JP2005114894A - Linear lighting unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a linear lighting unit which is free of lighting unevenness and has high light use efficiency even with one light source. <P>SOLUTION: The linear lighting unit is equipped with the light source 10, a photoconductive member 20 which converts the light emitted by the light source 10 into linear light by projecting the light to the front side while guiding the light from a 1st end surface 21 to a 2nd end surface 22, and a reflector 30 which reflects the light transmitted through the 2nd end surface 22 toward the 2nd end surface 22, and an optical path conversion part P for projecting the light being guided to the front side is formed on a back-side surface of the photoconductive member 20. Representing the end of the optical path conversion part P closest to the 1st end surface 21 as a light-incidence end P1 and the end closest to the 2nd end surface 22 as a non-light-incidence end P2, the width of the optical path conversion part P is varied from the light-incidence end P1 to the non-light-incidence end P2 and maximized between the light-incidence end P1 and non-light-incidence end P2 so that a conditional expression 0.1≤M/L≤0.45 or 0.55≤M/L≤0.9 is satisfied (where L is the distance from the light-incidence end P1 to the non-light-incidence end P2 of the optical path conversion part P; and M is the distance from the light-incidence end P1 to a maximum-width position Pt of the optical path conversion part P). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a linear illumination device, for example, a linear illumination device for neutralizing a photosensitive member in an electrophotographic apparatus such as a copying machine, a printer, and a facsimile machine.

  The mainstream of electrophotographic technology adopted in copying machines and the like is the dry electrostatic drawing method. In the dry electrostatic drawing method, for example, the surface of the photosensitive drum is negatively charged, a latent image is formed thereon by laser exposure, toner is attached to the latent image, and the obtained toner image is transferred to a sheet. An operation such as fixing is performed. After the toner image is transferred, the toner remaining on the surface of the photosensitive drum is cleaned with a blade or the like, and the electrostatic latent image remaining on the surface of the photosensitive drum is illuminated and exposed by a static eliminator (eraser). The charge is erased.

2. Description of the Related Art As a static eliminating device, an LED (Light Emitting Diode) arranged in an array on a substrate is known. However, in order to neutralize the surface of the photosensitive drum having a width of several hundred mm, it is necessary to arrange a large number of LEDs, which causes an increase in cost. In order to solve this problem, the following Patent Documents 1 and 2 have been proposed. The linear illumination device proposed in Patent Document 1 includes a cylindrical light guide having a V-shaped cutting surface formed as a light diffusion surface so as to have a maximum width at the center, LEDs disposed at both ends thereof, It has. The charge erasing device proposed in Patent Document 2 includes a light transmission fiber that is mirror-coated at one end and a lamp that is disposed at the other end. Therefore, in the thing of patent document 1, linear illumination can be performed with two light sources, and in the thing of patent document 2, linear illumination can be performed with one light source.
Japanese Patent No. 2900799 Japanese Patent Publication No. 6-25897

  In the apparatus described in Patent Document 1, the shape of the light diffusing surface is symmetrical with respect to the light source arrangement, which is effective in making the light quantity distribution of the emitted light uniform. However, since it is necessary to use two light sources, the cost increase is inevitable. In the apparatus described in Patent Document 2, since the width of the light emitting portion of the light transmission fiber gradually increases as the distance from the light source increases, it is effective in suppressing a decrease in the amount of emitted light accompanying an increase in the distance from the light source. . However, the balance of the light amount distribution of the emitted light is lost due to the reflected light from the mirror-coated end face, which causes illumination unevenness.

  The present invention has been made in view of such a situation, and an object of the present invention is to provide a linear illumination device having high light utilization efficiency without uneven illumination even with a single light source.

  In order to achieve the above object, a linear illumination device according to a first aspect of the present invention includes a light source and a line by emitting light emitted from the light source to the front side while guiding light from the first end surface to the second end surface. A linear illumination device comprising: a light guide body that converts light into a light; and a reflector that reflects at least light transmitted through the second end face to the second end face side, wherein the back side surface of the light guide body An optical path conversion unit for emitting the light being guided to the front side is formed, and the end of the optical path conversion unit closest to the first end surface is the light incident end and the end of the second end surface is the opposite side. When the light entrance end, the width of the optical path changing unit changes from the light entrance end to the light entrance end, and the light entrance end and the light entrance end so as to satisfy the following conditional expression (1) or (2): The width of the optical path changing unit is maximized between the optical ends.

0.1 ≦ M / L ≦ 0.45 (1)
0.55 ≦ M / L ≦ 0.9 (2)
However,
L: distance from the light incident end to the light incident end of the optical path changing unit,
M: distance from the light incident end of the optical path changing unit to the maximum width position,
It is.

  A linear illumination device according to a second aspect of the present invention is a light source and a light guide that converts light emitted from the light source into linear light by emitting the light from the first end surface to the second end surface while emitting the light to the front side. A linear illuminating device including a body and a reflector that reflects at least the light transmitted through the second end surface to the second end surface side, and the light being guided to the back surface of the light guide An optical path conversion unit for emitting light to the side is formed, and the reflector diffuses and reflects the light transmitted from the optical path conversion unit to the back side toward the optical path conversion unit, and the amount of diffuse reflection is guided by the light guide. It changes along the light direction.

  A linear illumination device according to a third aspect of the present invention is characterized in that, in the first or second aspect of the invention, the optical path changing unit is composed of a plurality of fine prisms.

  According to a fourth aspect of the present invention, there is provided the linear illumination device according to any one of the first to third aspects, wherein the optical path conversion unit is configured on a plane provided in a part of the light guide. And

  According to a fifth aspect of the present invention, there is provided an electrophotographic apparatus including the linear illumination device according to any one of the first to fourth aspects as a static eliminator.

  According to the first invention, the width of the optical path changing portion changes from the light incident end to the counter light incident end, and the maximum width position is optimized, so even a single light source has a uniform light amount distribution. Illuminating light can be obtained. Therefore, uniform illumination can be performed with high light use efficiency. In addition, according to the second invention, the amount of diffuse reflection by the reflector changes from the incident light end to the opposite incident light end, so that even one light source can obtain illumination light with a uniform light amount distribution. become. Therefore, uniform illumination can be performed with high light use efficiency.

  According to the third aspect of the invention, since the optical path changing unit is composed of a plurality of fine prisms, it is possible to manufacture using a mold that is easier to manufacture than a diffusion pattern consisting of minute irregularities. Therefore, a linear illumination device capable of easily forming the optical path conversion unit with good reproducibility can be realized at low cost. According to the fourth aspect of the invention, since the optical path changing unit is configured on a plane provided in a part of the light guide, a mold that can be easily manufactured even if the back side surface of the light guide is a curved surface. Can be used. This facilitates the formation of the optical path conversion unit, so that the linear illumination device can be realized at low cost. According to the fifth invention, since the linear illumination device according to any one of the first to fourth inventions is provided as a static eliminator, an electrophotographic apparatus (a copying machine, a printer, a facsimile machine) that can be surely eliminated at low cost. Etc.) can be realized.

  Hereinafter, a linear illumination device embodying the present invention will be described with reference to the drawings. In addition, the same code | symbol is mutually attached | subjected to the part which is the same in each embodiment etc., and the corresponding part, and duplication description is abbreviate | omitted suitably.

  FIG. 2 schematically shows a printing mechanism of an electrophotographic apparatus in which a linear illumination device is mounted as a static eliminator. The photosensitive drum 1 has a coating film made of a photosensitive charging material (that is, a photoconductive material) such as selenium on the surface. As the photosensitive drum 1 rotates, the charging device 2 uniformly charges the surface of the photosensitive drum 1, and the exposure device 3 performs exposure on a portion that is not printed, thereby removing the charge. The developing device 4 electrically attaches the toner 4a to the latent image formed by removing the electric charge. The toner 4a adhering to the latent image on the photosensitive drum 1 is transferred to the paper 7 by heat and pressure. The toner 4 a remaining on the photosensitive drum 1 after the transfer is cleaned by the blade 5, and the remaining charge is neutralized by light irradiation by a neutralization device (that is, an eraser) 6. The linear illumination device described below has made it possible to perform illumination for this static elimination with a single light source without any unevenness.

  FIG. 1 shows an embodiment of a linear illumination device. The linear illumination device shown in FIG. 1 includes a light source 10, a cylindrical transparent light guide 20, a reflector 30 having reflection characteristics, and the like. The light L0 emitted from the light source 10 enters the light guide 10 and is guided to the front side (that is, the object to be illuminated) while being guided from the first end face 21 to the second end face 22 therein. It is converted into linear light L1. The linear emitted light L1 is used for the linear illumination for the static elimination.

  Examples of the light source 10 include LEDs. In consideration of the charge removal of the photoreceptor as an application, an LED that emits red light having a wavelength of around 630 to 650 nm is preferable. Moreover, it is preferable to use a bullet-type LED having a lens-shaped tip. This is because the emitted light L0 can be incident on the light guide 20 without waste due to the strong directivity. Considering mass productivity (for example, manufacturing advantages such as being able to be manufactured by injection molding), optical characteristics (transparency, refractive index, etc.), cost, etc., a molded product made of an acrylic plastic material as the light guide 20 The reflector 30 is preferably a molded product made of a polycarbonate plastic material. However, the material is not limited to these, and other plastic materials, glass materials, and the like may be used.

  FIG. 3 schematically shows a schematic configuration of the light guide 20. 3A is a front view of the light guide 20, and FIG. 3B is an end view of a cross section taken along the line U-U 'of FIG. 3A. As shown in FIG. 3, an optical path conversion unit P for emitting light being guided to the front side is formed on the rear surface of the light guide 20. The optical path conversion part P is enlarged and shown in FIG. The optical path conversion unit P is composed of a plurality of fine prisms. That is, a structure in which a plurality of prisms having the same shape including the prism reflection surface Pa and the prism light guide surface Pb are arranged along the light guide axis AX, and the prism reflection surface Pa and the prism light guide surface Pb are alternately and repeatedly arranged. Have taken. In addition, although the optical path conversion part P is comprised so that it may adjoin to the curved-surface shape surface of the light guide 20, like other embodiment mentioned later (FIG. 11, FIG. 12), the light guide 20 of FIG. It is preferable for manufacturing to form on a partly provided plane.

  The light L0 (FIG. 1) emitted from the light source 10 enters the light guide 20 with a predetermined spread, but the incident light is reflected to the front side as the emitted light L1 by the prism reflection surface Pa. When incident light L0 is emitted from the first end face 21 to the second end face 22 and then emitted to the front side by reflection on the prism reflection surface Pa, light having an incident angle reflected to the front side by the prism reflection surface Pa. Decreases as the ratio approaches the second end face 22 side. The prism light guide surface Pb solves this problem. The light incident on the prism light guide surface Pb changes its inclination with respect to the light guide axis AX by its reflection. That is, a light beam incident at an angle θ with respect to the light guide axis AX has an angle 2α with respect to the light guide axis AX due to reflection on the prism light guide surface Pb, where α is the angle of the prism light guide surface Pb with respect to the light guide axis AX. Only near the light guide axis AX. As a result, the proportion of light having an incident angle reflected to the front side by the prism reflecting surface Pa increases.

  The ridge lines of the prisms constituting the optical path conversion unit P are inclined with respect to the light guide axis AX. For this reason, even if oblique illumination corresponding to the unevenness of each prism occurs in the illumination light, it is canceled on the surface of the rotating photosensitive drum 1 and a uniform exposure state is obtained. The cross-sectional shape of each prism constituting the optical path conversion unit P is not limited to an inequilateral triangle, but may be an isosceles triangle or the like, and may be a flat portion having a V-shaped groove. Further, the present invention is not limited to the prism, and may be a diffusion pattern composed of fine irregularities. The cross-sectional shape of the light guide 20 is not limited to a circle but may be a polygon, an ellipse, a combination thereof, or the like.

  The reflector 30 is installed in a substantially close contact state so as to surround the light guide 20, but a slight air gap (25 in FIGS. 6 to 9) is ensured between them. For this reason, the light incident on the light guide 10 from the first end face 21 can travel inside the light guide 10 toward the second end face 22 by total reflection. The light emitted from the light guide 20 in the direction other than the front side (that is, each direction toward the second end face 22 side, the upper surface side, the lower surface side, and the back surface side) is reflected by the reflector 30 and again in the light guide body 20. Led to. Accordingly, the leakage light other than the illumination light L1 is reused by the reflection at the reflector 30, so that the light use efficiency is improved. The reflector 30 may be composed of two members: a member having a reflective surface on the second end surface 22 side and a member having a reflective surface on the upper surface side, the lower surface side, and the back surface side of the light guide 20. Further, instead of using the reflector 30, a mirror coat may be applied to the surface of the light guide 20.

  Reflection by the reflector 30 may be either regular reflection or diffuse reflection, but the reflection characteristics of the reflector 30 affect not only the light utilization efficiency but also the light quantity distribution of the emitted light L1. For example, since the second end face 22 of the light guide 20 is covered with the reflector 30, the light transmitted through the second end face 22 is reflected by the reflector 30 toward the second end face 22, and is reflected at the second end face 22 side. The light quantity of the emitted light L1 is increased. In order to clarify the influence of the reflection on the second end face 22 side by the reflector 30, it is assumed that the reflector 30 only performs the reflection on the second end face 22 side, and the width of the region shape as shown in FIG. Is assumed to be formed in the light guide 20 with a constant optical path changing portion Q. Then, a valley-shaped emission light quantity distribution C0 as shown in FIG. 5A is obtained (X: light guide distance, I: emission light intensity).

  As can be seen from the graph C0 shown in FIG. 5A, the light quantity of the emitted light L1 gradually decreases from the first end face 21 side, becomes the lowest at the valley position x2 shifted by dx from the center position x1, and the second end face. It increases again toward the 22 side. Thus, the amount of emitted light on the second end surface 22 side increases due to the reflection contribution from the second end surface 22 side, and the emitted light amount distribution becomes a valley shape as a whole. If the emitted light L1 has a valley-shaped light amount distribution, uneven illumination occurs. In this embodiment, the shape of the formation region of the optical path conversion portion P is optimized so that the light amount distribution of the emitted light L1 is uniform. That is, as shown in FIGS. 3A and 5D, the end closest to the first end face 21 of the optical path changing portion P is set as the light incident end P1, and the end closest to the second end face 22 is anti-incident light. When it is defined as the end P2, the width of the light path conversion unit P changes from the light incident end P1 to the counter light incident end P2, and satisfies the following conditional expression (1) or (2). The configuration is such that the width of the optical path changing portion P is maximum between the light incident end P2 and the opposite light incident end P2.

0.1 ≦ M / L ≦ 0.45 (1)
0.55 ≦ M / L ≦ 0.9 (2)
However,
L: distance from the light incident end P1 to the light incident end P2 of the light path conversion unit P (that is, the total length of the light path conversion unit P),
M: distance from the light incident end P1 of the optical path changing unit P to the maximum width position Pt,
It is.

  The optical path conversion action of the optical path conversion unit P varies depending on the prism shape (FIG. 4) and the like, but the emission light intensity I increases at the corresponding position as the width of the optical path conversion unit P increases. However, when the width of the optical path conversion unit P is changed from the light incident end P1 to the counter light incident end P2, and the maximum width position of the optical path conversion unit P is set between the light incident end P1 and the counter light incident end P2. Since the emission of light to the front side is suppressed by the optical path conversion unit P having a narrow width on the light incident end P1 side, the valley position x2 shown in FIG. 5A is shifted to the counter light incident end P2 side. become. It is preferable to set the maximum width position Pt of the optical path conversion unit P at the second valley position at that time, and the conditional expressions (1) and (2) define it. If the maximum width position Pt of the optical path conversion unit P is set so as to satisfy the conditional expression (1) or (2), the amount of light at the valley position x2 increases as shown in FIG. The light quantity distribution of L1 is made uniform from C0 to C1, and the occurrence of illumination unevenness is suppressed. Further, the maximum width position Pt of the optical path conversion section P may be set to a position shifted by 0.1 L to 0.2 L from the valley position x2 to the counter-incident light end P2 side, and even in that case, the conditional expression (1) Alternatively, it is possible to obtain the same effect as when (2) is satisfied.

  Examples of numerical values when the maximum width position Pt is adjusted and optimized so that the light quantity distribution is uniform as described above will be given below. In the following numerical examples, M / L = 0.6, which satisfies the conditional expression (2). The change in the width from the light incident end P1 to the maximum width position Pt and the change in the width from the maximum width position Pt to the counter light incident end P2 are both linear, but the required amount of emitted light is required. Depending on the uniform distribution, these width changes may be configured in a curve.

[Numeric example]
Total length L of the optical path conversion part P = 250 mm,
Distance M to maximum width position Pt = 150 mm,
The diameter of the light guide 20 = 4.0 mm,
The width of the optical path changing part P at the light incident end P1 = 0.8 mm,
The width of the optical path conversion part P at the maximum width position Pt = 2.0 mm,
Width of the optical path conversion part P at the counter light incident end P2 = 1.2 mm

  In the conventional way of thinking, when an optical path conversion unit is provided in the light guide, the optical path conversion action is set to increase as the distance from the light source increases. For example, when light is incident from one side of the light guide 20 as shown in FIG. 10A, the width of the optical path conversion unit R is set to a shape that gradually increases from the light incident end R1 to the counter light incident end R2. When the light is incident from both sides of the light guide 20 as shown in FIG. 10B, the width of the optical path changing unit S is set to gradually increase from both ends S1, S2 to the center. In the case of FIG. 10 (A), when the light emitted from the second end face 22 is reflected to improve the light utilization efficiency, the reflected light quantity from the second end face 22 side loses the balance of the emitted light quantity distribution to the front side. This will cause uneven illumination. In the case of FIG. 10B, since two light sources 10a and 10b are necessary, an increase in cost is inevitable. According to the present embodiment, all of these problems are solved. In other words, since only one light source 10 is used, the cost can be significantly reduced, and it is possible to achieve both reduction in illumination unevenness and high light utilization efficiency even though the number of light sources 10 is one.

  The light quantity distribution C1 in FIG. 5C assumes that the reflector 30 performs only reflection on the second end face 22 side. However, as described above, the reflector 30 extends from the light guide 20 to the upper surface side and the lower surface side. The light emitted in each direction on the side and back side is also reflected and guided again into the light guide 20. Therefore, the reflection characteristics of the reflector 30 on the upper surface side, the lower surface side, and the back surface side of the light guide 20 also affect the light amount distribution of the emitted light L1. In particular, since an optical path conversion unit P for emitting light being guided to the front side is formed on the back surface of the light guide 20, the light transmitted from the optical path conversion unit P to the back side is an optical path. The reflection characteristics of the reflector 30 reflected to the conversion unit P side greatly influences the light amount distribution of the emitted light L1.

  When the reflection of the reflector 30 that reflects the light emitted from the light guide 20 in the direction other than the front side (that is, each direction toward the second end face 22 side, the upper surface side, the lower surface side, and the rear surface side) is regular reflection. A light amount distribution C2 of the emitted light L1 is shown in FIG. 6 (A), and a light amount distribution C3 of the emitted light L1 in the case of uniform diffuse reflection is shown in FIG. 7 (A). A light amount distribution C4 of the emitted light L1 in a certain case is shown in FIG. However, the emitted light quantity distributions C2 to C4 shown in FIGS. 6A to 8A are the light guide distances X corresponding to the light guides 20, the reflectors 30 and the like shown in FIGS. It is expressed by the emission light intensity I.

  In any of the cases of FIGS. 6 to 8, the light use efficiency is improved. However, when the reflector 30 that performs uniform diffuse reflection is used (FIG. 7), the obtained light amount distribution C3 is insufficiently uniformized. . However, diffuse reflection is effective for making the emitted light quantity distribution uniform, and if it is used, the emitted light quantity distribution can be improved as shown in FIG. Therefore, the reflector 30 diffuses and reflects the light transmitted from the optical path conversion unit P to the back side toward the optical path conversion unit P, and the amount of diffuse reflection is along the light guide direction by the light guide 20 (that is, the light guide axis AX direction). It is preferable that the configuration changes.

  Examples of the method of changing the degree of diffusion due to reflection depending on the position include a method of changing the molding shape of the reflecting surface of the reflector 30 depending on the position, a method of printing on the reflecting surface of the reflector 30 with different reflection characteristics depending on the position, and the like. It is done. As a method of changing the shaping shape of the reflecting surface of the reflector 30 depending on the position, a method of changing the number of scatterers having the same scattering characteristics (such as wrinkles) (that is, the density of the scatterers) depending on the position, a scattering angle that varies depending on the position. Examples include a method of forming a scatterer having characteristics (that is, a method of changing the shape and size of the scatterer depending on a location), a method of performing a surface treatment different depending on a position (for example, a method of changing sandblasting), and the like. Considering the manufacture of the reflector 30, a method of changing the number of scatterers having the same scattering characteristics depending on the position is preferable, and an example of adopting this method is shown in the graph of FIG. 8C (X: light guide distance, J: Scatterer density).

  As the density J of the scatterers increases, the degree of diffusion due to reflection increases, and as a result, the emission light intensity I at that position increases. This will be described with reference to FIG. FIG. 9A shows an optical path when the degree of diffusion at the reflecting surface of the reflector 30 is small, and FIG. 9B shows an optical path when the degree of diffusion at the reflecting surface of the reflector 30 is large. Since most of the light rays transmitted from the optical path changing unit P to the back side are incident on the reflecting surface of the reflector 30 at a shallow angle, the degree of diffusion due to reflection is small as shown in FIG. In the case of a mirror surface), the angle formed with respect to the light guide axis AX is returned to the light guide 20 again with a small angle. There are few such lights that travel to the front side (large arrows), and the light is further guided by total reflection. On the other hand, when the degree of diffusion due to reflection is large as shown in FIG. 9B, the light intensity of each light beam is reduced by the increase in the diffusion angle, but the emitted light intensity increases because the light beam toward the illumination direction increases. I will increase. Therefore, for the same reason as in the case of optimizing the formation region shape of the optical path changing portion P described above, {as can be seen from the correspondence between the positions of (B) and (C) in FIG. It is preferable to optimize the position where the amount of diffuse reflection by the reflector 30 is maximized so as to correspond to the shape.

  FIG. 11 shows a rear side external configuration of another embodiment, and FIG. 12 shows a cross-sectional structure taken along line V-V ′. Although the basic configuration is the same as that of the above-described embodiment (FIG. 1 and the like), a light guide 20A that is partially bent and disposed so as to cover it so as to be able to deal with restrictions on installation space and the like. And a reflector 30A. In the bent portion 23 of the light guide 20A, the reflection portion is cut at 45 degrees so that the light beam is reflected by bending the light guide axis AX approximately 90 ° (that is, 90 ° or substantially 90 °). . As a result, the light L0 emitted from the light source 10 is once bent and then enters the optical path conversion unit P from the light incident end P1, so that the linear illumination device can be miniaturized by bending the optical path efficiently. It becomes possible.

  The optical path conversion part P is formed on a flat surface part F provided in a part of the cylindrical light guide 20A. The light guide 20A in which the optical path conversion part P is formed on the flat surface part F has an advantage of easy manufacture. In the case where the optical path conversion part P is configured to be adjacent to the curved surface of the light guide 20A, the core shape of the mold for forming the optical path conversion part P is approximately the same rhombus shape as the optical path conversion part P You have to do it. Therefore, if it is going to perform the additional process for changing the formation area shape of the optical path conversion part P, correction of all the metal molds is needed. On the other hand, if the optical path changing part P is formed on the flat part F, the core shape of the mold can be made rectangular. In that case, if it is necessary to change the formation region shape of the optical path conversion portion P, only the formation region shape of the mold for forming the optical path conversion portion P may be corrected. Therefore, additional machining of the mold can be easily performed.

  By having the linear illumination device described above as the static eliminator 6 (FIG. 2), an electrophotographic apparatus (copying machine, printer, facsimile, etc.) that can reliably eliminate static electricity can be realized. Further, the linear illumination device can be used as an illumination device or a part thereof in devices other than the electrophotographic apparatus. For example, when a long fluorescent tube or a long halogen lamp is used instead of a linear illumination device using a light source, illumination with no unevenness and high light utilization efficiency can be performed at low cost and in a compact manner. Examples of such a linear illumination device include a backlight and a front light used for a non-light-emitting display element such as an LCD (Liquid Crystal Display).

  Each of the above-described embodiments includes inventions (i), (ii),... Having the following configuration. According to the configuration, even a single light source has no illumination unevenness and has high light utilization efficiency. A state lighting device can be provided.

  (i) a light source, a light guide that converts light emitted from the light source into linear light by guiding the light from the first end surface to the second end surface, and converting the light into linear light, and at least the second end surface And a reflector that reflects the light that has passed through the second end face to the second end face side, and is an optical path conversion for emitting light being guided to the front side on the back side surface of the light guide And the end of the optical path conversion unit closest to the first end surface is the light incident end, and the end of the second end surface is the counter incident light end. A linear illumination device, wherein the linear illumination device changes from an end to a counter-incident light end, and the width of the optical path conversion unit is maximized between the incident light end and the counter-incident light end.

  (ii) The linear illumination device according to (i), wherein the conditional expression (1) or (2) is satisfied.

  (iii) The optical path at a position shifted by 0.1 L to 0.2 L from the valley position of the emitted light amount distribution obtained when the width of the formation region shape of the optical path conversion portion is constant. The linear illumination device according to (i) or (ii) above, wherein the maximum width position of the conversion unit is set.

  (iv) a light source, a light guide that converts light emitted from the light source to the front side while guiding light from the first end surface to the second end surface, and converts the light into linear light, and at least the second end surface And a reflector that reflects the light that has passed through the second end face to the second end face side, and is an optical path conversion for emitting light being guided to the front side on the back side surface of the light guide Part is formed, the reflector diffusely reflects the light transmitted from the optical path conversion unit to the back side to the optical path conversion unit side, the diffuse reflection amount changes along the light guide direction by the light guide, A linear illumination device characterized in that the amount of diffuse reflection is maximized during light guide.

  (v) The diffuse reflection at a position shifted by 0.1 L to 0.2 L from the valley position of the emitted light amount distribution obtained when the width of the formation region shape of the optical path changing portion is constant. The linear illumination device as described in (iv) above, wherein a maximum position of the quantity is set.

  (vi) The light guide has a bent portion that bends an optical path between the first end surface and the optical path conversion unit, according to any one of the above (i) to (v), Linear lighting device.

The perspective view which shows one Embodiment of a linear illuminating device. 1 is a system configuration diagram schematically showing a printing mechanism of an electrophotographic apparatus. The schematic diagram which shows schematic structure of a light guide. The perspective view which expands and shows the optical path conversion part of a light guide. The figure for demonstrating the relationship between the formation area shape of an optical path conversion part, and emitted light quantity distribution. The figure for demonstrating the change of the emitted light intensity in case the reflection in a reflector is regular reflection. The figure for demonstrating the change of the emitted light intensity in case the reflection in a reflector is uniform diffuse reflection. The figure for demonstrating the change of the emitted light intensity in case the reflection in a reflector is a diffuse reflection from which a diffusion degree differs with positions. The figure for demonstrating the relationship between the spreading | diffusion degree of a reflector, and the emitted light quantity. The schematic diagram which shows the reference example of a light guide. The rear view which shows other embodiment of a linear illuminating device. FIG. 12 is a sectional view taken along line V-V ′ of FIG. 11.

Explanation of symbols

6 Static eliminator (linear illumination device)
DESCRIPTION OF SYMBOLS 10 Light source 20 Light guide 30 Reflector 21 1st end surface 22 2nd end surface P Optical path conversion part Pa Prism reflective surface Pb Prism light guide surface P1 Light incident end P2 Opposite light incident end AX Light guide shaft 20A Light guide 30A Reflector 23 Bending Part F Flat part

Claims (5)

A light source, a light guide that converts light emitted from the light source to the front side while guiding light from the first end surface to the second end surface, and converted to linear light, and at least transmitted through the second end surface A linear illumination device including a reflector that reflects light toward the second end face, and an optical path conversion unit that emits light being guided to the front side is formed on a rear surface of the light guide. When the end closest to the first end surface of the optical path conversion unit is the light incident end and the end closest to the second end surface is the anti-incident light end, the width of the optical path conversion unit is opposite to the light incident end. The width of the optical path conversion unit is maximized between the light incident end and the counter light incident end so as to change toward the light incident end and satisfy the following conditional expression (1) or (2): A linear lighting device;
0.1 ≦ M / L ≦ 0.45 (1)
0.55 ≦ M / L ≦ 0.9 (2)
However,
L: distance from the light incident end to the light incident end of the optical path changing unit,
M: distance from the light incident end of the optical path changing unit to the maximum width position,
It is.   A light source, a light guide that converts light emitted from the light source to the front side while guiding light from the first end surface to the second end surface, and converted to linear light, and at least transmitted through the second end surface A linear illumination device including a reflector that reflects light toward the second end face, and an optical path conversion unit that emits light being guided to the front side is formed on a rear surface of the light guide. The reflector diffuses and reflects the light transmitted from the optical path conversion unit to the back side to the optical path conversion unit side, and the diffuse reflection amount changes along the light guide direction by the light guide. Linear lighting device.   The linear illumination device according to claim 1, wherein the optical path conversion unit includes a plurality of fine prisms.   The linear illumination device according to claim 1, wherein the optical path conversion unit is configured on a plane provided in a part of the light guide.   An electrophotographic apparatus comprising the linear illumination device according to claim 1 as a static eliminator.

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