JP2716177B2 - Camera temperature compensation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a camera having a temperature measuring means for measuring an environmental temperature and having a heat source around the temperature measuring means which disturbs the environmental temperature. The present invention relates to a camera temperature compensating device for performing the following.

[Related Art] In recent years, since a mold is frequently used in a camera body or the like, a positional relationship in an optical component of a camera has been greatly affected by a temperature. For example,
Since the refractive index of a plastic lens, which has been frequently used recently, changes depending on the temperature, the focus is greatly shifted depending on the environmental temperature, and a high-quality photograph cannot be taken.

Therefore, a technique has been developed in which the environmental temperature is measured in advance, and the focus is adjusted by correcting the temperature to obtain a good-looking photograph (JP-A-57-64204). reference).

In addition, since the load torque at the time of film winding changes with temperature, a technique of changing the drive voltage of the film winding motor according to the temperature has been developed. In particular, in the case where a motor is used for AF (auto focus) and shutter operation, constant speed rotation of the motor is indispensable, and the above method is very effective in removing the influence of temperature.

As described above, it is necessary to measure the environmental temperature in order to operate the camera satisfactorily. As one of the measurement methods, for example, as described in JP-A-57-64204, Generally, a resistance temperature detector such as a thermistor is used.

On the other hand, a method of measuring an environmental temperature by measuring an electrical output corresponding to a temperature change generated in an IC (integrated circuit) without using a temperature measuring resistor as described above, a so-called method. There is an IC temperature measurement method, which will be described below.

Usually, the camera is a sequence controller (SC) that controls the camera sequence as shown in Fig. 10.
41. An autofocus IC (hereinafter, referred to as an autofocus IC) connected to the sequence controller 41 and performing autofocus control.
AFIC) 42, which is connected to the sequence controller 41 and has functions such as transmitting luminance information and pulse information of a photointerrupter to the sequence controller 41, and driving the motor 45 in accordance with commands from the sequence controller 41. It has a face IC (hereinafter abbreviated as IFIC) 43 as a component. Reference numeral 44 denotes a motor driver.

Since the IFIC 43 usually has an electrical output corresponding to a temperature change therein, it is possible to measure an environmental temperature by measuring the electrical output. However, in the IC temperature measurement method, when power is supplied to the IC, heat is generated in the IC itself, and a difference occurs between the environmental temperature and the IC temperature. In particular, with respect to a motor having a function of driving a motor or the like, the influence of this heat generation is remarkable.

FIGS. 11 (a), (b) and (c) show the time change of the temperature of the IFIC 43 after driving the motor by winding up, autoloading and rewinding one frame of the film. 1
It can be seen that a steady state is reached after about 8 seconds during frame winding and auto loading and about 100 seconds after rewinding. The time to reach the steady state is determined by the heat dissipation characteristics of the IC package.

[Problems to be Solved by the Invention] As described above, in the IC temperature measurement method, the temperature between the IC temperature immediately after operating a power circuit such as a motor driver and the external environment temperature is about 10 to 20 ° C. A significant difference occurs, and there is a fatal drawback that accurate temperature measurement cannot be performed unless the temperature measurement after operating the power circuit once takes about 10 to 100 seconds. Therefore, it has been difficult to accurately correct the temperature of the camera in the temperature measurement by the IC temperature measurement method.

However, the temperature measurement method using the IC temperature measurement method does not require an external element such as a thermistor as in the past, and for cameras that are more compact and cost-effective, both the space and cost advantages can be discarded. Has great appeal.

The present invention is a critical disadvantage of the above IC temperature measurement method.
It is an object of the present invention to provide a camera temperature compensating device that solves the problem of the influence of heat generation, and provides a remarkable space advantage and cost advantage for a camera that aims to be more compact and lower in cost.

[Means for Solving the Problems] As shown in FIG. 1, a camera temperature correction device according to the present invention includes a temperature measuring means 1 for measuring an environmental temperature, and a heat generation device which disturbs the environmental temperature around the temperature measuring means. In a camera with a source,
A storage means 3 for storing environmental temperature data measured by the temperature measuring means 1, a temperature correction operation means 4 for performing a temperature correction operation on external data 5 based on the environmental temperature data stored in the storage means 3, , This temperature correction calculating means 4
Camera driving control means 6 for controlling the operation of the camera based on the output of the camera, and writing the environmental temperature data measured by the temperature measuring means 1 to the storage means 3 at a timing in the camera sequence at which the influence of the heat source is eliminated. And writing means 2 for performing a writing operation.

[Operation] For example, before the power circuit block (heat source) in the IC that causes the IC heat is activated, the environmental temperature data measured by the temperature measuring means 1 is stored in the storage means 3 and this stored data is stored. Based on the environmental temperature data, a temperature correction operation is performed on external data (for example, a distance measurement operation result, a photometry result, or ROM data of a CPU) 5, and a camera drive control is performed based on the result of the temperature correction operation. And
The environmental temperature data measured by the temperature measuring means 1 is stored in the storage means 3 at a timing in a camera sequence at which the heat generation of the IC ends and the IC temperature becomes substantially equal to the environmental temperature. As a result, the environmental temperature data stored in the storage means 3 is updated at a time at which the IC heating ends and the IC temperature becomes substantially equal to the environmental temperature, so that the environmental temperature data sufficiently follows the temperature change of the external environment. can do.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 2 shows one embodiment of the present invention more specifically, and shows a first embodiment in which the present invention is applied, for example, to temperature correction of AF (auto focus) feeding control.

In FIG. 2, a CPU (Central Processing Unit) 11 controls a camera sequence. The distance measuring device 12 is for obtaining a distance to a subject based on, for example, the principle of triangulation, and includes a light emitting element (for example, a light emitting diode) 13 for projecting light and a PSD (Position Sensit).
ve Detector) 14, a light projecting lens 15, and a light receiving lens 16. AFIC (Auto Focus IC) 17
Is for driving the distance measuring device 12, and the terminal C of the CPU 11
Signal AFSTART from ₆ starts ranging by being input to the terminal A _1, the distance measurement is completed, the terminal A ₂ converts the distance data corresponding to the distance to the subject to serial data, A
_{From 3} use the DATA and CLOCK signal lines to
And it sends it to the C _1, C _2.

Here, the external data 5 is, for example, AFIC17 in this embodiment.
Is the distance measurement data output from.

The digital memory 18 as the storage means 3 stores environmental temperature data obtained from the temperature measuring means, and is, for example, an EEPROM (Electrically Erasable Programmable ROM).
The terminals M ₃ , M ₄ , and M ₅ have terminals C ₃ ,
Input and output of signals ▲, R /, ， from C ₄ and C ₅ control writing and reading of data.

The temperature measuring means 1 outputs an electric signal related to the environmental temperature. In the present embodiment, for example, IFIC (for interface)
It refers to temperature measuring circuit blocks 19 ₁ IC) in 19. The output voltage from the temperature measuring circuit block 19 ₁ is inputted in an analog quantity to a terminal C ₁₃ of CPU 11, after being converted into a digital amount by the CPU 11 built-in A / D converter, is converted into a digital code corresponding to the temperature Are stored in the digital memory 18.

A specific circuit example of the temperature measuring circuit block 19 ₁ is shown in Figure 3. Temperature measuring circuit block 19 _1, the reference current circuit 51 is connected to the reference current circuit 51, and T proportional voltage output which changes in output in proportion to the absolute temperature, is not affected by the absolute temperature T stable voltage two outputs It comprises a circuit 52 for generating an output voltage, and a differential amplifier 53 for taking a difference between two output voltages output from the circuit 52. In the circuit 52, the voltage generated by the resistor 20R ₁ becomes 10V _T ln 10. Here, V _T is the thermal _{voltage, V T = (K / q} ) T, k is Boltzmann's constant, q is the Coulomb charge, T is the absolute temperature.

Further, in the circuit 52, the anode potential of the diode D ₁ becomes a band gap reference voltage 1.26 volts, which is constant regardless of the temperature. Therefore, the output voltage v ₀ of the differential amplifier 53 is And a voltage proportional to the absolute temperature T is output.

The environmental temperature data stored in the digital memory 18 is sent from the terminals M ₁ and M ₂ to the terminals C ₁ and C ₂ of the CPU 11 using the DATA and CLOCK signal lines. That is, the CPU 11
Environmental temperature data stored in the digital memory 18;
The drive amount of the focusing lens is determined based on the distance measurement data from the AFIC 17, and drive control is performed according to the drive amount.

Driving of the focusing lens, a motor 20 connected between the motor drive circuit block 19 _{and second} terminal D _4, D ₅ in IFIC19
Done by Motor 20 is, for example, a DC motor. Motor drive circuit block 19 _2, CPU 11 of the terminal
The motor 20 is driven according to the signals CW, CCW, and BRAKE from C ₇ , C ₈ , and C ₉ .

The power transmission mechanism 21 reduces the rotation speed of the motor 20 and transmits power to the focusing lens group 22. The focusing lens group 22 is extended or retracted by the power from the power transmission mechanism 21.

The encoder 23 is for monitoring the drive amount of the focusing lens unit 22, is connected to the terminal C _10, C ₁₁ of CPU 11, the light emitting element (e.g. light emitting diode) 24, the photo interrupter 26 consisting of phototransistor 25. , And a rotating slit 27.

The CPU 11 is connected to the terminal C while the focusing lens group 22 is driven.
_A drive signal is output from ₁₀ to the light emitting element 24. Rotating slit
27 is a member rotated by the rotation of the motor 20,
Encoder 23 by the rotation of the rotary slit 27 is output to the encoder pulse to terminal C ₁₁ of the CPU 11. CPU1
1 monitors the driving amount of the focusing lens group 22 by counting the encoder pulses.

Between the terminal C ₁₂ of CPU11 ground terminal, the release switch 40 is connected.

Here, the mechanism around the motor 20 will be described with reference to FIGS. 4 and 5. FIG. In the figure, the rotational force of a motor 20 is controlled by a power transmission mechanism comprising a pinion gear 28 provided on an output shaft thereof and gears 29, 30, and 31 meshing with the pinion gear 28 sequentially.
The power is transmitted to the gear 33 provided on the focusing frame 32 through the 21, and as a result, the focusing frame 32 rotates. A helicoid 34 is provided on the outer periphery of the focusing frame 32.

On the other hand, a lens barrel 36 is fixed to a part 35 of the camera body,
A fixed frame 37 is fixed to the lens barrel 36. A helicoid is formed on the inner peripheral surface 37a of the fixed frame 37, and is fitted to the helicoid 34 provided on the focusing frame 32.
The focusing lens group 22 is fixed to an inner peripheral portion of the focusing frame 32.

Therefore, when the motor 20 is rotated by the direction signal CCW, the focusing frame 32 is extended with respect to the fixed frame 37. Further, when rotated by the direction signal CW, the focusing frame 32 is moved into the fixed frame 37. Rotating slit
27 is coaxial with the reduction gear 29 of the power transmission mechanism 21, and both rotate at the same rotation speed. Reference numeral 38 denotes a shutter blade.

Next, the operation in such a configuration will be described. The CPU 11 is a control means for controlling the entire sequence of the camera. The operation around focusing related to the present invention will be described with reference to the flowchart shown in FIG.

When the release switch 40 is turned on, the focusing operation is started. First, CPU 11 performs a check of the power flag, a temperature measuring data from the temperature measuring circuit blocks 19 ₁ unless power flag is not ON A
After performing a / D conversion and an appropriate arithmetic process, the data is converted into a digital value corresponding to the temperature, and then written into the temperature data storage address of the digital memory 18 as environmental temperature data. If the power flag is on, the above steps are jumped.

The power flag is a flag for determining whether or not the power circuit block (the motor drive circuit block 19 _{2 in} this embodiment) in the IFIC 19 has been operating within a predetermined time before the release switch 40 is turned on. Yes, “1” (ON) when operating, “0” when not operating
(Off). Here, the predetermined time is heating generated by operation of the power circuit blocks subsided, the time up to the measurement temperature circuit block 19 ₁ outputs approximately equal temperature measuring data and the environmental temperature.

The power flag is set to a predetermined bit in a predetermined address of the RAM in the CPU 11 (may be a predetermined address in the EEPROM). After the end of the routine for operating the power circuit block of the IFIC 19 on the program of the CPU 11, the predetermined bit is set to "1". Then, after completing the above routine, CPU1
1 performs a timekeeping operation. If a routine for operating the power circuit block (for example, a zoom motor driving routine, a shutter motor driving routine, a winding motor driving routine, etc.) is not executed within the predetermined time, the predetermined bit is set to "0". "

Next, the CPU 11 reads the environmental temperature data from the digital memory 18 and generates an address based on the environmental temperature data. Then, the CPU 11 performs data communication with the digital memory 18 so that the data DFOCUs stored at the above address in the 8-bit data table for focusing adjustment of the digital memory 18 is stored in the B0 address of the RAM in the CPU 11. Write.

Then, CPU 11 is outputted from the terminal C ₆ "H" level signal AFS
Outputs TART, is input to the terminal A ₁ of AFIC17. AFIC17 is
It has a function to divide the range of the photographable distance into 15 zones, detect which zone the subject is in, and output this detection zone as the distance measurement result. Here, the relationship between the subject distance and the zone (distance measurement result) is shown in Table 1 below.

The AFIC 17 starts the distance measuring operation when the signal AFSTART is input, and ends the distance measuring operation within a predetermined time (100 ms in the present embodiment).

After outputting the signal AFSTART, the CPU 11 operates the timer for 100 ms, and waits for the AFIC 17 to complete the distance measurement operation. After the expiration of the 100 ms timer, the CPU 11 performs data communication with the AFIC 17 to acquire 8-bit distance measurement data. The data communication method is the serial communication
Rising in synchronism with the signal CLOCK from the terminal C ₂ of sequential 8-bit data is taken as a signal DATA from the terminal C ₁ of the CPU 11. Then, the CPU 11 stores the data at the address C of the RAM as the distance measurement data STEP.

After the data communication with the AFIC 17 ends, the CPU 11
After setting FSTART to the “L” level, the amount of extension of the focusing lens is calculated. The amount of extension (the number of encoder pulses) N of the focusing lens is obtained by adjusting the focusing adjustment value DFOCUs stored at the address B0 of the RAM in the CPU 11 and RA
From the distance measurement data STEP stored at the address C of M, it is obtained according to the following equation.

N = DFOCUS + STEP × 8 + 30 One stage of the distance measurement data STEP corresponds to 8 pulses of the encoder. The data itself of the adjustment value DFOCUS corresponds to the correction amount of the pulse number of the encoder. Further, the constant “30” in the third term of the above equation corresponds to the feeding amount when [STEP = 0]. The payout amount is a mechanical adjustment margin value for absorbing the correction amount when the adjustment value DFOCUS takes a negative value.

When the calculation of the extension amount is completed, the extension operation of the focusing lens is performed next. The extension operation of the focusing lens will be described with reference to FIG.

First, the CPU 11 sets the value of the built-in register BC to “0”. Then, CPU 11 is to the terminal C ₁₀ to "H" level, after turning on the light emitting element 24 in the photo-interrupter 26, the terminal
To "H" level direction signal CCW output from C _8. As a result, the motor drive circuit block 19 _2, a driving current for rotating the motor 20 by the direction signal CCW motor 2
0 is output, whereby the focusing lens group 22 starts extending.

Then, CPU 11, the level of the terminal C _11, i.e., monitoring the output level of the phototransistor 25, "L" → added to the value of the register BC for each change in "H" by "1". Then, the value of the register BC is becomes equal to the driving amount (the number of encoder pulses) N of the focusing lens, the level of the terminal C _8, namely to "L" level signal CCW. As a result, the motor drive circuit block 19 ₂ stops the power supply to the motor 20.

Then, CPU 11 is a terminal C ₁₀ to the "L" light emitting element
Turn off the 24, then the level of the terminal C _9, or signal
Set the BRAKE level to “H”. As a result, the motor drive circuit block 19 _2, braking by the motor 20 is short-circuited. Then, CPU 11 operates the 100ms timer, after the completion of the timer, the level of the terminal C _9, namely exit brake and the level of the signal BRAKE to "L", the ends the operation of the focusing.

Thus, the power circuit blocks in IC responsible for IC fever, for example provided in IFIC19, before the motor drive circuit block 19 ₂ for driving the focusing motor 20 is operated, temperature measuring circuit in IFIC19 block 19 ₁ is stored in the digital memory 18, and based on the stored environmental temperature data, the AFIC 17
A temperature correction operation is performed on the distance measurement data (distance measurement operation result) from the camera, and the driving control of the focusing motor 20 is performed based on the temperature correction operation result. Then, the environmental temperature data measured by the temperature measuring circuit blocks 19 _1, IFI
The heat is stored in the digital memory 18 at the timing in the camera sequence at which the heat of the C19 ends and the temperature of the IFIC 19 becomes substantially equal to the environmental temperature.

Thus, the environmental temperature data stored in the digital memory 18 is updated at a time when the heat of the IFIC 19 ends and the temperature of the IFIC 19 becomes substantially equal to the environmental temperature.
It can sufficiently follow the temperature change of the external environment.

Therefore, the fatal drawback of the IC temperature measurement method due to the difference between the IC temperature and the ambient temperature caused by IC heat generation can be eliminated, eliminating the need for an external temperature measuring element such as a thermistor as in the past. Since measurement becomes possible, a significant space and cost advantage is provided for a camera that aims to be more compact and lower in cost.

The power flag for determining whether or not the power circuit block has been operated does not need to be provided in the memory. For example, the power flag is configured by externally connecting a CR circuit as shown in FIG. Is also good. That is, CPU11
On the program output port P ₁ after the end of the routine for operating the power circuit blocks IFIC19 to "H" level, the high impedance state the output port P ₁ after charged sufficiently capacitor C _F to "H" level set. Electric charge accumulated in the capacitor C _F, the resistance R predetermined time mentioned above through _F (subsides heat generation caused by the operation of the power circuit block, the measuring temperature circuit block 19 ₁ outputs approximately equal temperature measuring data and environmental temperature Constant until the discharge time). Capacitor C _F
The potential, read from the input port P ₂ in the CPU11 rare, which is used as a power flag. In this case, CPU11
This is an effective method when it is not necessary to perform the clocking operation from the end of the routine for operating the power circuit block, and it is necessary to perform other arithmetic processing or the like.

Note that a plurality of the CR circuits may be provided corresponding to each power circuit block, or a circuit having a maximum value may be set.

In the first embodiment, the external memory is used as the storage means. However, the external memory is not necessarily required. For example, an internal memory such as a RAM provided in a CPU may be used.

Further, in the first embodiment, the power flag is set by monitoring whether or not the power circuit block is activated.
It is not particularly necessary to perform such processing. For example, the temperature measurement operation is started after the CPU has risen from the standby mode (low current consumption mode) to the normal mode, and the temperature measurement data at that time is stored in the RAM. A system may be set up to keep it. Normally, when the camera is left for 90 seconds, for example, the CPU automatically shifts from the normal mode to the standby mode (the clock is stopped and the current consumption is extremely reduced. Since the system is configured to return to a mode for executing a program, that is, a so-called normal mode), it is not necessary to change and add conventional software.

Next, the second case in which the present invention is applied to the drive of the shutter
An embodiment will be described. FIG. 9 is a diagram showing a time change of the opening area of the shutter. The time integral value of the opening area is the exposure amount of the film. The relationship between the opening area and time is affected by the temperature and changes as shown by the straight lines a and b in FIG. This is not only because the drive voltage of the shutter drive motor changes depending on the temperature, but also because of the load fluctuation caused by the change in the coefficient of friction and the fitting until the drive force is transmitted to the shutter blades due to the temperature. It is inevitable. Therefore, by detecting the environmental temperature in the same manner as in the first embodiment and correcting the drive voltage of the shutter drive motor so that the straight lines a and b become the ideal opening straight lines c, the film exposure can be performed with high accuracy and stability. Can be realized.

[Effects of the Invention] As described above in detail, according to the present invention, the problem of the influence of IC heat generation, which is a fatal drawback of the IC temperature measurement method, is solved, and a camera aiming at more compactness and lower cost is required. It is possible to provide a camera temperature compensating device that provides significant space and cost advantages.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating the present invention, FIG. 2 is a block diagram showing a first embodiment of the present invention, FIG. 3 is a block diagram of a temperature measuring circuit block in the first embodiment, and FIG. FIG. 5 is a perspective view showing the peripheral mechanism of the focusing motor, FIG. 5 is a vertical sectional side view showing the peripheral mechanism of the focusing motor, FIGS. 6 and 7 are flowcharts for explaining the operation, and FIG. 8 is a modified example of the power flag. FIG. 9
FIG. 10 is a diagram showing a relationship between the opening area of a shutter and time for explaining a second embodiment of the present invention. FIG. 10 is a block diagram showing a general electric configuration of a camera. FIG. 6 is a diagram illustrating a time change of the temperature of the IFIC after driving. 1 ... temperature measuring means, 2 ... writing means, 3 ... storage means, 4
... Temperature correction calculating means, 5... External data, 6... Camera driving control means.

Claims (1)

(57) [Claims] 1. A camera having a heat source that disturbs an environmental temperature around a temperature measuring means for measuring an environmental temperature, a storage means for storing environmental temperature data measured by the temperature measuring means, and a storage means for storing the data in the storage means. Temperature correction calculation means for performing a temperature correction calculation on external data based on the obtained environmental temperature data; camera drive control means for performing drive control of a camera operation based on an output of the temperature correction calculation means; Writing means for performing an operation of writing the environmental temperature data measured by the temperature measuring means into the storage means at a timing on the camera sequence at which the influence of the camera temperature is eliminated.