KR102093692B1 - Focus-fixing apparatus of camera with image sensor, and camera with the focus-fixing apparatus - Google Patents

Abstract

The present invention relates to a focus fixing device of a camera having an image sensor and a camera having the same and, more specifically, to a focus fixing device enabling a focus not to be changed according to a temperature change of a camera having an image sensor, and a camera having the focus fixing device. According to the present invention, provided is the focus fixing device of the camera which maintains a focal distance set at the beginning even if the temperature of the camera rises. More specifically, the present invention proposes the focus fixing device to not have a change in focus according to the temperature change only with an instrumental structure even if a lens automatically setting a focus may not be used even if the focus is changed.

Description

Focus-fixing apparatus of camera with image sensor, and camera with the focus-fixing apparatus

The present invention relates to a focus fixing device for a camera having an image sensor and a camera having the same, and more particularly, for a camera having an image sensor, a focus fixing device that prevents a focus from changing according to a change in temperature of the camera and It relates to a camera having such a focus lock.

In many application fields related to images, high-resolution images are required, and image photographing apparatuses for acquiring images can be applied to various inspection devices, imaging devices, and communication devices. For example, aerial photographs or satellite images require high-resolution images for accurate diagnosis in the medical field, and high-resolution images for recognition of targets in fields related to military purposes.

In particular, in recent years, high-resolution cameras have been developed and used for smaller and more precise measurements, and further development of lenses suitable for use to maximize the performance of these cameras is becoming more sophisticated. Cameras and lenses are used with an optimal focus on the object to be measured. Due to the nature of the camera, a type of image sensors (Charge-Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor) sensor and The temperature of the electronic component rises. Alternatively, the temperature at which the camera is installed may change depending on the temperature control ability of the air conditioning system, and sometimes it may change depending on the season.

Due to the temperature change inside or outside the camera, the physical focus of the mechanical parts to which the sensor is fastened is also slightly changed, and the initial focus is changed. Therefore, it is impossible to shoot the desired image beyond the optimal focus. There was a problem that a problem occurred.

KR 10-2007-0103097 A

The present invention was devised to solve this problem, and provides a focusing device for a camera to maintain a focal length initially set even when the temperature of the camera rises. In particular, focus is automatically adjusted even when the focus changes. It is an object of the present invention to propose a focus fixing device that prevents a change in focus due to a change in temperature even with a mechanical structure when a lens that can be used as a lens cannot be used.

In order to achieve the above object, a focus fixing device of a camera having an image sensor according to the present invention includes: a cover housing on a rear surface of a camera; A camera housing having one end connected to a lens housing surrounding the lens of the front of the camera, and the other end connected to and fixed to the cover housing; A circuit unit installed in the camera at a position spaced apart from the cover housing; As an element constituting the circuit portion, an image sensor provided in the circuit portion around a point where the center line of the lens passes through the circuit portion; And, one end is connected to the circuit portion, the other end includes a connector (connector) connected to the cover housing, the temperature of the camera rises or falls, even if the equipment constituting the camera expands or contracts the focus of the camera In order not to change, the total amount of expansion of the devices expanding in the forward direction and the total amount of expansion of the devices expanding in the rear direction are the same amount so that the position of the image sensor is maintained at a certain distance from the lens, and the The length L ₁ , the length of the connector L ₂ , the thickness of the circuit board PCB board L ₃ , the thermal expansion coefficient of the camera housing α ₁ , the thermal expansion coefficient of the connector α ₂ , the thermal expansion in the thickness direction of the circuit board PCB board When the coefficient is α ₃ , L ₁ x α ₁ = (L ₂ x α ₂ ) + (L ₃ x α ₃ ).
According to another aspect of the present invention, a focus fixing device of a camera including an image sensor includes: a cover housing on a rear surface of a camera; A camera housing having one end connected to a lens housing surrounding the lens of the front of the camera, and the other end connected to and fixed to the cover housing; A circuit unit installed in the camera at a position spaced apart from the cover housing; As an element constituting the circuit portion, an image sensor provided in the circuit portion around a point where the center line of the lens passes through the circuit portion; And, one end is connected to the circuit portion, the other end includes a connector (connector) connected to the cover housing, the temperature of the camera rises or falls, the camera constituting the camera expands or contracts even if the focus of the camera In order not to change, the total amount of expansion of the devices expanding in the forward direction and the total amount of expansion of the devices expanding in the rear direction are the same amount so that the position of the image sensor is maintained at a certain distance from the lens, and the camera housing When it is composed of n (n≥1) materials of different materials along the length direction of L _1, the length of each material is L ₁₁ , L ₁₂ , ..., L _1n (L ₁₁ + L ₁₂ + ... + L _1n = L ₁ ), and the coefficient of thermal expansion of each material is α ₁₁ , α ₁₂ , ..., α _1n , and the connector is m (m) of different materials along the length direction of L ₂ . ≥1) When divided, the length of each material is L ₂₁ , L ₂₂ , ..., L _2m (L ₂₁ + L ₂₂ + ... + L _2m = L ₂ ), and the coefficient of thermal expansion of each material is α ₂₁ , α ₂₂ , ..., α _2m , and when the circuit section is composed of k (k≥1) PCB substrate layers of different materials along the thickness direction, the thickness of each substrate layer is L ₃₁ , L ₃₂ , ..., L _3k (L ₃₁ + L ₃₂ + ... + L _3k = L ₃ ), and the coefficient of thermal expansion of each material is α ₃₁ , α ₃₂ , ..., α _3k , L ₁₁ x α ₁₁ + L ₁₂ x α ₁₂ + ... + L _1n x α _1n = (L ₂₁ x α ₂₁ + L ₂₂ x α ₂₂ + ... + L _2m x α _2m ) + (L ₃₁ x α ₃₁ + L ₃₂ x α ₃₂ + ... + L _3k x α _3k ).
The image sensor may be installed to be spaced apart from the focal length by the rearmost surface of the lens.
The cover housing may be configured as a separate component from the camera housing.
The cover housing may be integrally formed with the camera housing.
According to another aspect of the present invention, a camera including one of the focus locks is provided.

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According to the present invention, although the temperature of the camera is raised, a focus lock of the camera is provided so that the focal length set at the beginning can be maintained. In particular, even when the focus changes, when a lens that automatically focuses cannot be used , It has the effect of suggesting a focus fixing device that prevents a change in focus due to temperature change even with a mechanical structure.

1 is a view showing a structure of a conventional camera having an image sensor as a sectional side view.
2 is a view showing a change in the focal length when a temperature change occurs in a conventional camera equipped with an image sensor.
3 is a view showing a structure of a camera having a focus fixing device according to the present invention as a cross-sectional side view.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, the terms or words used in the present specification and claims should not be construed as being limited to ordinary or lexical meanings, and the inventor appropriately explains the concept of terms to explain his or her invention in the best way. Based on the principle that it can be defined, it should be interpreted as meanings and concepts consistent with the technical spirit of the present invention. Therefore, the embodiments shown in the embodiments and the drawings described in this specification are only the most preferred embodiments of the present invention and do not represent all of the technical spirit of the present invention, and at the time of this application, various alternatives are possible. It should be understood that there may be equivalents and variations.

1 is a view showing a structure of a conventional camera having an image sensor as a cross-sectional side view, and FIG. 2 is a view showing a change in a focal length when a temperature change occurs in a conventional camera having an image sensor.

The image sensor 111 is an element of the circuit unit 110 that is provided in the circuit unit 110 around the point where the center line of the lens 10 passes through the circuit unit 110.

1 to 3, the left side is represented by the front of the camera and the right side by the rear of the camera. The distance between the lens and the camera sensor is called a focal length, and is indicated by L ₀ in FIG. 1. Each lens has a different focal length value. In general, when focusing the camera, the lens is adjusted to achieve the optimal focus, and thereafter, it is fixed and used so that the focus does not change mechanically.

Referring to FIG. 1, the image sensor 111 is a sensor that converts a signal of light into an electrical signal, and a CCD (Charge-Coupled Device) or a Complementary Metal Oxide Semiconductor (CMOS) sensor may be used as an embodiment.

The structure of the camera having the conventional image sensor of FIG. 1 is as follows.

The camera housing 120 is connected to the lens housing 20 surrounding the lens 10 at the front portion, and is fixed to the cover housing 140 at the rear portion. The image sensor 111 is composed of one element of the circuit unit 110 for processing the converted electrical signal, and is spaced apart from the rearmost surface of the lens 10 by a focal length L ₀ , and at this time, the circuit unit 110 ) And the camera housing 120 are connected by a connector 130. The camera is connected to a PC through an interface (not shown), and looks for an object to be photographed to find a focus having an optimal image. The lines in the box 11 shown in dotted lines represent the light 12 that has passed through the lens.

In the inspection camera used continuously for a long time, the temperature of the CCD or CMOS sensor or other electronic components increases over time, and the temperature of the camera increases due to internal heat generation. Or, the temperature of the place where the camera is installed varies depending on the temperature control ability of the air conditioning system, and sometimes it changes depending on the season. The temperature of the camera is also affected by the ambient temperature.

Due to the temperature change inside or outside the camera, the position of the image sensor 111 changes while the mechanism constituting the camera expands due to heat.

The material of the connector 130 to the M ₂ and, even if the material of the camera housing 120 is different from each other in M ₁ is expanded in the same direction.

In the case of the conventional camera structure as shown in FIG. 1, when the temperature rises as described above, both the camera housing 120 and the connector 130 expand in the same direction, that is, in the rear direction, as shown in FIG. 2. Likewise, a deformation of ΔL ₀ occurs. Due to this, there is a problem in that the image quality of the image is changed badly as the focus set in the first place is changed. Since the temperature at which the camera is raised is affected by the surrounding environment, each △ L ₀ has a different value in various use environments. In particular, if the object to be measured is a very thin and precise part, depending on the temperature as above, When the focus is changed, a desired level of image is not obtained, which causes a serious problem that the product cannot be judged for defects or failed to be analyzed.

As the temperature changes, the length L ₀ value changes by ΔL ₀ = L ₀ x α x △ t. Where α is the coefficient of thermal expansion of the object, and △ t is the temperature change that the camera has risen (or decreased) from when it focused.

For example, aluminum material (α = 24x10 ^-6 ), L ₀ = 30mm length, for a 20 degree temperature change,

△ L ₀ = 30 x (24x10 ^-6 ) x 20 = 0.014mm

In other words, △ L ₀ = 14μm length change occurs, and the thickness to be measured is getting thinner. Especially, when measuring to a thickness of 1μm or less, this change amount (△ L ₀ ) is very serious. It is very important to reduce the amount of change (△ L ₀ ).

To solve this problem, a fan is attached to the outside of the camera to blow the wind, and in special cases, the camera can be cooled with water. However, if a fan is used, a problem due to vibration may occur, or there is an adverse effect of dispersing dust in the air to various places, and, conclusively, the temperature cannot be reduced by the temperature increase of the camera. When cooling with water, the structure is very complicated, and there is a problem in that it is very difficult to use and the cost is high because water leakage or water temperature control is very difficult.

3 is a view showing a structure of a camera having a focus fixing device 200 according to the present invention as a sectional side view.

The difference from the structure of FIGS. 1 and 2 is that the circuit part 210 including the image sensor 211 is not connected to the camera housing 220 by the connector, but the cover housing 240 on the rear surface by the connector 230. ). That is, the connector 230 has one end connected to the circuit unit 210 and the other end connected to the cover housing 240.

In this case, the cover housing 240 to which the connector 230 is fixed may be a separate part from the camera housing 220, or the cover housing 240 and the camera housing 220 may be integrally formed. The camera is connected to a PC through an interface (not shown), and looks for an object to be photographed to find a focus having an optimal image.

In the case of FIG. 3 as well, the temperature of the CCD or CMOS sensor or other electronic component increases over time, and the temperature of the camera increases due to internal heat generation. Or, the temperature of the place where the camera is installed varies depending on the temperature control ability of the air conditioning system, and sometimes it changes depending on the season.

Due to the temperature change inside or outside the camera, the camera mechanism expands due to heat.

In this case, the length L ₁ of the camera housing 220 expands in the direction away from the lens by ΔL ₁ , and the length L ₂ of the connector 230 expands in the direction closer to the lens by ΔL ₂ .

The length L ₁ and L ₂ are different, so that the material of the material M ₁ and the connector 230 of the camera housing (220), M ₂ must also be different. This is that the thermal expansion coefficient α ₂ is different from each other in thermal expansion coefficient α ₁ and the connector 230 of the camera housing (220). In conclusion, for the camera housing 220 and the connector 230 expanding in opposite directions, if the amount of expansion of the camera housing 220 and the amount of expansion of the connector 230 are the same, the rear surface of the lens 10 is There is no change in the distance to the image sensor 211, that is, the focal length. This can be expressed in the following equation.

[Equation 1]

Expansion amount of M ₁ material of the camera housing 220 = L ₁ x α ₁ x △ t

[Equation 2]

Expansion amount of M2 material of connector 230 = L ₂ x α ₂ x △ t

That is, the following must be satisfied.

[Equation 3]

L ₁ x α ₁ x △ t = L ₂ x α ₂ x △ t

From this, the final conditional expression to be satisfied is as in Equation 4 below.

[Equation 4]

L ₁ / L ₂ = α ₂ / α ₁

According to Equation 4, it can be seen that the shorter the length of the component, the higher the coefficient of thermal expansion.

In summary, when designing the focus fixing device 200 of the present invention inside the camera, two materials having a coefficient of thermal expansion that can satisfy the above equation are selected, and the camera housing 220 and It is only necessary to determine the lengths L ₁ and L ₂ of each connector 230. When the material and the length are determined in this way, the camera sensor 220 and the connector 230 expand in the same amount in opposite directions to each other even if the camera's temperature rises or falls and the equipment constituting the camera expands or contracts. The position of 211) maintains a constant distance from the lens 10, so that the focus of the camera does not change.

Furthermore, the present invention can obtain the same effect even if the camera temperature falls below room temperature.

In the description so far, the thermal expansion of the thickness of the circuit part 210 including the image sensor 211 is relatively small, so the calculation was ignored, but if necessary, it can also be calculated by including it. In this case, it can be expressed as follows.

[Equation 5]

L ₁ x α ₁ x △ t = (L ₂ x α ₂ x △ t) + (L ₃ x α ₃ x △ t)

Here, L ₃ and α ₃ are the thickness of the circuit unit 210 and the coefficient of thermal expansion.

From this, the final conditional expression to be satisfied is as in Equation 6 below.

[Equation 6]

L ₁ x α ₁ = (L ₂ x α ₂ ) + (L ₃ x α ₃ )

Therefore, according to Equation 6, the length and thermal expansion coefficient of the camera housing 220, the length and thermal expansion coefficient of the connector 230, and the thermal expansion coefficient in the thickness and thickness direction of the circuit board 210 PCB substrate may be determined.

Furthermore, when the structure as shown in FIG. 3 is further generalized, the camera housing 220 may be divided into n (n ≧ 1) materials of different materials along the length direction of L ₁ . At this time, the length of each material is called L ₁₁ , L ₁₂ , ..., L _1n (L ₁₁ + L ₁₂ + ... + L _1n = L ₁ ), and the coefficient of thermal expansion of each material is α ₁₁ , α ₁₂ , ..., let's say α _1n .

In addition, the connector 230 may also be divided into m (m≥1) materials of different materials along the length direction of L ₂ . At this time, the length of each material is called L ₂₁ , L ₂₂ , ..., L _2m (L ₂₁ + L ₂₂ + ... + L _2m = L ₂ ), and the coefficient of thermal expansion of each material is α ₂₁ , α ₂₂ , ..., let's say α _2m .

In addition, the circuit unit 210 may also be divided into k (k≥1) PCB substrate layers of different materials along the thickness direction. At this time, the thickness of each substrate layer is called L ₃₁ , L ₃₂ , ..., L _3k (L ₃₁ + L ₃₂ + ... + L _3k = L ₃ ), and the coefficient of thermal expansion of each material is α ₃₁ , α ₃₂ Let, ..., α _3k .

 In this case, it can be expressed as follows.

[Equation 7]

L ₁₁ x α ₁₁ x △ t + L ₁₂ x α ₁₂ x △ t + ... + L _1n x α _1n x △ t = (L ₂₁ x α ₂₁ x △ t + L ₂₂ x α ₂₂ x △ t + ... + L _2m x α _2m x △ t) + (L ₃₁ x α ₃₁ x △ t + L ₃₂ x α ₃₂ x △ t + ... + L _3k x α _3k x △ t)

From this, the final conditional expression to be satisfied is as in Equation 8 below.

[Equation 8]

L ₁₁ x α ₁₁ + L ₁₂ x α ₁₂ + ... + L _1n x α _1n = (L ₂₁ x α ₂₁ + L ₂₂ x α ₂₂ + ... + L _2m x α _2m ) + (L ₃₁ x α ₃₁ + L ₃₂ x α ₃₂ + ... + L _3k x α _3k )

Therefore, according to Equation 8, the length and the thermal expansion coefficient of each material constituting the camera housing 220, the length and the thermal expansion coefficient of each material constituting the connector 230, and of each PCB substrate layer constituting the circuit unit 210 It is sufficient to determine the coefficient of thermal expansion in the thickness and thickness direction.

In addition, if the expansion of the thickness of the PCB of the circuit unit 210 in Equation 8 is neglected, it is obvious that the expression is as follows.

[Equation 9]

L ₁₁ x α ₁₁ + L ₁₂ x α ₁₂ + ... + L _1n x α _1n = L ₂₁ x α ₂₁ + L ₂₂ x α ₂₂ + ... + L _2m x α _2m

In this case, the length and thermal expansion coefficient of each material constituting the camera housing 220 and the length and thermal expansion coefficient of each material constituting the connector 230 may be determined according to Equation (9).

In addition, the core technical idea of the present invention is to increase or decrease the temperature of the camera, so that even if the equipment constituting the camera expands or contracts, the focus of the camera does not change. By making the amount of expansion of the same amount, the position of the image sensor is to maintain a constant distance from the lens.

Therefore, in the structure of the focus fixing device 200 inside the camera, which has been exemplified so far, the expansion mechanism in the forward direction and the expansion mechanism in the rear direction, which are not mentioned above, which change the focal length according to changes in the camera temperature. Even though they are further included in various ways, the focal length does not change with respect to such devices, such that the total amount of expansion of the devices expanding in the forward direction and the total amount of expansion of the devices expanding in the rear direction are the same amount. It can be said that it is obvious that it does not belong to the scope of the present invention.

10: lens
12: Light passing through the lens
20: lens housing
100: camera structure with a conventional image sensor
110: circuit part including the image sensor
111: Image sensor
120: camera housing
130: connector
140: cover housing
200: focus lock of the camera with the image sensor of the present invention
210: circuit part including an image sensor
211: image sensor
220: camera housing
230: connector
240: cover housing

Claims (9)

A focus lock for a camera having an image sensor,
A cover housing at the rear of the camera;
A camera housing having one end connected to a lens housing surrounding the lens of the front of the camera, and the other end connected to and fixed to the cover housing;
A circuit unit installed in the camera at a position spaced apart from the cover housing;
As an element constituting the circuit portion, an image sensor provided in the circuit portion around a point where the center line of the lens passes through the circuit portion; And,
One end is connected to the circuit part, the other end is connected to the cover housing (connector)
Including,
The total amount of expansion of the objects that expand in the forward direction and the total amount of expansion of the devices that expand in the rear direction, so that the focus of the camera does not change even if the equipment constituting the camera expands or contracts because the temperature of the camera rises or falls. To be the same amount so that the position of the image sensor maintains a constant distance from the lens,
The length of the camera housing is L ₁ , the length of the connector is L ₂ , the thickness of the circuit board PCB board is L ₃ , the thermal expansion coefficient of the camera housing is α ₁ , the thermal expansion coefficient of the connector is α ₂ , the thickness of the circuit board PCB board If the coefficient of thermal expansion in the direction is α ₃ ,
L ₁ x α ₁ = (L ₂ x α ₂ ) + (L ₃ x α ₃ )
Configured to satisfy the relationship of,
Focus lock for a camera with an image sensor. A focus lock for a camera having an image sensor,
A cover housing at the rear of the camera;
A camera housing having one end connected to a lens housing surrounding the lens of the front of the camera, and the other end connected to and fixed to the cover housing;
A circuit unit installed in the camera at a position spaced apart from the cover housing;
As an element constituting the circuit portion, an image sensor provided in the circuit portion around a point where the center line of the lens passes through the circuit portion; And,
One end is connected to the circuit part, the other end is connected to the cover housing (connector)
Including,
The total amount of expansion of the objects that expand in the forward direction and the total amount of expansion of the devices that expand in the rear direction, so that the focus of the camera does not change even if the equipment constituting the camera expands or contracts because the temperature of the camera rises or falls. To be the same amount so that the position of the image sensor maintains a constant distance from the lens,
When the camera housing is divided into n (n≥1) materials of different materials along the length direction of L _1, the length of each material is L ₁₁ , L ₁₂ , ..., L _1n (L ₁₁ + L ₁₂ + ... + L _1n = L ₁ ), and the coefficient of thermal expansion of each material is α ₁₁ , α ₁₂ , ..., α _1n ,
When the connector is divided into m (m≥1) materials of different materials along the length direction of L _2, the length of each material is L ₂₁ , L ₂₂ , ..., L _{2 m} (L ₂₁ + L ₂₂ + ... + L _2m = L ₂ ), and the coefficient of thermal expansion of each material is α ₂₁ , α ₂₂ , ..., α _2m ,
When the circuit portion is composed of k (k≥1) PCB substrate layers of different materials along the thickness direction, the thickness of each substrate layer is L ₃₁ , L ₃₂ , ..., L _3k (L ₃₁ + L ₃₂ + ... + L _3k = L ₃ ), and the coefficient of thermal expansion of each material is α ₃₁ , α ₃₂ , ..., α _3k ,
L ₁₁ x α ₁₁ + L ₁₂ x α ₁₂ + ... + L _1n x α _1n = (L ₂₁ x α ₂₁ + L ₂₂ x α ₂₂ + ... + L _2m x α _2m ) + (L ₃₁ x α ₃₁ + L ₃₂ x α ₃₂ + ... + L _3k x α _3k )
Configured to satisfy the relationship of,
Focus lock for a camera with an image sensor. The method according to claim 1 or claim 2,
The image sensor,
Installed to be separated by the focal length from the rearmost surface of the lens
Focus fixing device of the camera having an image sensor, characterized in that. The method according to claim 1 or claim 2,
The cover housing,
Consists of a separate part from the camera housing
Focus fixing device of the camera having an image sensor, characterized in that. The method according to claim 1 or claim 2,
The cover housing,
Being integral with the camera housing
Focus fixing device of the camera having an image sensor, characterized in that.
delete delete delete A camera comprising the focus lock of claim 1 or claim 2.

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