Illumination device, method for manufacturing same, and image reading device

Abstract

An illumination device (2) is provided with an illumination housing (21) including: a plate (233) disposed with a circuit board (232) on which a light source element (231) is disposed; and a groove part (26) for guiding light emitted from the light source element (231) to the outside. A plurality of a first hole for position alignment and a second hole (52) for position fixing are formed in a placement surface of the illumination housing (21). A plurality of a third hole for position alignment and a fourth hole (62) for position fixing are formed in the plate (233). The plate (233) and the illumination housing (21) can be positioned by overlapping the first hole and the third hole. The plate (233) is fixed to the illumination housing (21) by a fixture (55) that passes through the second hole (52) and reaches the fourth hole (62).

Description

Illumination device, manufacturing method thereof, and image reading device

[0001] The present disclosure relates to an illumination device, a manufacturing method thereof, and an image reading device.

[0002] Image reading devices such as contact image sensors (CIS) are used in facsimiles, copiers, scanners, surface inspection machines, etc. The image reading device includes an illumination device that illuminates a medium to be read. As a measure to improve the luminance of the illumination device of the image reading device, there is a structure in which a reflection plate is arranged close to the LED, a diffusion plate is arranged on the light emitting surface, and light is guided to this diffusion plate (see Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2005-283563

[0004] In the illumination device of Patent Document 1, a substrate on which an LED is mounted is arranged via a heat dissipation grease on the surface opposite to the light emission port. With such a configuration, high accuracy must be ensured for the relative positions of the emitted light, the wall surface of the opening, and the LED. However, Patent Document 1 does not disclose a method for ensuring high accuracy. Therefore, the accuracy of the relative positions of the opening and the wall surface of the opening and the LED is low, it is difficult to obtain high illuminance, and there is a risk that high reading performance of the reading device cannot be obtained.

[0005] In addition, the length in the main scanning direction of recent image reading devices, so-called reading length, has been increasing. Therefore, it has become difficult to mount all the LEDs linearly on a single substrate. On the other hand, it is not easy to obtain a row of LEDs mounted at accurate positions from a plurality of substrates on which the LEDs are mounted.

[0006] The present disclosure has been made in view of the above problems, and an object thereof is to provide an illumination device capable of obtaining high illuminance and being easily manufactured, a manufacturing method thereof, and an image reading device using the illumination device.

[0007] To achieve the above objective, the lighting device according to this disclosure comprises a plate on which a plurality of circuit boards, each having a plurality of light source elements, are arranged; a lighting housing having a hollow portion for housing the plate; and a light output port for emitting light emitted from the light source elements arranged on the circuit boards mounted on the plate housed in the hollow portion. The mounting surface of the lighting housing has a plurality of first alignment holes and a second position fixing hole, and the plate has a plurality of third alignment holes and a fourth position fixing hole. Positioning between the plate and the lighting housing is possible by aligning the first and third holes, and the plate is fixed to the lighting housing by a fixing device that passes through the second hole and reaches the fourth hole.

[0008] According to this disclosure, the lighting device is easy to align and fix. Therefore, it is possible to easily and accurately position the light source element in the appropriate location. As a result, a lighting device with high illuminance can be obtained.

[0009] Figure 4 shows a perspective view of an image reading device according to an embodiment. Figure 5 shows an exploded side view of an image reading device according to an embodiment. Figure 6 shows a perspective view of an illumination device according to an embodiment. Figure 7 shows an exploded perspective view of an illumination device according to an embodiment. Figure 8 shows a cross-sectional view of the illumination frame shown in Figure 4, taken along the cutting line V-V. Figure 9 shows a cross-sectional view of the illumination frame shown in Figure 5, taken along the cutting line VI-VI. Figures (a) and (b) are a bottom view of the illumination frame according to an embodiment and a partially enlarged view thereof. Figure 9 shows a perspective view of an LED sub-assembly according to an embodiment. Figure 10 shows a cross-sectional view of the illumination device shown in Figure 3, taken along the cutting line X-X. Figure 10 shows how to insert an LED sub-assembly into the illumination frame according to an embodiment. Figure 10 shows a cross-sectional view of the cutting line XIII-XIII. Figure 10 shows a perspective view showing that a positioning pin is inserted to position the LED sub-assembly within the illumination frame according to an embodiment. Figure 10 shows a cross-sectional view of the cutting line XIII-XIII. Figure 11 shows a cross-sectional view of the LED sub-assembly being inserted into the illumination frame according to an embodiment. Figure 12 shows a cross-sectional view of the LED sub-assembly being inserted into the illumination frame according to an embodiment. Figure 13 shows a cross-sectional view of the LED sub-assembly being inserted into the illumination frame according to an embodiment. Figure 14

[0010] (Embodiments) Hereinafter, an illumination device, a method for manufacturing the same, and an image reading device according to embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals.

[0011] Figure 1 is a perspective view of an image reading device 100 according to an embodiment of the present disclosure. The image reading device 100 according to this embodiment is a contact image sensor (CIS). As shown in the figure, an xyz orthogonal coordinate system is set up in which the main scanning direction of the image reading device 100 is the x direction, the sub-scanning direction is the y direction, and the reading depth direction is the z direction, and is referenced as appropriate.

[0012] Figure 2 is an exploded side view of the image reading device 100.

[0013] As shown in Figures 1 and 2, the image reading device 100 comprises a CIS main body 1 (hereinafter referred to as the main body 1) and an illumination device 2 attached to the main body 1 by screws 3. Figure 2 shows the illumination device 2 in a state where the main body 1, the illumination device 2, and the screws 3 are separated.

[0014] The main unit 1 is an example of a reading unit that optically reads information from a reading medium containing image information, such as banknotes, securities, or general documents, i.e., from a document M. The illumination device 2 is a device that illuminates the area of ​​the document M that is to be read by the main unit 1.

[0015] As shown in Figure 2, the main body 1 has a convex shape in the z direction when viewed from the side and extends in the x direction.

[0016] The main unit 1 comprises a housing 11 with a convex shape in side view, a transparent body 12 positioned on the part of the housing 11 facing the original document M, an imaging optical system 13 that forms an optical image of the original document M that has passed through the transparent body 12, an image sensor 14 that converts the optical image formed by the imaging optical system 13 into an electrical signal, a circuit board 15 on which the image sensor 14 is mounted, another circuit board 16, a substrate support plate 17 that supports the circuit boards 15 and 16, a lens fixing plate 18 that supports the imaging optical system 13, and a frame 19 that supports the entire main unit 1.

[0017] The housing 11 is made of, for example, an aluminum extruded profile and is formed to be convex in the z direction and extending in the x direction. Inside the housing 11, a hollow section is formed to house the components, and an opening is formed in the part facing the document M to guide reflected light from the document M into the hollow section. The housing 11 has a dustproof function that blocks light entering the image sensor 14 from the outside and prevents dust and other debris from entering the imaging optical system 13 and the image sensor 14.

[0018] The transparent body 12 comprises a transparent plate-like member or transparent film made of resin, glass, etc., and is positioned on the opening and extends in the x direction. The transparent body 12 has a light-guiding function that directs reflected light from the original document M to the imaging optical system 13, and a dustproof function that prevents dust and other debris from entering the housing 11.

[0019] The imaging optical system 13 is installed within the hollow section, between the transparent body 12 and the image sensor 14. The optical axis AX1 of the imaging optical system 13 is positioned perpendicular to the reading surface (document surface) of the document M, and it images the reflected light from the document M onto the imaging surface of the image sensor 14. An array of rod lenses can be used as the imaging optical system 13.

[0020] The image sensor 14 converts the light from the image formed by the imaging optical system 13 into photoelectric signals and outputs an electrical signal. The image sensor 14 is composed of a sensor IC such as a CMOS sensor and is equipped with a light receiving section made of semiconductor chips, other drive circuits, etc. The image sensor 14 is fixed to the circuit board 15 with a fixing member such as an adhesive.

[0021] Circuit board 15 supports the image sensor 14, processes the electrical signal output by the image sensor 14, and transmits it to a higher-level device. Other circuit boards 16 perform other signal processing.

[0022] The circuit board support plate 17 is fixed to the circuit boards 15 and 16 with fastening materials such as adhesive, double-sided tape, and screws, and supports them. The circuit board support plate 17 is fixed to the frame 19.

[0023] The imaging optical system 13 is fixed to the lens fixing plate 18 by fixing members such as double-sided tape. The lens fixing plate 18 is fixed to the frame 19 by fixing members such as screws.

[0024] The frame 19 supports the housing 11, the substrate support plate 17, the lens fixing plate 18, etc. The lighting device 2 is fixed to the frame 19.

[0025] As shown in Figures 1 and 2, a pair of illumination devices 2 are attached to the main body 1 opposite each other, sandwiching the convex portion, by fixing members such as screws 3. The pair of illumination devices 2 illuminate the reading target position of the original document M. Note that the illumination devices 2 are not limited to a pair; one unit may also be used.

[0026] Figure 3 is a perspective view of one lighting device 2, and Figure 4 is an exploded view of one lighting device 2. As shown in Figure 4, the lighting device 2 comprises a lighting frame 21, a side plate 22, an LED sub-assembly 23, and a diffuser plate 24. It also includes the wiring cover 210 shown in Figure 1.

[0027] As shown in Figure 5, the lighting frame 21 has a roughly pentagonal y-z cross-section, extends in the x-direction, and is a frame that supports the entire lighting device 2. It is formed, for example, from an aluminum extruded profile. The lighting frame 21 is one embodiment of the lighting housing. Inside the lighting frame 21, a hollow portion 25 and a groove portion 26 are formed, both extending in the x-direction. As will be described later, the LED sub-assembly 23 is placed on the bottom surface of the hollow portion 25, i.e., the mounting surface. The groove portion 26 is composed of a pair of walls 44 facing each other, flanking a row of LEDs 231 placed on the LED sub-assembly 23. The pair of walls 44 are part of the lighting frame 21 and are integrally constructed with the lighting frame 21. The pair of walls 44 extend in the main scanning direction and the depth direction. The wall surfaces of the pair of walls 44 are, for example, parallel to each other. The groove portion 26 becomes a path for the illumination light emitted from the LEDs 231, i.e., an optical path. As shown in Figure 3, the hollow portion 25 is exposed on both end faces of the illumination frame 21 in the main scanning direction.

[0028] Figure 6 is a cross-sectional view of the lighting frame 21 shown in Figure 5, taken along the line VI-VI. As shown in Figure 6, the hollow portion 25 and groove portion 26 have reliefs 25a and 26a formed at both ends in the main scanning direction, sub-scanning direction, and depth direction to accommodate the power supply connector 235, which will be described later. The size and shape of the reliefs are such that they can accommodate the power supply connector 235. Details will be described later.

[0029] As shown in Figure 5, the lighting frame 21 has a projection 41 for fixing the lighting device 2 to the main body 1. Multiple screw holes 31 are formed in the projection 41 in the main scanning direction for fixing the lighting device 2 to the main body 1 with screws 3. The lighting device 2 is fixed to the main body 1 by pressing the outer surface 43 of the projection 41 against the convex part of the main body 1 and using screws 3 passed through the screw holes 31.

[0030] As shown in Figures 5 and 7(a) and (b), the back surface of the lighting frame 21, that is, the surface facing the diffuser plate 24, has through holes 51 for positioning the LED subassembly 23 (hereinafter referred to as positioning holes), through holes 52 for screwing the LED subassembly 23 (hereinafter referred to as fixing holes), taps 53 for screwing the wiring cover 210 shown in Figure 1, and notches 54 for pulling out the power cable (hereinafter referred to as pull-out holes). Taps 53 refer to holes with internal threads. Taps 53 may be through holes or closed holes. Positioning holes 51 are an example of a first hole, and fixing holes 52 are an example of a second hole.

[0031] From the viewpoint of environmental resistance, the outer surface 43 of the lighting frame 21 is preferably anodized. For the inner surfaces of the hollow portion 25 and groove portion 26 of the lighting frame 21, i.e., the walls 44, it is desirable to apply white anodizing or leave the surface untreated, i.e., leave the bare aluminum, in order to increase reflectivity. However, if the groove portion 26 is formed or modified by machining after the lighting frame 21 has been formed by extrusion molding, surface treatment must be performed after machining, which adds extra work time. Therefore, from the viewpoint of reducing work time, it is preferable to leave the surface untreated.

[0032] Single-sided tape 261 is attached to both ends of the lighting frame 21 in the main scanning direction, sealing the hollow portion 25 and the groove portion 26. A rigid side plate 22 is fixed to the end face of the lighting frame 21 on top of the single-sided tape 261 using fasteners such as screws and adhesive.

[0033] Each LED subassembly 23 shown in Figure 4 consists of a plurality of LEDs 231, which are an example of a light source element, an LED substrate 232 on which the plurality of LEDs 231 are arranged, and a base plate 233 on which the plurality of LED substrates 232 are arranged, as shown in Figure 8.

[0034] As shown in Figure 8, the multiple LEDs 231 are arranged in a straight line along the center line in the sub-scanning direction of the LED substrate 232. The multiple LEDs 231 are mounted on the wiring of each LED substrate 232 by soldering. The LED substrate 232 is an example of a circuit board on which light source elements are mounted.

[0035] Multiple LED boards 232 are arranged on a base plate 233 such that the multiple LEDs 231 arranged on them are aligned in a straight line on the center line in the sub-scanning direction. The power lines and ground lines of the multiple LED boards 232 are interconnected. In addition, a power supply connector 235 is provided at the end of the LED board 232 at the outermost end of each LED sub-assembly 23 to supply power to the multiple LEDs 231 contained in that LED sub-assembly 23. Power is supplied to the power supply connector 235 via wiring. The ends of this wiring are covered by a wiring cover 210.

[0036] To arrange multiple LED substrates 232 on the base plate 233, fixing taps are formed on the lower surface of each LED substrate 232, along the center line in the sub-scanning direction.

[0037] When the LED substrate 232 is placed on the base plate 233, one side of the double-sided tape is attached to the underside of the LED substrate 232, that is, the side facing the base plate 233, and the other side is attached to the base plate 233.

[0038] As shown in Figure 9, the base plate 233 has positioning holes 61, fixing holes 62, and substrate fixing holes 63 formed in a straight line along the center line in the sub-scanning direction.

[0039] The positioning holes 61 are formed on the back surface of the lighting frame 21, that is, on the surface facing the diffuser plate 24, at positions corresponding to the positioning holes 51. When fixing the LED subassembly 23 to the hollow portion 25 of the lighting frame 21, the positioning holes 61 and the positioning holes 51 of the lighting frame 21 are aligned, allowing the LED subassembly 23 to be positioned correctly on the lighting frame 21. As a result, the axis of the arrangement of the LEDs 231 coincides with the central axis AX2 in the sub-scanning direction of the groove portion 26 shown in Figure 5, and the position of each LED subassembly 23 in the main scanning direction also coincides with the specified position. In addition, the positions of the positioning holes 61, fixing holes 62, and substrate fixing holes 63 of the base plate 233 are also located on the central axis AX2 in the sub-scanning direction. The central axis AX2 corresponds to the midline of the pair of walls 44.

[0040] The fixing holes 62 in the base plate 233 are formed in a position that overlaps with the fixing holes 52 of the lighting frame 21 when the base plate 233 is aligned with the lighting frame 21, that is, when the positioning holes 61 and 51 are aligned. The fixing holes 62 are taps that form female threads. The base plate 233 is temporarily fixed in place when the positioning holes 61 and 51 are aligned with the lighting frame 21. Next, as shown in Figure 10, screws 55 are inserted into the fixing holes 52 on the back of the lighting frame 21 and screwed into the fixing holes 62. This allows the LED sub-assembly 23 to be positioned and fixed in the appropriate location.

[0041] The substrate fixing holes 63 in the base plate 233 shown in Figure 9 are through holes for fixing the LED substrate 232. The LED substrate 232 is fixed to the base plate 233 by passing a screw through the substrate fixing holes 63 and screwing it into a tap formed on the back of the LED substrate 232. If double-sided tape is present between the tap for fixing the LED substrate 232 and the substrate fixing holes 63 in the base plate 233, the screw should be passed through the double-sided tape and fixed to the tap.

[0042] The base plate 233 is an example of a plate for fixing the light source element to the illumination housing, the positioning hole 61 is an example of a third hole for aligning the plate, the fixing hole 62 is an example of a fourth hole for fixing the plate to the illumination housing, and the board fixing hole 63 is an example of a fifth hole for fixing the circuit board on which the light source element is mounted to the illumination housing.

[0043] As shown in FIG. 10, the width C of the groove portion 26 in the sub-scanning direction is set to be not less than the dimension D of the LED 231 in the sub-scanning direction and not more than the width E of the LED substrate 232 in the sub-scanning direction. This is to maximize the illuminance at the focal position P of the main body 1. Usually, the light emitted from the LED 231 spreads based on the emission characteristics of the LED 231. However, by setting the width C of the groove portion 26 of the illumination frame 21 in the sub-scanning direction within the above range, the light diffused in the sub-scanning direction is reflected by the wall 44 of the groove portion 26, and a part of the light reaches the focal position P of the CIS, so that the effect of increasing the illuminance at the focal position P can be obtained.

[0044] The diffusion plate 24 is fixed to the light exit port 29 of the illumination frame 21 by the double-sided tape 27. The diffusion plate 24 diffuses the light from the LED 231 and irradiates the original M. Further, the diffusion plate 24 has a dust-proof function of sealing the hollow portion 25 and the groove portion 26 to prevent the entry of dust and the like.

[0045] When using the illumination device 2 with an image reading device 100 that photographs specific subjects such as metal surfaces, ripple may occur in the captured image based on the radiation characteristics of the LEDs 231. One method to eliminate ripple is to increase the mounting density of the LEDs 231 in the main scanning direction and arrange the LEDs 231 at equal intervals. However, in this disclosure, in order to reduce the external size F of the illumination device 2 in the sub-scanning direction as shown in Figure 10, a structure is adopted in which the LEDs 231 and the taps for fixing the LED substrate 232 are arranged in a straight line in the main scanning direction. In this case, constraints arise on the spacing of the LEDs 231. To improve the ripple in the output waveform caused by this constraint, a diffuser plate 24 is fixed to the light output port 29 of the illumination device 2. Figure 11 shows a comparison image of output ripple (imaging result). When imaging a metal surface with and without the diffuser plate 24, a difference in output uniformity may appear due to the illumination, as shown in Figure 11. Therefore, in order to improve the uniformity of illumination, a diffuser plate 24 is preferable to be attached to the light output opening 29 of the lighting frame 21.

[0046] When the lighting device 2 is used for print inspection or the like, there is a risk of paper dust scattering from the original document M. If this dust enters the interior of the lighting device 2, the illuminance may change in the entire or a part of the main scanning direction, so it is necessary to prevent this. For this reason, the LED 231 needs to be housed in a closed space. Therefore, as shown in Figure 4, both ends of the lighting frame 21 are sealed on both sides with single-sided tape 261 cut to the shape of the lighting frame 21 and side plates 22, and the light emission opening 29 is sealed by fixing a diffuser plate 24 to it, preventing dust from entering the hollow part 25 and groove part 26 of the lighting frame 21.

[0047] When manufacturing the lighting device 2, as shown in Figure 12, two LED subassemblies 23 are prepared and inserted into the hollow section 25 from both sides of the main operating direction of the lighting frame 21. If two power supply connectors 235 are required for one lighting device 2 due to power supply capacity considerations, manufacturing becomes easier by adopting a configuration in which the LED subassembly 23 is divided in the middle, i.e., the configuration shown in Figure 12.

[0048] When the capacity of the lighting device 2 is small, one LED sub-assembly 23 may be prepared, a power supply connector 235 may be arranged at one end thereof, and the LED sub-assembly 23 may be inserted into the hollow portion 25 from an opening on one side in the main scanning direction of the lighting frame 21.

[0049] At the ends of the hollow portion 25 and the groove portion 26 of the lighting frame 21, escape portions 25a and 26a are provided in the main scanning direction, the sub-scanning direction, and the depth direction so as not to interfere with the power supply connector 235. However, with respect to the escape in the main scanning direction, as shown in FIG. 13, it is necessary to set it within a range that does not affect the adjacent LED 231'. This is to prevent a decrease in illuminance at the main scanning end of the lighting device 2.

[0050] In this embodiment, it is desirable to align the center in the sub-scanning direction of the groove portion 26 of the lighting frame 21 with the center in the direction of the column of the LEDs 231. This is because if the positions of the LEDs 231 in the sub-scanning direction vary, the uniformity of the illuminance of the lighting device 2 may decrease.

[0051] In this embodiment, a structure for accurately aligning the position in the sub-scanning direction of the LEDs 231 in the hollow portion 25 of the lighting frame 21 with the center in the sub-scanning direction of the groove portion 26 and the sub-scanning center of the LEDs 231 is presented.

[0052] First, the LED substrate 232 to which a plurality of LEDs 231 are soldered in the main scanning direction is screwed to the base plate 233. The center in the sub-scanning direction of the LEDs 231 and the center in the sub-scanning direction of the LED substrate 232 are designed and fixed to be coincident. When screwing the LED substrate 232 to the base plate 233, a jig or the like is used to align the center in the sub-scanning direction of the LED substrate 232 with the sub-scanning center of the base plate 233.

[0053] Next, as described above, the LED sub-assembly 23 is inserted into the hollow section 25 from both ends of the lighting frame 21 and fixed in place. Therefore, the LED sub-assembly 23 is fixed inside the hollow section 25 of the lighting frame 21, where visibility is poor. Consequently, a structure is needed to accurately determine the position of the LED sub-assembly 23 inside the lighting frame 21 in this poorly visible environment. For this reason, in this embodiment, the side plate 22 is assembled to the lighting frame 21, and the gap between the power supply cable and the outlet hole 54 is sealed with silicone resin or the like to prevent foreign matter from entering the inside of the lighting device 2.

[0054] Positioning holes 51 are pre-formed on the back surface of the lighting frame 21, that is, on the surface facing the diffuser plate 24, while positioning holes 61 are formed in the base plate 233 at the same locations as the positioning holes 51. Therefore, for example, by inserting a positioning pin 71, as shown in Figure 14, into the positioning holes 51 of the lighting frame 21 and the positioning holes 61 of the base plate 233, the position of the LED sub-assembly 23 in the hollow portion 25 of the lighting frame 21 can be easily and accurately determined. When inserting the positioning pin 71 into the positioning holes 51 and 61, care should be taken not to damage the double-sided tape placed between the LED substrate 232 and the base plate 233. Two or more positioning holes 61 are provided in the base plate 233 in the main scanning direction, and positioning holes 51 in the lighting frame 21 are provided at corresponding positions. To facilitate the insertion of the positioning pin 71, the entire positioning hole 61 of the base plate 233 or a part of the back side of the lighting frame 21 may be tapered.

[0055] The light emitted from the lighting device 2 is directed onto the main body 1 at an irradiation angle determined by the angle θ formed by the contact surface between the outer surface 43 of the projection 41 of the lighting frame 21 and the base plate 233 of the hollow portion 25 of the lighting frame 21. By changing the angle θ, the irradiation angle when illuminating the main body 1 can be arbitrarily changed.

[0056] Double-sided tape is present between the LED board 322 and the base plate 323. This is because the positioning holes 51 in the lighting frame 21 are through holes, and after the positioning pins 71 are removed, a cavity is created. This can cause dust to enter, so the LED board 232 is attached to the base plate 233 with double-sided tape, and the entry path is sealed with the tape to prevent foreign matter from entering the inside of the lighting device 2. It also serves as temporary fixing until the LED board 232 is completely fixed to the base plate 233 with screws 55. Therefore, it is desirable that there are no holes, indentations, etc. on the positioning holes 61 on the LED board 232 attached to the base plate 233.

[0057] As described above, the width C of the groove 26 of the illumination frame 21 in the sub-scanning direction is set to be greater than or equal to the dimension D of the LED 231 in the sub-scanning direction, and less than or equal to the substrate width E of the LED substrate 232 in the sub-scanning direction. This is to maximize the illuminance at the focal position P of the main body 1. Normally, the light emitted from the LED 231 spreads based on the radiation characteristics of the chip. However, in this embodiment, the sub-scanning width C of the groove 26 of the illumination frame 21 reflects the light diffused during sub-scanning, and a portion of it reaches the focal position P of the CIS, thereby increasing the illuminance at the focal position P. The experimental results are shown in Figure 15.

[0058] Figure 15 shows that when the width of the groove 26 exceeds the sub-scan dimension D of the LED 231, the brightness increases, and when it exceeds the sub-scan dimension E of the LED substrate 232, the output begins to decrease. This suggests that when the sub-scan dimension E of the LED substrate 232 is exceeded, even if the light emitted from the LED 231 is reflected by the walls of the groove 26, the amount of light that can reach the focal position P decreases, and the reflection from the white resist portion of the LED substrate 232 also decreases. This is also affected by the radiation angle of the LED 231, but it remains necessary to ensure that the sub-scan width C of the groove 26 is greater than or equal to the sub-scan width D of the LED 231.

[0059] Next, we will consider the surface treatment of the walls of the hollow portion 25 and groove portion 26 of the lighting frame 21. The lighting frame 21 is expected to extend about 1 m in the main scanning direction. Therefore, it is preferable to form it by aluminum extrusion. After that, surface treatment is often applied considering requirements such as surface scratch prevention and optical properties. In this disclosure, it is necessary to improve the brightness of the lighting device 2. Also, since the lighting frame 21 of the lighting device 2 is exposed as an external part, aesthetics (scratch prevention) is required. Therefore, as mentioned above, anodizing is preferable for the outer wall of the lighting frame 21. On the other hand, it is preferable for the hollow portion 25 of the lighting frame 21 to have a high reflectivity, and white anodizing or no treatment (exposed aluminum) is preferable. In order to achieve dustproof performance, the groove portion 26 of the lighting frame 21 needs to be machined after extrusion. Therefore, applying white anodizing after machining will increase manufacturing costs. For this reason, in this embodiment, it is preferable to leave at least the groove portion 26 without surface treatment. Figure 16 compares the brightness of the lighting frame 21 with and without black anodizing treatment on the hollow portion 25 and groove portion 26 under the same measurement conditions. It can be seen that the brightness of the untreated product is about twice that of the black anodized product. From this, it can be seen that the properties change significantly depending on the surface treatment of the hollow portion 25 and groove portion 26 of the lighting frame 21, and that no surface treatment is preferable.

[0060] As shown in Figure 17, a configuration in which part of the groove 26 is white anodized and other parts are left untreated is also conceivable, such as white anodizing the single-dotted line portion 26b and leaving the double-dotted line portion 26c untreated. Such a configuration can be obtained by the following process. First, the lighting frame 21 is extruded from aluminum, and the inner surface of the groove 26, including the single-dotted line portion 26b and the double-dotted line portion 26c, is white anodized. Then, the white anodized portion of the double-dotted line portion 26c is removed by machining, leaving it untreated. An increase in brightness can also be expected with such a configuration.

[0061] As described above, this embodiment makes it possible to improve the output brightness of the lighting device 2, easily ensure the necessary assembly precision, and improve workability. Furthermore, it has a simple dustproof structure, and under normal conditions, foreign matter will not enter the inside of the lighting device 2, preventing deterioration of its characteristics. Power is also supplied to the LEDs 231 from both ends of the lighting device 2, which is expected to prevent localized heat generation by dispersing the substrate arrangement and improve handling by making the power supply cable thinner. In addition, the assembly structure to the CIS body 1 and the structure housing the LED substrate 232 are integrated as the lighting frame 21, eliminating the need to connect them with screws or the like, and enabling miniaturization of the lighting device 2.

[0062] This disclosure allows for various embodiments and modifications without departing from the broad spirit and scope of this disclosure. Furthermore, the embodiments described above are for illustrative purposes only and do not limit the scope of this disclosure. In other words, the scope of this disclosure is indicated by the claims, not by the embodiments. Various modifications made within the scope of the claims and the equivalent significance of the disclosure are considered to be within the scope of this disclosure.

[0063] This application is based on Japanese Patent Application No. 2024-227825, filed on 24 December 2024. The entire specification, claims, and drawings of Japanese Patent Application No. 2024-227825 are incorporated herein by reference.

[0064] 1 CIS main unit (main body), 2 Illumination device, 3 Screw, 11 Housing, 12 Transparent body, 13 Imaging optical system, 14 Image sensor, 15 Circuit board, 16 Circuit board, 17 Board support plate, 18 Lens fixing plate, 19 Frame, 21 Illumination frame, 22 Side plate, 23 LED sub-assembly, 24 Diffuser plate, 25 Hollow section, 25a, 26a Relief, 26 Groove section, 29 Light output opening, 31 Screw hole, 41 Protrusion, 43 Outer surface, 51 Through hole (positioning hole), 52 Through hole (fixing hole), 53 Tap, 54 Notch for power cable outlet (outlet hole), 61 Positioning hole, 62 Fixing hole, 63 Board fixing hole, 71 Positioning pin, 100 Image reading device, 210 Wiring cover, 231 LED, 232 LED board, 233 Base plate, 235 Power supply connector, 261 Single-sided tape, P Focal position, C Sub-scan width, D Sub-scan width

Claims

1. A lighting device comprising: a plate on which multiple circuit boards, each having multiple light source elements, are arranged; a hollow portion housing the plate; and a light output port for emitting light emitted from the light source elements arranged on the circuit boards mounted on the plate housed in the hollow portion; wherein the mounting surface of the lighting device has multiple first alignment holes and second position fixing holes; the plate has multiple third alignment holes and fourth position fixing holes; the plate and the lighting device can be positioned by aligning the first and third holes; and the plate is fixed to the lighting device by fasteners that pass through the second holes and reach the fourth holes.

2. The lighting device according to claim 1, wherein a fifth hole for fixing the circuit board is formed in the plate.

3. The lighting device according to claim 2, wherein the center of the fifth hole in the plate and the center of the light source element mounted on the circuit board are positioned to coincide with the midpoint of a pair of walls formed to sandwich the light source element provided in the lighting housing.

4. The lighting device according to any one of claims 1 to 3, wherein the lighting housing has a metal base material exposed on some or all surfaces, extends to sandwich a row of light source elements, and comprises a pair of walls that form the light emission opening, and the pair of walls are provided integrally with the lighting housing.

5. The lighting device according to claim 4, wherein the distance between the pair of walls is greater than or equal to the width of the light source element and less than or equal to the width of the circuit board.

6. The lighting device according to any one of claims 1 to 5, wherein the circuit board is coated with a white resist and its surface faces the light output port.

7. The lighting device according to claim 6, wherein a light diffusing member is arranged at the light emission port.

8. The lighting device according to any one of claims 1 to 7, wherein a power supply connector for supplying power to the light source element via wiring on the circuit board is arranged on the plate, and the hollow portion of the lighting housing has a region for housing the power supply connector.

9. An image reading device comprising: a reading unit for reading an image on a medium; and an illumination device having the configuration described in any one of claims 1 to 8, connected to the reading unit, and illuminating the medium to be read.

10. A method for manufacturing a lighting device, comprising positioning and installing a plate on which multiple circuit boards, each having multiple light source elements, are fixed, into a lighting housing having a hollow portion and a light output port for emitting light emitted from the light source elements arranged on the circuit boards mounted on the plate and housed in the hollow portion, wherein the surface on which the plate is placed has a first hole for alignment and a second hole for fixing the plate, the plate has a plurality of third holes for alignment and a fourth hole for position fixing, the first hole and the third hole are aligned to position the plate and the lighting housing, and the plate is fixed to the lighting housing by passing a fixing member through the second hole in the lighting housing to reach the fourth hole in the plate.

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