JPH095819A - Camera - Google Patents

Abstract

PURPOSE: To provide a camera capable of performing high-speed operation even in the case that power supply voltage is low by providing a one chip microcomputer, a reset means and a booster means, which are specified respectively. CONSTITUTION: A battery 1 is a power supply for which a comparatively low voltage system is assumed, and a power-on reset means 3 monitors the voltage of the battery 1 and outputs a reset signal to the one chip microcomputer 4 when the voltage becomes equal to or under a specified value. The micrcomputer 4 receives the reset signal from the reset means 3 and fixes respective ports at an 'H' level or an 'L' level. The booster means 2 is equipped with a chip enable terminal for starting boosting operation when the signal at the 'H' level or the 'L' level is inputted, and starts the boosting operation as soon as the battery is applied by previously connecting the specified port of the microcomputer 4 to the chip enable terminal of the booster means 2. Thus, a high-frequency main clock is generated even when the power supply voltage is low.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera, and more particularly to a camera using a one-chip microcomputer which operates at high speed.

[0002]

2. Description of the Related Art Conventionally, technical means for controlling all or part of the operation of various devices and apparatuses by a one-chip microcomputer is widely known. As an example of this one-chip microcomputer, Fujitsu semiconductor device / DATASHEET (published by Fujitsu Limited Electronic Device Business Headquarters 1994), microcontroller 8-bit original MB89650A
On page 26 of the series, the operating voltage as shown in Figure 8
Those having characteristics of operating frequency are shown.

According to this characteristic diagram, in order to operate the microcomputer shown in the figure at an operating frequency of 10 MHz, it is necessary to apply a power supply voltage of at least 3.5 [V] or higher.

In addition, Fujitsu semiconductor device / CONTR
In page 76 of "8-bit Microcontroller MB89650 Series User's Manual" described in OLLER MANUAL (published by Fujitsu Limited, Electronic Device Business Headquarters, January 1994), see FIG.
The state transition diagram as shown in FIG.

[0005]

However, in the microcomputer shown in the characteristic diagram of FIG. 8, as is apparent from the characteristic diagram, the oscillation start voltage tends to increase in proportion to the operating frequency of the main clock. Yes, for example, at 8 MHz, a power supply voltage of 3.2 [V] or higher is required. Therefore, the system you want to operate at high speed (8MHz ~
At 10 MHz), it becomes difficult to start oscillation in a normally used 3 [V] system (for example, a system using one lithium single cell (CR-123A etc.)).

Further, as is clear from the state transition diagram shown in FIG. 9, immediately after the power-on reset, the transition always starts from the rising of the main clock (main RUN). This idea is not limited to the above-described one-chip microcomputer manufactured by Fujitsu, but is common to many one-chip microcomputers manufactured by other companies.

The present invention has been made in view of the above problems, and an object thereof is to provide a camera that can operate at high speed even under a low power supply voltage.

[0008]

In order to achieve the above object, a first camera according to the present invention comprises a 1-chip microcomputer in which oscillation means is built in, and a reset signal to the 1-chip microcomputer when power is turned on. And a boosting means for boosting the power supply voltage supplied to the one-chip microcomputer to a predetermined voltage according to the reset operation of the reset means.

In order to achieve the above object, the second camera according to the present invention is the same as the first camera, wherein the boosting means boosts the power supply voltage to a voltage level at which the operation of the oscillating means is guaranteed. It is characterized by

To achieve the above object, a third camera according to the present invention is the first camera, and the boosting means is the one-chip microcomputer.
It is characterized in that it is connected to an output terminal fixed to a predetermined output level by a reset operation, and performs a boosting operation according to the output of the output terminal.

[0011]

The first camera according to the present invention outputs the reset signal from the reset means to the one-chip microcomputer having the built-in oscillation means when the power is turned on. And
In response to the reset operation of the reset means, the power supply voltage supplied to the one-chip microcomputer is boosted to a predetermined voltage by the boosting means.

According to a second camera of the present invention, in the first camera, the boosting means boosts the power supply voltage to a voltage level at which the operation of the oscillating means is guaranteed.

According to a third camera of the present invention, in the first camera, the boosting means is connected to an output terminal of the one-chip microcomputer fixed to a predetermined output level by a reset operation, Boosting operation is performed according to the output of the output terminal.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a schematic configuration of a camera which is an embodiment of the present invention.

As shown in the figure, the battery 1 uses, for example, one lithium battery having a nominal value of 3 [V], or an AA alkaline manganese battery (nominal value 1.5).
This is a power supply assuming a relatively low voltage system such as the case where two [V]) are used. Power-on reset means 3
Is configured to monitor the voltage of the battery 1 and output a reset signal to a one-chip microcomputer (hereinafter abbreviated as one-chip microcomputer) 4 when the voltage becomes equal to or lower than a predetermined voltage value. The one-chip microcomputer 4 receives the reset signal of the power-on reset means 3 and sets each port to "H" level or "L".
Fixed to level.

The boosting means 2 is provided with a chip enable terminal for starting a boosting operation when a signal of "H" level or "L" level is inputted, and the above-mentioned 1
By connecting a predetermined port of the chip microcomputer 4 to the chip enable terminal of the boosting means 2, the boosting operation is started at the same time when the battery is turned on.

Next, the camera of the embodiment shown in FIG. 1 will be described in more detail.

FIG. 2 is a block diagram showing the main structure of the camera of the above embodiment.

As shown in the figure, among the plurality of registers provided with the reset signal inside the one-chip microcomputer 50,
The state is being input to Reg 51. Less than,
The configuration will be described along the flow of signals.

The Reg 51 outputs a predetermined output signal to the output cell 52 at the time of resetting,
The output state of the output cell 52 is determined. For example, Reg
When the output of 51 is "H", the output of the output cell 52 is "L"
And when the output of Reg 51 is “L”, the output cell 52
Output is "H". In addition, Reg5 is output to the output cell 52.
Output cell 5 by a control signal input in a system different from that of 1
2 can also have high impedance. When the output cell 52 has high impedance, the pull-up resistor 5
By 3, the output of the output cell 52 is apparently fixed at "H".

In the present embodiment, for the convenience of the description given later,
It is assumed that the output of the output cell 52 is fixed to "H" at reset.

The boosting IC 57 having a chip enable terminal for controlling ON / OFF of boosting according to the output signal of the output cell 52 carries out boosting operation when the output of the output cell 52 is "H". Therefore, at the time of reset, the output of the output cell 52 is fixed to "H", and the boosting operation is forcibly started. The battery 54 supplies power to the one-chip microcomputer 50 via the boost coil 55 and the Schottky diode 56 when the boost operation is stopped. During the boost operation, the boost voltage with a large ripple component is supplied to the Schottky diode. After being smoothed by the capacitor 58 via the capacitor, it is supplied to the one-chip microcomputer and the peripheral system.

In this way, a series of sequence of reset signal input → fixing 1-chip microcomputer output → starting boosting operation is established.

FIG. 3 is an electric circuit diagram showing in more detail the main structure of the camera of the embodiment shown in FIG.

As shown in the figure, in this embodiment, the battery 30 is a lithium single cell (CR-123A, etc.) 1 as described above.
A 3 [V] system power source such as a book is used. Voltage detector 36
The (hereinafter, reset IC) constantly monitors the voltage of the battery 30, and inverts the output (H → L or L → H) when the battery voltage becomes a predetermined value or less. For example, a high precision voltage detector "S-80718" manufactured by Seiko Instruments Inc.
The output of AL-AE-X "changes from H to L when a voltage of 1.8 [V] or less is detected. That is, it is detected that the battery voltage becomes lower than 1.8 [V]. A reset signal (active "L" in this case) is output to the external reset terminal RSTX of the one-chip microcomputer 37.

The one-chip microcomputer 37 has the oscillator 42 connected to the main clock terminals (X0, X1) and normally operates at the speed (operating frequency) of the main clock. Furthermore, this 1-chip microcomputer 37 is
The sub clock terminal (X0A, X1A) is provided, and by connecting the oscillator 40, the resistor 41, and the capacitors 38, 39, the oscillator operates at a frequency lower by two to three digits than the main clock. This sub clock
It is used as the auxiliary clock when the clock function generates the time or in the energy-saving operation (sleep mode).

The output port P30 of the one-chip microcomputer 37 is a port whose output is fixed at "H" at the time of resetting, and controls the step-up ON / OFF terminal of the step-up IC 34. The booster IC 34 performs a boosting operation when the ON / OFF terminal is at H level. Incidentally, Vcc and Vss in the one-chip microcomputer 37 are power supply terminals.

The boosting IC 34 boosts the battery voltage VE to a predetermined voltage VCC. For example,
The step-up switching regulator "S-8435CF-SD-X" manufactured by Seiko Denshi Kogyo Co., Ltd. is designed to perform the step-up operation from the minimum operation voltage 0.9 [V] to the output voltage 5.0 [V]. There is. Since the booster IC 34 internally includes a reference voltage source, a CR oscillation circuit, a switching power transistor, and an output voltage reference comparator, an external boosting coil 31, a power supply filter capacitor 33, a Schottky diode 32. , And the smoothing capacitor 35 are respectively connected to predetermined terminals to form a step-up switching regulator.

FIG. 4 is a time chart showing an actual operating state of the camera of this embodiment shown in FIG.

As shown in the figure, the symbols on the left side of each waveform correspond to VE, RSTX, P30, VCC and X1 shown in FIG. 3, respectively.

First, as soon as the battery is turned on, the potential of each terminal starts to rise, and when the potential of VE exceeds 1.0 [V], the reset IC becomes operable and the one-chip microcomputer 37
The reset signal is output to RSTX. Further, when the potential of VE continues to rise and exceeds 1.8 [V], the reset IC shifts the output of the reset signal from L to H and releases the reset state of the one-chip microcomputer 37.

During this reset state, the state of the output port P30 of the one-chip microcomputer 37 is confirmed (H level),
The boosting IC 34 starts boosting operation.

At the same time when the boosting operation starts, the VCC potential rises sharply, but the main clock of the one-chip microcomputer 37 is
As is clear from the characteristic diagram shown in FIG. 8, the oscillation does not start until the operating voltage matches the set operating frequency of the main clock. 8MH for X0 and X1 terminals shown in FIG.
Assuming that the oscillator of z is connected, the oscillation start voltage is about 3.2 [V].

Therefore, the oscillation of the main clock starts when the potential of Vcc exceeds 3.2 [V] and settles to a substantially steady oscillation state when the oscillation stabilization time (several 10 mS) has elapsed.

After that, the one-chip microcomputer 37 repeats the operation in the state transition as shown in FIG. 9, but does not activate the main clock in the above sequence unless it transits to the power-on (battery-on) state. This is because the voltage of VE VCC (2.5V≤VE) is applied to the one-chip microcomputer 37 when the battery 30 is in a substantially no-load state, and in this state, a sub clock capable of operating with low current consumption is used. Since it can be oscillated, the transition from the standby state (sleep mode, clock mode, etc.) to the main clock oscillation can be easily performed.

Further, the detection voltage of the voltage detector 36 is boosted by I
If the voltage is set to a value lower than 1.8 [V] within the boosting capacity range of C34 (however, depending on the balance with the operating voltage of the actuator), the voltage can be lower than the battery NG determination voltage, so the battery energy is effectively used. It goes without saying that you can do it. In addition, if the reset of the one-chip microcomputer 37 may be made relatively rough (limited by the threshold value of the RSTX input), the cost can be kept low by replacing the voltage detector 36 with a CR integrating circuit. You can

FIG. 5 is an electric circuit block diagram showing the configuration of a camera system including the camera of the above embodiment.

As shown in the figure, the one-chip microcomputer 10 controls the operation of the entire camera and starts the operation when a reset signal is input from the reset circuit 14. The reset circuit 14 normally generates a reset pulse when the battery is turned on. Below, the 1
Each component connected to the chip microcomputer 10 will be described along the flow of signals.

The EEPROM 18 stores camera status data (during winding, rewinding, etc.), abnormal data (fault location),
The nonvolatile memory stores adjustment data (autofocus correction data, battery check data, etc.). The AF circuit 19 is, for example, a phase difference type sensor, and is adapted to supply distance data to the subject to the one-chip microcomputer 10. The AE circuit 20 is a circuit that measures the subject brightness and supplies the photometric value to the 1-chip microcomputer 10. The SW 13 is composed of various operation switches (release switch, mode changeover switch, etc.) of the camera. The LCD display 12 is an external display panel provided on the upper surface of the camera, and displays the number of frames, camera mode, and the like.

The motor driver 21 is a circuit for driving the hoisting motor (Mw), the zoom motor (Mz), and the shutter motor (Ms) in the block 22 according to the control signal from the one-chip microcomputer 10. The photo interrupter (PIw, PIz, PIs) outputs a positioning pulse signal in conjunction with the three motors (Mw, Mz, Ms), and the signal is sent to the one-chip microcomputer 10. It is being supplied.
These photo interrupters do not require a special interface circuit if they are directly input to the one-chip microcomputer 10 by using OPIC (processing circuit built-in photo interrupter).

The oscillator circuit 11 is composed of a main clock and a sub clock oscillator for operating the one-chip microcomputer 10.

The strobe circuit 17 emits light when the subject brightness is darker than a certain value or when the subject is in the backlit state, and the one-chip microcomputer 10 controls the light emission and the charging so as to obtain proper exposure. There is. DC / DC
The converter 16 converts the voltage VE of the battery 15 into a predetermined voltage V
Boosted to CC, the above-mentioned one-chip microcomputer 10, EEPROM
18, the AF circuit 19, the AE circuit 20, etc. are supplied to the IC system.

Next, the operation of the camera system will be described in detail with reference to the flow charts shown in FIGS.

Normally, a camera is provided with a power SW (or another switch having exactly the same function), and when the power SW is turned on, all the functions of the camera are activated. FIG. 6 is a flowchart showing this state.

First, in step S10, the power SW
When is turned on, the reset circuit 14 outputs a reset signal to the one-chip microcomputer 10. Next, step S11
At this time, the state of the output port of the one-chip microcomputer 10 is determined, and the Vcc boosting operation of the DC / DC converter 16 is started. When this voltage Vcc becomes an operating voltage commensurate with the operating frequency of the main clock in the one-chip microcomputer 10, oscillation of the main clock is started.

After this, the routine proceeds to step S12, where a battery check is performed. Here, the battery check is OK
If so, the process proceeds to step S14 to turn on the LCD display, but if the battery check is NG, a battery check NG process not particularly shown here is performed.

In step S16, the strobe is charged so that the subject can be photographed even when the subject has low brightness or backlight. When the charging is completed, the process proceeds to step S18 and waits for release (1st. Release).

Here, 1st. Release input (1s
t. When the release SW is turned on, the process proceeds to step S20 and the release processing subroutine is immediately executed.
Then, 1st. When the release is not input, or when the release process is completed, the process proceeds to step S22 to determine the ON state of the power SW. If it is on, the process returns to step S18 and the 1st. Determine the release status. If it is off, the process proceeds to step S24 to turn off the LCD display, further proceeds to step S26 to set the energy saving mode (sleep mode, clock mode, etc.), and then returns to step S10.

Next, referring to the flowchart shown in FIG. 7, 1st. The operation of the release process after the release will be described.

The above 1st. When the release is turned on, photometry is first started in step S30. After that, when the photometry is completed, the process proceeds to step S32, and the distance measurement of auto focus (AF) is started. Then step S34
2nd. Wait for the release. The 2nd. If the release is not input, the process proceeds to step S36 and 1s
t. It is determined whether or not the release is input. 1s
t. If the release is input, the process returns to step S34.

On the other hand, the above 1st. When the release is turned off, the process immediately returns to the main flow. The detailed description of the above-described subroutine photometry and distance measurement is not particularly related to the present invention, and thus the description thereof is omitted here.

In step S34, 2nd. When the release is input, a series of sequences required for the fully automatic camera is executed. That is, lens driving (step S3
8), shutter driving (step S40), and film winding (step S42) are executed, and then the process returns to the main flow. Similarly, detailed description of the sub-lens driving, shutter driving, and film winding is not particularly related to the present invention, and a description thereof will be omitted here.

Although a camera has been described as an embodiment of the present invention as described above, the present invention is not limited to this. For example, a one-chip microcomputer with a low power supply voltage and a high-speed clock, such as a portable recorder or a wireless device. Of course, it can be applied to a system using.

According to the embodiment described above, the main clock having a high frequency can be generated even at a low power supply voltage, so that a camera capable of high speed operation (high speed operation) can be realized. Further, since the operating voltage range is expanded to the low voltage side, the voltage range of the battery NG is also expanded, and it is possible to provide a camera that effectively uses the energy of the battery without waste.

[Additional Remarks] According to the embodiments of the present invention described in detail above, the following configurations can be obtained. That is, (1) a one-chip microcomputer including an oscillating means, a reset means for outputting a reset signal to the one-chip microcomputer when the power is turned on, and the one-chip microcomputer according to the reset operation of the reset means. A camera comprising: a booster that boosts a power supply voltage supplied to a computer to a predetermined voltage.

(2) In a system provided with a one-chip microcomputer having a built-in oscillating means, a reset means for outputting a reset signal to the one-chip microcomputer when the power is turned on, and a reset operation of the reset means A system including a one-chip microcomputer, comprising: a boosting unit that boosts a power supply voltage supplied to the one-chip microcomputer to a predetermined voltage.

(3) In the above (1) and (2), the boosting means boosts the power supply voltage to a voltage level at which the operation of the oscillating means is guaranteed.

(4) In the above (1) and (2), the one-chip microcomputer includes a main oscillation means and a sub oscillation means.

(5) In the above (1) and (2), the boosting means is connected to an output terminal fixed to a predetermined output level by a reset operation in the one-chip microcomputer. The boosting operation is performed according to the output of.

(6) In (4), the one-chip microcomputer starts its operation by exciting the main oscillating means.

(7) In the above (4), the one-chip microcomputer stops the operation of the boosting means in the operation standby state and operates only by the output of the sub-oscillation means.

(8) In the above (4), the main oscillation means oscillates at a frequency higher than the oscillation frequency of the sub oscillation means.

(9) Main oscillating means, a one-chip microcomputer that oscillates a signal having a frequency lower than the oscillation signal of the main oscillating means, and a reset means that outputs a reset signal to the one-chip microcomputer when the power is turned on. And an output terminal whose output level changes in synchronization with the reset signal in the one-chip microcomputer, and the output level of the output terminal is one of "H" level and "L" level. Fixed to the step-up means for boosting the power supply voltage to a level at which the operation of the main oscillation means is guaranteed,
A camera equipped with.

(10) A one-chip microcomputer having a built-in oscillating means, a reset means for outputting a reset signal to the one-chip microcomputer when the power is turned on, and in synchronization with the reset signal in the one-chip microcomputer. It is connected to an output terminal whose output level changes, and the power supply voltage is boosted to a predetermined level by fixing the output level of the output terminal to either "H" level or "L" level. And a boosting means for controlling the camera.

(11) In a system including a one-chip microcomputer having a built-in oscillating means, reset means for outputting a reset signal to the one-chip microcomputer when power is turned on, and the reset signal in the one-chip microcomputer Is connected to an output terminal whose output level changes in synchronism with, and the output level of the output terminal is fixed to either the "H" level or the "L" level, so that the power supply voltage is set to a predetermined level. A system including a one-chip microcomputer including: a boosting unit that boosts the voltage to the above level.

(12) In the above (10) and (11), the voltage boosted by the boosting means is a voltage that guarantees the operation of the oscillating means.

[0068]

As described above, according to the present invention, it is possible to provide a camera that can operate at high speed even under a low power supply voltage.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a camera that is an embodiment of the present invention.

FIG. 2 is a block diagram showing the main configuration of the camera of the above embodiment.

FIG. 3 is an electric circuit diagram showing in more detail the main configuration of the camera of the above embodiment.

FIG. 4 is a time chart showing an actual operation state of the camera of the above embodiment.

FIG. 5 is an electric circuit block diagram showing a configuration of a camera system including the camera of the above embodiment.

6 is a flowchart illustrating the operation of the camera system shown in FIG.

7 is a flowchart illustrating a release processing operation in the camera system shown in FIG.

FIG. 8 is an explanatory diagram showing an example of characteristics of operating voltage-operating frequency of a conventional one-chip microcomputer.

FIG. 9 is a diagram illustrating an example of state transition of a conventional one-chip microcomputer.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Battery 2 ... Boosting means 3 ... Power-on reset means 4 ... 1 chip microcomputer (1 chip microcomputer)

Claims (3)

[Claims] 1. A 1-chip microcomputer having a built-in oscillating means, a reset means for outputting a reset signal to the 1-chip microcomputer when the power is turned on, and the 1-chip microcomputer according to the reset operation of the reset means. A camera comprising: a boosting unit that boosts a power supply voltage supplied to a computer to a predetermined voltage. 2. The camera according to claim 1, wherein the boosting means boosts the power supply voltage to a voltage level at which the operation of the oscillating means is guaranteed. 3. The boosting means is connected to an output terminal fixed to a predetermined output level by a reset operation in the one-chip microcomputer, and performs the boosting operation according to the output of the output terminal. Camera according to claim 1, characterized in that