JP6078826B2 - Line light irradiation device - Google Patents

Description

  The present invention relates to a line light irradiation apparatus for irradiating line light to a measurement object in order to inspect a surface shape such as a three-dimensional shape of the measurement object.

  As shown in Patent Document 1, a conventional three-dimensional shape measuring apparatus generates line-shaped slit light from a laser beam using a cylindrical lens, and irradiates the object to be measured with the slit light. Then, the three-dimensional shape measuring apparatus captures the bright line generated in the portion irradiated with the slit light from the direction different from the irradiation direction of the slit light, and performs image processing to perform the image processing. The three-dimensional shape is measured.

  However, when the object to be measured is irradiated with slit light generated from laser light, a speckle pattern is formed on the bright line generated in the portion irradiated with the slit light due to the coherence of the laser light. The obtained image includes speckle noise. For this reason, in order to improve the measurement accuracy of the three-dimensional shape of the object to be measured, it is necessary to perform dedicated image processing for removing speckle noise, resulting in a reduction in processing speed.

JP 2001-324313 A

  Therefore, the present invention has been made to solve the above problems all at once, and improves the measurement accuracy by irradiating the object to be measured with line light that does not generate speckle noise and removes speckle noise. Therefore, the main intended task is to make it possible to improve the processing speed of the inspection without the need for image processing.

  That is, the line light irradiation apparatus according to the present invention is a line light irradiation apparatus that irradiates the measurement object with line light in order to inspect the surface shape of the measurement object, and includes a plurality of LEDs as a light source, The first slit member, the light diffusion member, and the second slit member that are sequentially arranged from the plurality of LED sides, and the plurality of LEDs, the first slit member, the light diffusion member, and the second slit member are accommodated. A plurality of LEDs arranged in a straight line on an LED mounting substrate, and the first slit member is formed along the arrangement direction of the plurality of LEDs. The light diffusing member has a plurality of convex lens portions extending in a direction perpendicular to the arrangement direction of the plurality of LEDs, and the second slit member has the plurality of slits. It has a second slit formed along the arrangement direction of the ED, the casing is formed in a substantially rectangular parallelepiped, and emits line light that has passed through the second slit member from one end. It is characterized by that.

  If this is the case, since the line light is generated using the incoherent light emitted from the LED, it is possible to irradiate the object to be measured with line light that does not cause speckle noise. Measurement accuracy can be improved. In addition, it is possible to improve the processing speed of the inspection of the surface shape of the object to be measured by eliminating the need for image processing for removing speckle noise. Furthermore, since the first slit member is provided on the light emission side of the LED mounting substrate, it can be used as a slit light source in relation to the light diffusing member or the like regardless of variations in position due to the mounting accuracy of a plurality of LEDs. . In addition, since the light diffusion member having a plurality of convex lens portions extending along the direction orthogonal to the arrangement direction of the plurality of LEDs is provided on the light transmission side of the first slit member, the light has passed through the first slit. The light intensity distribution in the arrangement direction of the plurality of LEDs in the light can be made uniform. In addition, since the second slit member is provided on the light transmission side of the light diffusing member, the light diffuses as a light diffusing member in a direction perpendicular to the arrangement direction of the plurality of LEDs (leaks) and inexpensive light diffusion. Even if a member is used, the line light line width is defined by the second slit member, so that the edge of the line light can be made clear.

  When the distance between the line light irradiation device and the object to be measured is short, the line light that has passed through the second slit member is irradiated on the object to be measured while maintaining the parallelism, causing a problem in measurement accuracy. Absent. On the other hand, when the distance between the line light irradiation device and the object to be measured becomes long, the line light that has passed through the second slit member gradually spreads, the parallelism deteriorates, and the line light becomes dark. Therefore, in addition to the first slit member, the light diffusing member, and the second slit member that are sequentially arranged from the plurality of LED sides, it further includes a collimating lens, and the collimating lens includes the second slit. It is desirable that the light passing through the beam is made parallel. Thereby, it is possible to irradiate bright line light while maintaining parallelism even for a measurement object having a long distance from the line light irradiation device. In addition, since the second slit member is disposed between the light diffusing member and the collimating lens, unnecessary light incident on the collimating lens can be eliminated.

  It is possible to arrange the light diffusing member between the second slit member and the collimating lens, but in this case, the distance between the second slit and the collimating lens becomes large, and the inner surface of the housing There is a possibility that unnecessary light that is reflected by the light enters the collimating lens. Further, since the aberration of the collimating lens increases toward the end, it is necessary to bring the second slit member as close as possible to the collimating lens. Therefore, the light diffusing member is not provided between the second slit member and the collimating lens. In addition, it is conceivable to provide a light diffusing member on the light transmitting side of the collimating lens. In this case, the parallelism of the light collimated by the collimating lens deteriorates by passing through the light diffusing member. There is a risk of doing. From the above, it is preferable that the light diffusion member, the second slit member, and the collimating lens are arranged in this order from the upstream side of the optical path.

  Since a plurality of LEDs are intermittently arranged on the LED mounting substrate, the light intensity distribution in the arrangement direction of the plurality of LEDs in the light emitted from the plurality of LEDs becomes more uneven as the distance from the substrate is closer. Even if the light diffusing member is transmitted in such a large variation state, the effect of uniforming the light intensity distribution is small. For this reason, the light diffusing member and the second slit member are arranged on one end side of the casing, while the LED mounting substrate and the first slit member are arranged on the opposite side of the one end side of the casing. It is desirable that In this case, the light diffusing member is disposed at a position where the variation in the light intensity distribution in the arrangement direction of the plurality of LEDs in the light emitted from the plurality of LEDs is reduced, and the light intensity in the arrangement direction of the plurality of LEDs is determined. The distribution can be made more uniform.

  In the case where the first slit member, the second slit member, or the light diffusing member is slid and fixed in a slide groove or the like provided in the housing, the members are rattled by play of the slide groove, and the relative position to the LED or the The relative position between members changes. When measurement is performed using line light emitted from the line light irradiation apparatus having such a configuration, a measurement error occurs due to the backlash of the first slit member, the second slit member, or the light diffusion member. In order to solve this problem, a fixing member for fixing the first slit member, the second slit member, or the light diffusion member to the casing is provided, and the fixing member is the casing. A substantially U-shape that is fixed in contact with one of the left and right inner surfaces and the upper and lower inner surfaces of the first and second slit members, It is desirable that the light diffusing member is fixed.

  The light that has passed through the first slit of the first slit member travels while spreading toward the second slit member. For this reason, the amount of light passing through the second slit of the second slit member is reduced. In order to solve this problem, the light that collects the light that has passed through the first slit member between the first slit member and the second slit member toward the second slit. It is desirable that a lens is provided. If this is the case, the light passing through the first slit of the first slit member is condensed and directed toward the second slit, and the second slit in the light that has passed through the first slit. It is possible to increase the proportion of light incident on the. Accordingly, the ratio of light lost on the incident side of the second slit member is reduced and the amount of light passing through the second slit is increased, so that brighter line light can be irradiated onto the object to be measured.

  It is preferable that a condensing lens for condensing light emitted from the plurality of LEDs toward the first slit is provided between the plurality of LEDs and the first slit member. In this case, the light emitted from the plurality of LEDs is condensed and directed to the first slit, and the ratio of the light incident on the first slit in the light emitted from the plurality of LEDs is increased. Can be made. Therefore, the ratio of light lost on the incident side of the first slit member is reduced and the amount of light passing through the first slit is increased, so that brighter line light can be irradiated onto the object to be measured.

  In order to utilize the light emitted from the plurality of LEDs as effectively as possible, reflection processing is applied to the left and right inner surfaces of the inner surface of the housing facing the arrangement direction of the plurality of LEDs. If it is this, the light which spreads along the sequence direction of several LED can be used effectively.

  In order to prevent the light emitted from the plurality of LEDs from being reflected by the inner surface of the casing to become unnecessary light, there is no need to dispose on the upper and lower inner surfaces orthogonal to the arrangement direction of the plurality of LEDs on the inner surface of the casing. It is desirable to have a reflection process. If it is this, the light which spreads in the up-down direction orthogonal to the arrangement direction of several LED can be prevented from becoming unnecessary light. Further, the entire inner surface of the casing may be subjected to antireflection processing.

  According to the present invention configured as described above, the measurement accuracy is improved by irradiating the object to be measured with line light that does not cause speckle noise, and the image processing for removing speckle noise is not required and the inspection is performed. The processing speed can be improved.

The cross-sectional view which shows the internal structure of the line light irradiation apparatus in one Embodiment of this invention. The top view which shows the line light irradiation apparatus of the state which removed the upper cover in the same embodiment. The front view seen from the front side of the line irradiation apparatus of the embodiment. The front view which shows the 1st slit member and fixing member of the embodiment. The expanded sectional view which shows the 1st slit (2nd slit) of the embodiment. The perspective view of the fixing member of the embodiment. The front view which shows the light-diffusion member and fixing member of the embodiment, and the partial expanded sectional view of a light-diffusion member. The front view which shows the 2nd slit member and fixing member of the embodiment. The front view which shows the modification of a light-diffusion member. The partial expanded sectional view which shows the modification of a light-diffusion member. The schematic diagram which shows the line light irradiation apparatus of deformation | transformation embodiment. The cross-sectional view which shows the internal structure of the line light irradiation apparatus of deformation | transformation embodiment. The cross-sectional view which shows the internal structure of the line light irradiation apparatus of deformation | transformation embodiment.

100 ... Line light irradiation device 2 ... LED array substrate 21 ... LED
P ... Arrangement direction Q of the plurality of LEDs 21 ... Direction 3 orthogonal to the arrangement direction ... 1st slit member 3S ... 1st slit 4 ... Light diffusion member (lenticular lens)
41 ... convex lens part 5 ... second slit member 5S ... second slit 6 ... parallelizing lens 7 ... housing 8 ... heat sink 91 ... fixing member 92・ Fixing member 93 ・ ・ ・ Fixing member

  Hereinafter, an embodiment of a line light irradiation apparatus according to the present invention will be described with reference to the drawings.

  The line light irradiation apparatus 100 according to this embodiment irradiates slit light (hereinafter, line light L) to an object to be measured, and indicates a bright line generated in a portion irradiated with the line light L as an irradiation direction of the line light. The present invention is used in a surface shape measuring apparatus that measures the surface shape of the object to be measured by performing image processing by picking up images from different directions. Note that the surface shape is a concept that includes scratches, foreign objects, concave portions, or the like existing on the surface of the measurement object in addition to the whole or a partial three-dimensional shape of the measurement object.

  Specifically, as shown in FIGS. 1 to 3, this includes a plurality of LEDs 21, an LED array substrate 2 on which the plurality of LEDs are linearly arranged, and a first slit having a first slit 3 </ b> S. A member 3, a light diffusing member 4, a second slit member 5 having a second slit 5S, a collimating lens 6 for collimating light that has passed through the second slit 5S, an LED array substrate 2, A housing 7 that houses the first slit member 3, the light diffusing member 4, the second slit member 5, and the collimating lens 6, and that emits the line light L transmitted through the collimating lens 6 from one end (front surface). I have.

  The LED array substrate 2 has a substantially rectangular shape in plan view, and a plurality of LEDs 21 are arranged on a surface of an LED mounting substrate, which is a printed wiring board, in a substantially straight line with the optical axes aligned in a certain direction. It is a machine-mounted one. The LED 21 is a so-called power LED that can continuously pass a current of 200 mA or more. In this embodiment, the LED 21 is a surface-mounted type. For example, the LEDs 21 are arranged such that the LED elements are arranged in a substantially straight line at a predetermined interval.

  The LED array substrate 2 is disposed on the other end side (rear surface side) opposite to the one end side of the housing 7, and a heat sink 8 having a plurality of heat radiation fins F is provided on the back surface of the LED array substrate 2. Is provided. The plurality of heat radiation fins F are formed along the arrangement direction P of the plurality of LEDs 21.

  The first slit member 3 is provided on the light emission side of the LED array substrate 2 and has a substantially rectangular shape in a plan view as shown in FIG. 4, and extends along the array direction P of the plurality of LEDs 21. The first slit 3S is formed. As shown in FIG. 5, the first slit 3S is provided so that the optical axis C of the plurality of LEDs 21 arranged on the LED array substrate 2 passes through the center of the slit width W1 of the first slit 3S. . The longitudinal dimension of the first slit 3S along the array direction P of the plurality of LEDs is longer than the width in which the plurality of LEDs 21 are arrayed (the distance between the LEDs 21 at the left and right ends). The slit width of the first slit 3S is, for example, 0.2 mm.

  Further, the opening end portion forming the first slit 3S is cut out so that the light incident side becomes an inclined surface as shown in FIG. That is, the slit width of the first slit 3S is wide on the light incident side (inlet side) and gradually narrows toward the light passing side (outlet side), and the exit portion is formed by a flat surface. The width of light passing through one slit 3S is defined. As a result, light diffraction and loss can be reduced, so that the light that has passed through the first slit 3S can have a constant width (for example, 0.2 mm) with high accuracy.

  As shown in FIGS. 4 and 6, the first slit member 3 is fixed to the front surface or the rear surface of the fixing member 91 fixed in contact with the lower inner surface and the left and right inner surfaces of the housing 7. The fixing member 91 is substantially U-shaped when viewed from the front. In the present embodiment, the first slit member 3 has the four corners of the first slit member 3 screwed to the rear surface of the fixing member 91 (that is, the LED array substrate 2 side). The fixing member 91 is fixed to the left and right side walls and / or the lower wall of the housing 7 with screws.

  The light diffusing member 4 is provided on the light passage side of the first slit member 3 and has a substantially rectangular shape in plan view as shown in FIG. 7, and the light that has passed through the first slit 3S. Is a lenticular lens that makes the light intensity distribution along the arrangement direction P of the plurality of LEDs 21 uniform. The light diffusing member 4 is configured by arranging a plurality of convex lens portions 41 extending in the vertical direction Q orthogonal to the arrangement direction P of the plurality of LEDs 21 (longitudinal direction of the first slit 3S) in the arrangement direction P of the plurality of LEDs 21. Sheet-like. The convex lens portion 41 has a light emitting surface 41a in a semicircular shape (see a partially enlarged sectional view in FIG. 7), and each convex lens portion 41 is formed over and under the light diffusing member 4 and functions as a cylindrical lens. Demonstrate. The planar view shape of the light diffusing member 4 is the same shape as the planar view shape of the first slit member 3.

  As shown in FIG. 7, the light diffusion member 4 is fixed to the front surface or the rear surface of a fixing member 92 that is fixed in contact with the lower inner surface and the left and right inner surfaces of the housing 7. The fixing member 92 is substantially U-shaped when viewed from the front. In the present embodiment, the light diffusing member 4 has the four corners of the light diffusing member 4 screwed to the front surface of the fixing member 92 (that is, the side opposite to the LED array substrate 2). Thereby, the light diffusing member 4 is configured to be separated from the LED array substrate 2 as much as possible. The fixing member 92 has substantially the same shape as the fixing member 91. The fixing member 92 is screwed to the left and right side walls and / or the lower wall of the housing 7.

  The second slit member 5 is provided on the light transmission side of the light diffusing member 4 and has a substantially rectangular shape in a plan view as shown in FIG. 8, along the arrangement direction P of the plurality of LEDs 21. The second slit 5S is formed. The second slit 5S is configured such that the optical axis C of the plurality of LEDs 21 arranged on the LED array substrate 2 passes through the center of the slit width W2 of the second slit 5S. The longitudinal dimension of the second slit 5S along the arrangement direction P of the plurality of LEDs 21 is, as with the first slit 3S, determined from the width in which the plurality of LEDs 21 are arranged (the distance between the LEDs 21 at the left and right ends). Also long. Further, the slit width of the second slit 5S defines the short direction dimension of the line light L, and is 2 mm, for example. As shown in FIG. 5, the opening end portion that forms the second slit 5S is also cut out so that the light incident side becomes an inclined surface as in the case of the first slip 3S. The plan view shape of the second slit member 5 is substantially the same shape as the plan view shape of the first slit member 3. The fixing member 93 is screwed to the left and right side walls and / or the lower wall of the housing 7.

  As shown in FIG. 8, the second slit member 5 is fixed to the front surface or the rear surface of the fixing member 93 that is fixed in contact with the lower inner surface and the left and right inner surfaces of the housing 7. The fixing member 93 is substantially U-shaped when viewed from the front. In the present embodiment, the second slit member 5 has the four corners of the second slit member 5 screwed to the rear surface of the fixing member 93 (that is, the LED array substrate 2 side). Accordingly, the second slit member 5 is configured to be as close as possible to the collimating lens 6. The fixing member 93 has substantially the same shape as the fixing member 91, similarly to the fixing member 92.

  As shown in FIG. 1, the collimating lens 6 is provided on the light passage side of the second slit member 5, and the cylindrical convex lens 61 and the plurality of LEDs 21 having an equal cross-sectional shape in the arrangement direction P of the plurality of LEDs 21. It consists of a cylindrical concave lens 62 having an equal cross-sectional shape in the arrangement direction P. The collimating lens 6 collimates the light that has passed through the second slit 5S in the vertical direction Q that is orthogonal to the arrangement direction P of the plurality of LEDs 21. That is, the light emitted from the collimating lens 6 becomes band-shaped light. The collimating lens 6 is screwed to the housing 7 via a lens fixing member.

  As shown in FIG. 3, the housing 7 has a substantially rectangular parallelepiped shape when viewed from the front. Specifically, the housing 7 includes the first slit member 3, the light diffusion member 4, and the second slit member 5. It has a cross-sectional shape substantially similar to the shape in plan view. In the housing 7, the light diffusion member 4, the second slit member 5, and the collimating lens 6 are adjacently arranged in this order on one end side (front side), and the other end side that is the opposite side of the one end side. The LED array substrate 2 and the first slit member 3 are adjacently disposed adjacent to each other (on the rear surface side). Here, the LED array substrate 2 and the first slit member 3 are arranged close to each other, thereby preventing the line light from being distorted due to variations in the position of the LEDs on the LED array substrate 2. By arranging the second slit member 5 and the collimating lens 6 close to each other, the light incident on the collimating lens 6 is preferably restricted, and unnecessary light generated by reflection on the inner surface of the housing is collimated. Is prevented from entering. Since the aberration of the collimating lens 6 increases toward the end, the second slit member 5 is made as close as possible to the collimating lens 6. A transparent cover glass (cover member) 10 is provided at one end (front surface) of the housing 7 to prevent dust from entering the housing 7. This cover glass 10 becomes a light emission surface from which the line light L is emitted.

  According to the line light irradiation device 100 according to the present embodiment configured as described above, the line light L is generated by using the incoherent light emitted from the LED 21, and therefore, the line light that does not generate speckle noise. Since the object to be measured can be irradiated with L, the measurement accuracy can be improved. In addition, it is possible to improve the processing speed of the inspection of the surface shape of the object to be measured by eliminating the need for image processing for removing speckle noise. Furthermore, since the 1st slit member 3 is provided in the light emission side of the LED array board | substrate 2, it can be set as a slit light source in relation to the light-diffusion member 4 grade | etc.,. In addition, since the light diffusion member 4 is provided on the light transmission side of the first slit member 3, the light intensity distribution in the arrangement direction P of the plurality of LEDs 21 in the light that has passed through the first slit 3S is made uniform. Can do. In addition, since the second slit member 5 is provided between the light diffusing member 4 and the collimating lens 6, unnecessary light incident on the collimating lens 6 can be eliminated.

The present invention is not limited to the above embodiment.
For example, reflection processing may be performed on the left and right inner surfaces facing the arrangement direction P of the plurality of LEDs 21 on the inner surface of the housing 7, and non-reflection processing may be performed on the upper and lower inner surfaces orthogonal to the arrangement direction P of the plurality of LEDs 21. If it is this, the light inject | emitted from several LED can be used as much as possible, reducing unnecessary light as much as possible. Further, non-reflective processing may be applied to the entire inner surface of the housing 7.

  As the light diffusing member 4, in addition to the lenticular lens, as shown in FIG. 9, a lens diffusing plate having a plurality of convex lens portions 41 extending along the vertical direction Q orthogonal to the arrangement direction P of the plurality of LEDs 21 is used. Also good. This lens diffuser diffuses in the arrangement direction P of the plurality of LEDs 21 in the light that has passed through the first slit 3S, and makes the light intensity distribution along the arrangement direction P uniform. As shown in FIG. 9, the plurality of convex lenses 41 are not limited to those arranged in a staggered pattern, but may be arranged in a lattice pattern (matrix form) or randomly, for example.

  Further, the convex lens portion 41 of the light diffusing member 4 is not limited to the shape of the light emitting surface 41a being semicircular, and as shown in FIG. It may be a continuous wave shape, or may be a mountain shape such as a triangle as shown in FIG.

  Furthermore, as a plurality of LEDs, LEDs having the same wavelength range are used, and LEDs having different wavelength ranges such as red (R) LED, green (G) LED, and blue (B) LED are alternately used as shown in FIG. The LEDs that are linearly arranged and turned on may be configured to be switchable according to the type of the object to be measured. For example, as shown in FIG. 11, when a red (R) LED, a green (G) LED, and a blue (B) LED are alternately arranged, the red (R) LED is turned on, and the green (G) LED You may comprise so that it may switch according to the kind etc. of a to-be-measured object, etc. when turning on and blue (B) LED are turned on. When a conventional laser light source is used, it is necessary to prepare a slit for each RGB, and there is a problem that the apparatus becomes large. In this case, a common slit (first slit) may be used. As a result, the apparatus can be miniaturized.

In addition, as shown in FIG. 12, the line light irradiation device 100 may have a condensing lens 11 between the first slit member 3 and the second slit member 5.
The condensing lens 11 is provided along the first slit 3S and is a cylindrical lens. Light that passes through the first slit 3S and spreads in the vertical direction Q in the vertical direction Q toward the second slit 5S and passes through the first slit 3S by the condenser lens 11 The ratio of the light incident on the second slit 5S is increased. Thereby, the loss of light generated between the first slit member 3 and the second slit member 5 can be reduced, the light incident on the second slit 5S can be increased, and the brighter line light L can be generated. The object to be measured can be irradiated.
In order to prevent the light amount of the line light L from decreasing and to make the edge of the line light L clear, it is preferable that the condenser lens 11 is disposed as close as possible to the first slit member 3. For example, it is conceivable to arrange the condenser lens 11 at a position of about 0 to 5 mm from the first slit member 3.

In addition, as shown in FIG. 13, the line light irradiation device 100 may have a configuration in which the condenser lens 12 is provided between the plurality of LEDs 21 and the first slit member 3.
This condensing lens 12 is a cylindrical lens provided along the plurality of LEDs 21 so as to cover them. It is conceivable that the condenser lens 12 is made of silicone and has a recess that accommodates the plurality of LEDs 21. The condensing lens 12 condenses the light emitted from the plurality of LEDs 21 and spreading in the up-down direction Q in the up-down direction Q toward the first slit 3S, and the first in the light emitted from the plurality of LEDs 21. The ratio of light incident on the slit 3S is increased. Thereby, the loss of light generated between the plurality of LEDs 21 and the first slit member 3 can be reduced, the light incident on the first slit 3S can be increased, and the brighter line light L can be measured. Can be irradiated.
In order to prevent a decrease in the amount of line light L, it is preferable that the condenser lens 11 is disposed as close as possible to the plurality of LEDs 21. Note that the plurality of LEDs 21 themselves may have a lens structure that enhances directivity, such as the plurality of LEDs 21 being bullet-type LEDs 21.

  Further, the line light irradiation device 100 may include both the condenser lens 11 and the condenser lens 12 described above. If this is the case, it is possible to reduce both the light loss that occurs on the incident side of the first slit member 3 and the light loss that occurs on the incident side of the second slit member 5, so that the brighter line light L Can be irradiated to the object to be measured.

  In addition, it goes without saying that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

  As described above, according to the line light irradiation device of the present invention, the measurement accuracy is improved by irradiating the measurement object with line light that does not generate speckle noise, and image processing for removing speckle noise is unnecessary. As a result, the inspection processing speed can be improved.

Claims (9)

A line light irradiation device for irradiating the measurement object with line light in order to inspect the surface shape of the measurement object,
With a plurality of LEDs as a light source,
It has the 1st slit member, light diffusing member, and 2nd slit member arrange | positioned in order from the said some LED side, These these LED, 1st slit member, light diffusing member, and 2nd slit member are included. Has a housing to house,
The plurality of LEDs are linearly arranged on the LED mounting substrate,
The first slit member has a first slit formed along the arrangement direction of the plurality of LEDs,
The light diffusing member has a plurality of convex lens portions extending along a direction orthogonal to the arrangement direction of the plurality of LEDs, and diffuses light that has passed through the first slit in the arrangement direction,
The second slit member has a second slit formed along an arrangement direction of the plurality of LEDs;
The housing is formed in substantially rectangular parallelepiped state, and are not to emit the linear light that has passed through the second slit member from one end,
The line light irradiation device , wherein the slit width of the first slit is narrower than the slit width of the second slit . In addition to the first slit member, the light diffusing member, and the second slit member, which are sequentially arranged from the plurality of LED sides, further includes a collimating lens,
The line light irradiation device according to claim 1, wherein the collimating lens collimates light that has passed through the second slit.   The light diffusing member and the second slit member are disposed on one end side of the casing, while the LED mounting substrate and the first slit member are disposed on the opposite side of the one end side of the casing. The line light irradiation apparatus according to claim 1. A fixing member for fixing the first slit member, the second slit member or the light diffusion member to the housing;
The fixing member has a substantially U-shape that is fixed in contact with one of the left and right inner surfaces and the upper and lower inner surfaces of the housing,
The line light irradiation apparatus according to claim 1, wherein the first slit member, the second slit member, or the light diffusion member is fixed to a front surface or a rear surface of the fixing member.   The condensing lens which condenses the light which passed the said 1st slit toward the said 2nd slit between the said 1st slit member and the said 2nd slit member is provided. Line light irradiation device.   The line according to claim 1, wherein a condensing lens that collects light emitted from the plurality of LEDs toward the first slit is provided between the plurality of LEDs and the first slit member. Light irradiation device.   The line light irradiation device according to claim 1, wherein the inner surface of the housing is subjected to reflection processing on left and right inner surfaces facing the arrangement direction of the plurality of LEDs.   The line light irradiation apparatus according to claim 1, wherein non-reflective processing is performed on upper and lower inner surfaces orthogonal to an arrangement direction of the plurality of LEDs on the inner surface of the housing.   The line light irradiation apparatus according to claim 1, wherein the entire inner surface of the casing is subjected to antireflection processing.

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