Illumination device, light guide plate arrangement determination method, and printing system

Abstract

The present invention provides an illuminating device, a method for determining disposition of a light-guiding plate, and a printing system, in which the appropriate disposition of a light-guiding plate is defined according to the condition of the light-guiding plate. In an illuminating device provided with a light-guiding plate (32) that utilizes total reflection, the light-guiding plate is disposed at a position where the distance from an emission surface (35) to a region to be illuminated is greater than or equal to Lt, which is calculated by Lt = ((1 / 2)×(n1 / n2)×W) / tanθimax where W is the total length in the thickness direction of the light-guiding plate, n1 is the refractive index of the periphery of the light-guiding plate, n2 is the refractive index of the light-guiding plate, and θimax is the maximum incident angle on a first surface according to the number of times of reflection.

Description

[Technical Field]

[0001] The present invention relates to a lighting device, a method for determining the layout of a light guide plate, and a printing system. [Background technology]

[0002] In inkjet printing systems, in order to check the quality of printed matter and maintain good quality of printed matter, printed images and specific charts, etc. are read, and image processing technology is used to detect ink ejection deflection, printing defects, etc., and to correct density unevenness.

[0003] Unlike analog printing such as offset printing, digital printing such as inkjet printing systems can produce characteristic print defects such as minute streak defects and density unevenness caused by differences in the ejection characteristics of each nozzle. In digital printing, print defects are detected with high precision and corrected appropriately.

[0004] Furthermore, if printing can be done in a relatively short time, a relatively large number of prints can be made in a certain time, and relatively high profits can be obtained. There is also a demand for faster inkjet printing devices, and inkjet printing devices that can print at high resolution while reducing printing time to about one-half to one-third of conventional printing times have been developed.

[0005] Patent Document 1 describes an illumination device that is applied to reading devices such as digital copiers and image scanners. The illumination device described in this document includes an LED array in which multiple LEDs are arranged in an array, and uses a plate-shaped light guide plate to relatively increase the light utilization efficiency and achieve uniform illumination.

[0006] Patent Document 2 describes an illumination unit comprising an LED substrate on which a plurality of LEDs are arranged in an array and a light-guiding member that guides light emitted from the LEDs to an illuminated portion. The document also describes a layout of two illumination units when the ratio of the distance from the light-emitting surface of the light-guiding member to the illuminated portion and the length of the light-guiding member satisfies a specified condition. LED is an abbreviation for Light Emitting Diode. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-17951 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-147143 Summary of the Invention [Problem to be solved by the invention]

[0008] To accurately detect and appropriately correct printing defects such as minute streaks on printed materials transported at high speed, it is necessary to apply the required resolution when reading printed images or specific charts using a scanner, etc., and obtain a read signal with a relatively high S / N ratio. The "S" in S / N ratio stands for "Signal," and the "N" in S / N ratio stands for "Noise."

[0009] In a reading device such as a scanner, when the image sensor that reads an image is a line sensor with multiple reading elements arranged, the resolution in the direction in which the reading elements are arranged is fixed, whereas the resolution in the direction in which the printed material is transported is determined by the transport speed of the printed material and the reading cycle of the image sensor.

[0010] For example, to maintain the same resolution in the transport direction of a printed material when the transport speed of the printed material is doubled, the reading cycle of the image sensor must be halved. If the accumulation time of the reading element is approximately equal to the reading cycle, maintaining the same S / N ratio when the reading cycle is halved requires the same amount of accumulated charge, and the amount of light received by the image sensor must be doubled. For example, to double the amount of light received by the image sensor, the printed material must be illuminated with illumination light with twice the illuminance.

[0011] When the same image sensors are used, the light receiving sensitivity of the image sensors is the same, and a method for increasing the amount of light reaching the image sensors with the intention of making the amount of charge accumulation the same can be adopted in which light that does not contribute to reading is reflected using a mirror and guided to the irradiation position of the illumination light. A light guide plate made of highly transparent acrylic resin can be used as the mirror.

[0012] When a light guide plate is used, the amount of illumination light can be increased efficiently by utilizing the total reflection of light incident on the light guide plate. However, the appropriate distance from the exit surface of the light guide plate to the irradiation position of the illumination light varies depending on the conditions of the light guide plate, such as the size of the light guide plate and the conditions for total reflection of the light guide plate.

[0013] In the lighting device described in Patent Document 1, the size of the light guide plate is specified, and furthermore, the arrangement of the light guide plate specifies the angle of incidence of the light rays emitted from the light guide plate onto the contact glass, but the distance from the light guide plate's emission surface to the illuminated surface is not specified.

[0014] Patent Document 2 describes an arrangement of a lighting unit that reduces illuminance ripple under conditions where the illuminance ripple is large and the range of parameters is not normally selected, but does not describe the optimal arrangement of a light guide plate.

[0015] The present invention has been made in consideration of the above circumstances, and aims to provide an illumination device, a method for determining the placement of a light guide plate, and a printing system that specify the appropriate placement of a light guide plate according to the conditions of the light guide plate. [Means for solving the problem]

[0016] The lighting device according to the present disclosure includes a light source that emits light to illuminate an illumination target area, and a light guide plate having a first surface onto which the light emitted from the light source is incident, a reflective surface that is a reflective surface that reflects the light incident from the first surface one or more times and that has a direction intersecting with the first surface, and an exit surface that faces the first surface and has a direction intersecting with the reflective surface, wherein the light guide plate has a length direction defined as a direction from the first surface toward the exit surface, and a thickness direction defined as a direction of a relatively shorter side of two directions orthogonal to the length direction, wherein the total length of the light guide plate in the thickness direction is defined as W, the refractive index of the periphery of the light guide plate is defined as n1, and the refractive index of the light guide plate is defined as n2, and θ is a maximum angle of incidence on the first surface corresponding to a number of reflections equal to or less than a maximum number of reflections defined under a condition for total reflection of light incident on the light guide plate. imax When the distance from the light source to the illumination target area is L t ={(1 / 2)×(n1 / n2)×W} / tanθ imax L is calculated as t The lighting device has a light guide plate disposed at the following position.

[0017] According to the lighting device of the present disclosure, in a light guide plate that utilizes total reflection, the overall length of the light guide plate in the thickness direction is defined as W, the refractive index of the periphery of the light guide plate is defined as n1, the refractive index of the light guide plate itself is defined as n2, and the maximum angle of incidence on the first surface according to the number of reflections is defined as θ imax If the distance from the light source to the illumination target area is L t ={(1 / 2)×(n1 / n2)×W} / tanθ imax L is calculated as t The light guide plate is disposed at the following position: This defines an appropriate position of the light guide plate according to the conditions of the light guide plate.

[0018] In another aspect of the lighting device, the light guide plate may be positioned at a position where the distance from the exit surface to the target illumination area is equal to or greater than the maximum size of a member that enters the target illumination area or the maximum size of a member that is placed in the target illumination area.

[0019] According to this aspect, it is possible to avoid contact between the light guide plate and a member entering the illumination target area or a member placed in the illumination target area.

[0020] In the lighting device according to another aspect, when the total length of the light guide plate in the longitudinal direction is B, the distance from the light source exit surface to the illumination target area is L, and the number of reflections is C, the maximum incident angle θ imax is θ imax =arctan[{B+(LB)×(n2 / n1)} / (C×W)].

[0021] According to this aspect, the maximum incident angle θ is calculated by using the total length B of the light guide plate in the longitudinal direction, the distance L from the light source exit surface to the illumination target area, the refractive index n1 of the periphery of the light guide plate, and the refractive index n2 of the light guide plate. imax may be defined.

[0022] In the atmospheric environment, the refractive index n1 of the air can be applied as the refractive index n1 of the surroundings of the light guide plate.

[0023] The distance L from the light source emission surface to the illumination target area may be the shortest distance from the light source emission surface to the illumination target area.

[0024] In the lighting device according to another aspect, the critical angle of the reflecting surface is θ t In this case, the maximum number of reflections is C m =INT[{B+(LB)×(n2 / n1)} / (W×tanθ t )], where the number of reflections C is an integer equal to or greater than 1, and the maximum number of reflections C m The following integers may be defined:

[0025] According to this aspect, the total length B of the light guide plate in the length direction, the distance L from the light source emission surface to the illumination target area, the total length W of the light guide plate in the thickness direction, the refractive index n1 of the periphery of the light guide plate, the refractive index n2 of the light guide plate, and the critical angle θ of the reflective surface are t Using the maximum number of reflections C m The maximum number of reflections C m The number of reflections C can be determined based on the above.

[0026] In the lighting device according to another aspect, the incident angle to the first surface of the light guide plate is θ i In this case, the incident angle θ° on the reflecting surface is 90°-arcsin{(n1 / n2)×sinθ i} may be used.

[0027] According to this aspect, the refractive index n1 of the periphery of the light guide plate, the refractive index n2 of the light guide plate, and the incident angle θ i can be used to define the angle of incidence θ on the reflecting surface.

[0028] In the lighting device according to another aspect, the critical angle θ of the reflecting surface t is θ t =arcsin(n1 / n2).

[0029] According to this aspect, the critical angle θ of the reflecting surface is calculated by using the refractive index n1 of the periphery of the light guide plate and the refractive index n2 of the light guide plate. t may be defined.

[0030] In the lighting device according to another aspect, when the light guide plate is fixed, a non-reflecting position different from a reflecting position of the reflecting surface may be supported.

[0031] According to this aspect, it is possible to avoid impeding total reflection at the position where the light guide plate is supported when the light guide plate is fixed.

[0032] In an illumination device according to another aspect, if the number of reflections is one, the position between the reflection position and the light exit surface of the light guide plate may be supported when the light guide plate is fixed.

[0033] According to this aspect, the support position that can avoid the inhibition of total reflection can be a position between the reflection position and the light exit surface of the light guide plate.

[0034] In an illumination device according to another aspect, if the number of reflections is two or more, the non-reflection position where the distance between adjacent reflection positions is longest may be supported when the light guide plate is fixed.

[0035] According to this aspect, the support positions of the light guide plate that avoid the inhibition of total reflection can be positioned so that the distance between the reflecting positions is relatively long.

[0036] In an illumination device according to another aspect, if the number of reflections is two or more, when the light guide plate is fixed, if the distance between the reflection position closest to the exit surface of the light guide plate and the exit surface of the light guide plate is longer than the distance between adjacent reflection positions, a non-reflection position between the reflection position closest to the exit surface of the light guide plate and the exit surface of the light guide plate may be supported.

[0037] According to this aspect, the support positions of the light guide plate that avoid the inhibition of total reflection can be positioned so that the distance between the reflecting positions is relatively long.

[0038] In the lighting device according to another aspect, when the number of reflections is two or more, the light guide plate may be supported at a position where the light density is low when the light guide plate is fixed.

[0039] According to this aspect, the support position of the light guide plate that avoids impeding total reflection can be determined according to the density of light on the reflecting surface.

[0040] In the lighting device according to another aspect, the light emitting surface of the light guide plate may have a diffusive property for diffusing light emitted from the light emitting surface of the light guide plate.

[0041] According to this aspect, it is possible to irradiate the illumination target area with diffused light having a uniform light intensity distribution.

[0042] In a lighting device according to another aspect, the exit surface of the light guide plate may be a smooth surface, and a diffusing member that diffuses the light emitted from the exit surface of the light guide plate may be disposed between the exit surface of the light guide plate and the illumination target area.

[0043] According to this aspect, it is possible to irradiate the illumination target area with diffused light having a uniform light intensity distribution.

[0044] A method for determining the arrangement of a light guide plate according to the present disclosure is a method for determining the arrangement of a light guide plate in an illumination device including: a light source that emits light to illuminate an illumination target area; a light guide plate having a first surface onto which the light emitted from the light source is incident; a reflective surface that is a reflective surface that reflects the light incident from the first surface one or more times and has a direction intersecting with the first surface; and an exit surface that faces the first surface and has a direction intersecting with the reflective surface, wherein the light guide plate has a length direction defined as a direction from the first surface toward the exit surface, and a thickness direction defined as a direction of a relatively shorter side of two directions orthogonal to the length direction, and the total length of the light guide plate in the thickness direction is defined as W, the refractive index of the periphery of the light guide plate is defined as n1, and the refractive index of the light guide plate is defined as n2; and a maximum incident angle to the first surface corresponding to a number of reflections equal to or less than a maximum number of reflections defined from a condition for total reflection of light incident on the light guide plate is defined as θ. imax When the distance from the light source to the illumination target area is L t ={(1 / 2)×(n1 / n2)×W} / tanθ imax L is calculated as t This is a method for determining the placement of a light guide plate in the following position.

[0045] According to the light guide plate arrangement determination method of the present disclosure, it is possible to obtain the same effects as the lighting device of the present disclosure. The constituent elements of the lighting device of other aspects may be applied to the constituent elements of the light guide plate arrangement determination method of other aspects.

[0046] A printing system according to the present disclosure includes a printing device and a reading device that reads a printed material generated using the printing device, the reading device including a light source that emits light to illuminate an illumination target area of ​​the printed material, and a light guide plate that includes a first surface onto which the light emitted from the light source is incident, a reflective surface that is a reflective surface that reflects the light incident from the first surface one or more times and has a direction intersecting with the first surface, and an exit surface that faces the first surface and has a direction intersecting with the reflective surface, the light guide plate having a length direction defined as a direction from the first surface to the exit surface and a thickness direction defined as a direction of a relatively shorter side of two directions orthogonal to the length direction, the total length of the light guide plate in the thickness direction is defined as W, the refractive index of the periphery of the light guide plate is defined as n1, the refractive index of the light guide plate is defined as n2, and the maximum angle of incidence on the first surface corresponding to a number of reflections equal to or less than the maximum number of reflections defined from the condition for total reflection of light incident on the light guide plate is defined as θimax When the distance from the light source to the illumination target area is L t ={(1 / 2)×(n1 / n2)×W} / tanθ imax L is calculated as t This is a printing system in which the light guide plate is disposed at the following position.

[0047] The printing system according to the present disclosure can achieve the same effects as the lighting device according to the present disclosure. The components of the lighting device according to other aspects can be applied to the printing system according to other aspects.

[0048] In the printing system according to the present disclosure, the printing device may include an inkjet head that ejects ink using an inkjet method.

[0049] In another aspect, the printing system includes a reference member that serves as a reference when setting reading conditions for a reading device, a support member that supports the reference member, and a reference member moving device that moves the reference member between a reading position that is a reading position at which the reference member is read using the reading device and is included in an illumination target area, and a retracted position at which the reference member is retracted from the reading position, and the light guide plate may be positioned at a position where the distance from the emission surface to the illumination target area is equal to or greater than the maximum size of the support member.

[0050] According to this aspect, when the reference member used to adjust the reading device is advanced into the illumination target area, contact between the support member that supports the reference member and the light guide plate can be avoided.

[0051] In another aspect of the printing system, the reading device includes an image sensor that reads the printed material and an imaging lens that forms an optical image of the printed material on the image sensor, and the exit surface may have irregularities formed in an area corresponding to the numerical aperture of the imaging lens that diffuse the light emitted from the exit surface.

[0052] According to this aspect, it is possible to irradiate the illumination target area with diffused light having a uniform light intensity distribution. [Effects of the Invention]

[0053] According to the present invention, in a light guide plate utilizing total reflection, the total length of the light guide plate in the thickness direction is defined as W, the refractive index of the periphery of the light guide plate is defined as n1, the refractive index of the light guide plate itself is defined as n2, and the maximum angle of incidence on the first surface according to the number of reflections is defined as θ imax If the distance from the light source to the illumination target area is L t ={(1 / 2)×(n1 / n2)×W} / tanθ imax L is calculated as t The light guide plate is disposed at the following position: This defines an appropriate position of the light guide plate according to the conditions of the light guide plate. [Brief explanation of the drawings]

[0054] [Figure 1] FIG. 1 is a diagram showing the overall configuration of a reading device equipped with an illumination device according to an embodiment. [Figure 2] 2 is a view of the reading device shown in FIG. 1 as seen in the direction of the arrow A shown in FIG. [Figure 3] FIG. 3 is a functional block diagram showing the electrical configuration of the reading device shown in FIG. [Figure 4] FIG. 4 is a schematic diagram showing an example of the configuration of the lighting device shown in FIG. [Figure 5] FIG. 5 is a schematic diagram showing the case where the light density shown in FIG. 4 is increased. [Figure 6] FIG. 6 is a schematic diagram of an example in which light emitted from a light guide plate is incident on a diffusion plate. [Figure 7] FIG. 7 is a schematic diagram of a light beam when the number of reflections is one. [Figure 8] FIG. 8 is an explanatory diagram of the angle of incidence on the first surface of the light guide plate and the angle of incidence on the reflecting surface. [Figure 9] FIG. 9 is a schematic diagram of a light beam when the number of reflections is two or more. [Figure 10] FIG. 10 is a cross-sectional view of a light guide plate having a hexagonal cross-sectional shape. [Figure 11] FIG. 11 is a perspective view showing a schematic configuration of the reference plate moving device. [Figure 12] FIG. 12 is a schematic diagram showing the standby state of the reference plate. [Figure 13] FIG. 13 is a schematic diagram showing a state in which the reference plate has reached the reading start position. [Figure 14] FIG. 14 is a schematic diagram showing a state in which the reference plate has reached the central reading position. [Figure 15] FIG. 15 is a schematic diagram showing a state in which the reference plate has reached the reading end position. [Figure 16] FIG. 16 is a perspective view of the reference plate bracket. [Figure 17] FIG. 17 is a side view of the reference plate bracket. [Figure 18] FIG. 18 is a diagram showing the overall configuration of a printing system according to an embodiment. [Figure 19] FIG. 19 is a functional block diagram showing the electrical configuration of the printing system shown in FIG. [Figure 20] FIG. 20 is a block diagram showing an example of the hardware configuration of a control device applied to the printing system shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0055] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. In this specification, the same components are designated by the same reference numerals, and redundant explanations will be omitted where appropriate.

[0056] [Schematic configuration of a reading device equipped with an illumination device according to an embodiment] Fig. 1 is an overall configuration diagram showing the schematic configuration of a reading device equipped with an illumination device according to an embodiment. The reading device 10 shown in the figure includes an image receiving device 12, an illumination device 14, and a transport device 16. The image receiving device 12 and the illumination device 14 are housed in a housing 18 with an open bottom. Fig. 1 shows the housing 18 in a see-through manner.

[0057] The reading device 10 irradiates illumination light onto a printed matter P, which is the object to be read and is transported using a transport device 16, receives reflected light from the printed matter P using an image receiving device 12, and generates and outputs reading data for the printed matter P.

[0058] The image receiving device 12 includes an image sensor 20 and an imaging lens 22. The image sensor 20 may be a line sensor in which a plurality of light receiving elements are arranged in a line in the width direction of the printed matter P, which is perpendicular to the transport direction of the printed matter P, or an area sensor in which a plurality of light receiving elements are arranged two-dimensionally. The arrow labeled "transport direction" in FIG. 1 indicates the transport direction of the printed matter P, and the arrow labeled "width direction" indicates the width direction of the printed matter P. The same applies to FIGS. 4 to 10.

[0059] The term "orthogonal" is not limited to "strictly orthogonal" and may include the concept of "substantially orthogonal" in which two directions may be considered to be orthogonal even when the actual angle between them is less than 90° or more than 90°. Similarly, the term "parallel" is not limited to "strictly parallel" and may include the concept of "substantially parallel" in which two directions may be considered to be parallel even when they actually intersect.

[0060] 1 illustrates an image sensor 20 in which a plurality of light receiving elements are arranged over a length that is shorter than the entire width of the printed matter P. Note that the illustration of the plurality of light receiving elements is omitted. Also, the line segment labeled OA in FIG. 1 indicates part of the optical axis of the imaging lens 22.

[0061] The imaging lens 22 forms an optical image of the printed matter P on the image sensor 20. A reduction optical system is applied to the imaging lens 22. This makes it possible to read the entire width of the printed matter P in the width direction at once using the image sensor 20, which has a reading length shorter than the entire width of the printed matter P in the width direction.

[0062] The illumination device 14 includes two LED light sources 30 and two light guide plates 32. One LED light source 30 and the other LED light source 30 are disposed symmetrically with respect to the reading line TL of the image receiving device 12 in the transport direction of the printed matter P. Similarly, one light guide plate 32 and the other light guide plate 32 are disposed symmetrically with respect to the reading line TL of the printed matter P in the transport direction of the printed matter P.

[0063] The reading line TL is a reading target position of the image sensor 20 provided in the image receiving device 12. The reading line TL has a length in the width direction of the printed matter P that is equal to or greater than the entire length of the printed matter P. In the transport direction of the printed matter P, the reading line TL is disposed at a position where a different position on the printed matter P is read for each reading cycle of the image sensor 20 as the printed matter P is transported by a length determined for each reading target in accordance with instructions from the reading control unit. The reading control unit is indicated by the reference numeral 106 and is shown in FIG. 3.

[0064] Each of the two LED light sources 30 and the two light guide plates 32 illuminates the printed matter P obliquely with respect to the normal to the printed matter P. Each of the two LED light sources 30 and the two light guide plates 32 is oriented such that the optical axis faces the reading line TL.

[0065] The LED light source 30 has a structure in which a plurality of LED elements 34 are arranged along the width direction of the LED light source 30. The plurality of LED elements 34 are mounted on an LED substrate 36. The LED substrate 36 includes electrical wiring that is electrically connected to the plurality of LED elements 34.

[0066] The LED elements 34 may be arranged in a single row or in a two-dimensional arrangement. Examples of two-dimensional arrangements include a two-row zigzag arrangement and a matrix arrangement. Fig. 1 illustrates an LED light source 30 in which the LED elements 34 are arranged over a length longer than the entire width of the printed matter P. The same configuration may be applied to one LED light source 30 and the other LED light source 30.

[0067] The light guide plate 32 shown in FIG. 1 has a rectangular parallelepiped shape and has a length direction, a width direction, and a thickness direction. The length direction, width direction, and thickness direction are perpendicular to each other. In the light guide plate 32 shown in the figure, the length direction is the direction from the LED light source 30 toward the reading line TL, and the width direction is parallel to the width direction of the LED light source 30. The thickness direction is perpendicular to the length direction of the light guide plate 32 and also perpendicular to the width direction of the light guide plate 32. In other words, of the two directions perpendicular to the length direction of the light guide plate 32, the direction of the relatively shorter side is the thickness direction, and the direction of the relatively longer side is the width direction.

[0068] The total width of the light guide plate 32 is equal to or greater than the total width of the LED light source 30, and the total length of the light guide plate 32 is less than the distance from the emission surface of the LED light source 30 to the reading line TL.

[0069] The light guide plate 32 has a first surface onto which the illumination light emitted from the LED light source 30 enters and an exit surface from which the illumination light is emitted onto the printed matter P, and functions as a mirror that reflects the illumination light emitted from the LED light source 30 that does not contribute to reading when the light guide plate 32 is not positioned, towards the vicinity of the reading line TL on the printed matter P.

[0070] 1 may have the same configuration and the same arrangement as the other light guide plate 32. Details of the structure of the light guide plate 32 and the arrangement of the light guide plate 32 will be described later.

[0071] The transport device 16 includes upstream transport rollers 40, background rollers 42, and downstream transport rollers 44. The upstream transport rollers 40, background rollers 42, and downstream transport rollers 44 are arranged in this order from the upstream side along the transport direction of the printed matter P.

[0072] The upstream transport rollers 40 receive the printed material P and send it to the background rollers 42. The background rollers 42 support the printed material P on the reading line TL and transport the printed material P along the transport direction of the printed material P. The downstream transport rollers 44 eject the printed material P transported from the background rollers 42 from the reading device 10.

[0073] The surface of the background roller 42 that supports the printed material P has a color and surface treatment that does not affect the reading of the printed material P using the image receiving device 12.

[0074] The upstream transport rollers 40, the background rollers 42, and the downstream transport rollers 44 are each connected to a rotating shaft of a motor, and rotate in response to the rotation of the rotating shaft of the motor. Note that the motors connected to the upstream transport rollers 40, etc. are not shown in the drawings.

[0075] The reading device 10 includes a reference plate 50 and a reference plate moving device 52. The reference plate 50 is a member that is read by the image sensor 20 when setting the reading conditions of the image sensor 20. The reference plate 50 may be a white reference plate whose surface that is to be read by the image sensor 20 is painted with white paint.

[0076] The reference plate moving device 52 includes a moving mechanism 54 and a motor 56. The moving mechanism 54 supports the reference plate 50 so that it can move freely between a retracted position of the reference plate 50 and a reading position of the reference plate 50. The moving mechanism 54 is connected to the rotation shaft of the motor 56, and moves the reference plate 50 in response to the operation of the motor 56.

[0077] The reference plate 50 described in the embodiment is an example of a reference member, and the reference plate moving device 52 described in the embodiment is an example of a reference member moving device.

[0078] The movement mechanism 54 includes a guide groove bracket 60, a drive arm 62, and a drive force transmission shaft 64. The guide groove bracket 60 is disposed on the outside of both ends in the width direction of the lighting device 14, and supports the drive arm 62 so as to be freely movable, and supports the drive force transmission shaft 64 so as to be rotatable.

[0079] The guide groove bracket 60 is formed with a first guide groove 66. The first guide groove 66 penetrates the guide groove bracket 60 in the thickness direction. The first guide groove 66 movably supports a reference plate bracket 70, which supports the reference plate 50, using a first guide pin 68 and a second guide pin 74.

[0080] The drive arm 62 is connected to the rotation shaft of the motor 56. One drive arm 62 and the other drive arm 62 are connected using a drive force transmission shaft 64. The drive arm 62 swings in response to the operation of the motor 56. A second guide groove 72 is formed in the drive arm 62. The second guide groove 72 movably supports the reference plate bracket 70 using a second guide pin 74 at the position where it intersects with the first guide groove 66 in response to the swing of the drive arm 62.

[0081] The reference plate 50, which is supported by the reference plate bracket 70, moves between a retracted position and a reading position in response to the operation of the motor 56. Fig. 1 shows the reference plate 50 in the retracted position.

[0082] Fig. 2 is a view of the reading device shown in Fig. 1 as seen from the arrow A direction shown in Fig. 1. The direction penetrating the paper surface of Fig. 2 is the width direction of the printed matter P, the width direction of the LED light source 30, and the width direction of the light guide plate 32. Note that Fig. 2 does not show some of the components shown in Fig. 1. Also, Fig. 2 shows the light guide plate 32 hidden by the guide groove bracket 60, the light emitted from the light guide plate 32, and the like, as being visible when viewed through the guide groove bracket 60.

[0083] 2 shows the state in which the reference plate 50 has moved to the reading position and stopped. The reference plate 50 is illuminated using the illumination device 14, and the surface of the reference plate 50 is read using the image receiving device 12. FIG. 2 also shows a schematic diagram of the illumination light illuminating the reference plate 50.

[0084] The illumination device 14 emits illumination light that provides a specified range of illuminance on the printed matter P, which is the object to be read, for an illumination target area that has a length equal to or greater than the overall width of the printed matter P in the width direction of the printed matter P and a specified length in the transport direction of the printed matter P. The illumination target area is indicated by the symbol AI in FIG. 4.

[0085] [Electrical configuration of the reading device] Fig. 3 is a functional block diagram showing the electrical configuration of the reading device shown in Fig. 1. The reading device 10 includes a system control unit 100. The system control unit 100 controls the reading device 10 in an overall manner.

[0086] The reading device 10 includes a transport control unit 102. The transport control unit 102 controls the operation of the transport device 16 in response to a command signal transmitted from the system control unit 100. For example, the transport control unit 102 controls the transport speed of the printed matter P, etc.

[0087] The reading device 10 includes an illumination control unit 104. The illumination control unit 104 controls the operation of the illumination device 14 in response to a command signal transmitted from the system control unit 100. For example, the illumination control unit 104 controls the amount of illumination light emitted from the illumination device 14.

[0088] The reading device 10 includes a reading control unit 106. The reading control unit 106 controls the operation of the image receiving device 12 in response to a command signal transmitted from the system control unit 100. For example, the reading control unit 106 controls the operation of the image sensor 20.

[0089] The reading device 10 includes a reference plate movement control unit 108. The reference plate movement control unit 108 controls the operation of the reference plate moving device 52 in response to a command signal sent from the system control unit 100.

[0090] The reading device 10 includes an information acquisition unit 120. The information acquisition unit 120 acquires various types of information applied to the reading device 10. The system control unit 100 generates command signals to various control units based on the various types of information acquired using the information acquisition unit 120.

[0091] The reading device 10 includes a memory 122. The memory 122 stores various pieces of information acquired using the information acquisition unit 120. The memory 122 stores programs that realize various functions of the reading device 10. The memory 122 stores various parameters used when executing the programs.

[0092] [Hardware configuration to realize the electrical configuration of the reading device] The electrical configuration of the reading device 10 shown in Fig. 2 is realized using a computer. That is, a processor provided in the computer executes instructions of a program stored in a memory to realize various functions of the reading device 10.

[0093] [Issues with reading devices] 1 and the like has a problem of wanting to increase the amount of light that reaches the image sensor 20. To solve this problem, the following methods can be considered.

[0094] (1) Increasing the amount of light emitted from the LED element 34.

[0095] (2) Increasing the number of LED elements 34 even if the LED elements 34 have the same amount of emitted light.

[0096] (3) The light emitted from the LED light source 30 is condensed using a condenser lens or the like.

[0097] (4) The LED light source 30 is brought closer to the reading line TL.

[0098] (5) Decrease the F-number of the imaging lens 22. The F-number is the focal length divided by the lens diameter.

[0099] (6) Of the light emitted from the LED light source 30, the light that does not contribute to reading is reflected by a mirror and irradiated onto the reading line TL.

[0100] The above (1) to (6) each have the following issues.

[0101] Issue (1) above Possible methods for increasing the amount of light emitted from the LED element 34 include using an LED element 34 with high luminous efficiency or increasing the current supplied to the LED element 34. For example, the theoretical limit of the luminous efficiency of a white LED that combines a blue LED chip and a phosphor is 260 to 300 lumens per watt, but LEDs that exceed this limit of 200 lumens per watt have already been developed, which means that the luminous efficiency is approaching its limit.

[0102] Furthermore, LEDs with high luminous efficiency do not increase their maximum luminous intensity in proportion to their luminous efficiency, but rather increase their luminous efficiency in the range of relatively small luminous intensities, and this does not necessarily mean that the total luminous flux increases and the illuminance increases.

[0103] Generally, LEDs with high luminous efficiency are expensive, and using LEDs with high luminous efficiency results in a significant increase in costs. Furthermore, increasing the amount of light emitted increases the current supplied, which promotes heat generation in the LED, and there is also the issue that luminous efficiency decreases if the LED is used without sufficient cooling. Furthermore, there is also the issue of the cost involved in cooling the heated LED.

[0104] Issue (2) above By increasing the number of LED elements 34, it is possible to increase the illuminance of the illumination light on the reading line TL in proportion to the number of LED elements 34, but the total amount of heat generated by all of the LED elements 34 also increases proportionally. This then poses the same problem as in (1) above, in that it increases the cost of cooling.

[0105] Furthermore, even if the number of LED elements 34 is increased, the LED light source 30 must be able to be placed inside the reading device 10. However, for example, if the number of LED elements 34 is doubled in order to double the amount of light emitted, there is a concern that it may become difficult to place the LED light source 30 inside the reading device 10.

[0106] Issue (3) above The method of using a condenser lens to condense the light emitted from the LED light source 30 onto the reading line TL is common and widely used. When a large printed matter P, such as a printed matter P with a width of 600 mm to 1200 mm, is to be read, it is difficult to irradiate the printed matter P with illumination light without causing significant unevenness in the illumination light across the entire width.

[0107] When using a condenser lens or the like to condense light from as many LED light sources 30 as possible, the numerical aperture of the condenser lens must be relatively large. Also, to relatively increase the illuminance of the illumination light at the reading line TL, the focal length of the lens must be relatively short, and the light must be condensed into a relatively narrow range.

[0108] Aspherical condenser lenses and rod lenses have been put to practical use as condenser lenses that meet the above conditions, but to illuminate a large print P, such as one with a width of 600 mm to 1200 mm, a condenser lens with a length equivalent to the width of the print P is required. Such long lenses pose challenges in terms of lens manufacturing accuracy and lens installation accuracy.

[0109] Issue (4) above When the LED light source 30 is an LED array having a plurality of LED elements 34, the light emitted from each LED element 34 is strongest in front of the LED element 34 and becomes weaker as it moves diagonally. When the LED light source 30 is brought closer to the reading line TL, the unevenness of the illuminance on the reading line TL becomes relatively large due to the distribution of the light emitted by each LED element 34.

[0110] Issue (5) above The aperture of the imaging lens 22 shown in FIG. 1 is opened to an F value of (1 / 2). 1 / 2 Although it is possible to double the aperture of the imaging lens 22 to make the amount of charge stored in the image sensor the same, this may result in a relatively shallow depth of focus or large aberrations, which is not a desirable method when reading printed matter P or the like at high resolution.

[0111] Issue (6) above When using a mirror to reflect light, deviations in the angle of the mirror surface or the position of the mirror can result in deviations in the position illuminated by the reflected light, so it is necessary to support the mirror with high precision.

[0112] The illumination device 14 provided in the reading device 10 described in this embodiment is based on the method (6) above, and uses a plate-like member made of highly transparent acrylic resin as a mirror to create a light guide plate 32, and uses total reflection of the light guide plate 32 to efficiently reflect light and illuminate the printed matter P.

[0113] [the purpose] In an illumination device 14 applied to a reading device 10 that uses a light guide plate 32 to illuminate a printed matter P, which is an object to be read, with diffused light from an LED light source 30 as illumination light, and that moves a reference plate 50 in and out relative to a reading line TL, the light guide plate 32 is configured to be positioned a specified distance from the reading line TL and realizes efficient use of illumination light using total reflection, and a method for fixing the light guide plate 32 that suppresses the effect on total reflection.

[0114] [Detailed description of lighting equipment] Fig. 4 is a schematic diagram showing an example of the configuration of the lighting device shown in Fig. 1. The direction penetrating the paper surface of Fig. 4 is the width direction of the LED light source 30 and the width direction of the light guide plate 32.

[0115] 4 illustrates an example of an LED light source 30 having a point light source such as an LED element 34. The light source applied to the lighting device 14 may be a line light source, a diffuse light source having a relatively small light-emitting surface, or a light source in which diffuse light sources having a relatively small light-emitting surface are arranged two-dimensionally. "Relatively small" means that the size in the width direction of the light guide plate 32 is equal to or smaller than the first surface 33 of the light guide plate 32, which is the surface into which light enters.

[0116] An illumination target area AI on the printed matter P is defined for the lighting device 14, and the distance between the LED light source 30 and the illumination target area AI is also defined. The light guide plate 32 is disposed between the LED light source 30 and the illumination target area AI. The light guide plate 32 has a reflective surface 32A that totally reflects at least a portion of the incident light.

[0117] Figure 4 shows a schematic diagram of light rays calculated using ray tracing. In order to make the light rays easier to see, the density of the light rays has been reduced and representative light rays representing the light irradiated from the LED light source 30 to the illumination target area AI via the light guide plate 32 are shown.

[0118] The schematic diagram of light rays calculated using ray tracing of the light guide plate 32 shown in Figure 4 is a schematic illustration of light rays at an arbitrary cross section applied to a cross-sectional line along the length direction of the light guide plate 32.

[0119] 4 is made of acrylic resin and has a refractive index of 1.49. The total length B of the light guide plate 32 in the length direction may be 40 mm, and the total length W of the light guide plate 32 in the thickness direction may be 4.0 mm.

[0120] The distance L from the light emitting surface 35 of the LED light source 30 to the illumination target area AI is 48.75 mm, the distance from the light emitting surface of the LED light source 30 to the first surface 33 of the light guide plate 32 is 2.25 mm, and the distance L from the light emitting surface 35 of the light guide plate 32 to the illumination target area AI is 1.25 mm. e The distance L from the light emitting surface 35 of the LED light source 30 to the illumination target area AI may be the shortest distance from the light emitting surface 35 of the LED light source 30 to the illumination target area AI. The distance L from the light emitting surface 35 of the light guide plate 32 to the illumination target area AI may be the shortest distance from the light emitting surface 35 of the LED light source 30 to the illumination target area AI. e The same is true for .

[0121] In the calculation example of the light ray shown in FIG. 4, the light R that reaches the reading line TL from the LED light source 30 without being reflected by the reflecting surface 32A of the light guide plate 32 is a In addition, light R that is reflected once on the reflecting surface 32A of the light guide plate 32 exists. b and light R reflected twice by the reflecting surface 32A of the light guide plate 32. c reaches the reading line TL.

[0122] In addition, among the light reflected twice by the reflecting surface 32A of the light guide plate 32, light R having a relatively large angle of incidence on the reflecting surface 32A is d passes right at the edge of the exit surface 35 of the light guide plate 32 and reaches a position in the illumination target area AI that is distant from the reading line TL.

[0123] Here, the angle of incidence on reflecting surface 32A is the angle between the light and the normal to reflecting surface 32A. The angle of incidence on reflecting surface 32A is not shown in Fig. 4. The angle of incidence on reflecting surface 32A is shown in Fig. 7 using the symbol θ.

[0124] If we calculate with a slightly higher light density than the calculation example shown in Figure 4, we can understand the existence of the following light. d The light emitted from the LED light source 30 at an angle larger than the angle at which the light is emitted is reflected a third time at the very edge of the light-emitting surface 35 of the light guide plate 32 and illuminates the reading line TL.

[0125] Fig. 5 is a schematic diagram of the case where the light ray density shown in Fig. 4 is increased. Fig. 5 is a diagram in which the light ray density is increased compared to the calculation example shown in Fig. 4, making it possible to grasp the continuous distribution of light. In Fig. 5, the light emitted from the emission surface 35 of the light guide plate 32 appears to have steps with light and dark shading for the following reason. When light that is emitted after being reflected one to five times inside the light guide plate 32 and light that is emitted without being reflected inside the light guide plate 32 travel the same path, the light appears relatively dark.

[0126] 5, the arrival position of the light ray that has been reflected three times inside the light guide plate 32 is checked and it is found to arrive at a position slightly away from the reading line TL. If the illumination target area AI is moved 1 millimeter toward the light guide plate 32 to bring the illumination target area AI closer to the light guide plate 32, the light ray that has been reflected three times inside the light guide plate 32 arrives at the reading line TL.

[0127] FIG. 6 is a schematic diagram of an example in which light emitted from a light guide plate is incident on a diffuser plate. An example of an illumination configuration using a light guide plate 32 is illumination that narrows the illumination target area AI of the illumination light to a narrow range. For example, this is applied when irradiating a printed material such as paper with reflected illumination light and reading a narrow range in a direction perpendicular to the arrangement direction of the reading elements of the image sensor. The illumination device 14A shown in FIG. 6 can be applied to illumination that narrows the illumination target area AI of the illumination light to a narrow range.

[0128] Another example of a lighting configuration using light guide plate 32 is diffuse lighting with a relatively uniform light intensity distribution. In lighting device 14A shown in Fig. 6, light emitted from LED light source 30 is reflected zero to several times by light guide plate 32 to generate light with a uniform light intensity distribution across the entire width of exit surface 35, and the diffused light is emitted via diffuser plate 37 located close to exit surface 35.

[0129] The illumination device 14A irradiates a printed material using a transparent substrate with transmitted illumination light and functions as a backlight when an image sensor is used to read the transmitted light from the printed material. The illumination device 14A can also be used as a diffused illumination device when an area sensor is used.

[0130] 4 to 6 may be used when designing the light guide plate 32, but a simple method may also be used to derive appropriate values ​​for the dimensions, arrangement, and support position of the light guide plate 32 that enable a relatively large amount of totally reflected light to be utilized. Below, a detailed description is given of an example configuration of the light guide plate 32 that enables deriving appropriate values ​​for the use of a relatively large amount of totally reflected light.

[0131] [Light guide plate arrangement example] Figure 7 is a schematic diagram showing an example of the layout of a light guide plate. Figure 7 shows an approximate solution for the ray trajectory. The approximate solution for the ray trajectory utilizes the fact that the optical path length of light traveling through a medium with refractive indexes n1 and n2 is proportional to the refractive index. When θ is large, the position of reflection point 32B on reflecting surface 32A of light guide plate 32 can be approximated by plotting the distance from the exit surface of LED light source 30 to first surface 33 of light guide plate 32 and the distance from exit surface 35 of light guide plate 32 to the illumination target area AI as longer by the ratio n2 / n1 between the refractive index n1 of air and the refractive index n2 of light guide plate 32, or by plotting the distance from first surface 33 of light guide plate 32 to exit surface 35 of light guide plate 32 as shorter by the refractive index ratio n1 / n2. Figure 8 is an explanatory diagram of the angle of incidence on the first surface of the light guide plate and the angle of incidence on the reflecting surface. 8 shows an exact solution of the trajectory of a light ray based on the law of refraction, unlike Fig. 7. The direction penetrating the paper in Figs. 7 and 8 is the width direction of the light guide plate 32.

[0132] FIG. 7 shows an example in which, focusing on any one of the plurality of LED elements 34, the length and arrangement in the length direction of a light guide plate 32 having a width direction length corresponding to the one LED element 34 are specified.

[0133] The symbol L shown in Fig. 7 is the shortest distance from the light emitting surface of the LED light source 30 to the illumination target area AI. In Fig. 7, the length indicated by the symbol L is shown as the shortest distance from the center of the light emitting surface of the LED element 34 to the reading line TL. Note that the illumination target area AI is not shown in Fig. 7. The same applies to Figs. 8 and 9.

[0134] The symbol B denotes the total length of the light guide plate 32 in the longitudinal direction, and the symbol L e is the shortest distance from the exit surface 35 of the light guide plate 32 to the illumination target area AI. In FIG. 7, the symbol L e The length indicated by is illustrated.

[0135] The refractive index of the surroundings of the light guide plate 32 is n1, and the refractive index of the light guide plate 32 is n2. The refractive index n1 may be 1, which is the refractive index of air. If the material of the light guide plate 32 is acrylic resin, the refractive index n2 of the light guide plate 32 may be 1.49.

[0136] Critical angle θ of the light guide plate 32 t is θ t =arcsin(n1 / n2). Note that arcsin is the inverse function of sin. The angle of incidence onto the first surface 33 of the light guide plate 32 is expressed as θ i and the incident angle to the reflecting surface 32A of the light guide plate 32 is θ. The incident angle θ to the reflecting surface 32A is the critical angle θ t The incident angle θ i is the angle between the normal to the first surface 33 and the light incident on the first surface 33. Here, the angle is expressed in degrees. The angle unit will be added as necessary.

[0137] The angle of incidence θ on the reflecting surface 32A is θ°=90°-arcsin{(n1 / n2)×sinθ iIn this case, the distance that light incident on the light guide plate 32 travels in the direction of the optical axis of the LED element 34 after one reflection is expressed as W × tan θ. As an approximate solution, the entire area from the exit surface of the LED light source 30 to the illumination target area AI was converted as the refractive index medium of the light guide plate 32.

[0138] Maximum number of reflections of the light guide plate 32 C m is C m =INT[{B+(LB)×(n2 / n1)} / (W×tanθ t )]. In the above formula, INT is a function that rounds down the decimal point of a number and converts it to an integer.

[0139] The number of reflections of the light guide plate 32 is C, and the maximum number of reflections is C m When the number of reflections C is specified as follows, the maximum incident angle on the first surface 33 of the light guide plate 32 is θ imax The maximum incident angle θ imax is expressed using Equation 1. In Equation 1, arctan is the inverse function of tan. The maximum number of reflections C m The following is an example of a maximum number of reflections or less. θ imax =arctan[{B+(LB)×(n2 / n1)} / (C×W)]…Equation 1

[0140] When the light is reflected C times in the light guide plate 32 and the final reflection, the Cth reflection, occurs at the exit surface 35, which is the end of the light guide plate 32 in the length direction, the index value L representing the distance from the exit surface 35 to the reading line TL is t L t ={(1 / 2)×(n1 / n2)×W} / tanθ imax is.

[0141] That is, the distance L from the light exit surface 35 of the light guide plate 32 to the illumination target area AI e is the index value L t and the distance from the LED light source 30 to the first surface 33 of the light guide plate 32 is also equal to or less than the index value L t Therefore, the total length B of the light guide plate 32 in the longitudinal direction is determined by the distance L from the light exit surface of the LED light source 30 to the illumination target area AI and the index value Lt Using L-2×L t ≦B. L-2×L t ≦B is the total length W of the light guide plate 32 in the thickness direction, the refractive index n1 of the periphery of the light guide plate, the refractive index n2 of the light guide plate, and the maximum incident angle θ imax When transformed using Equation 2, L-(n1 / n2)×W / tanθ imax ≦B…Formula 2

[0142] Maximum number of reflections C m The following number of reflections C is specified, and the maximum incident angle θ is calculated using Equation 1. imax of Derivation Maximum incident angle θ imax When the total length B of the light guide plate 32 in the length direction does not satisfy Equation 2 when the above equation is derived, the size of the light guide plate 32, such as the total length B of the light guide plate 32 in the length direction and the total length W of the light guide plate 32 in the thickness direction, is changed, or the number of reflections C is changed.

[0143] The above calculation method is based on the maximum incident angle θ imax Although this is an approximate formula under the condition that is relatively small, the above calculation results can be used to roughly design the dimensions and arrangement of the light guide plate 32, and after the rough design, the reflection position can be accurately calculated to finalize the design of the light guide plate 32.

[0144] [Example of light guide plate support position] When fixing a light guide plate 32 that utilizes total reflection, if the surface opposite the reflecting surface 32A is supported from the outside, total reflection may not occur depending on the refractive index of the support member that is attached to the support position, which may result in a decrease in the amount of light emitted from the light guide plate 32.

[0145] Furthermore, if the support positions of the light guide plate 32 are set discretely in the width direction of the light guide plate 32, the discrete arrangement of the support positions will result in a local decrease in the amount of light emitted from the light guide plate 32, causing uneven illuminance distribution in the illuminated area AI.

[0146] In an illumination device 14 that uses a light guide plate 32 to efficiently utilize the light emitted from the LED light source 30, a method of supporting the light guide plate 32 that can suppress a decrease in illumination efficiency and suppress non-uniformity in the illuminance distribution is required. In particular, when the light guide plate 32 is used under conditions where the number of reflections is about one or two, the amount of light per reflection contributes relatively greatly to the illuminance, and it is useful to present a method of supporting the light guide plate 32 that can suppress the effect of reflection.

[0147] A preferred method of supporting the light guide plate 32 will be described below mainly with reference to Figs. 7 and 9. Fig. 7 schematically illustrates light when it is reflected once. Fig. 9 schematically illustrates light when it is reflected once and when it is reflected two or more times. Fig. 9 uses solid lines to illustrate light rays that are reflected once and twice, dotted lines to illustrate light when it is reflected three times, and dashed lines to illustrate light when it is reflected four and five times.

[0148] 7 and 9, for ease of examination, the total length B of the light guide plate 32 in the longitudinal direction is reduced to 1 / n2 using the refractive index n2 of the light guide plate 32, and it is possible to illustrate, as an approximate solution, a state in which light rays at the first surface 33 and the exit surface 35 of the light guide plate 32 travel in an approximately straight line.

[0149] When the total length B of the light guide plate 32 in the length direction is reduced to 1 / n2, the actual length of the light guide plate 32 becomes n2 times that of the illustrated example. In addition, the actual distance from the LED light source 30 to the reading line TL also becomes n2 times the total length B of the light guide plate 32 in the length direction. Note that Figures 7 and 9 schematically illustrate a state in which light from the first surface 33 and the exit surface 35 of the light guide plate 32 travels in an approximately straight line.

[0150] Fig. 7 shows a state in which light that has been reflected once inside the light guide plate 32 reaches the reading line TL. In the example shown in Fig. 7, the distance L from the light guide plate 32 to the illumination target area AI is relatively large, and the exit surface 35 of the light guide plate 32 is relatively far from the illumination target area AI, so that no light that has been reflected two or more times reaches the reading line TL.

[0151] In Figure 7, the light reflection position 32B inside the light guide plate 32 is as shown, and when the light guide plate 32 is fixed, the light guide plate 32 is supported so as to avoid the reflection corresponding position 32D on the outer surface 32C of the light guide plate 32 that corresponds to the reflection position 32B.

[0152] 9 illustrates a configuration in which the distance L from the exit surface 35 of the light guide plate 32 to the illumination target area AI can be relatively narrowed. In the light guide plate 32E illustrated using a solid line in the figure, light that has been reflected one to five times reaches the reading line TL. In addition, in the light guide plate 32F illustrated using a dashed line, light that has been reflected one to three times reaches the reading line TL.

[0153] In either case, support positions 32G, 32H, and 32I are positions on the outer surface corresponding to non-reflecting positions, and the positions on the reflecting surface 32A corresponding to support positions 32G, 32H, and 32I are non-reflecting positions different from the reflecting position 32B. Therefore, when fixing the light guide plate 32, it is sufficient to support support positions 32G, 32H, and 32I.

[0154] Specifically, when the number of reflections is one, the light guide plate 32 is fixed at a support position 32H, which is a position between the reflection position 32B and the end of the light guide plate on the side of the emission surface 35.

[0155] If the number of reflections is two or more, when the light guide plate 32 is fixed, the support position 32H corresponding to the non-reflection position where the distance between the adjacent reflection positions 32B is the longest is supported.

[0156] When the number of reflections is two or more, if the distance between the reflection position 32B closest to the exit surface 35 and the exit surface 35 is longer than the distance between adjacent reflection positions 32B when fixing the light guide plate 32, the support position 32I corresponding to the non-reflection position between the reflection position 32B closest to the exit surface 35 and the exit surface 35 is supported.

[0157] When the number of reflections is two or more, the non-reflection positions where the light density is relatively low are supported when fixing the light guide plate 32. For example, when the distance between the adjacent reflection positions 32B is D i i is an integer equal to or greater than 1 and equal to or less than the number of all reflection positions 32B.

[0158] The average value θ of the incident angle θ for each adjacent reflection position 32B a Calculate D i ×cosθ a Let D1 be the distance between the reflection position 32B closest to the emission surface 35 and the emission surface 35, and let θ1 be the angle of incidence at the reflection position 32B closest to the emission surface 35. i Calculate ×cosθ1.

[0159] D i ×cosθ a and D i ×cosθ1 is the formula corresponding to the density of light, and D i ×cosθ a and D i The non-reflection position where the maximum value of ×cosθ1 is ,light This corresponds to a non-reflective position where the density of

[0160] [Examples of light guide plates] [When light emitted from the light guide plate reaches the reading line] Consider a case where the distance L from the LED light source 30 to the illumination target area AI is 50 mm, and the total length W in the thickness direction of the light guide plate 32 is 10 mm. When the distance L from the LED light source 30 to the illumination target area AI is 50 mm, the total length B in the length direction of the light guide plate 32 is realistically equal to or greater than 40.8 mm and less than 50 meters.

[0161] When the light guide plate 32 is surrounded by air and made of an acrylic resin, the refractive index n1 is 1, the refractive index n2 is 1.49, and the critical angle θ t The maximum number of reflections C of the light guide plate 32 calculated by applying the above conditions is 42.2°. m is five times.

[0162] Light that is reflected a relatively large number of times has a low intensity when emitted obliquely from the light source when the LED element 34 is used as the light source. When light that is reflected a relatively large number of times is viewed as the amount of light per unit angle, the original amount of light is relatively small, and the proportion of the total light that reaches the reading line TL is relatively small.

[0163] Therefore, when the number of reflections is relatively large, the intermediate position between light reflection positions 32B can be set as support position 32G of light guide plate 32, thereby suppressing unevenness in illumination light caused by impeded reflection due to the support member being in close contact with light guide plate 32 at support position 32G. Furthermore, by making the size of the support member relatively small, the influence of the support member on unevenness in illumination light can be suppressed.

[0164] If the total length B of the light guide plate 32 in the length direction is shorter than the maximum value of the total length B of the light guide plate 32 in the length direction calculated using Equation 2, the number of available reflections decreases. m Using the formula for:

[0165] [When the light emitted from the light guide plate is diffused using a diffusion plate] When illumination light is used as transmitted illumination, an illumination device 14A including a diffuser plate 37 shown in FIG. 6 and generating backlight is applied. When the diffuser plate 37 is not provided, minute irregularities can be formed on the surface of the exit surface 35 of the light guide plate 32 within the range of the numerical aperture of the imaging lens 22 shown in FIG. 1 to impart diffusivity to the exit surface 35 of the light guide plate 32. This can reduce unevenness in the illumination light. Areas of the exit surface 35 of the light guide plate 32 where the minute irregularities are not formed can be made smooth and transparent. The diffuser plate 37 described in the embodiment is an example of a diffusing member.

[0166] On the exit surface 35 of the light guide plate 32, light that is reflected more times than other light passing through a position away from the line connecting the LED elements 34 and the reading line TL is emitted at a more oblique angle to the exit surface 35. This light is irradiated onto the ink that makes up the printed matter P from a position away from the line connecting the LED elements 34 and the reading line TL, and is diffused by the components of the ink to generate a component that diffuses within the range of the numerical aperture of the imaging lens 22, and functions as illumination light.

[0167] When forming minute irregularities on the light exit surface 35 of the light guide plate 32, protrusions with triangular cross-sectional shapes may be formed in areas where the minute irregularities are not formed, thereby refracting the light emitted from the light exit surface 35 toward the reading line TL.

[0168] [Light guide plate installation error] If there is a shift error in the fixed position of the light guide plate 32 that is shifted parallel to the length direction of the light guide plate 32, a shift in the reflection position 32B of the light guide plate 32 may occur. If the light guide plate 32 is shifted in a direction perpendicular to the line connecting the LED light source 30 and the reading line TL, the arrival position of the light will shift from the reading line TL by a distance twice the amount of shift of the light guide plate 32. Therefore, the relationship between the allowable range of installation error of the light guide plate 32 and the setting of the fixed position is specified.

[0169] [Modification of Light Guide Plate] Fig. 10 is a cross-sectional view of a light guide plate having a hexagonal cross-sectional shape. Illumination device 14B shown in the figure includes light guide plate 320 instead of light guide plate 32 shown in Fig. 4 etc. Light guide plate 320 includes first surface 322, which is the surface through which light enters, and exit surface 324. First surface 322 and exit surface 324 are flat surfaces parallel to each other.

[0170] The light guide plate 320 has a first reflecting surface 326, a second reflecting surface 328, a third reflecting surface 330, and a fourth reflecting surface 332 between a first surface 322 and an exit surface 324. The first reflecting surface 326 and the second reflecting surface 328 form a continuous surface, and the third reflecting surface 330 and the fourth reflecting surface 332 form a continuous surface.

[0171] The reflective surface consisting of first reflective surface 326 and second reflective surface 328 and the reflective surface consisting of third reflective surface 330 and fourth reflective surface 332 face each other. That is, light guide plate 320 has non-parallel reflective surfaces that face each other from first surface 322 toward output surface 324, and has a structure in which the distance between the two facing reflective surfaces increases. In other words, light guide plate 320 has a cross-sectional shape in which the lower base of one of two trapezoids is connected to the upper base of the other trapezoid.

[0172] The light guide plate 320 can irradiate the illumination target area AI with light that is incident from the first surface 322 and is emitted from the emission surface 324 without being reflected by a reflective surface such as the first reflective surface 326, as well as light that is reflected by a reflective surface such as the first reflective surface 326.

[0173] The light guide plate 320 can emit nearly five times the amount of light as compared to when only light that is incident from the first surface 322 and is not reflected by a reflective surface such as the first reflective surface 326 and is emitted from the emission surface 324. Furthermore, the light guide plate 320 employs a structure in which the distance between the two opposing reflective surfaces increases from the first surface 322 toward the emission surface 324, and the distance L from the emission surface 324 to the illumination target area AI is e can be relatively long.

[0174] FIG. 10 illustrates a light guide plate 320 in which the distance between two opposing reflective surfaces increases in two stages from the first surface 322 to the exit surface 324, but the light guide plate 320 may also be configured so that the distance between the reflective surfaces increases in multiple stages, or so that the distance increases continuously.

[0175] [Detailed explanation of the reference plate moving device] Fig. 11 is a perspective view showing the schematic configuration of the reference plate moving device. In this figure, the reference plate moving device 52 is extracted from the reading device 10 shown in Fig. 1. Here, explanations that overlap with the explanations given with reference to Fig. 1 will be omitted as appropriate.

[0176] 11, the arrows shown near the reference plate 50 indicate the direction of movement of the reference plate 50. The arrows shown near the drive arm 62 indicate the direction of swing of the drive arm 62. The arrows shown near the drive force transmission shaft 64 indicate the direction of rotation of the drive force transmission shaft 64.

[0177] Fig. 12 is a schematic diagram showing the standby state of the reference plate. Fig. 12 is a view seen from the direction of the arrow A shown in Fig. 11. The same applies to Figs. 13 to 15. Note that in Figs. 12 to 15, illustration of components of the reference plate moving device 52, such as the motor 56 shown in Fig. 11, is omitted.

[0178] 12 is a state in which the reading of the printed matter P is carried out using the image receiving device 12. Note that the position of the reference plate 50 in the standby state of the reference plate 50 described in the embodiment is an example of a retracted position where the reference member is retracted from the reading position.

[0179] FIG. 13 is a schematic diagram showing the state in which the reference plate 50 has reached the reading start position. FIG. 13 also shows the state in which one end of the reference plate 50 in the short direction has reached the reading position of the image sensor. The lighting device 14 starts irradiating the reference plate 50 with illumination light before the reference plate 50 reaches the reading start position, so that the LED elements 34 reach an equilibrium temperature and stabilize the amount of light emitted. Furthermore, the image receiving device 12 starts reading the reference plate 50 when the reference plate 50 reaches the reading start position.

[0180] Fig. 14 is a schematic diagram showing the state when the reference plate 50 has reached the reading center position. Fig. 14 also shows the state when the center position in the short direction of the reference plate 50 has reached the reading position of the image receiving device 12. The lighting device 14 continues to emit illumination light when the reference plate 50 has reached the reading center position. The image receiving device 12 continues to read the reference plate 50 when the reference plate 50 has reached the reading center position.

[0181] Fig. 15 is a schematic diagram showing the state where the reference plate 50 has reached the reading end position. Fig. 15 also shows the state where the other end of the reference plate 50 in the short direction has reached the reading position of the image sensor. The illumination device 14 can stop emitting illumination light after the reference plate 50 has reached the reading end position. Furthermore, the image receiving device 12 can stop reading the reference plate 50 after the reference plate 50 has reached the reading end position.

[0182] Figure 16 is a perspective view of the reference plate bracket. Figure 17 is a side view of the reference plate bracket. Reference plate bracket 70 comprises a reference plate fixing portion 70A, a guide pin mounting portion 70B, and a bent portion 70C. The reference plate bracket 70 shown in Figure 16 can be manufactured by bending three sides of a plate member such as a metal plate at right angles.

[0183] The reference plate 50 is fixed to the reference plate fixing portion 70A. The reference plate 50 may be fixed to the reference plate fixing portion 70A by adhesion using an adhesive or the like, or by screw fastening using screws. The reference plate fixing portion 70A may be painted white and used as the reference plate 50.

[0184] The guide pin mounting portion 70B is fitted with a first guide pin 68 and a second guide pin 74. The first guide pin 68 is inserted into the first guide groove 66, and the second guide pin 74 is inserted into the first guide groove 66 and the second guide groove 72. This allows the reference plate bracket 70 to be supported so as to be able to swing relative to the guide groove bracket 60.

[0185] The bent portion 70C has the function of improving the rigidity of the reference plate bracket 70 in the longitudinal direction and suppressing deflection in the longitudinal direction of the reference plate bracket 70. Although Figures 16 and 17 show the bent portion 70C bent perpendicular to the reference plate fixing portion 70A, the angle of the bent portion 70C with respect to the reference plate fixing portion 70A may be less than 90° or greater than 90°.

[0186] The longitudinal length of the reference plate 50 is equal to or greater than the readable length of the image sensor 20, and if the longitudinal length of the reference plate 50 is 450 mm, the longitudinal length of the reference plate bracket 70 may be 470 mm.

[0187] The length of the reference plate 50 in the short side direction is determined from the viewpoint of avoiding contact with the light guide plate 32 and the like when the reference plate 50 is moved. The length of the reference plate 50 in the short side direction may also be determined taking into account the reading resolution and reading cycle of the image sensor 20. If the length of the reference plate 50 in the short side direction is 14 millimeters, the length of the reference plate bracket 70 in the short side direction may be 17 millimeters.

[0188] The thickness of the reference plate 50 may be determined based on the processing conditions for manufacturing the reference plate 50. The thickness of the reference plate 50 may be 0.2 millimeters. The height of the reference plate bracket 70 may be 5 millimeters. The height of the reference plate bracket 70 may be determined based on the viewpoint of suppressing deflection of the reference plate bracket 70 and preventing contact with the light guide plate 32 during swinging.

[0189] For example, when the upper end of the bent portion 70C is closest to the lower end of the light guide plate 32, contact between the upper end of the bent portion 70C and the lower end of the light guide plate 32 can be avoided by setting the distance between the upper end of the bent portion 70C and the lower end of the light guide plate 32 to 1.5 millimeters or more.

[0190] 14, if the distance between the lower end of the reference plate bracket 70 and the lower end of the light guide plate 32 is set to 8 mm or more, contact between the upper end of the bent portion 70C and the lower end of the light guide plate 32 when the reference plate bracket 70 is swung can be avoided. e can be determined depending on the size of the datum plate bracket 70 that supports the datum plate 50.

[0191] The longitudinal direction of the reference plate 50 and the longitudinal direction of the reference plate bracket 70 are the width direction of the printed matter P, and correspond to the width direction of the LED light source 30 and the width direction of the light guide plate 32. The short-side direction of the reference plate 50 and the short-side direction of the reference plate bracket 70 correspond to the transport direction of the printed matter P. The height direction of the reference plate bracket 70 is a direction perpendicular to the longitudinal direction of the reference plate 50 and the short-side direction of the reference plate bracket 70, and is a direction perpendicular to the surface on which the reference plate 50 is supported.

[0192] The reference plate bracket 70 supporting the reference plate 50 described in the embodiment is an example of a member that enters the illumination target area and is an example of a member that is placed in the illumination target area. In addition, the size of the reference plate bracket 70 or larger is an example of a member that is larger than the maximum size.

[0193] [Action and effect] The reading device 10 according to the embodiment can achieve the following effects.

[0194] [1] A light guide plate 32 that utilizes total reflection is disposed between the LED light source 30 and the illumination target area AI of the illumination light. m Based on the number of reflections C below, the maximum incident angle θ to the light guide plate 32 imax The distance L from the light exit surface 35 of the light guide plate 32 to the illumination target area AI is defined as e is the total length W of the light guide plate 32 in the thickness direction, the refractive index n1 of the periphery of the light guide plate, the refractive index n2 of the light guide plate, and the maximum incident angle θ to the light guide plate 32. imax Using L t ={(1 / 2)×(n1 / n2)×W} / tanθ imax The index value L is expressed as t This defines an efficient arrangement of the light guide plate 32 when using total reflection of the light guide plate 32 to provide relatively brighter illumination than when only direct light from the LED light source 30 is used.

[0195] [2] The total length B of the light guide plate 32 in the length direction is determined by the distance L from the emission surface of the LED light source 30 to the illumination target area AI, the total length W of the light guide plate 32 in the thickness direction, the refractive index n1 of the periphery of the light guide plate, the refractive index n2 of the light guide plate, and the maximum incident angle θ to the light guide plate 32. imax Using L-(n1 / n2)×W / tanθ imax ≦B. This defines the dimensions of the light guide plate 32 that are efficient.

[0196] [3] The support position 32G of the light guide plate 32 when fixing the light guide plate 32 is set to a position on the outer surface corresponding to a non-reflecting position on the reflecting surface 32A of the light guide plate 32. This makes it possible to present the support position 32G when fixing the light guide plate 32, which reduces the influence of the illumination light on the illuminance distribution in the illumination target area AI.

[0197] [4] The power consumption of the LED element 34 is reduced without increasing the current supplied to the LED element 34. This reduces heat generation by the LED element 34 and reduces changes in the amount of light emitted by the LED element 34 due to heat generation by the LED element 34.

[0198] [5] A relatively high illuminance can be obtained in the illumination target area AI of the illumination light, and high-speed reading by the image sensor 20 can be achieved.

[0199] [Application example to lighting equipment] The illumination device 14 shown in Fig. 1 can be used as an independent device separate from the reading device 10. The illumination device 14 can include, as an electrical configuration, a system control unit 100, an illumination control unit 104, an information acquisition unit 120, and a memory 122 shown in Fig. 3. The electrical configuration of the illumination device 14 is realized using a computer.

[0200] [Example of application to determining the direction of light guide plate placement] 1 to 17 can be understood as a method for determining the arrangement of the light guide plate 32 and the dimensions of the light guide plate 32. The method for determining the arrangement of the light guide plate 32 includes steps corresponding to the above-described procedure for determining the arrangement of the light guide plate 32 and the dimensions of the light guide plate 32.

[0201] [Configuration example of printing system according to embodiment] [Overall structure] Fig. 18 is an overall configuration diagram showing a schematic configuration of a printing system according to an embodiment. The printing system 400 is equipped with a digital printing device 406 that uses single-pass printing to print a color image on a substrate. Note that the substrate is not shown in Fig. 18. An example of the substrate is the medium used for the printed matter P shown in Fig. 1.

[0202] The substrate may be a paper medium such as a sheet or continuous paper, a sheet-like metal medium, or a cloth medium such as a fabric. The substrate may be a flexible packaging such as a plastic film. The substrate may be a single layer or a plurality of layers superimposed. The substrate may be in a roll-to-roll continuous form or in the form of a sheet cut to a specified length. The substrate may also be called a medium, media, sheet, film, substrate, or the like.

[0203] The printing system 400 includes a substrate supply device 402, a first intermediate conveyance device 404, a printing device 406, a second intermediate conveyance device 408, a measuring device 410, a drying device 412, and a stacking device 414. Each of these devices will be described in detail below.

[0204] [Base material supply device] When the substrate is in a continuous form, the substrate supply device 402 includes a roll storage unit that stores a roll of wound substrate. When the substrate is in a sheet form, the substrate supply device 402 includes a tray that stores the substrate. The substrate supply device 402 supplies the substrate to the first intermediate conveying device 404 in response to printing control of the printing device 406. The substrate supply device 402 may include a correction mechanism that corrects the attitude of the substrate.

[0205] [First intermediate conveying device] The first intermediate conveying device 404 transfers the substrate supplied from the substrate supplying device 402 to the printing device 406. A known configuration may be applied to the first intermediate conveying device 404 depending on the shape of the substrate. The arrow line pointing from the substrate supplying device 402 to the first intermediate conveying device 404 indicates the substrate conveyance direction.

[0206] [Printing device] Printing device 406 includes inkjet head 420C, inkjet head 420M, inkjet head 420Y, inkjet head 420K, and inkjet head 420W.

[0207] Inkjet head 420C, inkjet head 420M, inkjet head 420Y, inkjet head 420K, and inkjet head 420W are arranged in the above-described order from the upstream side along the substrate transport direction.

[0208] Inkjet head 420C ejects cyan ink, inkjet head 420M ejects magenta ink, inkjet head 420Y ejects yellow ink, inkjet head 420K ejects black ink, and inkjet head 420W ejects white ink.

[0209] The inkjet head 420C and the like may be a line head in which multiple nozzles are arranged across a length equal to or greater than the entire length of the substrate in the width direction of the substrate. An example of a line head configuration is a configuration in which multiple head modules are connected together. The multiple nozzles provided in the inkjet head 420C and the like are arranged two-dimensionally, such as in a matrix.

[0210] The inkjet head 420C may employ a piezoelectric ejection method that uses a piezoelectric element as an ejection pressure element to generate ejection pressure, or a thermal method that uses film boiling of ink to eject ink.

[0211] The printing device 406 forms a color image on a substrate using color ink such as cyan ink, and forms a white image that serves as a background image for the color image using white ink.

[0212] The printing device 406 includes a printing drum 422. The printing drum 422 has a cylindrical shape. The printing drum 422 includes a substrate support area on its circumferential surface that supports a substrate. Note that the substrate support area is not shown in the figure.

[0213] The rotation shaft of the print drum 422 is connected to a motor (not shown) via a drive mechanism (not shown). When the motor is rotated, the print drum 422 rotates in the direction indicated by the arrow. When the print drum 422 is rotated, the substrate supported on the circumferential surface of the print drum 422 is transported in the direction of rotation of the print drum 422.

[0214] The substrate support area has a plurality of suction holes formed therein. The plurality of suction holes are arranged based on a specified pattern. The plurality of suction holes communicate with a suction flow path (not shown). The suction flow path is connected to a suction pump (not shown). The suction pump is operated to generate negative pressure in the plurality of suction holes, which is used to suction-support the substrate onto the circumferential surface of the print drum 422.

[0215] The transport form of the substrate in the printing device 406 is not limited to a transport form using the print drum 422. For example, a transport form using a transport belt or a transport form using a plurality of rollers can be applied.

[0216] [Second intermediate conveying device] The second intermediate conveying device 408 transfers the substrate material transferred from the printing drum 422 to the measuring device 410. The second intermediate conveying device 408 may have a similar configuration to the first intermediate conveying device 404. The arrow line shown on the second intermediate conveying device 408 indicates the substrate material conveying direction in the second intermediate conveying device 408.

[0217] [Measuring equipment] 1 and the like can be applied to the measuring device 410. The measuring device 410 can read a test pattern printed on a substrate and detect ejection abnormalities in the inkjet head 420C and the like based on the read data of the test pattern.

[0218] The measuring device 410 can read the printed image printed on the substrate and detect defects in the printed image based on the read data of the printed image.

[0219] The measuring device 410 provided in the printing system 400 realizes a relatively high illuminance in the illumination target area AI, enabling high-speed reading of the reading target. As a result, when high-speed printing is performed, high-speed reading of the printed image and test pattern of the printed material is performed, and image processing is performed on the read data, making it possible to detect ejection abnormalities in the inkjet head 420C, etc., detect defects in the printed image, and correct density unevenness.

[0220] [Drying equipment] The drying device 412 performs a drying process on the printed substrate. The drying device 412 may be equipped with a heater and a fan, and may be configured to blow warm air onto the printed substrate. The drying device 412 is equipped with a drying conveying unit that conveys the printed substrate. As a conveying form for the printed substrate, a known conveying form such as a drum conveying, a belt conveying, or a roller conveying may be applied. The arrow shown on the drying device 412 indicates the substrate conveying direction from the drying device 412.

[0221] [Stacking device] The accumulation device 414 accommodates the substrate delivered from the drying device 412. When the substrate is in a continuous form, the accumulation device 414 includes a roll accommodation section that accommodates a roll on which the substrate is wound. When the substrate is in a sheet form, the accumulation device 414 includes a tray that accommodates the substrate.

[0222] [Electrical Configuration of Inkjet Printing System] Fig. 19 is a functional block diagram showing the electrical configuration of the printing system shown in Fig. 18. The printing system 400 includes a system control unit 460, a transport control unit 462, a print control unit 466, a measurement control unit 468, a drying control unit 470, and an information acquisition unit 472.

[0223] The system control unit 460 comprehensively controls the overall operation of the printing system 400. The system control unit 460 sends command signals to various control units. The system control unit 460 functions as a memory controller that controls the storage of data in the memory 474 and the reading of data from the memory 474.

[0224] The system control unit 460 acquires a sensor signal transmitted from the sensor 476 and transmits a command signal based on the sensor signal to various control units. The sensor 476 includes a position detection sensor and a temperature sensor provided in each part of the printing system 400.

[0225] The conveyance control unit 462 sets conveyance conditions based on command signals sent from the system control unit 460, and controls the operation of the conveyance device 464 based on the set conveyance conditions. The conveyance device 464 shown in Fig. 19 includes the first intermediate conveyance device 404, the printing drum 422, and the drying conveyance device provided in the drying device 412 shown in Fig. 18. The conveyance device 464 also includes the conveyance device 16 shown in Fig. 1. The conveyance device 464 may also include the base material supply device 402 and the accumulation device 414.

[0226] The print control unit 466 sets print conditions based on command signals sent from the system control unit 460, and controls the operation of the printing device 406 based on the set print conditions. That is, the print control unit 466 has an image processing unit that performs color separation processing, color conversion processing, correction processing for each processing, and halftone processing on the print data to generate halftone data for each color.

[0227] The print control unit 466 includes a drive voltage generation unit that generates drive voltages to be supplied to the inkjet head 420C, etc. based on halftone data for each color. The print control unit 466 also includes a drive voltage output unit that supplies drive voltages to the inkjet head 420C.

[0228] The print control unit 466 corrects the print device 406 based on the measurement data obtained using the measurement device 410. The print system 400 may include, separate from the print control unit 466, a correction processing unit that corrects the print device 406 based on the measurement data obtained using the measurement device 410.

[0229] The measurement control unit 468 sets measurement conditions based on command signals sent from the system control unit 460, and controls the operation of the measuring device 410 based on the set measurement conditions. The measurement control unit 468 shown in FIG. 19 may have the functions of the reading device 10 shown in FIG.

[0230] The drying control unit 470 sets processing conditions for the main drying process based on a command signal sent from the system control unit 460, and controls the operation of the drying device 412 based on the set processing conditions.

[0231] The information acquisition unit 472 acquires various pieces of information that are applied to the control of the printing system 400. The system control unit 460 transmits command signals to various control units based on the various pieces of information acquired using the information acquisition unit 472.

[0232] The memory 474 can store various data, parameters, and programs applied to the printing system 400. The memory 474 can function as the memory 122 shown in FIG.

[0233] [Example of hardware configuration of a control device applied to a printing system] Fig. 20 is a block diagram showing an example of the hardware configuration of a control device applied to the printing system shown in Fig. 18. The control device 500 provided in the printing system 400 includes a processor 502, a computer-readable medium 504 which is a non-transitory tangible entity, a communication interface 506, and an input / output interface 508.

[0234] A computer is applied to the control device 500. The computer may be in the form of a server, a personal computer, a workstation, or a tablet terminal.

[0235] The processor 502 includes a central processing unit (CPU). The processor 502 may include a graphics processing unit (GPU). The processor 502 is connected to a computer-readable medium 504, a communication interface 506, and an input / output interface 508 via a bus 510. An input device 512 and a display device 514 are connected to the bus 510 via the input / output interface 508.

[0236] The processor 502 can function as a first processor that performs processing related to generation of tone correction data, a second processor that performs processing related to image formation, and a third processor that performs processing related to measurement.

[0237] The computer-readable medium 504 includes a memory serving as a primary storage device and a storage serving as an auxiliary storage device. The computer-readable medium 504 may be a semiconductor memory, a hard disk drive, a solid-state drive, or the like. The computer-readable medium 504 may be any combination of multiple devices.

[0238] A hard disk drive may be referred to as an HDD, which is an abbreviation of the English term Hard Disk Drive, and a solid state drive may be referred to as an SSD, which is an abbreviation of the English term Solid State Drive.

[0239] The control device 500 is connected to a network via a communication interface 506, and is communicably connected to an external device. The network may be a local area network (LAN), etc. The network is not shown in the figure.

[0240] The computer-readable medium 504 stores a transport control program 520, a print control program 522, a measurement control program 524, and a drying control program 526.

[0241] 19. The print control program 522 corresponds to the print control applied to the print device 406. The measurement control program 524 corresponds to the measurement control applied to the measurement device 410. The drying control program 526 corresponds to the drying control applied to the drying device 412.

[0242] The various programs stored in the computer-readable medium 504 include one or more instructions. Various data, various parameters, etc. are stored in the computer-readable medium 504. Note that the memory 474 shown in Fig. 19 is included in the computer-readable medium 504 shown in Fig. 20.

[0243] In the printing system 400, a processor 502 executes various programs stored in a computer-readable medium 504 to realize various functions of the printing system 400. Note that the term "program" is synonymous with the term "software."

[0244] The control device 500 performs data communication with an external device via a communication interface 506. The communication interface 506 may be compliant with various standards such as USB (Universal Serial Bus). The communication form of the communication interface 506 may be either wired communication or wireless communication.

[0245] The control device 500 is connected to an input device 512 and a display device 514 via an input / output interface 508. The input device 512 is implemented by input devices such as a keyboard and a mouse. The display device 514 displays various information applied to the control device 500.

[0246] The display device 514 may be a liquid crystal display, an organic EL display, a projector, or any combination of multiple devices. The EL in organic EL display is an abbreviation for Electro-Luminescence.

[0247] Examples of the hardware structure of the processor 502 include a CPU, a GPU, a PLD (Programmable Logic Device), and an ASIC (Application Specific Integrated Circuit). A CPU is a general-purpose processor that executes programs and functions as various functional units. A GPU is a processor specialized for image processing.

[0248] A PLD is a processor whose electrical circuit configuration can be changed after the device is manufactured. An example of a PLD is an FPGA (Field Programmable Gate Array). An ASIC is a processor with dedicated electrical circuitry designed specifically to perform a specific task.

[0249] A processing unit may be configured with one of these various processors, or may be configured with two or more processors of the same or different types. Examples of combinations of various processors include a combination of one or more FPGAs and one or more CPUs, and a combination of one or more FPGAs and one or more GPUs. Another example of a combination of various processors is a combination of one or more CPUs and one or more GPUs.

[0250] A single processor may be used to configure multiple functional units. An example of using a single processor to configure multiple functional units is a configuration in which a single processor is configured by applying a combination of one or more CPUs and software, such as an SoC (System On a Chip), which is typified by a computer such as a client or server, and this processor operates as multiple functional units.

[0251] Another example of using one processor to configure multiple functional units is to use a processor that uses one IC chip to realize the functions of an entire system including multiple functional units. Note that IC is an abbreviation for Integrated Circuit.

[0252] In this way, the various functional units are configured as hardware structures using one or more of the various processors described above.More specifically, the hardware structures of the various processors described above are electric circuits (circuitry) that combine circuit elements such as semiconductor elements.

[0253] The computer-readable medium 504 may include semiconductor devices such as read-only memory (ROM) and random access memory (RAM). The computer-readable medium 504 may include a magnetic storage medium such as a hard disk. The computer-readable medium 504 may comprise multiple types of storage media.

[0254] The above-described embodiments of the present invention may be modified, added, or deleted as appropriate within the scope of the spirit of the present invention. The present invention is not limited to the above-described embodiments, and many modifications are possible within the technical concept of the present invention by those skilled in the art. [Explanation of symbols]

[0255] 10 Reading device 12 Image receiving device 14 Lighting equipment 14A lighting equipment 14B Lighting equipment 16. Conveying equipment 18. Cabinet 20 Image Sensor 22 Imaging lens 30 LED light sources 32 Light guide plate 32A reflective surface 32B Reflection position 32C External surface 32D Reflection Corresponding Position 32E Light guide plate 32F Light guide plate 32G support position 32H Support position 32I Support position 33 Page 1 34 LED elements 35 Exit surface 36 LED boards 37 Diffuser 40 Upstream transport roller 42 Background Roller 44 downstream transport roller 50 Reference plate 52 Reference plate moving device 54 Moving mechanism 56 Motor 60 Guide groove bracket 62 Drive arm 64 Drive force transmission shaft 66 First guide groove 68 First guide pin 70 Reference plate bracket 70A Reference plate fixing part 70B Guide pin mounting part 70C bending part 72 Second guide groove 74 Second guide pin 100 System control unit 102 Transport control unit 104 Lighting control unit 106 Reading control unit 108 Reference plate movement control section 120 Information Acquisition Department 122 memory 320 Light guide plate 322 Page 1 324 Exit Surface 326 1st reflective surface 328 Second reflective surface 330 Third reflective surface 332 4th reflective surface 400 Printing System 402 Base material supply device 404 First intermediate transport device 406 Printing device 408 Second intermediate transport device 410 Measuring Equipment 412 Drying equipment 414 Accumulation Device 420C inkjet head 420K inkjet head 420M inkjet head 420W inkjet head 420Y inkjet head 422 Printing drum 460 System Control Unit 462 Transport control section 464 Transport Equipment 468 Measurement control section 470 Drying control unit 472 Information Acquisition Department 474 memory 476 Sensors 500 control device 502 processor 504 Computer-Readable Medium 506 Communication Interface 508 Input / Output Interface 510 Bus 512 Input Device 514 Display device 520 Transport Control Program 522 Printing Control Program 524 Measurement Control Program 526 Drying Control Program θ Incident angle to the reflecting surface θ i Angle of incidence to the first surface θ imax maximum angle of incidence B Overall length of the light guide plate L The shortest distance from the emission surface of the LED light source to the illuminated area L e The shortest distance from the light guide plate's exit surface to the illuminated area L t Index value P Printed matter R a light R b light R c light R d light TL reading line W: Total length of the light guide plate in the thickness direction n1 Refractive index around the light guide plate n2 Refractive index of the light guide plate

Claims

1. a light source that emits light that illuminates an illumination target area; a light guide plate including: a first surface onto which light emitted from the light source is incident; a reflective surface that is a reflective surface that reflects the light incident from the first surface one or more times and has a direction intersecting with the first surface; and an exit surface that faces the first surface and has a direction intersecting with the reflective surface; Equipped with a direction from the first surface toward the light exit surface of the light guide plate is defined as a length direction, and a direction of a relatively shorter side of two directions perpendicular to the length direction is defined as a thickness direction, The total length of the light guide plate in the thickness direction is W, and the refractive index of the periphery of the light guide plate is n １ and the refractive index of the light guide plate is n ２ and the maximum angle of incidence onto the first surface corresponding to the number of reflections equal to or less than the maximum number of reflections defined by the condition for total reflection of light incident on the light guide plate is θ ｉｍａｘ In this case, the distance from the light exit surface to the illumination target area is L ｔ = {(1 / 2) × (n １ / n ２ ) × W} / tan θ ｉｍａｘ L is calculated as ｔ An illumination device in which the light guide plate is disposed at the following position.

2. 2. The lighting device according to claim 1, wherein the light guide plate is positioned at a position where a distance from the exit surface to the illumination target area is equal to or greater than a maximum size of a member that may enter the illumination target area or a maximum size of a member that may be placed in the illumination target area.

3. When the total length of the light guide plate in the length direction is B, the distance from the light source exit surface to the illumination target area is L, and the number of reflections is C, the maximum incident angle θ ｉｍａｘ is θ ｉｍａｘ = arctan[{B+(LB)×(n ２ / n １ )} / (C×W)].

4. The critical angle of the reflecting surface is θ ｔ In this case, the maximum number of reflections C ｍ is C ｍ =INT[{B+(LB)×(n ２ / n １ ) / (W × tan θ ｔ ) ] and The number of reflections C is an integer equal to or greater than 1, and the maximum number of reflections C ｍ 4. The lighting device of claim 3, wherein the following integers are defined:

5. The incident angle to the first surface of the light guide plate is θ ｉ In this case, the incident angle θ° to the reflecting surface is θ°=90°−arcsin{(n １ / n ２ ) × sin θ ｉ 5. The lighting device according to claim 4, wherein:

6. The critical angle θ of the reflecting surface ｔ is θ ｔ = arcsin(n １ / n ２ 5. The lighting device of claim 4, wherein:

7. The lighting device according to claim 1 , wherein the light guide plate is fixed such that a non-reflecting position on the reflecting surface, which is different from a reflecting position of light, is supported.

8. The lighting device according to claim 7 , wherein when the number of reflections is one, a position between the reflection position and the light exit surface of the light guide plate is supported when the light guide plate is fixed.

9. The lighting device according to claim 7 , wherein when the number of reflections is two or more, the non-reflection positions where the distance between adjacent reflection positions is longest are supported when the light guide plate is fixed.

10. 10. The lighting device according to claim 7, wherein, when the number of reflections is two or more, the non-reflection position between the reflection position closest to the exit surface of the light guide plate and the exit surface of the light guide plate is supported when the distance between the reflection position closest to the exit surface of the light guide plate and the exit surface of the light guide plate is longer than the distance between adjacent reflection positions when fixing the light guide plate.

11. 10. The lighting device according to claim 7, wherein, when the number of reflections is two or more, the light guide plate is supported at a position where the light density is low when the light guide plate is fixed.

12. The lighting device according to claim 1 , wherein the light exit surface of the light guide plate has a diffusibility of light that is emitted from the light exit surface of the light guide plate.

13. the light exit surface of the light guide plate is a smooth surface, The lighting device according to claim 1 , further comprising a diffusing member disposed between the light exit surface of the light guide plate and the illumination target area, the diffusing member diffusing the light exiting from the light exit surface of the light guide plate.

14. a light source that emits light that illuminates an illumination target area; a light guide plate including: a first surface onto which light emitted from the light source is incident; a reflective surface that is a reflective surface that reflects the light incident from the first surface one or more times and has a direction intersecting with the first surface; and an exit surface that faces the first surface and has a direction intersecting with the reflective surface; A method for determining a light guide plate arrangement in a lighting device comprising: a direction from the first surface toward the light exit surface of the light guide plate is defined as a length direction, and a direction of a relatively shorter side of two directions perpendicular to the length direction is defined as a thickness direction, The total length of the light guide plate in the thickness direction is W, and the refractive index of the periphery of the light guide plate is n １ and the refractive index of the light guide plate is n ２ and the maximum angle of incidence onto the first surface corresponding to the number of reflections equal to or less than the maximum number of reflections defined by the condition for total reflection of light incident on the light guide plate is θ ｉｍａｘ In this case, the distance from the light exit surface to the illumination target area is L ｔ = {(1 / 2) × (n １ / n ２ ) × W} / tan θ ｉｍａｘ L is calculated as ｔ A method for determining the placement of a light guide plate, the method determining the placement of the light guide plate at a position such that:

15. a printing device; a reading device that reads a printed matter generated using the printing device; Equipped with The reading device a light source that emits light to illuminate a target illumination area of ​​a printed matter; a light guide plate including: a first surface onto which light emitted from the light source is incident; a reflective surface that is a reflective surface that reflects the light incident from the first surface one or more times and has a direction intersecting with the first surface; and an exit surface that faces the first surface and has a direction intersecting with the reflective surface; Equipped with a direction from the first surface toward the light exit surface of the light guide plate is defined as a length direction, and a direction of a relatively shorter side of two directions perpendicular to the length direction is defined as a thickness direction, The total length of the light guide plate in the thickness direction is W, and the refractive index of the periphery of the light guide plate is n １ and the refractive index of the light guide plate is n ２ and the maximum angle of incidence onto the first surface corresponding to the number of reflections equal to or less than the maximum number of reflections defined by the condition for total reflection of light incident on the light guide plate is θ ｉｍａｘ In this case, the distance from the light exit surface to the illumination target area is L ｔ = {(1 / 2) × (n １ / n ２ ) × W} / tan θ ｉｍａｘ L is calculated as ｔ A printing system in which the light guide plate is disposed at the following position:

16. a reference member that serves as a reference when setting reading conditions for the reading device; a support member that supports the reference member; a reference member moving device that moves the reference member between a reading position where the reference member is read using the reading device and is included in the illumination target area, and a retracted position where the reference member is retracted from the reading position; Equipped with The printing system according to claim 15 , wherein the light guide plate is disposed at a position where the distance from the light exit surface to the illumination target area is equal to or greater than the maximum size of the support member.

17. The reading device an image sensor that reads the printed matter; an imaging lens that forms an optical image of the printed matter on the image sensor; Equipped with 17. The printing system according to claim 15, wherein the light exit surface has an area corresponding to the numerical aperture of the imaging lens, and the area has projections and recesses formed thereon to diffuse the light exiting from the light exit surface.

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