JP2007163598A - Optical device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical device capable of properly adjusting a light qauntity, even when a change in ambient temperature, the self-heating of a light quantity adjusting means, etc. occur. <P>SOLUTION: The optical device includes: a position detecting means 2 outputting a signal corresponding to the operational position of a light quantity adjusting means 1; and a control means 5 controlling the operation of the light quantity adjusting means by using a signal from the position detecting means. A memory 6 stores temperature in such a state that the operational position of the light quantity adjusting means corresponds to the signal from the position detecting means. A control means executes processing for associating the operational position of the light quantity adjusting means with the signal from the position detecting means, when the temperature detected by the temperature detecting means 4 is different from the temperature stored in a storage means. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical apparatus that includes a light amount adjusting unit that is generally called a diaphragm or an iris, and more particularly to an optical device that includes a sensor that detects an operating position of the light amount adjusting unit.

  Optical devices such as video cameras, digital still cameras, and interchangeable lenses are equipped with a diaphragm that adjusts the amount of light by opening and closing the diaphragm blades. The diaphragm is provided with a sensor such as a Hall element that outputs a signal corresponding to the position of the diaphragm blade (diaphragm position). Then, the diaphragm position is detected by a signal from the sensor, and the diaphragm operation is controlled so that the diaphragm detection position becomes a target position set so as to obtain an appropriate amount of light.

  Here, the Hall element is a magnetoelectric conversion element utilizing the Hall effect, and has a function of converting a magnetic quantity into an electric quantity. The Hall effect is an action in which a voltage is generated in directions perpendicular to the current direction and the magnetic field direction when a magnetic field is applied perpendicularly to the solid surface in a state where an electric current is passed through the solid semiconductor thin film.

  The output of such a Hall element is likely to fluctuate when the temperature changes. For this reason, if the operating environment temperature of the optical device changes or the temperature of the diaphragm rises due to heat generated by an actuator or the like that drives the diaphragm, an error may occur in the diaphragm detection position and appropriate light quantity control may not be performed. There is. In other words, it is erroneously detected that the aperture has reached the open position, the small aperture position, or the fully closed position, but the exposure control becomes inappropriate or the shutter function becomes incomplete. To do.

As a means to avoid such a problem, generally, the operating range of the diaphragm blades is given a margin from the open position and the fully closed position to the open direction and the close direction, so that a position detection error due to a temperature change is reduced. A method of absorbing and reducing the control error is employed.
Japanese Patent Laid-Open No. 5-260368 (paragraphs 0013 to 0022, FIG. 1, etc.)

  However, with the avoidance means described above, the entire operating range of the diaphragm blades cannot be used for light quantity adjustment. In addition, the larger the margin provided in the operating range of the diaphragm blades, the larger the diaphragm, or the lower the resolution for adjusting the light amount.

  The present invention makes it possible to adjust the amount of light appropriately even if there is a change in the environmental temperature, self-heating of the light amount adjusting means, etc. An object is to provide an optical device that can be used.

  An optical device according to one aspect of the present invention includes a light amount adjusting unit that changes a light amount, a position detecting unit that outputs a signal corresponding to an operation position of the light amount adjusting unit, and a light amount using a signal from the position detecting unit. Control means for controlling the operation of the adjusting means. In addition, a storage unit that stores the temperature in a state where the operation position of the light amount adjusting unit and the signal from the position detection unit correspond to each other, and a temperature detection unit that detects the temperature are included. Then, when the temperature detected by the temperature detection unit is different from the temperature stored in the storage unit, the control unit performs processing for associating the operation position of the light amount adjustment unit with the signal from the position detection unit. Features.

  An optical device according to another aspect of the present invention includes a light amount adjusting unit that changes a light amount, a position detecting unit that outputs a signal according to an operation position of the light amount adjusting unit, and a signal from the position detecting unit. And control means for controlling the operation of the light quantity adjusting means, and storage means for storing a signal from the position detecting means in a state where the light quantity adjusting means is at a predetermined operation position. When the signal from the position detecting unit when the light amount adjusting unit is moved to the predetermined operating position is different from the signal stored in the storage unit, the control unit receives the operation position of the light amount adjusting unit from the position detecting unit. It is characterized by performing processing for making the signal correspond.

  According to the present invention, when the correspondence between the operation position of the light amount adjusting unit and the signal from the position detecting unit is shifted due to a temperature change or the like, the processing is performed to correspond to this. An appropriate light quantity adjustment function can be maintained without providing a margin in the operating range of the adjustment means.

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

  FIG. 1A shows an imaging apparatus such as a video camera or a digital still camera as an optical apparatus that is Embodiment 1 of the present invention.

  In FIG. 1A, in order from the subject side, 11 is a fixed first lens unit, and 12 is a second lens unit that can move in the optical axis direction for zooming. Reference numeral 13 denotes a fixed third lens unit, and reference numeral 14 denotes a fourth lens unit that can move in the optical axis direction in order to correct image plane fluctuations accompanying focus adjustment and zooming.

  Reference numeral 1 denotes a diaphragm as a light quantity adjusting unit disposed between the third and fourth lens units 13 and 14, which adjusts the light quantity by driving diaphragm blades by an actuator as will be described later. The aperture 1 also has a function as a shutter that operates during still image shooting. The diaphragm 1 is configured such that its open position and fully closed position are mechanical operating ends. That is, it differs from the conventional diaphragm in which the position moved further in the opening direction from the open position and the position moved further in the closing direction from the fully closed position becomes the mechanical operation end.

  Reference numeral 15 denotes an image sensor such as a CCD sensor or a CMOS sensor that photoelectrically converts a subject image formed by a photographing optical system including the first to fourth lens units 11 to 14 and the diaphragm 1.

  The analog output from the image sensor 15 is converted into a digital signal by the A / D converter 16. The digital signal is subjected to various processes such as gain adjustment and white balance in the image processing circuit 17 to generate an image signal. The image signal is displayed on a display 18 constituting an electronic viewfinder, or recorded on a recording medium 19 such as a semiconductor memory, an optical disk, or a magnetic tape. Here, an image displayed on the display 18 without being recorded on the recording medium 19 is referred to as a finder image (or a through image). An image recorded on the recording medium 19 (which may also be displayed on the display 18) is referred to as a recording image.

  A control unit 20 controls lens driving, diaphragm driving, image sensor driving, image processing, and the like.

  FIG. 1B shows the relationship between the configuration of the control unit 20 and the diaphragm 1. The control unit 20 includes a microprocessor 5 such as a CPU that executes a control / processing sequence, and an aperture drive circuit 3 that drives the aperture 1 in accordance with a drive command from the microprocessor 5.

  Reference numeral 4 denotes a temperature sensor that measures the use environment temperature of the image pickup apparatus and the ambient temperature of the diaphragm 1. Reference numeral 6 denotes a memory. The memory 6 stores and holds the environmental temperature measured in the adjustment process performed before the image pickup apparatus is shipped from the factory and the ambient temperature of the diaphragm 1 (hereinafter referred to as an adjustment temperature T).

  Reference numeral 2 denotes a hall element provided as a position detecting means provided in the diaphragm 1. Here, a specific configuration of the diaphragm 1 including the Hall element 2 will be described with reference to FIG. However, the configuration shown in FIG. 6 is merely an example, and a diaphragm having another configuration may be used.

  In FIG. 6, 31 and 32 are aperture blades having aperture opening forming portions 31a and 32a, respectively, which are driven in the directions opposite to the arrows. Reference numeral 33 denotes an aperture driving lever that is reciprocally rotated by press-fitting a rotor shaft 34 of a motor, which is an actuator, in the hole 33c.

  Reference numeral 35 denotes a motor rotor, and 36 denotes a motor drive coil.

  The hall element 2 is arranged at a predetermined interval with respect to the outer peripheral surface of the rotor 5. Reference numeral 38 denotes a spring that biases the drive lever 33 in the closing direction.

  The pins 33 a and 33 b provided at both ends of the aperture driving lever 33 are engaged with elongated holes formed at the ends of the aperture blades 31 and 32. The diaphragm base plate 37 is formed with a light passage opening 37 a that is opened and closed by the diaphragm blades 31 and 32. The diaphragm base plate 37 is formed with guide pins 37b for engaging the guide holes 39 formed in the diaphragm blades 31 and 32 to guide the movement of the diaphragm blades 31 and 32 in the arrow direction.

  An S pole region and an N pole region are circumferentially divided and formed on the outer peripheral surface of the rotor 35. The rotor 35 is rotated and driven by the interaction between the current flowing through the drive coil 36 and the magnetic field of the rotor 35. This driving force is transmitted to the aperture blades 31 and 32 via the aperture drive lever 33 and is driven to open and close in the direction of the arrow.

  The guide pins 37b provided on the diaphragm base plate 37 are in contact with both ends of the guide holes 39 formed in the diaphragm blades 31 and 32, thereby mechanically moving the diaphragm blades 31 and 32 between the open position and the fully closed position. It is a stopper.

  When the rotor 35 rotates, the magnetic field acting on the Hall element 2 also changes. The Hall element 2 has a semiconductor thin film, and a voltage is applied to the input terminal of the semiconductor thin film to flow a control current. When a magnetic field is applied perpendicularly to the thin film, a voltage is output from the output terminal that is diagonal to the input terminal. When the rotor 35 rotates and the magnetic field applied to the Hall element 2 changes, the voltage from the output terminal changes. Therefore, by monitoring the voltage, the operating position of the diaphragm 1 (hereinafter simply referred to as the diaphragm position) can be detected.

  In the adjustment step described above, the diaphragm 1 is driven to a predetermined operation position, for example, an open position, a fully closed position, and a predetermined small diaphragm position, and the predetermined operation position and the output signal of the Hall element 2 have a predetermined correspondence relationship. Adjusted to The Hall element output voltage measured in this adjustment step is stored in the memory 6.

  Next, the operation sequence of the image pickup apparatus of the present embodiment will be described using the flowchart of FIG. 2A. This operation sequence is executed in accordance with software (computer program) stored in the microprocessor 5. This is the same in other embodiments described later.

  First, when an image is being output in STEP 1 (here, a viewfinder image is being output (displayed)), the process proceeds to STEP 2, and an output (detected temperature) T 1 from the temperature sensor 4 is read and stored in the memory 6.

  Next, in STEP 3, the adjustment temperature T is read from the memory 6 and compared with the detected temperature T1 detected by the current temperature sensor 4 read in STEP2. When the difference between the adjustment temperature T and the current detected temperature T1 is smaller than the predetermined value ΔT, the process returns to STEP 2 and continues to monitor the current detected temperature T. If the difference between the adjustment temperature T and the current detected temperature T1 is larger than the predetermined value ΔT, the process proceeds to STEP4.

  In STEP 4, it is determined whether or not the imaging apparatus is performing a recording image recording operation. If the recording operation is in progress, the process proceeds to STEP 5 where a warning a is displayed on the electronic viewfinder (display 18) or the like to prompt the photographer to interrupt the recording. The warning a may be by voice. Then, the process returns to STEP 4 and continues the warning a until recording is stopped.

  If it is determined in STEP 4 that the recording operation is not being performed (that is, the finder image is being output), the process proceeds to STEP 6.

  In STEP 6, a warning b is displayed on the electronic viewfinder (display 18) or the like, and a sound is output. In the next STEP 7, the mode is forcibly shifted to the aperture adjustment mode.

  In this aperture adjustment mode, as shown in the flowchart of FIG. 2B, first, in STEP 71, the aperture 1 is moved to the mechanical operating end that is the open position or the fully closed position. In STEP 72, the driving condition of the Hall element 2 is changed (corrected). Specifically, the voltage or current applied to the input terminal of the semiconductor thin film is increased or decreased so as to obtain the same output voltage as the Hall element output voltage at the open position or the fully closed position measured in the adjustment step.

  Thus, the operating position of the diaphragm 1 and the signal (voltage) from the Hall element 2 are automatically readjusted so as to obtain the correspondence set in the adjusting process. After this readjustment, the detected temperature T1 may be updated and stored in the memory 6 as the adjustment temperature T.

  When STEP7 ends, the output of warning b is stopped and the process returns to STEP2.

  As described above, according to this embodiment, the aperture position detection error of the Hall element 2 due to temperature change is automatically corrected. Therefore, appropriate aperture control can be maintained regardless of temperature changes. In addition, since the diaphragm drive control can be performed accurately and at high speed between the open position and the fully closed position from the open position to the fully closed position, the diaphragm 1 can also be used as a shutter.

  Since the aperture position detection error is automatically corrected, there is no need to provide a margin in the operation range of the light amount adjusting means as in the prior art, and the aperture 1 (the aperture blades 31 and 32 in FIG. The closed position can be a mechanical operating end. Therefore, the position detection resolution by the Hall element 2 can be distributed from the open position to the fully closed position, and as a result, the light amount adjustment resolution by the diaphragm 1 can be increased.

  Further, in this embodiment, the aperture position detection error is automatically corrected during the output of the finder image, and is not performed during the image recording, so that the image recording is not affected.

  FIG. 3 shows an operation sequence of the image pickup apparatus that is Embodiment 2 of the present invention. The basic configuration of the imaging apparatus of the present embodiment is the same as that of the first embodiment.

  When the image is being output in STEP 8 (here, the finder image is being output and the recording image is being recorded), in STEP 9, the current temperature T detected by the temperature sensor 4 is stored in the memory 6.

  Next, in STEP 10, the adjustment temperature T1 is read from the memory 6 and compared with the detected temperature T stored in STEP 9. If the difference between the adjustment temperature T1 and the detected temperature T is smaller than the predetermined value ΔT, the process returns to STEP 9 and continues to monitor the current detected temperature T. If the difference between the adjustment temperature T1 and the detected temperature T is larger than the predetermined value ΔT, the process proceeds to STEP11.

  In STEP 11, a correction value for correcting the aperture driving command is extracted from the memory 6 in accordance with the difference between the adjustment temperature T 1 and the current detected temperature T. This correction value is stored in the memory 6 in a table format for each difference between the adjustment temperature T1 and the detected temperature T. However, it may be given in the program in the form of a mathematical expression having T1 and T or a difference between these as variables.

  In STEP 12, the aperture driving command is corrected by the correction value. As a result, the diaphragm 1 is driven to the diaphragm position corresponding to the detection position by the Hall element 2 in which an error is caused by the difference between the adjustment temperature T1 and the detection temperature T.

  That is, the operating position of the diaphragm 1 and the signal (voltage) from the Hall element 2 are automatically readjusted so as to obtain the correspondence set in the adjustment process.

  After this readjustment, in this embodiment, the detected temperature T1 when correction is performed in STEP 13 is updated and stored in the memory 6 as the adjustment temperature T. And it returns to STEP9.

  As described above, according to the present embodiment, the aperture position detection error of the Hall element 2 due to the temperature change is automatically corrected by changing the operating position of the aperture 1. Accordingly, as in the first embodiment, appropriate aperture control can be maintained regardless of temperature changes. In addition, since the diaphragm drive control can be performed accurately and at high speed between the open position and the fully closed position from the open position to the fully closed position, the diaphragm 1 can also be used as a shutter.

  Since the aperture position detection error is automatically corrected, the open position and the fully closed position of the aperture 1 can be set as mechanical operating ends. Therefore, the position detection resolution by the Hall element 2 can be distributed from the open position to the fully closed position, and as a result, the light amount adjustment resolution by the diaphragm 1 can be increased.

  Further, in this embodiment, since the mode switching for correction is not performed as in the first embodiment, the correction can be performed with little influence on the finder image and the recording image.

  FIG. 4 shows the configuration of the control unit 20 ′ of the image pickup apparatus that is Embodiment 3 of the present invention. In the first and second embodiments, the temperature sensor 4 is provided. However, in this embodiment, the temperature sensor is not provided, and an exposure amount determination circuit 8 is provided instead.

  The exposure amount determination circuit 8 obtains an image signal from the image processing circuit 17 shown in FIG. 1A, and determines whether or not the exposure amount of the image is under a predetermined appropriate exposure amount.

  Further, in the present embodiment, the memory 6 stores the Hall element output corresponding to the opening position of the diaphragm 1 (hereinafter referred to as the opening detection position A during adjustment) in the adjustment process performed before the factory shipment of the imaging apparatus. Is retained.

  Other configurations of the imaging apparatus of the present embodiment are the same as those of the first and second embodiments, and common constituent elements are denoted by the same reference numerals as those of the first and second embodiments.

  FIG. 5 shows an operation sequence of the imaging apparatus of the present embodiment.

  When the image is being output in STEP14 (here, the finder image is being output and the recording image is being recorded), in STEP15, the exposure amount determination circuit 8 determines whether or not the exposure amount is under. If it is determined that the exposure is underexposed, the process proceeds to STEP16.

  In STEP 16, it is determined whether or not the aperture drive command indicates the open position. If the opening position is not instructed, the process proceeds to STEP 17, and an aperture driving command is output so as to drive the aperture 1 in the opening direction by a predetermined amount.

  On the other hand, if it is determined that the underexposure is determined in STEP 15, but the aperture drive command indicates the open position in STEP 16, the process proceeds to STEP 18.

  In STEP 18, the current output (aperture detection position) A 1 of the Hall element 2 is read and stored in the memory 6.

  Next, in STEP 19, the aperture detection position A1 stored in STEP 18 is compared with the opening detection position A for adjustment stored in the memory 6 in advance. If they are the same, the process proceeds to STEP 20, and the gain for generating an image signal based on the signal from the image sensor 15 is increased by an automatic gain adjustment (AGC) circuit in the image processing circuit 17 for exposure correction. Process.

  On the other hand, when the aperture detection position A1 and the adjustment opening detection position A are different in STEP 19, the process proceeds to STEP 21 and the difference ΔA is calculated.

  Next, in STEP 22, a Hall element drive correction value for correcting the output difference ΔA stored in advance in the memory 6 is read out. In STEP 23, the correction value is used to input the semiconductor thin film input terminal, which is the drive condition of the Hall element 2. Increase or decrease the voltage or current to be applied. Thus, the aperture detection position (Hall element output) A1 is made to coincide with the opening detection position A during adjustment.

  As described above, according to this embodiment, it is possible to automatically correct the aperture position detection error of the Hall element 2 caused by the temperature change without using the temperature sensor. Therefore, appropriate aperture control can be maintained regardless of temperature changes. In addition, since the diaphragm drive control can be performed accurately and at high speed between the open position and the fully closed position from the open position to the fully closed position, the diaphragm 1 can also be used as a shutter.

  Since the aperture position detection error is automatically corrected, the open position and the fully closed position of the aperture 1 can be set as mechanical operating ends. Therefore, the position detection resolution by the Hall element 2 can be distributed from the open position to the fully closed position, and as a result, the light amount adjustment resolution by the diaphragm 1 can be increased.

  Further, in this embodiment, since the mode switching for correction is not performed as in the first embodiment, the correction can be performed with little influence on the finder image and the recording image.

  According to the present embodiment, not only the temperature change but also the aperture position detection error due to other factors such as humidity and change over time can be automatically corrected.

  In each of the above-described embodiments, the lens-integrated imaging device has been described. However, the present invention can also be applied to an interchangeable lens device (optical device) that can be attached to and detached from a lens-exchangeable imaging device. In this case, the interchangeable lens device can determine whether the imaging device is outputting a finder image, recording a recording image, and whether the exposure is under or not by communication from the imaging device. .

  Further, although cases have been described with the above embodiments where a Hall element is used as the position detection means, the present invention can also be applied to the case where a position detection means other than the Hall element is used.

1 is a block diagram illustrating a configuration of an imaging apparatus that is Embodiment 1 of the present invention. FIG. 3 is a block diagram illustrating a configuration of a control unit in the imaging apparatus according to the first embodiment. 6 is a flowchart illustrating the operation of the imaging apparatus according to the first embodiment. 6 is a flowchart illustrating the operation of the imaging apparatus according to the first embodiment. 9 is a flowchart showing the operation of an image pickup apparatus that is Embodiment 2 of the present invention. FIG. 9 is a block diagram illustrating a configuration of a control unit in an imaging apparatus that is Embodiment 3 of the present invention. 10 is a flowchart illustrating the operation of the imaging apparatus according to the third embodiment. FIG. 3 is a perspective view illustrating a specific example of a diaphragm provided in the imaging apparatus according to the first embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Diaphragm 2 Hall element 3 Diaphragm drive circuit 4 Temperature sensor 5 Microprocessor 6 Memory 8 Exposure amount discrimination circuit 17 Image processing circuit 20, 20 'Control part

Claims (8)

A light amount adjusting means for changing the light amount;
Position detecting means for outputting a signal corresponding to the operating position of the light amount adjusting means;
Control means for controlling the operation of the light amount adjusting means using a signal from the position detecting means;
Storage means for storing the temperature in a state where the operation position of the light amount adjustment means and the signal from the position detection means correspond to each other;
Temperature detecting means for detecting the temperature,
The control means performs processing for associating the operation position of the light amount adjusting means with the signal from the position detecting means when the temperature detected by the temperature detecting means is different from the temperature stored in the storage means. An optical device characterized in that: A light amount adjusting means for changing the light amount;
Position detecting means for outputting a signal corresponding to the operating position of the light amount adjusting means;
Control means for controlling the operation of the light amount adjusting means using a signal from the position detecting means;
Storage means for storing a signal from the position detection means in a state where the light amount adjustment means is at a predetermined operating position;
The control means, when the signal from the position detection means and the signal stored in the storage means when the light quantity adjustment means is moved to the predetermined operation position, and the operation position of the light quantity adjustment means and the An optical apparatus that performs processing for corresponding to a signal from a position detection means.   The optical apparatus according to claim 1, wherein the process is a process of changing a driving condition of the position detection unit.   The optical apparatus according to claim 1, wherein the process is a process of changing an operation position of the light amount adjusting unit.   5. The optical apparatus according to claim 1, wherein the control unit performs the processing during acquisition of an image using the optical apparatus.   5. The optical apparatus according to claim 1, wherein the control unit performs the processing during acquisition of a finder image using the optical apparatus.   The optical apparatus according to claim 6, wherein the control unit prohibits the processing during image recording using the optical apparatus.   The optical device according to claim 1, wherein the control unit performs a warning operation when the processing is performed.