JP2008197253A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve speeding-up in moving a photographic lens group while maintaining stopping accuracy without causing the upsizing of an imaging apparatus. <P>SOLUTION: The screws of a male screw means 4 and a female screw means 5 used for moving the photographic lens group are set so that a pitch is xmm, the number of lines is y, lead is xymm, and thickness of a nut is xy+αmm, where α<xy, and the number of lines y is set to two or more. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an imaging apparatus having a lens barrel provided in a film camera, a digital camera, or the like.

  Conventionally, a film camera using a silver salt film has been widely used, but in recent years, a digital camera capable of capturing an image in a memory without using a film has been rapidly spread. Some digital cameras include a zoom mechanism that moves a plurality of optical lenses in the optical axis direction to change a photographing magnification. When performing zooming to focus the lens on the subject, the so-called focusing is performed by moving the last lens group from the subject in the longitudinal direction of the optical axis. An example of the focus configuration is shown in Patent Document 1.

  The screw is rotated by the stepping motor, and the nut that operates integrally with the lens holder is driven to determine the position of the lens. It is desirable to set the resolution for the normal stop to the stop position of the 2-2 phase excitation where the control of the stepping motor is relatively easy. In this case, the rotor of the stepping motor stops at a stable position in a non-excited state, so that it is easy to stop the lens accurately without aiming for the lens stop accuracy.

  However, in recent years, there has been an increasing demand for speeding up the entire camera, and there has been an increasing demand for miniaturization and noiselessness.

  Various proposals have been proposed as methods for solving such problems. In general, in order to increase the speed, there is a method of operating the stepping motor itself at a high speed.

Further, Patent Document 2 tries to achieve both high speed and high accuracy of the focus drive by switching between micro step drive for stopping the rotor at a finer stop position and 2-2 phase drive.
JP-A-10-282395 JP 2003-224998 A

  In order to operate the stepping motor itself at a high speed rotation in order to increase the speed as in the conventional example, it is necessary to secure a sufficient torque, and there is a problem that the stepping motor becomes large. In general, torque tends to decrease at high speed rotation, so it is common to secure the torque by increasing the size of magnets and coils inside the motor. In addition, there is a problem that operating noise increases when driven at high speed.

  Next, Patent Document 2 is an example in which a stepping motor driving method is shown. In a certain region, 2-2 phase driving is performed to operate at a high speed, and when a certain region is reached, microstep driving is performed. If this method of use is used, it will eventually depend on the rotation speed of the stepping motor. To achieve both accuracy, it is necessary to enable high-speed rotation and sufficient torque, and the stepping motor must be enlarged. In addition, the operating noise increases.

  From the above, it is necessary to provide a configuration that increases the driving speed of the focus, stably secures the stopping accuracy, and reduces the operating noise.

  In order to achieve the above object, a first imaging device of the present invention includes a photographing lens group, the photographing lens group holding means, a female screw means that operates substantially integrally with the photographing lens group holding means, and a male screw means. And a male screw driving means which is a stepping motor that drives the male screw means and can be stopped with a fine resolution, wherein the male screw means and the female screw means have a pitch xmm, a thread number y, a lead xymm, and a nut thickness xy + αmm, α < xy, the stop position is the 2-2 phase position, the 1-2 phase position, or both, and the number y is 2 or more.

  In order to achieve the above object, a second imaging apparatus of the present invention includes a photographing lens group, the photographing lens group holding means, a female screw means that operates substantially integrally with the photographing lens group holding means, and a male screw means. And a male screw drive means which is a stepping motor capable of driving the male screw means and stopping at a fine resolution, and the pitch xmm, the number of threads y, the lead xymm, the nut thickness of the male screw means and the female screw means x + αmm, and α < x, the stop position is the 2-2 phase position, the 1-2 phase position, or both, and the number y is 2 or more.

  Since the present invention has the above-described configuration, the moving speed of the focus can be increased without increasing the size of the stepping motor, and the stopping accuracy can be maintained at the same level as the conventional one.

(Example)
Hereinafter, the present invention will be described in detail based on the illustrated embodiments.

  5 to 9 show a digital camera as a device including the imaging device according to the present embodiment. The digital camera 9 shown in the present embodiment is a camera having a zoom mechanism that can change the photographing magnification.

  FIG. 5 is an external perspective view showing a state in which the power source of the digital camera 9 is turned off. FIG. 6 is an external perspective view showing a state in which the power source of the digital camera 9 is turned on.

  7 shows a top view, FIG. 8 shows a rear view, and FIG. 9 shows a bottom view.

  FIG. 10 shows the waist configuration of the digital camera 9.

  A finder 14 for determining the composition of a subject, an auxiliary light 13 for assisting a light source in the case of photometric distance measurement, a strobe 15 and a photographing lens barrel means 16 are provided on the front of the digital camera of this embodiment.

  A release button 10, a power switch button 12, and a zoom switch 11 are arranged on the top surface, and a card battery cover 25 having a tripod mounting portion 24, a memory card drive 37 and a battery insertion portion (not shown) inside is disposed on the bottom surface. Has been.

  Operation buttons 18, 19, 20, 21, 22, and 23 are arranged on the back, and various function switching can be performed. An LCD display 17 and a viewfinder eyepiece 16 are arranged.

  The operation buttons 18, 19, 20, 21, 22, and 23 are used to select an operation mode of the digital camera, for example, a shooting mode, a playback mode, a moving image shooting mode, and the like.

  The display 17 is an image display means, and displays the image data stored in the memory 35 and the image data read from the memory card on the screen. When a mode is selected, a plurality of shooting data can be reduced and displayed on the screen.

  The control unit includes a CPU 41, a ROM 40, and a RAM 42, and various components such as a release button 10, operation buttons 18 to 23, a display 17, a memory 35, and a memory card drive 37 are connected via a bus 39.

  The zoom motor driving means 26 and the focus motor driving means 8 are connected to the drive circuit 38 connected to the control system via the bus 39. Further, a shutter driving unit 27, an aperture driving unit 30, an image pickup device 31 such as a CCD or a CMOS, and a strobe 15 are connected, and each drive is controlled by a signal from a control system.

  The ROM 40 stores a program for controlling each functional component described above. The RAM 42 stores data necessary for each control program.

  As described above, the first embodiment of the present invention is configured. However, when the user turns the power source from OFF to ON by operating the power switch button 12, the CPU 41 reads the necessary control program from the ROM 40. Start initial operation. That is, the photographing lens barrel is moved to a predetermined photographing possible area, the photographing function is activated, and the photographing standby state is set.

  When the release button 10 is pressed to take a picture, the brightness of the subject is detected by the image sensor 31, and the aperture value, shutter speed, and whether or not the flash 15 is to be emitted are determined based on the photometric value. In addition, the user can select whether the strobe 15 is forced to emit light or not by using the operation button 18 in advance. Next, distance measurement is performed, the distance to the subject is measured, and the focus motor driving means 8 is driven to move the focus means 2 to a predetermined focus position. Next, the shutter unit 27 is opened and closed, and a desired image is taken into the image sensor 31.

  Charges corresponding to the amount of incident light are accumulated in the image pickup device 31 based on the exposure control value, and the charges become image signals and output to the analog signal processing means 32.

  The analog signal processing unit 32 performs analog processing on the captured image data and outputs the processed image data to the A / D conversion unit 33. The A / D converter 33 converts the captured analog data into digital data. This digital data is output to the digital signal processing means 34, where the digital data is processed. Finally, the digital data is stored in the memory 35.

  The data stored in the memory 35 is subjected to compression processing such as JPEG or TIFF by the compression / expansion means 36 by the operation of the operation button 19, and is output to and stored in the memory card.

  In the case of a digital camera not having the memory 35, the digital data processed by the digital signal processing means 34 is output to the compression / expansion means 36 and stored in the memory card drive 37.

  The image data stored in the memory 35 and the image data stored in the memory card drive 37 can be expanded by the compression / expansion means 36, and the image data can be displayed on the display 17 via the bus 39. When the user views the data on the display 17 and determines that the image is unnecessary, the user can delete the image by operating the operation button 20.

  The zoom switch 11 is disposed on the upper surface, and the zoom lens 11 is operated to control the zoom motor drive means 26 via the drive circuit 38 to move the photographing lens barrel 16 in the optical axis direction of the lens. . In addition, the stored image displayed on the display 17 can be enlarged and reduced by the operation of the zoom switch 11, so-called digital zoom.

  Next, the configuration of the focus mechanism provided in the photographing lens barrel 16 provided in the digital camera 9 according to this embodiment will be described. FIG. 2 is a perspective view when the photographing lens group 1 and the photographing lens group holding means 2 (hereinafter referred to as a focus lens) are present in the storage position. FIG. 3 is a perspective view when the focus lens 1 is extended and in use. FIG. 4 is a side view when the focus lens 1 is extended and in use.

  A so-called nut-shaped female screw means 5 is incorporated in the photographing lens group holding means 2 that holds the photographing lens group 1 substantially integrally. The screw-shaped male screw means 4 meshes with the female screw means 5. The male screw means 4 is held by the focus base plate 3. The photographic lens group holding means 2 is fitted and incorporated in a guide bar 6 standing vertically with respect to the focus base plate 3. Similarly, the photographing lens group holding means 2 is rotated in the rotational direction by a sub guide bar 3 a standing vertically with respect to the focus base plate 3. It is regulated and its position is determined. A biasing means 7 that is a coil spring is provided between the taking lens group holding means 2 and the focus base plate 3. By taking the photographic lens group holding means 2 into the focus base plate 3, it is possible to prevent the female screw means 5, the photographic lens group holding means 2, the female screw means 5 and the male screw means 4 from rattling. The male screw means 4 and the male screw means driving means 8 which is a stepping motor are gear-connected, and the screw (male screw means 4) is rotated by the rotation of the male screw driving means 8 which is a stepping motor, and the focus lens 1 is moved back and forth in the optical axis direction. it can. By rotating the stepping motor, the focus storage state of FIG. 2 is moved to the focus in-focus state of FIG.

  Conventionally, the number of screws and nuts is one. For example, if the pitch is 0.2 mm, the lead is 0.2 mm. In order to increase the speed that the focus lens 1 extends, it is necessary to increase the rotational speed of the male screw driving means 8. Further, it is assumed that the stop resolution of the male screw driving means 8 is 20 points in the 2-2 phase excitation stop state, which can be stably maintained normally without energization, even at the stop position. Along with this, the rotation amount of the focus lens 1 becomes 0.01 mm / round by one rotation of the male screw means 4.

  In addition to means for increasing the rotational speed of the male screw driving means 8, the moving speed of the focus lens 1 can be increased by a method of increasing the screw lead. For example, in order to set the lead of the screw to 0.4 mm, the pitch may be set to 0.4 mm. In this way, it is necessary to increase the amount of engagement between the nut and screw by the screw pitch, and assuming that the tooth thickness for one rotation is required, the thickness of the nut 5 (female screw means) in FIG. Requires a minimum of 0.4 mm. The thickness of the nut must be accommodated in the camera, and the camera is enlarged accordingly.

  Therefore, in this proposal, a method is adopted in which the lead lens is raised without changing the pitch to increase the moving speed of the focus lens 1 by increasing the number of stripes. That is, if the pitch is 0.2 mm and the number of strips is 2, the lead is 0.4 mm. At this time, if the thickness of the nut 5 is 0.5 mm, it is possible to secure the meshing of the screw for one lead and two pitches, so that the meshing can be secured more stably than when the pitch is simply increased. In summary, the pitch xmm, the number of stripes y, the lead xymm, and the nut thickness are xy + αmm, and α <xy.

  Further, in order to further reduce the meshing of the screw and reduce the thickness of the nut 5, the pitch is 0.2 mm and the number of threads is 2, so that the lead is 0.4 mm and the thickness of the nut 5 is 0. If it is 3 mm, it is possible to ensure the meshing of the screw pitch, so there is no problem in operation. In this way, it is possible to reduce the thickness of the taking lens barrel while keeping the nut thin, so that a great merit can be obtained.

  In summary, the pitch xmm, the number of stripes y, the lead xymm, and the nut thickness are x + αmm, and α <x.

  Here, if the half stop point in the above-mentioned case 1 is sufficient, it is sufficient to stop at the 2-2 phase excitation position (2-2 phase position), but if the same number of stop points is required, 2- It is necessary to stop at the 1-2 phase excitation position (1-2 phase position) which is half of the 2 phase excitation position (2-2 phase position). In recent years, the performance of the stepping motor 8 has been remarkably improved, and the stop at the 1-2 phase excitation position (1-2 phase position) is used without any particular problem. In addition, the performance can be further stabilized by conducting holding current to the stepping motor 8.

  In recent years, various control methods for stepping motors have been developed, and drive control that is more varied can be achieved by stopping the microstep position, which is a finer stop position.

  If the above method is adopted, it is not necessary to increase the size of the stepping motor in order to improve speed and accuracy. In addition, noise due to high-speed rotation of the stepping motor can be reduced.

  FIG. 11 shows a flowchart from the power-on to the end of photographing of a digital camera which is a photographing apparatus having the lens barrel mechanism of the present invention. When the user turns on the power of the photographing apparatus, the CPU 41 sends a command to the zoom motor driving means 26 to rotate the lens barrel driving motor CW. Thereafter, a predetermined operation is performed, and when it is confirmed that the photographing lens barrel means 16 has moved to the photographing position, it is stopped. At this time, the state of the lens barrel changes from the state of FIG. 5 to the state of FIG.

  Next, when the user turns on the release button 10, photometry is performed to obtain luminance information of the subject. When the obtained luminance information is higher than the predetermined luminance, the diaphragm means 29 is inserted into the optical axis to change the amount of incident light. When the obtained luminance information is lower than the predetermined luminance, the diaphragm means 29 is not operated and is kept away from the optical axis.

  Thereafter, the focusing unit 2 is operated to move the subject to a focus position, and image capture is started there. Next, the shutter means 28 is moved from the open state to the closed state to block the amount of incident light, and the image capture is completed. Thereafter, the diaphragm means 29 is retracted from the optical axis, the focus means 2 is moved to the initial position, and the operation ends.

  With the above configuration, it is possible to configure a photographing lens barrel that is thin, can increase the speed of the focus lens, and can maintain stop accuracy.

It is sectional drawing which shows the structure of the imaging device in one Example of this invention. 1 is a perspective view illustrating a configuration of an imaging apparatus according to an embodiment of the present invention. 1 is a perspective view illustrating a configuration of an imaging apparatus according to an embodiment of the present invention. 1 is a side view illustrating a configuration of an imaging apparatus according to an embodiment of the present invention. 1 is a perspective view of a photographing apparatus having an imaging apparatus according to an embodiment of the present invention in a power-off state. 1 is a perspective view of a photographing apparatus having an imaging apparatus according to an embodiment of the present invention in a power-on state. It is a top view of the imaging device which has an imaging device in one Example of this invention. It is a rear view of the imaging device which has an imaging device in one Example of this invention. It is a bottom view of the imaging device which has an imaging device in one example of the present invention. It is a block diagram which shows the principal part of a structure of the digital camera which is an imaging device which has an imaging device in one Example of this invention. It is a flowchart which shows the sequence at the time of imaging | photography from the power supply ON of the digital camera which is an imaging device which has an imaging device in one Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Shooting lens group 2 Shooting lens group holding means 3 Focus base plate 3a Sub guide bar 4 Male screw means 5 Female screw means (nut)
6 Guide bar 7 Shifting means 8 Male screw driving means 9 Imaging device (digital camera)
DESCRIPTION OF SYMBOLS 10 Release button 11 Zoom switch 12 Power switch button 13 Auxiliary light 14 Finder 15 Strobe 16 Finder eyepiece 17 Display 18-23 Operation button 24 Tripod mounting part 25 Card battery cover 26 Zoom motor drive means 27 Shutter drive means 28 Shutter means DESCRIPTION OF SYMBOLS 29 Diaphragm means 30 Diaphragm drive means 31 Image pick-up element 32 Analog signal processing means 33 A / D conversion part 34 Digital signal processing means 35 Memory 36 Compression / decompression means 37 Memory card drive 38 Drive circuit 39 Bus 40 ROM
41 CPU
42 RAM

Claims (5)

  A photographing lens group, a photographing lens group holding means, a female screw means that operates substantially integrally with the photographing lens group holding means, a male screw means, and a male screw that is a stepping motor that can drive the male screw means and stop at a fine resolution Drive means, pitch xmm of male screw means and female screw means, thread number y, lead xymm, nut thickness xy + αmm, α <xy, stop position 2-2 phase position or 1-2 phase position , Or both, and the number y of stripes is 2 or more.   A photographing lens group, a photographing lens group holding means, a female screw means that operates substantially integrally with the photographing lens group holding means, a male screw means, and a male screw that is a stepping motor that can drive the male screw means and stop at a fine resolution Driving means, male screw means and female screw means pitch xmm, number of threads y, lead xymm, nut thickness x + αmm, α <x, stop position 2-2 phase position or 1-2 phase position The imaging apparatus is characterized in that the stop position is the 2-2 phase position and the 1-2 phase position, and the number of stripes y is 2 or more.   3. The imaging apparatus according to claim 1, wherein the stop position is a microstep position.   4. The imaging apparatus according to claim 1, wherein x = 0.2 mm, y = 2, and lead = 0.4 mm.   5. The imaging apparatus according to claim 1, wherein the photographing lens group is a focus lens that focuses a subject.

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