Imaging device

Abstract

To provide an imaging apparatus including a plurality of optical filters, without increasing a size.SOLUTION: An imaging apparatus includes a first optical filter which includes at least one optical filter, a first holding frame which holds the first optical filter, a second optical filter which includes at least one optical filter, a second holding frame which holds the second optical filter, and a first guide bar and a second guide bar which movably support the first holding frame and the second holding frame. The first holding frame has a first engagement part which engages with the first guide bar and a second engagement part which engages with the second guide bar. The second holding frame has a third engagement part which engages with the first guide bar and a fourth engagement part which engages with the second guide bar. The first guide bar is held by the first engagement part of the first holding frame and the third engagement part of the second holding frame and the second guide bar is held by the second engagement part of the first holding frame and the fourth engagement part of the second holding frame.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to an imaging device, and particularly to a device equipped with a mechanism for switching an optical filter according to the application.

Background Art

[0002] In surveillance cameras assumed to be used in various shooting situations such as indoors and outdoors, many enable appropriate shooting by inserting and removing a plurality of optical filters with different applications. For example, in a situation where it is bright around, such as during the day, a filter that blocks light in the infrared region is inserted to obtain a good image. In a situation where sunlight shines strongly, a dimming filter may be inserted to further reduce the amount of incident light. Also, when shooting at a distance, a filter that transmits only a specific wavelength in the near-infrared region may be used to obtain an image with high sharpness.

[0003] In this way, in surveillance cameras, a plurality of optical filters may be properly used according to the situation, but there are also situations where a plurality of these filters are inserted simultaneously.

[0004] On the other hand, in order to achieve both optical performance and miniaturization, it is effective to shorten the flange back, which is the distance from the mounting surface of the lens camera body to the imaging element. By shortening the flange back, the space where the optical filter switching mechanism inserted between the lens and the imaging element can be arranged also becomes narrow.

[0005] Therefore, in Patent Document 1, the distance from the optical axis of a pair of shafts that guide a holding frame for holding an optical filter and a pair of shafts that guide a holding frame for holding another optical filter is made different, thereby aiming to reduce the thickness in the optical axis direction.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

[0007] However, the prior art disclosed in Patent Document 1 has the problem of becoming large due to the arrangement of multiple shafts.

[0008] Therefore, the object of the present invention is to solve the above problems and provide an imaging device equipped with multiple optical filters without increasing its size. [Means for solving the problem]

[0009] To solve the above problems, the imaging device of the present invention comprises a first optical filter group including at least one optical filter, and the first optical filter group A first retaining frame that holds the first optical filter, a second optical filter group that includes at least one optical filter, and the second optical filter group The optical filter group comprises a second retaining frame for holding the first and second optical filter groups, and a first guide bar and a second guide bar that support the first and second retaining frames so as to be movable in a direction perpendicular to the optical axis, wherein the first retaining frame has a first engaging portion that engages with the first guide bar and a second engaging portion that engages with the second guide bar, and the second retaining frame has a third engaging portion that engages with the first guide bar and a fourth engaging portion that engages with the second guide bar, wherein the first guide bar is held between the first engaging portion of the first retaining frame and the third engaging portion of the second retaining frame, and the second guide bar is held between the second engaging portion of the first retaining frame and the fourth engaging portion of the second retaining frame, and the first and second retaining frames can be moved in a direction perpendicular to the optical axis to position the first and second optical filter groups on the optical axis, respectively. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide an imaging device equipped with multiple optical filters without increasing its size. [Brief explanation of the drawing]

[0011] [Figure 1] This is a front perspective view of the imaging device in this embodiment. [Figure 2] This is an exploded perspective view of the imaging device in this embodiment. [Figure 3] This is an XZ cross-sectional view of the imaging device in this embodiment. [Figure 4] This is an exploded perspective view of the filter switching mechanism of the imaging device in this embodiment. [Figure 5] This is an XY cross-sectional view of the imaging device in this embodiment. [Figure 6] This figure shows the switching process of the filter switching mechanism of the imaging device in this embodiment. [Figure 7] This is a cross-sectional view of the lead screw and rack engagement portion in the first holding frame of the imaging device according to this embodiment. [Figure 8] This is a cross-sectional view of the engagement portion between the lead screw and the rack in the second holding frame of the imaging device in this embodiment. [Figure 9] This diagram shows the relationship of biasing forces related to the filter holding frame of the imaging device in this embodiment. [Modes for carrying out the invention]

[0012] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In the following embodiments, a lens-interchangeable camera 1 is given as an example of the imaging device of the present invention.

[0013] The imaging device and filter switching mechanism according to this embodiment will be described below with reference to Figures 1 to 9. Figure 1 is a front perspective view of the imaging device in this embodiment.

[0014] The interchangeable-lens camera 1 mainly consists of a lens 10 and a body 20. The lens 10 can be replaced depending on the shooting application and is attached to the mount portion 201 of the body 20. The optical axis O of the lens 10 coincides with the X-axis direction in the figure.

[0015] Next, the internal structure of the lens-exchangeable camera 1 will be described. FIG. 2 is an exploded perspective view of the imaging device in the present embodiment. Inside the body 20, a filter switching mechanism 30 is arranged, and the filter switching mechanism 30 is fixed inside the body 20. Details of the filter switching mechanism 30 will be described later.

[0016] 40 is an imaging element, which is mounted on the imaging element substrate 42, and the imaging element substrate 42 is fixed to the filter switching mechanism 30. A sealing member 41 is sandwiched between the imaging element substrate 42 and the filter switching mechanism 30, preventing the intrusion of stray light, dust, etc. into the imaging element 40.

[0017] The sealing member 41 is formed of an elastic black rubber material.

[0018] Behind the imaging element substrate 42, a first substrate 21 is arranged. The first substrate is fixed to the body 20. The first substrate 21 and the imaging element substrate 42 are electrically connected by electrical wiring (not shown), and the imaging element 40 receives the light rays guided by the lens 10 and converts them into image information. The image information acquired by the imaging element 40 is transmitted to the first substrate 21 via the imaging element substrate 42. Various video processes are performed on the acquired image information on the first substrate 21.

[0019] 23 is a second substrate, which mainly performs the power supply and network processing of the lens-exchangeable camera 1. The second substrate 23 is held by the first substrate 21 via a spacer 22 and is also electrically connected to the first substrate 21 by electrical wiring (not shown).

[0020] 24 is a cover, and the body 20 and the cover 24 form an accommodation space inside, in which the filter switching mechanism 30, the imaging element 40, the first substrate 21, the second substrate 22, and other components (not shown) are accommodated.

[0021] Next, the filter switching mechanism 30 will be described. Figure 3 is an XZ cross-sectional view of the imaging device in this embodiment. The distance from the mounting surface, where the lens 10 and the mounting portion 201 of the body 20 come into contact, to the imaging surface on the image sensor 40 is called the flange back. The filter switching mechanism 30 is housed within the flange back of the interchangeable lens camera 1. In addition, a portion of the lens 10 protrudes beyond the mounting surface towards the image sensor 40, and the filter switching mechanism 30 performs the filter switching operation within a range that does not interfere with the protruding portion of the lens 10.

[0022] Figure 4 is an exploded perspective view of the filter switching mechanism of the imaging device in this embodiment. Figure 5 is an XY cross-sectional view of the imaging device in this embodiment.

[0023] 34 is the first retaining frame, which holds the first optical filter group 33, consisting of an infrared cut filter 331 and a bandpass filter 332. The infrared cut filter 331 and the bandpass filter 332 are arranged on the same plane perpendicular to the optical axis O of the lens 10, with their long sides facing each other. The first retaining frame 34 is supported so as to be movable in the direction perpendicular to the optical axis by a guide bar 39a as the first guide bar and a guide bar 39b as the second guide bar. The guide bars 39a and 39b are fixed by being sandwiched between the housing, which consists of a front cover 31 and a rear cover 32. The guide bars 39a and 39b are made of metal.

[0024] 341 is the first engaging portion of the first retaining frame 34, which engages with the guide bar 39a. At this time, the first engaging portion 341 engages with the guide bar 39a for at least 180 degrees of its diameter. As a result, the engagement between the first engaging portion 341 and the guide bar 39a will not be disengaged. In other words, the portion of the first engaging portion of the first retaining frame 34 that contacts the guide bar 39a is wider than the portion of the third engaging portion 382 of the second retaining frame 38 that contacts the guide bar 39a.

[0025] 342 is the second engaging portion of the first retaining frame 34, which engages with the guide bar 39b. At this time, the second engaging portion 342 engages with the guide bar 39b only over a range of less than 180 degrees of its diameter. At this time, a contact portion 343 is provided at a position opposite the front cover 31 to the second engaging portion 342. In addition, a restricting portion 311 is provided on the front cover 31 at a position opposite the contact portion 343. As a result, the movement of the second engaging portion 342 is restricted between the guide bar 39b and the restricting portion 311.

[0026] 35a is a rack, which is rotatably fixed to a rack engagement portion 344 provided on the first retaining frame 34, while being biased in the direction perpendicular to the optical axis by a biasing spring 351a. The rack 35a is also engaged with the lead screw 361a of the stepping motor 36a, and is driven in the direction perpendicular to the optical axis together with the first retaining frame 34 by the rotation of the lead screw 361a. At this time, a force F0 acts on the rack 35a by the biasing spring 351a, biasing it in the direction of the lead screw 361a. The stepping motor 36a is fixed to the rear cover 32.

[0027] The infrared cut filter 331 is a filter that blocks infrared wavelengths of light outside the visible light range from the light rays guided by the lens 10. The shooting mode in which the infrared cut filter 331 is positioned on the optical axis is called the day mode, which focuses visible light, and is mainly used for photographing subjects during the daytime.

[0028] On the other hand, the bandpass filter 332 is a filter that transmits only a portion of the infrared wavelengths of the light rays guided by the lens 10. The shooting mode in which the bandpass filter 332 is positioned on the optical axis is called the distant view mode and is mainly used for shooting in environments where haze or mist is present or in environments where infrared illumination is on.

[0029] 38 is the second holding frame, which holds the dummy glass 371 and ND (Neutral Density) filter 372, which are part of the second optical filter group 37. The dummy glass 371 and ND filter 372 are arranged on the same plane perpendicular to the optical axis O of the lens 10, with their longer sides facing each other. The second holding frame 38 is supported by guide bars 39a and 39b so as to be movable in the direction perpendicular to the optical axis. In this case, the first holding frame 34 is positioned on the object side (lens side), and the second holding frame 38 is positioned on the image plane side (image sensor side).

[0030] 381 engages with the guide bar 39b at the fourth engaging portion of the second retaining frame 38. At this time, the fourth engaging portion 381 engages with the guide bar 39b for at least 180 degrees of its diameter. In other words, the portion of the fourth engaging portion of the second retaining frame 38 that contacts the second guide bar 39b is wider than the portion of the second engaging portion of the first retaining frame 34 that contacts the second guide bar 39b. As a result, the engagement between the fourth engaging portion 381 and the guide bar 39b will not be disengaged.

[0031] 382 is the third engaging portion of the second retaining frame 38, which engages with the guide bar 39a. At this time, the third engaging portion 382 engages with the guide bar 39a only over a range of less than 180 degrees of its diameter. At this time, a contact portion 383 is provided at a position opposite the rear cover 32 to the third engaging portion 382. In addition, a restricting portion 321 is provided on the rear cover 32 at a position opposite the contact portion 383. As a result, the movement of the third engaging portion 382 is restricted between the guide bar 39a and the restricting portion 321.

[0032] 35b is a rack, which is rotatably fixed to a rack engagement portion 384 provided on the second retaining frame 38, while being biased in the direction perpendicular to the optical axis by a biasing spring 351b. The rack 35b is also engaged with the lead screw 361b of the stepping motor 36b, and is driven in the direction perpendicular to the optical axis together with the second retaining frame 38 by the rotation of the lead screw 361b. At this time, a force F0 acts on the rack 35b by the biasing spring 351b, biasing it in the direction of the lead screw 361b. The stepping motor 36b is fixed to the rear cover 32.

[0033] Furthermore, at this time, the image sensor substrate 42 on which the image sensor 40 is mounted is positioned between the stepping motors 36a and 36b fixed to the rear cover 32 in a direction perpendicular to the optical axis. This allows the stepping motors 36a and 36b and the image sensor substrate 42 to be arranged in a space-saving manner.

[0034] The dummy glass 371 is a filter that transmits light rays guided by the lens 10 without blocking them. When the dummy glass 371 is placed on the optical axis, it is mainly used during normal shooting in non-special environments, for purposes such as preventing dust and other particles from entering the image sensor, or to avoid changes in the optical path length when switching by making its thickness the same as other switching filters.

[0035] The ND filter 372, on the other hand, is a filter that reduces the amount of light guided by the lens 10. By placing the ND filter 372 on the optical axis, the amount of light incident on the image sensor can be greatly reduced, so it is used for purposes such as slowing down the shutter speed in daylight or in environments with strong light sources, or for long-exposure photography.

[0036] The first retaining frame 34 and the second retaining frame 38 are mutually supported by a pair of guide bars 39a and 39b so as to be movable in a direction perpendicular to the optical axis. As described above, the first engaging portion 341 of the first retaining frame 34 and the third engaging portion 382 of the second retaining frame 38 engage with the guide bar 39a. At this time, the engaging portion 341 engages with the guide bar 39a over a range of at least 180 degrees of its diameter. The third engaging portion 382 engages with the guide bar 39a over a range of at least less than 180 degrees of its diameter. Therefore, the first engaging portion 341 and the third engaging portion 382 engage with the guide bar 39a without interfering with each other.

[0037] Similarly, the second engaging portion 342 of the first retaining frame 34 and the fourth engaging portion 381 of the second retaining frame 38 engage with the guide bar 39b. In this case, the second engaging portion 342 engages with the guide bar 39b over a range of at least less than 180 degrees of its diameter. The fourth engaging portion 381 engages with the guide bar 39b over a range of at least more than 180 degrees of its diameter. Therefore, the second engaging portion 342 and the third engaging portion 382 engage with the guide bar 39b without interfering with each other.

[0038] Since the first retaining frame 34 and the second retaining frame 38 do not interfere with each other around the guide bars 39a and 39b, they can move independently in the direction perpendicular to the optical axis.

[0039] Figure 6 shows the switching of the filter switching mechanism of the imaging device in this embodiment. (a) in the figure shows the state in which the infrared cut filter 331 held in the first holding frame 34 and the dummy glass 371 held in the second holding frame 38 are positioned on the optical axis O. This state is mainly used for daytime photography. (b) in the figure shows the state in which the second holding frame 38 has moved in the +Z direction from the state in (a), and the infrared cut filter 331 and the ND filter 372 held in the second holding frame 38 are positioned on the optical axis O. This state is mainly used for photography during the day or in the presence of a strong light source. (c) shows the state in which the first holding frame 34 has moved in the +Z direction from the state in (b), and the bandpass filter 332 and the ND filter 372 are positioned on the optical axis O. This state is mainly used for photography at night or in environments where strong infrared illumination is on. (d) shows the state in which the second holding frame 38 has moved in the -Z direction from the state in (c), and the bandpass filter 332 and dummy glass 371 are positioned on the optical axis O. This is mainly used when photographing distant objects where haze or mist occurs during the daytime.

[0040] Next, the force relationship between the first and second retaining frames will be explained. Figure 7 is a cross-sectional view of the engagement portion between the lead screw and the rack in the first retaining frame of the imaging device in this embodiment.

[0041] Figure 7 illustrates the mechanism by which the biasing force F0 acting on the rack 35a is generated. The tip of the rack 35a is provided with rack teeth 35a1 and rack biasing teeth 35a2, and the lead screw 361a of the motor 36a is inserted between the rack teeth 35a1 and the rack biasing teeth 35a2. At this time, the biasing force of the rack spring 351a presses the rack biasing teeth 35a2 against the lead screw 361a, causing the rack teeth 35a1 and the lead screw 361a to mesh.

[0042] In this case, by tilting the contact surface between the rack biasing teeth 35a2 and the lead screw 361a by α° with respect to the tooth surface of the rack teeth 25a1, a component force corresponding to the biasing force F0 in Figure 7 is generated on the first retaining frame 34 with which the rack 35a is engaged. Figure 8 is a cross-sectional view of the meshing portion between the lead screw and the rack in the second retaining frame of the imaging device according to an embodiment of the present invention.

[0043] Like rack 35a, rack 35b is provided with rack teeth 35b1 and rack biasing teeth 35b2 at its tip, and the lead screw 361b of motor 36b is inserted between rack teeth 35b1 and rack teeth 35b2. At this time, the biasing force of rack spring 351b presses the rack biasing teeth 35b2 against the lead screw 361b, causing the rack teeth 35b1 and the lead screw 361b to mesh.

[0044] In this case, by tilting the contact surface between the rack biasing teeth 35b2 and the lead screw 361b by α° with respect to the tooth surface of the rack teeth 25b1, a component force corresponding to the biasing force F0 in Figure 7 is generated on the second movable frame 38 with which the rack 35b is engaged.

[0045] Figure 9 is a diagram showing the relationship of biasing forces related to the filter holding frame of the imaging device in this embodiment. As described above, a biasing force of F0 acts on the first holding frame 34 with which the rack 35a is engaged. Since the first engaging portion 341 of the first holding frame 34 is engaged with the guide bar 39a, when F0 acts, a rotational moment M1 is generated around the guide bar 39a. Then, at the other engagement point, a biasing force of F1 acts in the direction that the second engaging portion 342 is pressed against the guide bar 39b. As a result, even if the second engaging portion 342 is engaged with the guide bar 39b for a range of at least less than 180 degrees of its diameter, the engagement becomes less likely to disengage.

[0046] In this case, the engagement portion 344 of the first retaining frame 34, which engages with the rack 35a, is always positioned on the imaging side of the dashed line connecting the engagement position of the rack 35a and the lead screw 361a shown in the figure, and the engagement position of the first engagement portion 341 of the first retaining frame 34 and the guide bar 39a. Also, the motor 36a is positioned further from the optical axis O than the guide bar 39a. As a result, the direction in which the vector F0 acts is always in the direction in which the biasing force F1 described above presses the second engagement portion 342 against the guide bar 39b. Since the metal guide bar 39b and the resin second engagement portion 342 of the first retaining frame 34 slide against each other, it can be driven with low sliding resistance.

[0047] Similarly, a biasing force of F0 acts on the second retaining frame 38, with which the rack 35b is engaged. Since the fourth engaging portion 381 of the second retaining frame 38 is engaged with the guide bar 39b, when F0 acts, a rotational moment M2 is generated around the guide bar 39b. At the other engagement point, a biasing force of F2 acts on the third engaging portion 382 in a direction that presses it against the guide bar 39a. As a result, even if the third engaging portion 382 is engaged with the guide bar 39a over a range of at least 180 degrees of its diameter, the engagement is less likely to disengage.

[0048] In this configuration, the engagement portion 384 of the second retaining frame 38 is always positioned closer to the object than the dashed line connecting the engagement position of the rack 35b and the lead screw 361b, and the engagement position of the fourth engagement portion 381 of the second retaining frame 38 and the guide bar 39b. Furthermore, the motor 36b is positioned further from the optical axis O than the guide bar 39b. As a result, the direction in which the vector F0 acts is always such that the aforementioned biasing force F2 presses the second engagement portion 342 against the guide bar 39b. Since the metal guide bar 39a and the resin third engagement portion 382 of the second retaining frame 38 slide against each other, the drive can be performed with low sliding resistance.

[0049] With the above configuration, this embodiment makes it possible to provide an imaging device equipped with multiple optical filters without increasing its size.

[0050] In this embodiment, the optical filters included in the first optical filter group 33 and the second optical filter group 37 may be various optical filters having characteristics other than those listed in this embodiment.

[0051] Although preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of its gist. [Explanation of symbols]

[0052] 1. Interchangeable lens camera 10 lenses 20 Body 30 Filter switching mechanism 31 Front cover 311 Regulatory Department 32 Rear cover 321 Regulatory Department 33 First Optical Filter Group 331 Infrared Cut Filter 332 Bandpass Filter 34 First holding slot 341 First engaging part 342 Second engaging part 37 Second Optical Filter Group 371 Dummy glass 372 ND filter 38 Second holding slot 381 Fourth engaging part 382 Third engaging part 39a Guide bar 39b Guide bar

Claims

1. A first optical filter group including at least one optical filter, A first retaining frame for holding the first optical filter group, A second optical filter group including at least one optical filter, A second holding frame for holding the second optical filter group, The system comprises a first guide bar and a second guide bar that support the first retaining frame and the second retaining frame so as to be movable in a direction perpendicular to the optical axis, The first retaining frame has a first engaging portion that engages with the first guide bar and a second engaging portion that engages with the second guide bar. The second retaining frame has a third engaging portion that engages with the first guide bar and a fourth engaging portion that engages with the second guide bar. The first guide bar is held by the first engaging portion of the first retaining frame and the third engaging portion of the second retaining frame, and the second guide bar is held by the second engaging portion of the first retaining frame and the fourth engaging portion of the second retaining frame. An imaging apparatus characterized in that the first holding frame and the second holding frame move in a direction perpendicular to the optical axis, thereby enabling the selective placement of the first optical filter group and the second optical filter group on the optical axis.

2. The first optical filter group includes a plurality of optical filters, and the plurality of optical filters are arranged on the same plane as each other. The second optical filter group includes a plurality of optical filters, and the plurality of optical filters are arranged on the same plane as each other. The imaging apparatus according to claim 1, characterized in that the first optical filter group is arranged closer to the lens than the second optical filter group.

3. The imaging apparatus according to claim 1 or claim 2, characterized in that the first retaining frame and the second retaining frame do not come into contact with each other.

4. The imaging apparatus according to any one of claims 1 to 3, characterized in that the portion of the first engaging part of the first retaining frame that contacts the first guide bar is wider than the portion of the third engaging part of the second retaining frame that contacts the first guide bar.

5. The imaging apparatus according to any one of claims 1 to 4, characterized in that the portion of the fourth engaging portion of the second retaining frame that contacts the second guide bar is wider than the portion of the second engaging portion of the first retaining frame that contacts the second guide bar.

6. The imaging apparatus according to any one of claims 1 to 5, characterized in that the first guide bar and the second guide bar are sandwiched between the first housing and the second housing.

7. The imaging apparatus according to claim 6, characterized in that the second engaging portion of the first retaining frame has a first contact portion, and the first housing has a restricting portion at a position opposite to the first contact portion.

8. The imaging apparatus according to claim 6 or 7, characterized in that the third engaging portion of the second retaining frame has a second contact portion, and the second housing has a restricting portion at a position opposite to the second contact portion.

9. It has a first motor for moving the first retaining frame and a second motor for moving the second retaining frame, The imaging apparatus according to any one of claims 6 to 8, characterized in that the first motor and the second motor are held in the second housing, and the substrate having the image sensor is arranged between the first motor and the second motor in a direction perpendicular to the optical axis.

Images