JP2006173830A - Digital camera with optical low-pass filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avoid the adhesion of dust as much as possible by employing a filmlike optical LPF having such a structure as touching a metallic body in a digital camera device and neutralizing static electricity charged on the filmlike optical LPF through the metallic body. <P>SOLUTION: The digital camera comprises a means for advancing and retracting a filmlike optical LPF in the vicinity of the light receiving surface of a photography apparatus, a conductive member located on a plane substantially parallel with the filmlike optical LPF and connected electrically, and a conductive means for neutralizing static electricity charged on the filmlike optical LPF when it advances and retracts. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical low-pass filter (hereinafter referred to as an optical LPF) used for an image pickup device such as a CCD or a CMOS, for example, and particularly relates to a film-like optical LPF when it is mounted in a device such as a digital camera. The present invention relates to a method for preventing adhesion of dust / dust that becomes a problem.

  Conventionally, in an imaging optical system using an imaging device such as a CCD or CMOS, in order to limit the high spatial frequency component of the subject light and to remove the color component different from the light due to the subject accompanying the generation of the pseudo signal, An optical LPF is used.

  As the optical LPF, a birefringent type using a quartz plate or the like has been widely used.

  This crystal plate has a refraction index anisotropy that is not so large, and in order to obtain a predetermined spatial frequency to be limited, the thickness of the crystal plate is usually about 1 mm. Since a plurality of such sheets are used together, the total thickness is increased. As a result, not only the apparatus is reduced in size and weight but also optical performance such as aberration and ghost is lowered.

  In addition, materials having a large refractive index anisotropy such as lithium niobate are known. In the case of this material, since the refractive index anisotropy is large, the thickness for obtaining a predetermined spatial frequency to be restricted can be made extremely thin compared to quartz, but on the other hand, it is technical in terms of thickness processing or bonding processing. There are difficulties that result in higher costs.

  On the other hand, Japanese Patent Application Laid-Open No. 08-122708 proposes a polymer optical LPF. This is made of an optically anisotropic polymer film, is easy to manufacture, and has specific optical characteristics, and thus has an excellent function as an optical LPF, and can be reduced in size and weight. In addition to being able to achieve this, it can be said to be advantageous in terms of cost.

If this optically anisotropic polymer film is used, it is possible to avoid the disadvantages of using quartz or lithium niobate, but because it is made of film, it is easy to be charged with static electricity, and dust, dust, etc. are attached. Therefore, when picking up an image on the image pickup device, there is a disadvantage that dust and dust are reflected. Further, when a film-like optical LPF such as an optically anisotropic polymer film is mounted in a device such as a digital camera, as a means for solving the above-mentioned drawbacks, from a member in which the film-like optical LPF is previously wound onto the photographing optical path. Proposals have been made to include retracting means for performing operations such as putting in or retracting outside the photographing optical path. In this case, the photographer can intentionally use the film-like optical LPF or not use it, and the film-like optical LPF is retracted depending on the selected mode. However, even this proposal has not yet reached a fundamental solution for adhesion of dust, dust, and the like due to electrostatic charging.
Japanese Unexamined Patent Publication No. 08-122708

  The present invention has been made in view of the above situation. When a film-like optical LPF such as an optically anisotropic polymer film is mounted in a device such as a digital camera, a metal body (GND in the device) ), And the static electricity charged in the film-like optical LPF can be removed to the metal body (GND), thereby avoiding the attachment of dust and dust as much as possible.

  2. The digital camera according to claim 1, wherein the digital camera according to the present invention is configured to achieve the above-described object, and a photographic optical system for forming a subject image and a subject image formed by the photographic optical system are converted into electrical signals. A film-like optical LPF disposed between a solid-state imaging device, the imaging optical system, and the solid-state imaging device, and positioned on a plane substantially parallel to a light receiving surface of the imaging device, and the film-like optical LPF The apparatus includes an advancing / retreating unit that advances and retreats in the vicinity of a light receiving surface of the apparatus, and an electrically connected conductive member that is positioned on a plane substantially parallel to the film-like optical LPF. It is characterized by having a conductive means for neutralizing.

  According to a second aspect of the present invention, in the digital camera according to the first aspect, at least one or more conductive means for neutralizing a charge generated by charging is arranged.

  As described above, according to the digital camera of the present invention, when the film-like optical LPF is retracted, the film-like optical LPF moves in contact with the first conductive roller and the second conductive roller and conducts through the conductive holding member. It is fixed to the internal housing having the property with a fixing screw. As a result, it is possible to neutralize the charge generated by charging such as static electricity by removing electricity from the conductive internal housing (GND), so that dust, dust, etc. adhere to the film-like optical LPF as much as possible. It can be avoided.

  Hereinafter, embodiments of a digital camera according to the present invention will be described with reference to the drawings.

  FIG. 1 is an explanatory view showing a central sectional view of a digital camera provided with the film-like optical LPF of the present invention.

  FIG. 2 is a diagram illustrating the configuration of the retracting mechanism and conductive member of the film-like optical LPF of FIG.

  FIG. 3 is an explanatory diagram relating to film detection of the retracting mechanism of the film-like optical LPF of FIG.

  FIG. 4 is an explanatory diagram relating to the connecting portion of the conductive member of the film-like optical LPF of FIG.

  FIG. 5 is an electric circuit block diagram of the digital camera according to the embodiment of the present invention.

  FIG. 6 is a flowchart showing the operation of the digital camera according to the embodiment of the present invention.

  The outline of the digital camera of the present invention will be described below.

  An interchangeable lens 2 that can be attached to and detached from the camera 1 in FIG. 1 includes a plurality of photographing lens groups 3 and an aperture 4 that controls the amount of light by changing the aperture diameter, and is mounted and fixed by a mount 5 of the camera 1. . An electrical connection is made by contact between a contact portion of the camera 1 (not shown) and a contact portion of the interchangeable lens 2 (not shown), and power is supplied from the camera 1 to the interchangeable lens 2 via this contact portion. Performs communication for control. The light beam that has passed through the photographing lens group 3 of the interchangeable lens 2 enters the main mirror 6 of the camera 1. The main mirror 6 is a half mirror, and the reflected light beam is guided to the finder, and the transmitted light beam is reflected downward by the sub mirror 7 and guided to the focus detection device 8. The focus detection device 8 detects the defocus amount of the photographing lens group 3, calculates the lens driving amount so that the photographing lens group 3 is in focus, and the lens driving amount obtained by the calculation is obtained via the contact portion. When sent to the interchangeable lens 2, the interchangeable lens 2 controls a motor (not shown) to drive the photographing lens group 3 to adjust the focus. The light beam guided to the finder by the main mirror 6 forms a subject image on the focus plate 9, and the photographer observes the subject image on the focus plate via the pentaprism 10 and the eyepiece 11. ing. Behind the pentaprism 10, a photometric lens 12 and a photometric sensor 13 for measuring the subject brightness in the observation screen of the camera 1 are arranged. Reference numerals 14 and 15 denote a rear curtain and a front curtain constituting a shutter. When the rear curtain 15 and the front curtain 14 are opened, the CCD (solid-state image pickup device) 20 which is a solid-state image pickup device disposed rearward can perform necessary exposure. give. Image data stored in the solid-state imaging device 20 at the time of shooting is sent to an external storage device (to be described later) through an image processing circuit (not shown) provided separately. From here, the configuration according to the present invention will be described. However, in order to describe in detail later, only the configuration will be briefly described here. Reference numeral 27 denotes a film-like optical LPF. As shown in FIG. 3A, a birefringent film 27a for horizontally separating a subject image, a birefringent film 27b for vertically separating a subject image, and a birefringent film 27a therebetween. It joins so that the phase film 27c which converts the linearly polarized light which passed through into circularly polarized light may be inserted | pinched. Reference numeral 16 denotes a second pulley which is a part of the retracting means for the film-like optical LPF. Reference numeral 18 denotes a first pulley that is also a part of the retracting means. The rotating shaft 18a of the first pulley 18 and the rotating shaft 16a of the second pulley 16 are both arranged in a direction in which the rotating shaft is substantially orthogonal to the photographing optical axis. Reference numeral 25 denotes a part of the conductive means of the film-like optical LPF, which is a second conductive roller made of a metal body arranged substantially parallel to the vicinity of the second pulley 16 described above. Similarly, reference numeral 26 denotes a first conductive roller which is a part of the conductive means and is made of a metal body disposed substantially in parallel in the vicinity of the first pulley 18. Below the first pulley 18, a motor 30 is disposed substantially parallel to the first pulley 18. Reference numeral 19 denotes a protective glass that protects the surface of the solid-state imaging device 20, and reference numeral 17 denotes an infrared cut filter that is bonded to the surface of the protective glass 19 and blocks light in the infrared wavelength region. Reference numeral 21 denotes a substrate (A), which holds the solid-state imaging device 20 and has a drive circuit for driving the solid-state imaging device 20 mounted thereon. Another substrate (B) 22 is disposed behind the substrate (A) 21, and a drive circuit for driving the LCD monitor device 23 is mounted on the substrate (B) 22. The board (A) 21 and the board (B) 22 are connected by a flexible printed board (not shown) to perform communication. On the outer surface of the substrate (B) 22, an LCD monitor device 23 for displaying a photographed image and a backlight illumination device 24 for visually recognizing the image are arranged. 28 is a detachable external storage device (recording means) for recording image data, and 29 is a detachable battery as a power source of the camera.

  The above is the main configuration of the digital camera according to the present invention.

  Next, the conductive means having the film-like optical LPF will be specifically described based on the configuration of the digital camera described above. 2 to 4 are diagrams illustrating the configuration of the retracting means of the film-like optical LPF according to the embodiment of the present invention and the conductive means for neutralizing charges generated by charging. In FIG. 2, reference numeral 18 denotes a first pulley, and an opening having the same width as the film-like optical LPF 27 is provided on the outer periphery of the first pulley. Further, at one end of the outer periphery, there is a rotation gear 18b disposed coaxially with the rotation shaft 18a. The rotation gear 18b and the rotation shaft 18a are coupled to each other and are configured to be rotatable. Further, inside the first pulley 18, one end of the film-like optical LPF 27 is fixed to the rotating shaft 18 a. A motor 30 is disposed below the first pulley 18, and the gear of the rotating gear 18b and the gear of the motor 30 are engaged with each other to transmit power. Reference numeral 16 denotes a second pulley, and an opening having the same width as the film-like optical LPF 27 is provided on the outer periphery of the second pulley, similarly to the first pulley 18. One end of the optical LPF 27 is fixed to the rotating shaft 16a, and the rotating shaft 16a is constantly urged clockwise in FIG. 2 by an urging member (not shown). Further, the film-like optical LPF 27 is urged by being wound around the rotary shaft 16 a in the second pulley 16 by a predetermined amount in advance. A solid-state imaging device 20 is disposed between the first pulley 18 and the second pulley 16, and a protective glass 19 and an infrared cut filter 17 are bonded to the surface. Reference numeral 31 denotes a photosensor for detecting the position of the film-like optical LPF 27, and the film-like optical LPF 27 is positioned by position indexing markers 32a and 32b formed on the film-like optical LPF 27. be able to. Reference numeral 25 denotes a second conductive roller made of a metal body that comes into contact with the film-like optical LPF, and is rotatably supported by a conductive holding member 33a also made of a metal body. Similarly, reference numeral 26 denotes a first conductive roller made of a metal body that is brought into contact with the film-like optical LPF, and is rotatably supported by the holding member 33b.

  FIG. 3A shows a cross section of the film-like optical LPF 27. As described above, the film-like optical LPF 27 is a birefringent film 27a that horizontally separates a subject image, a birefringent film 27b that vertically separates a subject image, and linearly polarized light that has passed through the birefringent film 27a therebetween is converted into circularly polarized light. It joins so that the phase film 27c to convert may be inserted | pinched. FIG. 3B is a plan view of the film-like optical LPF 27 and is a view for explaining the position detection of the retracting means. As described above, the position indexing marker 32a and the position indexing marker 32b are markers for determining the retracted position of the film-like optical LPF 27, and light-shielding printing is applied. When this marker interrupts the detection optical axis of the photosensor 31 shown in FIG. 2, an electric signal is generated, and the driving of the motor 30 arranged below the first pulley 18 is stopped, and the position of the film-like optical LPF 27 is stopped. To decide. Reference numeral 34 denotes an LPF forming portion of the film-like optical LPF 27. In other words, the photo sensor 31 detects the position of the position indexing markers 32a and 32b of the film-like optical LPF 27, and controls to stop the LPF forming part 34 of the film-like optical LPF 27 on the front surface of the solid-state imaging device 20. is doing.

  As shown in FIGS. 3C and 3D, an LPF forming portion 34 may be provided on the entire surface of the film-like optical LPF 27.

  FIG. 4 is an explanatory diagram of the conductive means having a retracting mechanism for the film-like optical LPF according to the embodiment of the present invention.

  In the figure, reference numeral 1a denotes an exterior part of the digital camera, and an inner casing 1b having conductivity for holding the conductive holding members 33a and 33b described above is formed inside the exterior part 1a. Reference numeral 18 denotes a first pulley, 16 denotes a second pulley, 27 denotes a film film optical LPF, and the rotation gear 18b is driven by the rotation of the motor 30, whereby the film optical LPF 27 is moved downward in the figure, The first pulley 18 is inserted. The first pulley 18 and the second pulley 16 are held by a frame (not shown) that is a separate member from the internal housing 1b. Reference numeral 26 denotes a first conductive roller, which is rotatably held by the conductive holding member 33b. The conductive holding member 33b is fastened to the inner casing 1b having conductivity by a fixing screw 35b. Similarly, the second conductive roller 25 is rotatably held by the conductive holding member 33a, and the conductive holding member 33a is fastened to the inner casing 1b having conductivity by a fixing screw 35a. With this configuration, when the film-like optical LPF 27 is retracted, the inner casing 1b moves in contact with the first conductive roller 26 and the second conductive roller 25 and has conductivity through the conductive holding members 33a and 33b. It is fixed with a fixing screw 35b. As a result, it is possible to neutralize the charge generated by charging such as static electricity by removing electricity from the conductive internal housing 1b (GND), so that dust, dust, etc. can adhere to the film-like optical LPF 27. It can be avoided as long as possible.

  FIG. 5 is a block diagram showing an electric circuit configuration of the digital camera according to the embodiment of the present invention. In the figure, reference numeral 101 denotes a printed circuit board, which is an image display control circuit that processes image data output from the microcomputer 102 and the solid-state image sensor 115 that controls all operations of the camera and displays an image on the LCD monitor device 117. (Image display means) 116 and the like are mounted. A control program, which is a part of the configuration of the saving means, is mounted inside the microcomputer 102. Reference numeral 103 denotes SW1, which is a switch that is turned on (ON) when a release button (not shown) is half-pressed. When the SW1 / 103 is turned on (ON), the digital camera is in a shooting preparation state. Reference numeral 104 denotes SW2, which is a switch that is turned on (ON) when a release button (not shown) is pressed to the end. When the SW2 / 104 is turned on (ON), the digital camera starts a photographing operation. Reference numeral 105 denotes a lens control circuit. Since this embodiment is a lens interchangeable digital camera, the interchangeable lens 2 is driven and the diaphragm blades are used for communication with the interchangeable lens 2 (see FIG. 1) and AF (autofocus). The lens control circuit 105 takes charge of the drive control. In FIG. 5, reference numeral 106 denotes an external display control circuit which controls the external display device 107 and a display device (not shown) in the viewfinder. A switch sense circuit 108 serves to transmit signals from a number of switches including an electronic dial 109 and a sub electronic dial 110 provided in the camera to the microcomputer 102. A strobe light emission dimming control circuit 111 is grounded via an X contact 111a and controls an external strobe. A ranging circuit 112 has a function of detecting a defocus amount with respect to a subject for AF (autofocus). A photometric circuit 113 has a function of measuring the luminance of the subject. Reference numeral 114 denotes a circuit that controls the shutter, and performs appropriate exposure on the solid-state image sensor 115. The LCD monitor device 117 and the backlight illumination device 118 constitute image display means. Reference numeral 119 denotes an external storage device serving as a recording unit. A retraction mechanism control circuit 120 is a part of the structure of the retraction means according to the present invention. 121 is a motor which is also a part of the configuration of the retracting means, and 122 is a photosensor which is also a part of the configuration of the retracting means. 123 is a retraction switch which is also a part of the structure of retraction means.

  Next, the operation of the digital camera according to the embodiment of the present invention will be described with reference to FIG. FIG. 6 is a flowchart showing a flow of operation of the digital camera according to the present embodiment. The control program shown in this flowchart is implemented in the microcomputer 102 shown in FIG. First, in step S201, it is determined whether or not a main switch of a digital camera (not shown) is turned on. If the main switch (not shown) is on (ON), the process proceeds to step S202. If the main switch (not shown) is in an off state (OFF), the process directly returns to step S201. If any one of the operation switches is turned on in step S202, the process proceeds to step S203, and processing corresponding to the operation switch that is turned on is performed by the microcomputer 102 (see FIG. 5). This process is, for example, a process of operating each operation member of the digital camera to change the shooting mode, to read a shot image, or to set the evacuation of the film-like optical LPF 27 (see FIG. 2). is there. As a result of executing step S203, it is determined in step S204 whether or not a retraction switch 123 (see FIG. 5) for changing (retracting) the position of the film-like optical LPF 27 (see FIG. 2) is turned on. . If the retract switch 123 (see FIG. 5) for changing (retracting) the position of the film-like optical LPF 27 (see FIG. 2) is not turned on (ON) in step S204, normal shooting is performed. The process proceeds to S209, and if the retraction switch 123 (see FIG. 5) is turned on, the process proceeds to step S205. In step S209, it is determined whether or not SW1 / 103 is turned on. SW1 / 103 is a state in which a release button (not shown) is half-pressed. When SW1 / 103 is turned on, the digital camera is in a shooting preparation state. If SW1 / 103 is off (OFF), the process returns to step S201. If SW1 / 103 is on (ON), the digital camera proceeds to the next step S210. In step S210, a photometry (AE) operation and a distance measurement (AF) operation are performed, respectively, and the interchangeable lens 2 (see FIG. 1), which is an imaging unit, is driven to perform focusing. Next, in step S211, it is determined whether SW2 / 104 is turned on. SW2 / 104 is a state in which a release button (not shown) has been pressed to the end. When SW2 / 104 is turned on, the process proceeds to the next step S212, and the digital camera starts a photographing operation. On the other hand, if SW2 / 104 is off (OFF), the process returns to step S209, and steps S209 to S211 are repeated. In step S212, the main mirror 6 (see FIG. 1) is activated, so-called mirror-up is performed, and the main mirror 6 (see FIG. 1) is retracted outside the photographing optical path. Next, in step S213, accumulation of the solid-state imaging device 20 (see FIG. 1), which is an imaging means, is started. In the next step S214, shutter exposure, that is, the front film 14 (see FIG. 1), the rear film 15 ( (See FIG. 1). In step S215, accumulation of the solid-state imaging device 20 (see FIG. 1) is completed, and in the next step S216, an image signal is read from the solid-state imaging device 20 (see FIG. 1), and the printed circuit board 101 (FIG. 5). Is temporarily stored in the internal memory. In step S217, the main mirror 6 (see FIG. 1) is activated, so-called mirror-down occurs, and the main mirror 6 (see FIG. 1) returns to a position (diagonal position) for guiding the subject light to the viewfinder optical system. The imaging operation ends. On the other hand, when the retreat switch 123 (see FIG. 5) is turned on (ON), the process proceeds to step S205. In step S205, the motor 121 (see FIG. 2) is energized by a signal from the retraction mechanism control circuit 120 (see FIG. 5) in FIG. When energization is performed in step S206, the motor 30 in FIG. 2 rotates, driving force is transmitted to the rotation gear 18b (see FIG. 2) of the first pulley 18 (see FIG. 2), and the film-like optical LPF 27 ( 2) is wound into the first pulley 18 (see FIG. 2) by the rotation of the rotating shaft 18a (see FIG. 2). At this time, the film-like optical LPF 27 (see FIG. 2) moves in contact with the first conductive roller 26 (see FIG. 2) and the second conductive roller 25 (see FIG. 2) when retracted, and the conductive holding member 33a (see FIG. 2). The charge charged by static electricity or the like to the internal housing 1b (GND (see FIG. 4)) having conductivity can be removed via the conductive holding member 33b (see FIG. 2). As a result, the charge generated by charging such as static electricity can be neutralized, so that it is possible to avoid adhesion of dust, dust, etc. to the film-like optical LPF 27 (see FIG. 2) as much as possible. In step S207, the position indexing marker 32b (see FIG. 2) in which a light-shielding gap (black pattern printing) is applied to the film-like optical LPF 27 in FIG. 2 detects the detection optical axis of the photosensor 31 (see FIG. 2). When blocked, an electrical signal is generated. This electrical signal is sent to the retracting mechanism control circuit 120 (see FIG. 5). In step S208, it is detected by the signal from the retract mechanism control circuit 120 in FIG. 5 that the position indexing marker 32b (see FIG. 2) has moved to the front surface of the detection optical axis of the photosensor 31 (see FIG. 2). . Next, the driving of the motor 30 (see FIG. 2) arranged below the first pulley 18 in FIG. 2 is stopped, the position of the film-like optical LPF 27 (see FIG. 2) is determined, and the solid-state imaging device. Control is performed to stop the formation portion 34 (see FIG. 3) of the film-like optical LPF 27 (see FIG. 2) on the front surface of 20 (see FIG. 2). Here, the retraction of the film-like optical LPF 27 (see FIG. 2) is completed.

  In addition, according to the present embodiment, the conductive roller and the conductive holding member that move in contact with the film-like optical LPF 27 have been described in the embodiment with two configurations. However, at least one or more conductive rollers may be disposed. .

It is explanatory drawing which showed the center sectional drawing of the digital camera provided with the film-form optical LPF of this invention. It is the figure explaining the structure of the evacuation mechanism and conductive member of the film-form optical LPF of FIG. It is explanatory drawing regarding the film detection of the evacuation mechanism of the film-form optical LPF of FIG. It is explanatory drawing regarding the connection part of the electrically-conductive member of the film-form optical LPF of FIG. It is an electric circuit block diagram of the digital camera which concerns on embodiment of this invention. It is a flowchart which shows operation | movement of the digital camera which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Camera 1a Appearance part 1b Internal housing | casing 2 Interchangeable lens 3 Shooting lens group 4 Aperture 5 Mount 6 Main mirror 7 Sub mirror 8 Focus detection apparatus 9 Focus plate 10 Penta prism 11 Eyepiece 12 Photometric lens 13 Photometric sensor 14 Front curtain 15 Rear curtain 16 Second pulley 16a Fixed shaft 17 Infrared cut filter 18 First pulley 18a Fixed shaft 18b Rotating gear 19 Protective glass 20 Solid-state imaging device 21 Substrate (A)
22 Substrate (B)
23 LCD monitor device 24 Backlight illumination device 25 Second conductive roller 26 First conductive roller 27 Film-like optical LPF
27a, 27b Birefringent film 27c Phase film 28 External storage device 29 Battery 30 Motor 31 Photo sensor 32a, 32b Position indexing marker 33a, 33b Conductive holding member 34 LPF forming portion 35a, 35b Fixed screw 101 Printed circuit board 102 Microcomputer 103 SW1
104 SW2
DESCRIPTION OF SYMBOLS 105 Lens control circuit 106 External display control circuit 107 External display apparatus 108 Switch sense circuit 109 Electronic dial 110 Sub electronic dial 111 Strobe light emission dimming control circuit 111a X contact 112 Distance measuring circuit 113 Metering circuit 114 Shutter control circuit 115 Solid-state image sensor 116 Image display control circuit 117 LCD monitor device 118 Backlight illumination device 119 External storage device 120 Retraction mechanism control circuit 121 Motor 122 Photo sensor 123 Retraction switch

Claims (2)

  A photographic optical system for forming a subject image, a solid-state image sensor for converting a subject image formed by the photographic optical system into an electrical signal, and disposed between the photographic optical system and the solid-state image sensor. A film-like optical low-pass filter positioned in a plane substantially parallel to the light-receiving surface, advancing / retreating means for moving the film-like optical low-pass filter in the vicinity of the light-receiving surface of the photographing apparatus, and the film-like optical low-pass filter And a conductive member electrically connected to a plane substantially parallel to the film, and the film-like optical low-pass filter has a conductive means for neutralizing charges generated by charging when the film is advanced and retracted. camera.   The digital camera according to claim 1, wherein at least one conductive means for neutralizing charges generated by charging is disposed.

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