanation of symbols]

 1 Control Circuit 8 Motor Driver M1 Shutter Drive Motor Vp Power Supply Voltage

Claims (1)

[Claims] 1. A motor for performing various operations of the camera, a power source for supplying power to the motor, and a direction other than a direction in which the motor is connected as a load of the power source to cause the motor to perform various operations of the camera. In a power supply voltage detection device for a camera, which includes drive means for applying a drive signal to drive the motor, and voltage detection means for detecting a voltage applied to the motor during energization of the motor by the drive means, the drive means is A power supply voltage detection device for a camera, wherein a current is increased stepwise at the start of energization of a motor, and the current is decreased stepwise at the end of energization.