JP2011227350A - Interchangeable lens for use on camera and camera system including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an interchangeable lens for use on camera using a variable refractive index lens, permitting mounting on a camera body having a conventional auto-focusing function.SOLUTION: A lens control circuit for interchangeable lenses receives data from a body CPU of a camera body (step S202). When the driving speed is high and the driving direction is outward, VCNT+3 (step S206), or when the driving direction is inward, VCNT-3 (step S207) is substituted for VCNT, a variable representing a digital voltage pertaining to the driving of the focusing lens to be outputted to a D/A converter circuit, followed by waiting for 20 msec (step S209). When the driving speed is low and the driving direction is inward, VCNT-1 (step S211), or when the driving direction is outward, VCNT+1 (step S212) is substituted for VCNT, followed by waiting for 50 msec (step S214).

Description

  The present invention relates to an interchangeable lens for a camera and a camera system including the same, more specifically, an interchangeable lens for a camera using an optical element whose refractive index changes according to an applied voltage, and a camera system including the interchangeable lens for a camera and a camera body. About.

  Various optical elements whose refractive index changes in accordance with the applied voltage (hereinafter referred to as a variable refractive index lens) have been proposed. Among them, a liquid lens is generally known in which two types of liquid are sealed in a container, the boundary surface shape of the liquid is changed by a change in applied voltage, and the refractive index of light is adjusted. Advantages of the variable refractive index lens include a high response speed and no need for a mechanical drive mechanism. Therefore, if a refractive index variable lens is applied to an interchangeable lens for a camera, a small interchangeable lens capable of high-speed autofocus (AF) can be provided. An example in which a refractive index variable lens is used as an interchangeable lens for a camera is disclosed in Patent Document 1, for example.

JP 2009-080187 A

  The principle of operation differs between an interchangeable lens having a conventional mechanical mechanism that moves the position of the lens in the focusing operation and an interchangeable lens using the above-described variable refractive index lens. For this reason, an interchangeable lens using a variable refractive index lens cannot be used as it is in a conventional camera body designed to use an interchangeable lens having a mechanical mechanism.

  Therefore, the present invention provides an interchangeable lens for a camera using a variable refractive index lens that can be attached to a camera body having an autofocus function that is assumed to be attached to a conventional interchangeable lens having a mechanical mechanism, and An object is to provide a camera system including the above.

  In order to achieve the above object, one aspect of the interchangeable lens for a camera according to the present invention includes a focus adjustment lens that forms part of a focus adjustment optical system and whose refractive index changes according to an applied voltage, and a contrast detection type autofocus function. A driving control unit that inputs a driving direction signal and a driving speed signal from a camera body having a driving voltage and that gradually increases or decreases a voltage applied to the focus adjustment lens based on the driving direction signal and the driving speed signal; It is characterized by comprising.

  In order to achieve the above object, one aspect of the camera system of the present invention is a driving system that inputs image information and outputs a contrast value that indicates the degree of in-focus and a contrast detection circuit that inputs the contrast value. A camera body having an AF control unit that outputs a direction signal and a driving speed signal; a focus adjustment lens whose refractive index changes according to an applied voltage that forms part of a focus adjustment optical system; and the drive from the camera body. An interchangeable lens for a camera, comprising: a drive control unit that inputs a direction signal and the drive speed signal, and that gradually increases or decreases a voltage applied to the focus adjustment lens based on the drive direction signal and the drive speed signal It is characterized by comprising.

  ADVANTAGE OF THE INVENTION According to this invention, the interchangeable lens for cameras using a refractive index variable lens which can be mounted | worn with the camera body which has the auto-focus function assumed to mount | wear with the conventional interchangeable lens which has a mechanical mechanism, and it Can be provided.

1 is a block diagram illustrating a configuration example of a camera system according to an embodiment of the present invention. The flowchart which shows an example of the focusing process by the side of a camera body. 7 is a flowchart illustrating an example of focusing processing on the interchangeable lens side. The figure for demonstrating the time change of a digital voltage signal value and a contrast value.

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an outline of the configuration of the camera according to the present embodiment. The camera 100 includes an interchangeable lens 200 and a camera body 300.
The camera body 300 includes an image sensor 311, an image sensor drive circuit 312, a preprocessing circuit 313, a data bus 314, an SDRAM control circuit 315, an SDRAM 316, an image processing circuit 317, a video signal output circuit 318, A liquid crystal monitor drive circuit 319, a liquid crystal monitor 320, a recording medium control circuit 321, a recording medium 322, a sequence controller (body CPU) 323, a flash memory control circuit 324, a flash memory 325, various switches 326, A switch detection circuit 327 and a contrast detection circuit 328 are provided.

  The image sensor 311 converts the subject image formed by the interchangeable lens 200 into an electrical signal (image signal) by photoelectric conversion. The image sensor drive circuit 312 controls driving of the image sensor 311 according to an instruction from the body CPU 323 and controls reading of an image signal from the image sensor 311. The pre-processing circuit 313 performs analog processing such as noise removal and amplification on the image signal read out through the image sensor driving circuit 312, and further converts the analog processed image signal into a digital signal (image data). Do. The converted image data is transmitted to the data bus 314. The image data is input to the contrast detection circuit 328. The contrast detection circuit 328 calculates a contrast value representing the degree of in-focus quality and outputs the contrast value to the data bus 314.

  The data bus 314 is a transfer path for transferring various data such as the image data obtained by the preprocessing circuit 313, the contrast value calculated by the contrast detection circuit 328, and the image data processed by the image processing circuit 317. It is. The SDRAM control circuit 315 controls writing and reading of data to and from the SDRAM 316. The SDRAM 316 is a buffer memory for temporarily storing data obtained in the preprocessing circuit 313. The image processing circuit 317 generates an image for live view display and an image for recording by reading the image data obtained in the preprocessing circuit 313 and storing the data in the SDRAM 316 and performing various image processing.

  The video signal output circuit 318 converts the image data processed by the image processing circuit 317 into a video signal and outputs the video signal to the liquid crystal monitor drive circuit 319. The liquid crystal monitor driving circuit 319 drives the liquid crystal monitor 320 according to the video signal input from the video signal output circuit 318. The liquid crystal monitor 320 displays various images such as an image for live view display. The recording medium control circuit 321 controls writing and reading of data to and from the recording medium 322. The recording medium 322 is a memory card configured to be detachable from the camera body 300, for example, and records recording image data obtained by the image processing circuit 317.

  The body CPU 323 controls each part in the camera body 300 according to the control program stored in the flash memory 325. Further, the body CPU 323 receives the contrast value calculated by the contrast detection circuit 328, and includes a driving direction signal indicating the changing direction of the focal length of the interchangeable lens 200 and a driving speed signal indicating the changing speed of the focal length based on the contrast value. Create a drive signal. The body CPU 323 outputs the created drive signal to the interchangeable lens 200.

  The flash memory control circuit 324 controls writing and reading of data to the flash memory 325. The flash memory 325 stores a control program read by the body CPU 323, various setting values of the camera body 300, and the like. The various switches 326 are switches that change states in response to various operation members for operating the camera body 300. The various operation members include a power switch for turning on / off the power of the camera body 300, a release button for giving a camera execution instruction, a playback button for giving an image reproduction instruction, and a menu screen display. Menu buttons for giving instructions, input keys for making various camera settings, and the like. The switch detection circuit 327 is a circuit that detects operation states of the various switches 326 and notifies the detection result to the body CPU 323. When the operation of the operation member is detected via the switch detection circuit 327, the body CPU 323 executes control according to the operation content of the operation member.

  The interchangeable lens 200 includes a focus adjustment lens 201 formed of a variable refractive index lens, a plurality of glass lenses 202 formed of a normal glass material, a diaphragm mechanism 203, a lens control circuit 204, and a D / A conversion circuit. 205 and an aperture drive mechanism 206. The focus adjustment lens 201 collects the luminous flux of the subject and forms a subject image on the image sensor 311 in the camera body 300. The diaphragm mechanism 203 adjusts the light amount of the light beam incident on the image sensor 311 via the focus adjustment lens 201.

  A liquid lens is used for the focus adjustment lens 201. This liquid lens is one in which two types of liquids that do not mix in a container are sealed, and the interface shape of the two types of liquids changes when a voltage is applied to the liquids. Here, since the interface shape changes according to the value of the applied voltage, the focal length of the liquid lens changes according to the voltage value. The liquid lens is described in detail in “Nikkei Electronics, October 24, 2005, Nikkei BP”.

  The lens control circuit 204 inputs signals for operating the focus adjustment lens 201 and the diaphragm mechanism 203 from the body CPU 323. The lens control circuit 204 outputs a digital voltage signal for operating the focus adjustment lens 201 to the D / A conversion circuit 205 based on the control signal input from the body CPU 323. Here, the signal for operating the focus adjustment lens 201 input from the body CPU 323 is the same as the drive signal for operating the interchangeable lens of the conventional mechanical drive type focus adjustment mechanism. That is, the driving signal includes a driving direction signal indicating the focus adjustment driving direction, that is, whether the lens is extended or retracted, and a focus adjustment driving speed, that is, a driving speed signal indicating the lens extension or retraction speed. Further, the lens control circuit 204 outputs a signal for operating the aperture mechanism 203 to the aperture drive mechanism 206 based on the control signal input from the body CPU 323.

The D / A conversion circuit 205 converts the digital voltage signal input from the lens control circuit 204 into an analog voltage signal and outputs it to the focus adjustment lens 201. The aperture driving mechanism 206 operates the aperture mechanism 203 based on the signal input from the lens control circuit 204.
In this way, for example, the lens control circuit 204 and the D / A conversion circuit 205 function as a drive control unit, and for example, the body CPU 323 functions as an AF control unit.

  Next, operations for focusing the camera 100 will be described. First, the operation on the camera body 300 side will be described with reference to the flowchart shown in FIG. First, in step S <b> 101, the body CPU 323 acquires a contrast value from the contrast detection circuit 328 via the data bus 314. Next, in step S102, the body CPU 323 substitutes “0” for the hill-climbing flag used for confirming the driving direction of the interchangeable lens. In step S103, the body CPU 323 outputs a command for extending the driving direction to the lens control circuit 204 to increase the driving speed.

  In step S104, the body CPU 323 obtains the contrast value from the contrast detection circuit 328 again. In step S105, the body CPU 323 determines whether or not the contrast is improved based on the contrast value acquired in step S104. If the contrast is improved as a result of the determination in step S105, in step S106, the body CPU 323 substitutes “1” for the hill-climbing flag, and the process returns to step S104. That is, when the contrast is improved, the body CPU 323 repeats the processing from step S104 to step S106.

  On the other hand, if the result of determination in step S105 is that the contrast has not improved, in step S107, the body CPU 323 determines whether or not the hill climbing flag is “0”. If it is determined in step S107 that the hill-climbing flag is “0”, in step S108, the body CPU 323 sets the drive direction to the opposite direction to the previous time, and returns the process to step S104. Here, when the hill-climbing flag is “0”, it means that the contrast acquired first after operating the interchangeable lens is not improved. If it is determined in step S107 that the hill-climbing flag is not “0”, in step S109, the body CPU 323 outputs to the lens control circuit 204 a command to set the driving direction to the opposite direction to the previous time and to reduce the driving speed.

Next, in step S110, the body CPU 323 acquires the contrast value from the contrast detection circuit 328 again. In step S111, the body CPU 323 determines whether or not the contrast is improved based on the contrast value acquired in step S110. If the contrast is improved as a result of the determination in step S111, the body CPU 323 returns the process to step S110. That is, when the contrast is improved, the body CPU 323 repeats the processes of step S110 and step S111. On the other hand, if the contrast is not improved as a result of the determination in step S111, the body CPU 323 outputs a command to stop driving to the lens control circuit 204 in step S112, and the process is terminated.
The operation on the camera body 300 side described above with reference to FIG. 2 is the same as the operation of an autofocus camera that employs a general contrast detection method.

  Next, an operation related to focusing on the interchangeable lens 200 side will be described with reference to a flowchart shown in FIG. First, in step S <b> 201, the lens control circuit 204 determines whether there is a communication request from the body CPU 323. If the result of determination in step S201 is that there is no communication request, the lens control circuit 204 returns the processing to step S201. That is, the lens control circuit 204 repeats the process of step S201 until there is a communication request from the body CPU 323. On the other hand, if there is a communication request as a result of the determination in step S201, the lens control circuit 204 receives data (drive signal) from the body CPU 323 in step S202. Next, in step S <b> 203, the lens control circuit 204 determines whether a drive stop command is input from the body CPU 323. If the result of this determination is that a drive stop command has been input, the lens control circuit 204 returns the process to step S201.

  On the other hand, if the result of determination in step S203 is that a drive stop command has not been input, in step S204, the lens control circuit 204 determines whether or not the drive speed is high in the command input from the body CPU 323. As a result of this determination, if the driving speed is high among the commands input from the body CPU 323, in step S205, the lens control circuit 204 determines whether the driving direction is extended out of the commands input from the body CPU 323. . As a result of this determination, if the driving direction is out of the commands input from the body CPU 323, the lens control circuit 204 outputs the digital voltage relating to the driving of the focus adjustment lens 201 output to the D / A conversion circuit 205 in step S206. A value obtained by adding 3 to the current VCNT is substituted into a variable VCNT indicating the value. That is, “VCNT + 3” is substituted for VCNT. Then, the lens control circuit 204 moves the process to step S208. On the other hand, as a result of the determination in step S205, if the driving direction is not extended among the commands input from the body CPU 323, in step S207, a value obtained by subtracting 3 from the current VCNT is substituted into the variable VCNT. That is, “VCNT-3” is substituted for VCNT. Then, the lens control circuit 204 moves the process to step S208. In step S <b> 208, the lens control circuit 204 outputs the value of VCNT to the D / A conversion circuit 205. In step S209, the lens control circuit 204 stands by for 20 msec, and the process proceeds to step S215.

  As a result of the determination in step S204, if the driving speed is not high among the commands input from the body CPU 323, in step S210, the lens control circuit 204 determines whether or not the driving direction is extended out of the commands input from the body CPU 323. to decide. As a result of this determination, if the driving direction is not extended among the commands input from the body CPU 323, “VCNT-1” is substituted into the variable VCNT in step S211. Then, the lens control circuit 204 moves the process to step S213. On the other hand, as a result of the determination in step S210, if the driving direction is out of the commands input from the body CPU 323, the lens control circuit 204 substitutes “VCNT + 1” for the variable VCNT in step S212. Then, the lens control circuit 204 moves the process to step S213. In step S213, the lens control circuit 204 outputs the value of VCNT to the D / A conversion circuit 205. In step S214, the lens control circuit 204 waits for 50 msec, and then proceeds to step S215.

In step S215, the lens control circuit 204 determines whether there is a communication request from the body CPU 323. If the result of determination in step S215 is that there is no communication request, the lens control circuit 204 returns the processing to step S204. On the other hand, if there is a communication request as a result of the determination in step S215, the lens control circuit 204 moves the process to step S202.
Of the above description, for example, the value for increasing / decreasing the variable VCNT and the standby time are examples, and can be changed as appropriate. However, the absolute value of the value that increases or decreases VCNT in steps S206 and S207 needs to be larger than the absolute value of the value that increases or decreases VCNT in steps S211 and S212, and the standby time in step S209 is the standby time in step S214. Shorter is preferred.

  An example of the operation as described above will be described with reference to FIG. FIG. 4 is a graph schematically showing time on the horizontal axis and the VCNT value and contrast value on the vertical axis. When the main switch is turned on at time A, a predetermined value is substituted into VCNT in order to make the focus of the focus adjustment lens 201 infinite. The predetermined value is input to the D / A conversion circuit 205, and a voltage corresponding to the value is applied to the focus adjustment lens 201. As a result, the focal length of the focus adjustment lens 201 is infinite.

  When the first release switch, which is a switch for starting the focusing operation, is turned on at time B, the body CPU 323 starts to acquire a contrast value (step S101). Then, the body CPU 323 outputs a driving direction to the lens control circuit 204 to increase the driving speed (step S103). The lens control circuit 204, which has input a command for extending the driving direction and increasing the driving speed, increases the VCNT value by 3 every 20 ms (step S206). The VCNT value is input to the D / A conversion circuit 205, and a voltage corresponding to the value is applied to the focus adjustment lens 201 to change the focal length. As a result, the contrast value acquired by the body CPU 323 at regular intervals (step S104) increases with a change in the VCNT value.

  At time C, the contrast value turns from increasing to decreasing. The body CPU 323 detects this decrease (step S105), and outputs a command for reducing the drive speed to the lens control circuit 204 in the drive direction (step S109). The lens control circuit 204 that has input this command decreases the VCNT value by 1 every 50 ms after the time C (step S211). The VCNT value is input to the D / A conversion circuit 205, and a voltage corresponding to the value is applied to the focus adjustment lens 201 to change the focus position. As a result, the contrast value acquired by the body CPU 323 at regular intervals (step S110) increases with a change in the VCNT value. At time D, when the body CPU 323 detects that the contrast value has decreased, it stops driving the focus adjustment lens 201 (step S112). As a result, the focus adjustment lens 201 reaches the in-focus position.

  As described above, according to the interchangeable lens 200 according to the present embodiment, an operation command is input from a camera body having a general contrast detection type autofocus function, and a refractive index variable lens such as a liquid lens is used. The interchangeable lens for a camera including the focus adjustment lens 201 can be driven. That is, the interchangeable lens for a camera according to the present embodiment is a camera body having a general autofocus function that is assumed to be equipped with an interchangeable lens having a mechanical mechanism, without using a special conversion adapter or the like. It can be used by mounting.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, even if some constituent elements are deleted from all the constituent elements shown in the embodiment, the problem described in the column of problems to be solved by the invention can be solved and the effect of the invention can be obtained. The configuration in which this component is deleted can also be extracted as an invention.

  DESCRIPTION OF SYMBOLS 200 ... Interchangeable lens, 201 ... Focus adjustment lens, 202 ... Glass lens, 203 ... Diaphragm mechanism, 204 ... Lens control circuit, 205 ... D / A conversion circuit, 206 ... Diaphragm drive mechanism, 300 ... Camera body, 311 ... Imaging element 323 ... Body CPU, 328 ... Contrast detection circuit.

Claims (2)

A focus adjusting lens that forms part of the focus adjusting optical system and whose refractive index changes according to the applied voltage;
A driving direction signal and a driving speed signal are input from a camera body having a contrast detection type autofocus function, and the voltage applied to the focus adjustment lens is increased or decreased stepwise based on the driving direction signal and the driving speed signal. A drive control unit,
An interchangeable lens for a camera, comprising: A contrast detection circuit for inputting image information and outputting a contrast value indicating the degree of in-focus quality;
An AF control unit that inputs the contrast value and outputs a driving direction signal and a driving speed signal;
A camera body having
A focusing lens whose refractive index changes according to an applied voltage that forms part of the focusing optical system;
A drive control unit that inputs the drive direction signal and the drive speed signal from the camera body, and that gradually increases or decreases the voltage applied to the focus adjustment lens based on the drive direction signal and the drive speed signal;
An interchangeable lens for a camera having
A camera system comprising:

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