Foreign substance detection apparatus for sensor

Abstract

A foreign substance detection apparatus for a sensor, according to an embodiment of the present invention, comprises: a stage having a seating space and having a sensor disposed in the seating space; a gripper for gripping a lens array in order to couple the sensor and the lens array to which a plurality of lenses are coupled; a rail unit for moving the stage between one end portion and the other end portion thereof; and an inspection unit that is disposed between the one end portion and the other end portion of the rail unit and emits light at the sensor, wherein the inspection unit emits light toward the seating space while the stage moves from the one end portion to the other end portion of the rail unit, and the stage stops at least once while moving through the rail unit.

Description

Sensor foreign matter detection device

[0001] The present invention relates to a sensor foreign substance detection device.

[0002] Camera modules can be produced through various processes during the assembly process.

[0003] In the process, various components such as a camera actuator forming a camera module, a plurality of lenses inserted into the camera actuator, and a lens array and sensor formed by a plurality of lenses can be combined through assembly and bonding to form a camera module.

[0004] In the process of producing the camera module described above, when combining a lens array and a sensor, the lens array is produced first, a sensor is combined with the lens array, and a light source is irradiated on the combined components to check for foreign substances in the lens array formed by stacking multiple lenses and foreign substances between the lens array and the sensor.

[0005] However, when checking for foreign substances through this process, the lens array and sensor, which are already connected to each other, must be separated. However, in the process of separating the lens array and sensor, which are already connected through a separate adhesive, there are frequent cases where the lens array or sensor is damaged, which may lead to the problem of having to discard both the lens array and sensor.

[0006] To address this issue, various methods are being developed to prevent lens arrays and sensors from being discarded during the production process by first identifying foreign substances in the lens array and sensor, and a means to address this is needed.

[0007] The present invention is an invention devised to solve the problems of the above-described prior art, and has as its task the reduction of the defect rate by checking for the presence of foreign substances before assembling a sensor.

[0008] The problems to be solved by the present invention are not limited to the problems mentioned above, and other problems not mentioned herein will be clearly understood by those skilled in the art from the description below.

[0009] According to an embodiment of the present invention for achieving the above-described object, a sensor foreign body detection device includes a stage having a mounting space provided and a sensor disposed in the mounting space, a gripper for holding a lens array in which a plurality of lenses are combined and the lens array to combine the sensor, a rail part for moving the stage between one end and the other end, and an inspection part disposed between one end and the other end of the rail part and irradiating light to the sensor, wherein the inspection part irradiates light toward the mounting space while the stage moves from one end to the other end of the rail part, and the stage stops at least once while moving through the rail part.

[0010] Here, the sensor is installed in the installation space at one end of the rail section, and can stop at a position corresponding to the inspection section while moving from one end of the rail section to the other end.

[0011] In addition, the rail section can be divided into an initial region where the sensor is seated in the mounting space, an inspection region where the inspection section irradiates light toward the sensor at a position corresponding to the inspection section, and a joining region where the lens array and the sensor are joined through the gripper.

[0012] In addition, the initial region may be provided at one end of the rail portion, the joining region may be provided at the other end of the rail portion, and the inspection region may be located between the initial region and the joining region.

[0013] Here, the inspection area is divided into a first area and a second area, and in the first area, light can be irradiated to the sensor through the inspection unit, and in the second area, light can be irradiated to the lens array and the sensor.

[0014] At this time, a defect detection unit may be further included, which is arranged in the second region and irradiates light to the lens array and the sensor.

[0015] Additionally, when the lens array and the sensor are combined, a first length from the bottom surface of the sensor to the top of the lens array may be shorter than a second length between the bottom surface of the inspection unit and the top surface of the stage in the first region.

[0016] Meanwhile, the inspection unit may include a light source unit that irradiates light, a lens unit that disperses or collects light irradiated from the light source unit, and a fixing unit that fixes the lens unit to the light source unit.

[0017] Here, the lens unit may include a lens corresponding to at least one of the plurality of lenses forming the lens array.

[0018] Additionally, the light source unit may be a surface light source.

[0019] A sensor foreign matter detection device according to an embodiment of the present invention for solving the above problem can have the effect of reducing the defect rate by checking for the presence of foreign matter before assembling the sensor.

[0020] The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims.

[0021] In addition, the effects of the present invention may be described in more detail in the detailed description of the present invention, and may not necessarily be limited to what is presented above.

[0022] The summary set forth above, as well as the detailed description of preferred embodiments of the present application described below, will be better understood when read in conjunction with the accompanying drawings.

[0023] For the purpose of illustrating the present invention, preferred embodiments are shown in the drawings.

[0024] However, it should be understood that the present application is not limited to the precise arrangements and means illustrated.

[0025] FIG. 1 is a drawing illustrating an overall description of a sensor foreign body detection device according to one embodiment of the present invention;

[0026] FIG. 2 is a drawing illustrating an inspection unit of a sensor foreign matter detection device according to one embodiment of the present invention;

[0027] FIG. 3 is a drawing illustrating an inspection area of ​​a sensor foreign body detection device according to one embodiment of the present invention;

[0028] FIG. 4 is a drawing illustrating an inspection process of a sensor foreign matter detection device according to one embodiment of the present invention;

[0029] FIG. 5 is a drawing illustrating an assembly area of ​​a sensor foreign body detection device according to one embodiment of the present invention;

[0030] FIG. 6 is a drawing illustrating an assembly process of a sensor foreign body detection device according to one embodiment of the present invention;

[0031] FIG. 7 is a drawing illustrating an overall description of a sensor foreign body detection device according to another embodiment of the present invention;

[0032] FIG. 8 is a drawing illustrating a first region of a sensor foreign body detection device according to another embodiment of the present invention; and

[0033] FIG. 9 is a drawing illustrating a second area of ​​a sensor foreign body detection device according to another embodiment of the present invention.

[0034] The present invention is susceptible to various modifications and embodiments, and specific embodiments are illustrated and described in detail in the drawings. However, this is not intended to limit the present invention to specific embodiments, but rather to encompass all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention. In describing the present invention, detailed descriptions of related known technologies will be omitted if they are deemed to obscure the gist of the present invention.

[0035] Terms such as first, second, etc. may be used to describe various components, but these components should not be limited by these terms. These terms are used solely to distinguish one component from another.

[0036] The terminology used in this application is only used to describe specific embodiments and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, it should be understood that the terms "comprises" or "has" indicate the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0037] Additionally, throughout the specification, when we say "connected," this does not only mean that two or more components are directly connected, but also that two or more components are indirectly connected through other components, that they are electrically connected as well as physically connected, or that they are referred to by different names depending on location or function but are one.

[0038] Additionally, when described as being formed or arranged "above or below" each component, "above" or "below" includes not only cases where the two components are in direct contact with each other, but also cases where one or more other components are formed or arranged between the two components. Furthermore, when expressed as "above" or "below," it can include the meaning of a downward direction as well as an upward direction based on one component.

[0039] Hereinafter, preferred embodiments of the present invention, in which the purpose of the present invention can be specifically realized, will be described with reference to the attached drawings.

[0040] First, a general description of a device according to an embodiment of the present invention can be provided through FIGS. 1 and 2.

[0041] Specifically, FIG. 1 is a drawing for explaining the overall description of a sensor foreign matter detection device according to one embodiment of the present invention, and FIG. 2 is a drawing for explaining an inspection unit of a sensor foreign matter detection device according to one embodiment of the present invention.

[0042] First, as illustrated in FIG. 1, the device according to the embodiment of the present invention includes a stage (100) in which a mounting space (101) is provided and a sensor (S) is placed in the mounting space (101), a gripper (200) that holds a lens array (LA) to combine a plurality of lenses (L) with the sensor (S), a rail unit (300) that moves the stage (100) between one end and the other end, and an inspection unit (400) that is placed between one end and the other end of the rail unit (300) and irradiates light to the sensor (S).

[0043] Here, the stage (100) is formed with a mounting space (101) for mounting the sensor (S) as described above, and can move back and forth between one end and the other end of the rail section (300) or stop at least once during the process of moving from one end to the other end by the rail section (300).

[0044] As will be explained in more detail through the drawings to be described later, the stage (100) moves by dividing the space formed in the rail section (300) and stops at least once in each space so that work can be performed in each space.

[0045] In addition, the vertical height of the stage (100), i.e., the vertical height facing upward and downward with reference to FIG. 1, may be smaller than the vertical height between the rail portion (300) and the gripper (200), and this may be to solve the problem of the sensor (S) being caught on the gripper (200) before the lens array (LA) is coupled to the sensor (S) while positioned at the lower portion of the gripper (200).

[0046] In addition, if the sensor (S) is not located in the settling space (101) of the stage (100), the stage (100) may be located at one end of the rail section (300), which may correspond to the initial position of the stage (100).

[0047] That is, the stage (100) can start from one end of the rail part (300) and move toward the other end of the rail part (300). The one end of the rail part (300) described above may refer to the left end side with reference to FIG. 1, and the other end of the rail part (300) described above may refer to the right end side with reference to FIG. 1.

[0048] Meanwhile, the gripper (200) is provided with a separate grip portion capable of holding the lens array (LA), and the grip portion can be provided to be selectively controlled to open, thereby allowing the lens array (LA) to be placed on the upper portion of the sensor (S).

[0049] Here, the grippy is positioned at the other end of the rail section (300), is arranged to be spaced apart from the other end of the rail section (300) in the vertical direction, and may be arranged lower than the inspection section (400) in the vertical direction, and may be formed to be rotatable as needed, but may not necessarily be limited thereto.

[0050] Meanwhile, the rail section (300) can move the stage (100) from one end to the other, and can be divided into an initial area (301), an inspection area (302), and a joining area (303).

[0051] Here, the initial region (301) corresponds to a space where the stage (100) is positioned before the sensor (S) is positioned and moved in the stage (100) mounting space (101) of the stage (100) when the sensor (S) is not positioned in the stage (100), and this can be distinguished based on the inspection unit (400).

[0052] That is, it may mean one end of the left side in Fig. 1 based on the area where the inspection section (400) and the rail section (300) do not overlap in the vertical direction, but may not necessarily be limited thereto.

[0053] In addition, the inspection area (302) refers to an area where the stage (100) stops while moving from one end of the rail section (300) to the other end, and may refer to a space where the inspection section (400) irradiates light to check whether a foreign substance (F) is located on the sensor (S).

[0054] Here, the inspection area (302) may mean an area where the inspection unit (400) overlaps with the upper and lower sleeve rails (300), and the rails (300) may be stopped at the moment when the inspection unit (400) and the stage (100) overlap in the inspection area (302) during the process of moving the stage (100), and the center point of the stage (100) and the center point of the inspection unit (400) overlap each other.

[0055] In this way, the rail section (300) can be stopped at least once during the process of moving the stage (100) from one end to the other end.

[0056] In addition, the joining area (303) may refer to an area where the gripper (200) is positioned and the lens array (LA) and the sensor (S) are joined and assembled, and the joining area (303) may refer to the other end of the rail portion (300) where the gripper (200) and the rail portion (300) overlap in the vertical direction.

[0057] In addition, when a foreign substance (F) is found by the sensor (S) during the process of moving the stage (100) of the inspection area (302) to the joining area (303) by the rail unit (300), if the foreign substance (F) is judged to be a defect that is difficult to remove, the stage (100) returns to the initial area (301), and if the foreign substance (F) is removed, the stage (100) can be moved from the inspection area (302) to the joining area (303).

[0058] Meanwhile, the inspection unit (400) is located above the inspection area (302) and may be placed between one end and the other end of the rail unit (300).

[0059] In addition, the inspection unit (400) is positioned relatively higher than the gripper (200) in the vertical direction to prevent the assembled lens array (LA) and sensor (S) from being caught on the inspection unit (400) and damaged during movement. To explain this in more detail, the length of the upper and lower sleeves between the upper surface of the rail unit (300) and the bottom surface of the inspection unit (400) may be greater than the length between the upper surface of the rail unit (300) and the upper surface of the lens array (LA) coupled with the sensor (S) in the mounting space (101) of the stage (100).

[0060] In addition, the inspection unit (400) may include a light source unit (410) that irradiates light, as illustrated in FIG. 2, a lens (L) unit that disperses or collects light irradiated from the light source unit (410), and a fixing unit (430) that fixes the lens (L) unit to the light source unit (410).

[0061] Here, the light irradiated by the light source (410) may be general light or a surface light source pattern, but may not necessarily be limited thereto.

[0062] In addition, the lens (L) portion is arranged at a predetermined distance from the light source portion (410) in the vertical direction, and may be composed of at least one lens (L), and the lens (L) constituting the lens (L) portion may correspond to at least one of the plurality of lenses (L) constituting the lens array (LA).

[0063] That is, the lens (L) used in the lens (L) section may be identical to or correspond to any one of the plurality of lenses (L) combined in the lens array (LA).

[0064] In addition, the fixing part (430) fixes the lens (L) to the light source part (410), and although it is illustrated in a simple form in the drawing according to the embodiment of the present invention, it may be provided to hold the lens (L) as needed, and this is only to help understanding by simplifying the drawing, and is not necessarily limited to what is illustrated and described above, and the lens (L) may be held to the light source part (410) by utilizing various methods, such as holding or placing a part of the periphery of the lens (L).

[0065] Here, in the inspection area (302), when the stage (100) is stopped, the light source unit (410), the lens (L) unit, the sensor (S), and the mounting space (101) can overlap each other in the vertical direction, and the light source unit (410) can irradiate the light source when the sensor (S) and the mounting space (101) overlap together.

[0066] For a more detailed explanation of the configuration according to the embodiment of the present invention described above, reference may be made to FIGS. 3 to 6.

[0067] Specifically, FIG. 3 is a drawing illustrating an inspection area of ​​a sensor foreign substance detection device according to an embodiment of the present invention, FIG. 4 is a drawing illustrating an inspection process of a sensor foreign substance detection device according to an embodiment of the present invention, FIG. 5 is a drawing illustrating an assembly area of ​​a sensor foreign substance detection device according to an embodiment of the present invention, and FIG. 6 is a drawing illustrating an assembly process of a sensor foreign substance detection device according to an embodiment of the present invention.

[0068] First, as shown in FIG. 3, when a sensor (S) is positioned at one end of the rail section (300), more specifically, at the settling space (101) of the stage (100) in the initial region, the rail section (300) can move the stage (100) from the initial region (301) to the inspection region (302).

[0069] If the above-described process is performed automatically, a separate control unit may be provided that senses the weight of the sensor (S) positioned on the stage (100), and when it is determined that the sensor (S) is positioned in the settling space (101), controls the rail unit (300) to move the stage (100) from the initial area (301) to the inspection area (302).

[0070] The above-described method is only one example to further explain the automation process and is not necessarily limited to what has been mentioned, and the additional mention of an example of applying the automation process in the drawings described below is only one example and is not intended to limit the embodiments of the present invention, so it should be understood as one exemplary embodiment and may not necessarily be limited thereto.

[0071] If the stage (100) is moved from the initial area (301) to the inspection area (302), the stage (100) is stopped so that the settling space (101), the sensor (S), the lens (L) and the light source (410) overlap in the vertical direction, and the light source (410) can irradiate light toward the sensor (S).

[0072] Here, a transmitting unit that irradiates light from a light source unit (410) and transmits image data of the sensor (S) to an external display may be further included, and when the operator determines that there is a foreign substance (F) on the sensor (S), the operator can determine whether the foreign substance (F) on the sensor (S) can be removed or not, and remove the foreign substance (F) or recover the sensor (S).

[0073] If the sensor (S) is recovered, the weight is reduced in the above-described automation process, so it is determined that the sensor (S) is recovered, and the rail unit (300) moves the stage (100) back to the initial area (301). If it is determined that the sensor (S) is not recovered within a preset time, the rail unit (300) can move the stage (100) from the inspection area (302) to the joining area (303).

[0074] At this time, as shown in FIG. 4, the stage (100) is stopped so that the light source (410), the lens (L), the mounting space (101), and the sensor (S) overlap in the inspection area (302), and a separate adhesive member (E) may be applied to the upper periphery of the sensor (S), and if a foreign substance (F) is located on the inside of the adhesive member (E), it may be judged as defective.

[0075] Here, the adhesive material (E) may be an epoxy resin of thermosetting plastic, i.e., epoxy, but this is only one exemplary material and may not necessarily be limited thereto.

[0076] When the foreign substance (F) described above is removed or the foreign substance (F) does not exist, as shown in FIG. 5, the rail unit (300) can move the stage (100) from the inspection area (302) to the joining area (303), and position the gripper (200) and the sensor (S) so as to overlap on the joining area (303).

[0077] More specifically, it may be desirable to stop in a state where the lens array (LA) is arranged to overlap the upper portion of the sensor (S), and in the state arranged as described above, the gripper (200) may be opened to position the lens array (LA) on the upper portion of the sensor (S), or the gripper (200) may be lowered to couple the lens array (LA) to the upper portion of the sensor (S).

[0078] Here, since the upper part of the sensor (S) moving to the bonding area (303) has been inspected for foreign substances (F) in the inspection area (302), the problem of discarding both the lens array (LA) and the sensor (S) due to defects occurring after the bonding process can be solved.

[0079] In addition, in the process of combining multiple lenses (L) forming a lens array (LA), it is difficult for separate foreign substances (F) to be introduced. This is because the lens array (LA) formed by stacking multiple lenses (L) and combining them has the advantage of being easy to remove and combine separate foreign substances (F) by using air. However, in the case of the sensor (S), even if the foreign substances (F) are removed using air, as described above, since the adhesive member (E) is applied to the peripheral side of the upper portion of the sensor (S), there may be a problem in that the foreign substances (F) do not come off the sensor (S) but stick to the adhesive member (E) and cause a defect.

[0080] Therefore, there may be an advantage in that the stage (100) is stopped in the inspection area (302) before the sensor (S) is combined with the lens array (LA) to inspect for foreign matter (F), and the foreign matter (F) is removed from the inspection area (302) to the combination area (303) or the sensor (S) without the foreign matter (F) is moved to significantly reduce the defect rate.

[0081] In case the above-described process is to be performed automatically, the positioning of the sensor (S) in the initial area (301) is performed through weight sensing, the positioning of the foreign substance (F) in the inspection area (302) is determined by comparing it with a captured image through separate deep learning to determine whether it is defective, and if the sensor (S) is recovered by the worker, it is determined that it has been removed through weight measurement, and the stage (100) is moved from the inspection area (302) to the initial area (301), and if the change in weight is within a preset range, it is determined that the sensor (S) is positioned, and the stage (100) can be moved from the inspection area (302) to the joining area (303).

[0082] In addition, a separate protrusion may be provided in the settling space (101) to position the sensor (S), or an additional camera sensor (S) may be provided in the light source unit (410) to check the position of the sensor (S) and stop the stage (100), and the present invention may not necessarily be limited to what has been mentioned.

[0083] That is, to briefly mention the movement path and process of the stage (100), it moves from the initial area (301) to the inspection area (302) and stops, and if the foreign substance (F) is removed or does not exist, it moves from the inspection area (302) to the joining area (303), and if the product is judged to be defective in the inspection area (302), it can return to the initial area (301) from the inspection area (302).

[0084] Meanwhile, reference may be made to FIGS. 7 to 9 to describe a device according to another embodiment of the present invention.

[0085] Specifically, FIG. 7 is a drawing for explaining the overall description of a sensor foreign substance detection device according to another embodiment of the present invention, FIG. 8 is a drawing for explaining a first area of ​​a sensor foreign substance detection device according to another embodiment of the present invention, and FIG. 9 is a drawing for explaining a second area of ​​a sensor foreign substance detection device according to another embodiment of the present invention.

[0086] First, as illustrated in FIG. 7, a device according to another embodiment of the present invention includes the stage (1100), gripper (1200), rail part (1300), and inspection part (1400) described above, and may further include a defect detection part (1000) between the inspection part (1400) and the gripper (1200).

[0087] In addition, the rail section (1300) is divided into an initial region (1301), an inspection region (1302), and a joining region (1303, 1304), and the joining region (1303, 1304) can be divided into a first region (1303) and a second region (1304).

[0088] To explain in more detail, as illustrated in FIG. 8, the stage (1100) is moved from the initial area (1301) to the first area (1303) with the sensor (S) positioned in the settling space (1101), and in the first area (1303), the presence of a foreign substance can be determined through the inspection unit (1400) as described above.

[0089] Here, when it is determined that a foreign substance is removed or absent in the first area (1303), the rail unit (1300) moves the stage (1100) into engagement in the first area (1303) and may not be stopped in the second area (1304).

[0090] In addition, as illustrated in FIG. 9, when the assembly (O) in which the lens array (LA) array and the sensor (S) are combined in the combination area (1303, 1304) is positioned in the settling space (1101) of the stage (1100), the rail unit (1300) moves the stage (1100) from the combination space to the second area (1304), and the defect detection unit (1000) irradiates light toward the assembly (O) positioned in the second area (1304) to finally determine whether there is a defect.

[0091] That is, to explain the movement path of the stage (1100), it can move from the initial area (1301) to the first area (1303) and stop, pass the second area (1304) from the first area (1303) and stop at the joining area (1303, 1304), and move from the joining area (1303, 1304) to the second area (1304) and stop.

[0092] However, as described above, the first region (1303) can detect only the sensor (S), and the second region (1304) can inspect only the combination (O).

[0093] In addition, when the assembly (O) needs to move back to the initial area (1301) to recover the assembly (O), in order to prevent the assembly (O) from being caught in the inspection section (1400), the first vertical length of the assembly (O) with respect to the first area (1303) may be smaller than the second length between the bottom surface of the inspection section (1400) and the upper surface of the stage (1100).

[0094] More specifically, since the first length between the bottom surface of the sensor (S) and the top of the lens array (LA) is smaller than the second length between the bottom surface of the inspection unit (1400) and the settling space (1101) of the stage (1100), the assembly (O) can be moved from the second area (1304) to the initial area (1301) without being caught by the lens array (LA).

[0095] Having described preferred embodiments of the invention, it will be apparent to those skilled in the art that the invention may be embodied in other specific forms without departing from the spirit or scope thereof, in addition to the embodiments described above.

[0096] Therefore, the above-described embodiments should be considered as illustrative rather than restrictive, and accordingly, the present invention is not limited to the above description but may be modified within the scope of the appended claims and their equivalents.

Claims

1. A stage in which a settling space is provided and a sensor is placed in the settling space; A gripper for holding a lens array to combine a plurality of lenses and the sensor; A rail section for moving the stage between one end and the other end; and It includes an inspection unit that is placed between one end and the other end of the rail section and irradiates light to the sensor, The above inspection unit irradiates light toward the settling space while the stage moves from one end of the rail to the other end, The above stage is a sensor foreign matter detection device that stops at least once during the process of moving through the above rail section.

2. In paragraph 1, At one end of the above rail section, the sensor is installed in the installation space, A sensor foreign matter detection device that stops at a position corresponding to the inspection section while moving from one end of the above rail section to the other end.

3. In paragraph 2, The above rail part, The initial area where the above sensor is installed in the above installation space; An inspection area in which the inspection unit irradiates light toward the sensor at a location corresponding to the inspection unit; and A sensor foreign matter detection device divided into a joining area where the lens array and the sensor are joined through the gripper.

4. In paragraph 3, The above initial area is provided at one end of the above rail section, The above-mentioned joining area is provided at the other end of the above-mentioned rail section, The above inspection area is a sensor foreign substance detection device located between the initial area and the bonding area.

5. In paragraph 4, The above inspection area is divided into a first area and a second area, In the first region, light is irradiated to the sensor through the inspection unit, In the second region, a sensor foreign matter detection device that irradiates light to the lens array and the sensor.

6. In paragraph 5, A sensor foreign matter detection device further comprising a defect detection unit disposed in the second region and irradiating light to the lens array and the sensor.

7. In paragraph 5, A sensor foreign matter detection device in which a first length from the bottom surface of the sensor to the top of the lens array in a state in which the lens array and the sensor are combined is shorter than a second length between the bottom surface of the inspection section and the top surface of the stage in the first region.

8. In paragraph 1, The above inspection department, A light source that irradiates light; A lens unit that disperses or gathers light irradiated from the light source unit; and A sensor foreign substance detection device including a fixing part that fixes the lens part to the light source part.

9. In paragraph 8, A sensor foreign matter detection device, wherein the lens unit includes a lens corresponding to at least one of a plurality of lenses forming the lens array.

10. In paragraph 8, The above light source unit is a surface light source sensor foreign body detection device.

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