JP2005338433A - Camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve accuracy in adjusting focal length of a lens for a camera having a lens with a large focal length variation due to change in temperature such as a plastic lens. <P>SOLUTION: In this camera 10, the first to the fourth lenses 19, 20, 21, 22 provided for an exchange lens 1 are formed with plastics. These first to fourth lenses 19, 20, 21, 22 are wrapped around with a fuel cell 5, so that temperature in the lens barrel 29 is maintained in a prescribed range by heat generation incident to the power generation of the fuel cell. Consequently, the focal length of the first to fourth lenses 19, 20, 21, 22 is maintained in a specific range. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a camera driven by electric power generated by a fuel cell.

  Conventionally, in order to reduce the manufacturing cost of a camera, a plastic lens is used instead of a glass lens. Since this plastic lens has a large change in focal length due to a temperature change compared to a glass lens, a camera using a plastic lens performs control to correct a focus shift in accordance with a temperature change of the lens (for example, , See Patent Document 1).

In Patent Document 1, the temperature in the lens barrel is detected by a temperature sensor. However, since the temperature in the lens barrel does not become constant due to the heat generated by the camera body, the outside air temperature, or the like, Thus, when the lens system is composed of a plurality of lenses, the temperatures of the plurality of lenses cannot be accurately detected. For this reason, there has been a problem that the focal length of the lens cannot be adjusted accurately.
Japanese Patent Laid-Open No. 5-93832

  The present invention has been made in consideration of the above facts, and an object of the present invention is to improve the accuracy of focal length adjustment in a camera using a lens such as a plastic lens that has a large focal length change due to a temperature change. .

  The camera according to claim 1 is a camera including a fuel cell that supplies power to a drive unit, wherein the fuel cell is disposed around a lens, and the temperature of the lens is generated by heat generated by power generation of the fuel cell. Is maintained in a predetermined range.

  In the camera according to the first aspect, the drive unit is driven by the power source supplied from the fuel cell. Here, the fuel cell is disposed around the lens, and the temperature of the lens is maintained in a predetermined range by heat generated by the power generation of the fuel cell. As a result, the focal length of the lens can always be maintained within a predetermined range. Further, by using the exhaust heat of the fuel cell, a heater is not necessary, and the cost can be reduced.

  The camera according to claim 2 is the camera according to claim 1, wherein when the temperature detected by the temperature detecting means falls within a predetermined range, the temperature detecting means for detecting the temperature around the lens. And a first control unit that enables a photographing operation.

  In the camera according to the second aspect, when the temperature detection means detects that the temperature around the lens has entered the predetermined range, the first control means enables the photographing operation. As a result, the focal length of the lens always falls within a predetermined range at the time of shooting, so that an image without blur can be shot.

  The camera according to claim 3 is the camera according to claim 1, and includes a temperature detection unit that detects a temperature around the lens, a focus drive unit that drives the lens to focus, and the temperature detection unit. And a second control unit that switches a driving range of the lens by the focus driving unit in accordance with the detected temperature.

  As the amount of power generated by the fuel cell changes in accordance with the operating state of the camera, the amount of heat generated by the fuel cell changes, and the temperature around the lens changes accordingly.

  Therefore, in the camera according to the third aspect, the second control unit switches the lens driving range by the focus driving unit in accordance with the temperature detected by the temperature detecting unit. This makes it possible to search for the focal point of the lens without expanding the focus driving range of the lens by the focus driving means, thereby reducing the time required for focusing.

  The camera according to claim 4 is the camera according to claim 1, wherein the lens and the lens barrel incorporating the fuel cell, and an internal temperature detecting means for detecting the temperature in the lens barrel. , An external temperature detecting means for detecting a temperature outside the lens barrel, a second power source for supplying power to the drive unit, and a source of power supply to the drive unit as the fuel cell and the second A predetermined value capable of preventing condensation in the lens barrel by switching between the power source and the difference between the temperature detected by the internal temperature detection means and the temperature detected by the external temperature detection means And a third control means maintained below.

  In the camera according to the fourth aspect, the temperature inside the lens barrel in which the lens and the fuel cell are incorporated is detected by the internal temperature detecting means, and the temperature outside the lens barrel is detected by the external temperature detecting means. Here, when the temperature difference between the inside of the lens barrel that becomes high temperature and the outside of the lens barrel becomes large due to the heat generated by the fuel cell, dew condensation occurs in the lens barrel.

  For this reason, the third control means changes the temperature difference between the inside and outside of the lens barrel by switching the source of power supply to the drive unit between the fuel cell and the second power source. Keeping it below a predetermined value that can prevent condensation in the interior. In other words, when the camera is used in a cold region, the temperature rise in the lens barrel due to the heat generated by the fuel cell is suppressed, thereby preventing condensation caused by the warm air in the lens barrel being cooled by the outside air. it can.

  Since the present invention is configured as described above, it is possible to improve the accuracy of adjusting the focal length in a camera using a lens such as a plastic lens that has a large change in focal length due to a temperature change.

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

  As shown in FIGS. 1 and 2, the camera 10 includes a camera body 2 and an interchangeable lens 1 that is detachably attached to the camera body 2.

  The interchangeable lens 1 corrects blurring by driving in a direction orthogonal or substantially orthogonal to the first lens group 21, the second lens group 22, and the optical axis (hereinafter referred to as the optical axis) I of the main optical system. A third lens group (hereinafter referred to as a blur correction lens) 19 and a fourth lens group that adjusts the focus to connect a subject image to an imaging surface (not shown) by moving in the same direction as the optical axis I. 20 is provided.

  The shake detection sensor 12 is a sensor that detects horizontal and vertical vibrations and outputs a vibration detection signal. The shake detection sensor 12 outputs the detected vibration detection signal to the shake detection processing system 13.

  The shake detection processing system 13 performs predetermined processing on the vibration detection signal from the shake detection sensor 12. The blur detection processing system 13 outputs the processed vibration detection signal to the lens side CPU 3.

  The shake correction lens position detection system 14 detects the position of the shake correction lens 19 and performs predetermined processing on the detected position detection signal.

  The lens side CPU 3 calculates a shake correction amount based on the output signals of the shake detection processing system 13 and the shake correction lens position detection system 14, and outputs a shake correction signal corresponding to the shake correction amount, or drives a shake correction lens. Based on temperature detection signals output from the lens-side temperature sensor 34 and the body-side temperature sensor 18, the feedback control is performed on the system 15, the operation start and stop of the blur correction lens driving system 15 is controlled, It is a central processing unit that controls switching of the changeover switch 8 and controls the center lock driving system 16, the focus driving system 17, and the like.

  The blur correction lens drive system 15 is for driving the blur correction lens 19. The blur correction lens drive system 15 drives the blur correction lens 19 based on the blur correction signal output from the lens side CPU 3.

  The center lock drive system 16 is for fixing the shake correction lens 19. For example, the center lock driving system 16 locks the shake correction lens 16 so that the optical axis I of the entire photographing optical system coincides with the center of the shake correction lens 19. The center lock drive system 16 includes an actuator (not shown).

  The focus drive system 17 drives the fourth lens group 20 in the direction of the optical axis I to perform a focusing operation. The focus drive system 17 includes a focus actuator (not shown).

  The fuel cell 5 provided on the lens side supplies power for driving the shake correction lens drive system 15, the center lock drive system 16, the focus drive system 17, and each drive unit on the camera body 2 side. . As shown in FIG. 3, the fuel cell 5 has a sheet shape and is wound around the first to fourth lenses 19, 20, 21, and 22. Details will be described later.

  The battery change-over switch 8 is used to switch between the body-side battery 6 and the lens-side fuel cell 5 based on a switching signal output from the lens-side CPU 3 that supplies power to the drive units of the interchangeable lens 1 and the camera body 2. It is a switch to switch between.

  The camera body 2 includes a body side CPU 4, a body side battery 6 that supplies power to the photometry unit 23, distance measurement 24, shutter unit 25, feeding unit 26, charging unit 27, and the like provided on the interchangeable lens 1 side, The power supply stabilization means 7, the temperature sensor 18, the memory 40, etc. are incorporated.

  The power stabilization means 7 is a means for supplying stable power to fluctuations that occur when the body side battery 6 supplies power to actuators (not shown) such as the shutter section 25 and the feeding section 26. The power stabilization means 7 is connected to electrical circuits such as the photometry unit 23, the distance measurement unit 24, the shutter unit 25, the feeding unit 26, and the charge unit 27, and supplies a stable power to them. The power stabilization means 7 supplies power (signal system power supply) via a signal system power contact 9 to an electrical circuit such as a shake detection sensor 12, a shake detection processing system 13, a shake correction lens position detection system 14 and a lens side CPU. ).

  The body side battery 6 may be a fuel cell, and the power source of the camera 10 may be a fuel cell.

  The temperature sensor 18 is a sensor that detects the temperature in the camera body 2 and outputs a temperature detection signal. The temperature detection sensor 18 outputs the detected temperature detection signal to the body side CPU 4.

  The body side CPU 4 is connected to the lens side CPU 3 through the photometric unit 23, the distance measuring unit 24, the shutter unit 25, the feeding unit 26, the charging unit 27, the temperature sensor 18, and the communication contact 10. .

  Various data are stored in the memory 40. An example of data stored in the memory 40 is a parameter table of temperature characteristics of the focal length of the lens.

  The interchangeable lens 1 and the camera body 2 are provided with a signal system power contact 9, a communication contact 11, and a power system power contact 28.

  The signal system power contact 9 is an electric circuit such as a power stabilization unit 7 on the camera body 2 side, a shake detection sensor 12 on the interchangeable lens 1 side, a shake detection processing system 13, a shake correction lens position detection system 14, and a lens side CPU 3. It is a contact for connecting to.

  Although the communication contact 11 is shown in a simplified manner in FIG. 1, the communication contact 11 is a contact for transmitting a command value such as a focus position from the body side CPU 4 and various information regarding the camera body 2 to the lens side CPU 3. The communication contact 11 is a contact for transmitting various information on the interchangeable lens side to the body side CPU 4.

  The power system power contact 28 is a contact for transmitting the power supplied from the body side battery 6 to the interchangeable lens 1 side. The power system power contact 28 connects the battery selector switch 8 and the body side battery 6, and connects the focus drive system 17 and the body side battery 6.

  Next, the structure of the interchangeable lens 1 will be described.

  As shown in FIGS. 3 and 4, the interchangeable lens 1 is provided inside a lens barrel 29, a sheet-like fuel cell 5 stretched over the entire inner wall of the lens barrel 29, and the fuel cell 5. A cylindrical body 30 having high thermal conductivity, first to fourth lenses 19, 20, 21, 22 attached to the inner wall of the cylindrical body 30 via a support member 31, and the lens barrel 29. And a drainage recovery tank 33 provided below the lens barrel 29.

  The lens barrel 29 has a plurality of air holes 29 </ b> A, a liquid supply port 29 </ b> B that connects the fuel tank 32 and the fuel cell 5, and a drain port 29 </ b> C that connects the drainage recovery tank 33 and the fuel cell 5.

As schematically shown in FIG. 5, the fuel cell 5 has a configuration in which a fuel electrode (oxidation electrode) 5A, a proton conductive membrane 5B, and an air electrode (reduction electrode) 5C are stacked, and methanol as a fuel. Electricity is generated by a chemical reaction between (CH ₃ OH + H ₂ O) and oxygen (O ₂ ).

As shown in FIG. 6, the fuel electrode 5A and the air electrode 5C contain platinum (Pt) as a catalyst. In the fuel electrode 5A, methanol is generated by an anodic reaction (CH ₃ OH + H ₂ O → CO ₂ + 6H ⁺ + 6e). Is decomposed into carbon dioxide (CO ₂ ), electrons (e) and hydrogen ions (H ⁺ ). At this time, power is generated by the generated electrons. Carbon dioxide is released from the fuel electrode 5A. The hydrogen ions move in the proton conducting membrane 5B and become water by being combined with oxygen supplied to the air electrode 5C by the cathode reaction (6H ⁺ + 6e + (3/2) O ₂ → 3H ₂ O) at the air electrode. The air electrode 5C is discharged.

  For this reason, the air hole 29A extends from the fuel electrode 5A and the air electrode 5C to the outer wall of the lens barrel 29, the liquid supply port 29B extends from the fuel tank 32 to the fuel electrode 5A, and the drain port 29C It extends from the air electrode 5C to the waste water collection tank 33.

  Here, in the present embodiment, the first to fourth lenses 19, 20, 21, and 22 are made of plastic, so that the focal length changes greatly due to temperature changes. However, since the first to fourth lenses 19, 20, 21, and 22 (hereinafter referred to as lenses 19 to 22) are housed inside the fuel cell 5 having a cylindrical shape, the temperature of the lenses 19 to 22 is While the fuel cell 5 is generating electric power, it is maintained at a predetermined temperature due to heat generated by the power generation of the fuel cell 5. This is because the amount of heat generated by the fuel cell 5 is proportional to the amount of power generated per unit area.

  Hereinafter, the operation method of the fuel cell 5 will be described with reference to the flowchart of FIG.

  First, when the power switch of the camera 10 is turned on, this flow is started and the process proceeds to Step 1. In step 1, power generation of the fuel cell 5 is started. Then, the process proceeds to Step 2.

  In step 2, the negative determination is repeated and affirmed until the temperature in the lens barrel 29 detected by the temperature sensor 34 provided on the interchangeable lens 1 side enters a predetermined range A (for example, 25 to 40 ° C.). Then, it proceeds to Step 3. In step 3, the lens side CPU 3 enables the shake correction lens drive system 15, the center lock drive system 16, and the focus drive system 17. Further, a signal is transmitted from the lens side CPU 3 to the body side CPU 4, and the body side CPU 4 enables the photometry unit 23, the distance measurement unit 24, the shutter unit 25, the feeding unit 26, and the charging unit 27 to operate. Then, the process proceeds to Step 4.

  In step 4, it is determined whether or not the temperature detected by the temperature sensor 34 is within a predetermined temperature range B (for example, 35 to 40 ° C.). Go to ´. Here, the focus control of the lenses 19 to 22 is performed in accordance with the focal length of the lens in the predetermined temperature range B. Depending on the operation state of the camera 10, the amount of power generated by the fuel cell 5 decreases, and accordingly. The temperature in the lens barrel 29 may not rise to the predetermined temperature range B due to the decrease in the heat generation amount. For this reason, in step 5 ′, the focal lengths of the lenses 19 to 22 at the temperature detected by the temperature sensor 34 are read from the parameter table of the temperature characteristics of the focal lengths of the lenses 19 to 22 stored in the memory 40, and The focus drive range of the lens is switched according to the temperature detected by the temperature sensor 34. This makes it possible to search for the focal point of the lens without expanding the focus driving range of the lens, thereby reducing the time required for focusing.

  In step 5, it is determined whether or not the difference between the temperatures detected by the body-side temperature sensor 18 and the lens-side temperature sensor 34 is equal to or greater than a predetermined value (for example, 20 ° C.). If the result is negative, the flow ends.

  In step 6, the battery selector switch 8 is operated to stop the power generation of the fuel cell 5, and the power supply source of each drive unit is switched to the body side battery 6. That is, if the temperature difference between the inside and outside of the lens barrel 29, which has become high due to the heat generated by the fuel cell 5, increases, the air inside the lens barrel 29 is cooled by the outside air and causes condensation. In order to prevent this, when the outside air temperature is low, the temperature rise in the lens barrel 29 is suppressed.

  As described above, according to the present invention, the temperature in the lens barrel 29 can be maintained within a predetermined temperature range regardless of the temperature of the outside air, and the focal lengths of the lenses 19, 20, 21, and 22 can be maintained. Change can be suppressed.

  In the present embodiment, the present invention has been described by taking the camera 10 in which the interchangeable lens 1 is detachably attached to the camera body 2 as an example. However, the present invention is not limited to this, and as shown in FIGS. The present invention can also be applied to the camera 100 including the trunk lens 102. In this case, as shown in FIG. 9A, not only when the lens 102 moves forward from the body 104, but also when the lens 102 is retracted into the body 104 as shown in FIG. In order to allow oxygen and carbon dioxide to enter and exit from the lens 5, it is necessary to form an air hole 106B in the front surface 106A of the lens barrel 106.

It is a perspective view which shows the camera of embodiment of this invention. It is a block diagram which shows the outline of the camera of embodiment of this invention. It is sectional drawing which shows the interchangeable lens of the camera of embodiment of this invention. It is sectional drawing which shows the interchangeable lens of the camera of embodiment of this invention. It is a perspective view showing typically a fuel cell of a camera of an embodiment of the present invention. It is a figure which shows the electric power generation principle of the fuel cell of the camera of embodiment of this invention. It is a flowchart for demonstrating the operating method of the fuel cell of the camera of embodiment of this invention. It is a perspective view which shows the modification of the camera of embodiment of this invention. (A), (B) is sectional drawing which shows the modification of the camera of embodiment of this invention.

Explanation of symbols

3 lens side CPU (first control means, second control means, third control means)
4 Body side CPU (first control means, second control means, third control means)
5 Fuel cell
6 Body side battery (second power supply)
10 camera 18 temperature sensor (temperature detection means, internal temperature detection means)
19 First lens (lens)
20 Second lens (lens)
21 Third lens (lens)
22 Fourth lens (lens)
29 Lens barrel 34 Temperature sensor (external temperature detection means)

Claims (4)

A camera including a fuel cell that supplies power to a drive unit,
A camera characterized in that the fuel cell is arranged around a lens, and the temperature of the lens is maintained within a predetermined range by heat generated by power generation of the fuel cell. Temperature detecting means for detecting the temperature around the lens;
First control means for enabling photographing operation when the temperature detected by the temperature detection means enters a predetermined range;
The camera according to claim 1, further comprising: Temperature detecting means for detecting the temperature around the lens;
Focus driving means for driving the lens in focus;
Second control means for switching the driving range of the lens by the focus driving means according to the temperature detected by the temperature detecting means;
The camera according to claim 1, further comprising: A lens barrel containing the lens and the fuel cell;
An internal temperature detecting means for detecting the temperature in the lens barrel;
An external temperature detecting means for detecting a temperature outside the lens barrel;
A second power source for supplying power to the drive unit;
The difference between the temperature detected by the internal temperature detection means and the temperature detected by the external temperature detection means by switching the power supply source of the drive unit between the fuel cell and the second power supply A third control means that maintains a predetermined value or less capable of preventing dew condensation in the lens barrel;
The camera according to claim 1, further comprising:

Images