JP4890169B2 - Lighting device - Google Patents

Description

The present invention relates to lighting equipment, in particular, it relates to a lighting equipment for irradiating a copier or a facsimile of the document surface.

  First, the basic operation of the image reading apparatus will be described. FIG. 29 is a schematic view of the image reading apparatus and shows the main configuration in a skeleton manner. FIG. 30 is a front view of the image reading apparatus so that the relationship between the first traveling body and the second traveling body that can scan the document surface while keeping the optical path from the document surface to the one-dimensional imaging device constant is understood. .

  The image reading apparatus includes a document placement location 30, a contact glass 31, a document 32, an illumination lamp 33, a turning mirror 34, a reflector 35, a one-dimensional image sensor 36, an imaging lens 37, a drive transmission means 38, a motor 39, a first A traveling body 40 and a second traveling body 41 are included.

  Here, the contact glass 31 is a transparent glass and is also referred to as a document table. A document 32 such as a sheet or book is placed on this. The illumination lamp 33 is a cold cathode tube, and a part of the tube wall is a window, from which illumination light is radiated toward the imaging region 45. The reflector 35 reflects the light leaked from the illumination lamp 33 to the imaging region 45. The turning mirror 34 bends the image of the imaging region 45 from vertical to horizontal. The folding mirrors 42 and 43 once bend the image from the turning mirror 34 vertically once by the folding mirror 42 and further bend it horizontally by the folding mirror 43 and return the direction to the original direction.

The imaging lens 37 is generally a lens that is formed by integrating a plurality of lenses with a lens barrel and forms an image of a reading region on the one-dimensional image sensor 36.
The one-dimensional imaging device 36 (hereinafter, abbreviated as one-dimensional CCD or simply CCD) uses a one-line CCD in a monochrome image reading device, and passes through corresponding R, G, and B color filters in a color image reading device. The three lines of the CCD are arranged close to each other, and the image light in the reading area obtained through the imaging lens 37 is converted into an electric signal. Hereinafter, a combination of the imaging lens 37 and the one-dimensional image sensor 36 is referred to as a reading unit 46.

The first traveling body 40 is formed by integrating an illumination lamp 33, a reflector 35, and a deflecting mirror 34, and is parallel to the contact glass 31 and in a sub-scanning direction (a main scanning direction in which a document surface is read by a one-dimensional CCD). In the direction perpendicular to the).
The second traveling body 41 is equipped with folding mirrors 42 and 43 and travels in the sub-scanning direction in parallel with the contact glass 31. The traveling speed is half of the traveling speed of the first traveling body 40.
By doing so, the distance from the imaging region 45 of the reading optical axis 47 to the imaging lens 37 is constant regardless of which position in the sub-scanning direction the imaging region 45 is read. The entire reading area is (a range read by the one-dimensional CCD × a range in which the traveling body moves).

Usually, the image resolution of an image reading apparatus is expressed by DPI (dot / inch), and a scanner mounted on a digital PPC is often 400 to 600 DPI.
In particular, in a color scanner, a 3-line CCD in which 3-line CCDs having sensitivity to light of R (red), G (green), and B (blue) are arranged in the sub-scanning direction is often used as an image sensor. There is a distance of about 4 to 8 times the CCD pixels between the pixel columns, and they are not necessarily integrated. When this is mounted on the image reading apparatus, the reading position of the CCD pixel corresponding to each RGB is shifted in the sub-scanning direction, and naturally the illumination needs to be adjusted to each reading position.

  In general, as shown in FIGS. 29 and 30, the image reading apparatus including the document setting table 30 and the imaging lens 37 is fixed, and two traveling bodies equipped with a plurality of mirrors are moved at a predetermined speed ratio between them. Thus, the cold cathode tube is used in the illumination method of the image reading apparatus for obtaining the image signal on the document surface 44 while keeping the distance between the document 32 and the imaging lens 37 constant.

As a problem of the image reading apparatus shown here, the illumination light entering the imaging region by the illumination lamp and the reflector on the first traveling body is less than 1% of the emitted light, and the illumination efficiency is very poor.
The concept is shown in FIG. The imaging region 45 in the sub-scanning direction is about 0.1 mm wide when using a one-line CCD, and less than 1 mm even when using a three-line CCD such as when reading a color document. A few millimeters is sufficient even when variations are taken into account. Nevertheless, the illuminance distribution in the sub-scanning direction is spread over a very wide range of several tens of mm centering on the imaging region 45.
In addition, the cold cathode fluorescent lamp itself and its lighting device (which generates a high voltage) are complicated, or are sources of electrical noise.

  As a method for solving these problems, in Patent Documents 1 and 2, by using a light source placed in the vicinity of an imaging lens far from the original surface without using a fixed side reflector, fluctuations in the amount of light can be suppressed. It is disclosed that a high-quality image can be read by reducing flare light generated by re-reflection of reflected light from a document.

Further, in Patent Documents 3 to 4, an LED (light emitting diode) is used in place of the above-described conventional bar light source such as a xenon lamp, and a reflection mirror is devised so that the image reading area on the original surface can be illuminated as uniformly as possible. In order to achieve this, a method using a special reflector, a method of increasing the amount of light by combining a plurality of LEDs and a concave mirror, and the like are disclosed.
JP 2000-250146 A JP 2000-253213 A JP-A-2005-234108 JP 2005-241681 A

However, in the method of illuminating the original surface with a light source placed in the vicinity of the imaging lens, the three mirrors that fold the reading optical axis are shared as mirrors for folding the illumination light. Of the luminous flux, the spread light is diffracted twice by the two mirrors on the second carriage and returns directly to the imaging lens without being directed to the original surface.
Although the amount of light is less than the light flux directed toward the original surface, there is a certain amount of light regardless of the image on the original surface, so that a black floating phenomenon occurs in which brightness increases even in a black state.

  In addition, due to the light emission principle and the characteristics of the manufacturing method, the emission efficiency varies greatly, and if a stable light quantity is required, a sorting step is required. Variation in luminous efficiency directly leads to uneven illuminance.

The present invention was made in view of the circumstances as described above, e suppress the spread of the light beam in the sub-scanning direction, the light beam in the main scanning direction (one-dimensional direction), uniformly illuminated target area so as to, and an object thereof is to provide a lighting equipment to efficiently illuminate so there is no divergence of the light at the end.

The following objects are achieved by the present invention.
1. Improved lighting efficiency (energy saving).
2. Improve lighting quality (reduce illuminance unevenness).
3. Simplification of lighting circuit (cost reduction).

In order to solve the above-described problem, the illumination device according to claim 1 of the present invention forms an image of the scattered light from the document surface illuminated by a plurality of light sources arranged in a straight line on an image sensor by an imaging lens. The image on the original surface is read one-dimensionally with a direction parallel to the direction in which the plurality of light sources are arranged as a reading direction, and is orthogonal to both the reading direction and the direction parallel to the irradiation optical axes of the plurality of light sources. In an illuminating device for an image reading apparatus that reads a two-dimensional image by moving in the moving direction and sequentially repeating one-dimensional reading , the light sources that correspond to the plurality of light sources on a one-to-one basis A plurality of bullet-type convex lenses having a light-emitting surface of the light source as a focal position for output as parallel light; and a condenser lens that divides and collects the light beam output from the bullet-type convex lens in the main scanning direction; A combination of an irradiation lens that irradiates the light beam output from the condenser lens in the main scanning direction of the original surface and an integrated lens that superimposes the light beam output from the irradiation lens on the original surface. The plurality of bullet-type convex lenses are configured as an illumination unit, and are arranged so that side surfaces in the reading direction are linearly cut so that adjacent side surfaces are in contact with each other, and the lighting units are arranged in the reading direction. A plurality of first side mirrors and second side mirrors that are arranged side by side and share a region illuminated by each of the plurality of illumination units and that are parallel to each other are arranged in a direction parallel to the irradiation optical axes of the plurality of light sources. and Nobezai, so that said first side mirror, the side in contact with the edge of the integrated lens of a lighting unit disposed at one end in a plurality lined lighting unit in reading direction becomes mirror Arrangement, and the second side mirror, wherein arranged to the side in contact with the edge of the integrated lens of a lighting unit disposed at the other end in a plurality lined lighting unit in reading direction is a mirror surface, said plurality of A plurality of light beams output from the illumination unit are superimposed on the document surface.

The illumination device according to claim 2 of the present invention is the imaging device according to claim 2, wherein the number of the illumination units is n, the illumination target region is divided by 2 × n, and the divided illumination target is provided. When the number is assigned to the boundary of the region from the end, the lighting unit is arranged at the odd boundary number, and the side mirror is arranged on the outer side of the lighting unit arranged outside the arranged lighting unit. It is characterized by arranging.

Moreover, the illumination device according to claim 3 of the present invention is the imaging device according to claim 3, wherein the number of the illumination units is 3, the illumination target area is divided into 6, and the illumination is divided into 6 When numbers are assigned to the boundaries of the target area from the end, the three illumination units are arranged at the odd boundary numbers No. 1, No. 3 and No. 5, and two of the three illumination units are arranged on both sides. The side mirror is arranged outside the illumination unit.

According to the present invention, the light beam in the main scanning direction can be illuminated with little illuminance unevenness even if a light source with uneven light distribution is used, and even if a wide imaging area is illuminated with a plurality of light sources, light emission by the light source is possible. The amount of illumination can be reduced by reducing the difference in amount. Further, it is possible to efficiently illuminate so that the divergence of light outside the imaging region is reduced.
Further, the spread of the light beam in the sub-scanning direction can be suppressed, and a high-quality image can be obtained from a document illuminated by the illumination device.
Further, by converging in the sub-scanning direction while diverging the light beam in the main scanning direction, the illumination light rate is greatly improved, which can contribute to energy saving.
Also, the main optical components can be made by plastic molding, and if an LED is used as the light source, only a low-voltage DC power source is required, so the lighting circuit becomes very simple and the cost is reduced.

With reference to the drawings, preferred embodiments of the illumination device and illumination method of the present invention will be described in detail.
FIG. 1 is a diagram showing the concept of the illumination system of the present invention.
First, the concept of efficiently illuminating the illumination target surface while suppressing the illuminance unevenness in the main scanning direction will be described with reference to the top view of FIG.
As shown in FIG. 1A, LEDs (light emitting diodes) 1 are arranged on a straight line as a light source. The individual LEDs 1 are encapsulated with a transparent resin, and a convex lens LL1 having a light emitting surface of the LED 1 as a focal position at the tip is formed. Thereby, the light beam emitted from the LED 1 is output as substantially parallel light. The method of collimating the luminous flux of the light source LED 1 may use a rotary parabolic mirror PR as shown on the left side, but here, a method using a convex lens will be mainly described.

The condensing lens CA1 divides the parallel light in the main scanning direction, and then condenses the extracted light beam to an individual cylinder (lens) of the next illumination lens CA2.
The condensing lens CA1 is a lens that divides the light beam from the light source LED1 in the main scanning direction and collects the extracted light beam through an individual cylinder (lens) of the illumination lens CA2, which will be described below. Thus, a cylinder (lens) array having a shape as shown in FIG. 9A, in which cylinders (lenses) as shown in FIG. 9C are arranged. The focal length f1 of the individual cylinder is the distance c in FIG. 1 (ie, f1 = c).

  The illumination lens CA2 is a lens for irradiating the original surface, which is the illumination target surface, in the main scanning direction. Similarly, the illumination lens CA2 is configured by a cylinder (lens) array (FIG. 9A), and includes individual cylinders (lenses). The focal length f2 is approximately f2 = 1 / (1 / (a + b) + 1 / c). Here, f1 = f2 can be designed, and by doing so, the condenser lens CA1 and the illumination lens CA2 can be used as members of the same standard.

  The integrated lens CL1 is a cylinder (lens) for superimposing the irradiated luminous flux divided and condensed by the condenser lens CA1 and the illumination lens CA2. The focal length f0 is set to f0 = a so that the optical axis (referred to as the secondary optical axis) of the light beam divided by the condenser lens CA1 and the illumination lens CA2 is aligned with the center (main optical axis) of the illumination target surface. The divided luminous flux can be superimposed on the illumination target surface (in FIG. 1, the expression is omitted every other cylinder in the cylinder array to avoid complication). The focusing lens CL2 is transmitted in the middle, but since the focusing lens CL2 is a cylinder as shown in FIG. 9E, it behaves as a parallel plate from the viewpoint from above, and from the integrated lens CL1 to the illumination target surface. Only a slight deviation in the distance a does not affect the essential operation.

  Here, when the magnification of the image is explained by the illumination lens CA2, the content obtained by combining the focal lengths f2 and f0 of the illumination lens CA2 and the integrated lens CL1 is originally used, but the explanation is simplified because it is f2 << f0. Therefore, it is assumed that b = 0 and ignoring f0 of the integrated lens CL1.

  Here, m0 is the width of each cylinder of the cylinder array CA1, and K is the width of the irradiation target region of the irradiation target surface 2 in the main scanning direction, and f0 and f1 are determined so that M / m = a / c. And the illumination target areas K and M coincide with each other from the light flux from m. With this setting, an image of the size m of the individual cylinder of CA1 is projected onto the illumination target surface 2 in the size M, and all the light beams that have passed through m reach the illumination target surface 2 (individually from this cylinder) Illumination by the luminous flux of the light has a very uneven illuminance, but the result of superimposing the whole is flat).

Here, the relationship between the number of light sources LED1 for reducing the illuminance unevenness on the illumination target region K and the number of cylinders constituting the cylinder array will be described.
The light sources LED1 are arranged at equal intervals in the main scanning direction, the portions including the light beams at both ends thereof are made to coincide with the cylinder array of the condenser lens CA1 and the illumination lens CA2, and the number of cylinders of this element is made to coincide with the number of LEDs1. If the axes are also combined, the luminous flux distributions of the individual LEDs 1 are overlapped as they are, so that the illuminance distribution as shown in FIG. 2A is proportional to the luminous flux distribution of the individual LEDs 1.

  One method for averaging this is to make the number of LEDs 1 of the light source and the number of cylinders inconsistent. In particular, if the number is changed by one, the averaging effect is best. As an example, FIG. 3A shows a case where the number of cylinders is reduced by one than the number of light source LEDs, and FIG.

  As shown in FIGS. 2B and 2C, the illuminance distribution in the case of such a configuration is averaged by overlapping of the distributions of light beams cut by individual cylinders. Here, CA11 to CA14 and CA11 to CA16 are numbered in order from the top of FIGS. 3A and 3B with respect to the individual cylinders of each condenser lens (cylinder array) CA1. Individual curves in 2 (B) and (C) indicate the illuminance on the illumination target region K irradiated by the light beams extracted by the respective condensing lens CA1 and each cylinder of the illumination lens (cylinder array) CA2. Yes.

FIG. 2B corresponds to FIG. 3A, and is an example in which five LEDs 1 and four cylinders in the cylinder array are used. FIG. 2C corresponds to FIG. 3B, and is an example in which five LEDs 1 and six cylinders in the cylinder array are used.
By configuring in this way, it is possible to perform illumination with very little illuminance unevenness without impairing illumination efficiency (the variation rate can be on the order of several percent).

Next, the illumination concept in a direction perpendicular to the main scanning direction (sub-scanning direction) will be described with reference to a front view shown in FIG.
The luminous flux emitted from the LED 1 encapsulated with the transparent resin is converted into a substantially parallel luminous flux by the lens at the tip and output. The condensing lens CA1, the illumination lens CA2, and the integrated lens CL1 behave in the same manner as a parallel plate from this viewpoint, so that their light beams pass through the light as they are with little influence.

The focusing lens CL2 collects light on the illumination target surface 2 because the focal length f0 ′ is f0 ′ = a ′. Thus, the illuminance distribution on the illumination target area K in the main scanning direction can be made uniform while the light beam emitted from the light source LED1 is kept in a very small divergence angle in the sub-scanning direction.
The method using a convex lens as the means for collimating the luminous flux of the LED 1 has been mainly described above, but the method of placing the light emitting surface of the LED 1 at the focal position of the rotary parabolic mirror PR operates in exactly the same way.
In addition, in order to make it easy to explain the focusing function member on the drawing, the focusing lens CL2 has been described. However, in terms of mounting, a parabolic mirror is more easily realized. In this case, this focusing function member is referred to as a focusing mirror.

The case where the basic concept described above is implemented in an image reading apparatus as shown in FIG. 30 is shown in FIGS.
FIG. 4 is a front view of the image reading apparatus. Here, only the parabolic mirror PM of the focusing member is placed on the first traveling body 3, and the other illumination members are collectively placed in the vicinity of the imaging lens 4 as the illumination unit LU. This illumination unit LU is placed below the imaging lens 4 and a folding mirror C and a folding mirror D are newly placed on the second traveling body 5 so as to be completely separated from the reading optical axis, and the luminous flux from the illumination unit LU. Is guided to a parabolic mirror PM on the first traveling body 3.
The parabolic mirror PM is focused on the imaging region on the contact glass 6, that is, the illumination target region K, via a plane mirror (folding mirror E).

  The radiation vector of light emitted from the illumination unit LU has a light distribution characteristic as shown in FIG. 5 in the sub-scanning direction. As can be seen, the vector intensity of parallel light is the strongest and decreases as the angle from the optical axis increases, but it becomes divergent light with an intensity about half that of the parallel light vector up to about ± 5 °. I understand. By reducing the divergence angle of the light shown as the diverging light, the downward movement amount (shift) of the illumination unit LU can be reduced. As a result, the vertical size of the entire image reading apparatus can be reduced. .

  FIG. 6 is a top view of the image reading apparatus, and shows a case where illumination units are arranged on both sides of the imaging lens 4. Here, the display of the members on the first and second traveling bodies 3 and 4 is omitted, and the contact glass 6 is displayed tilted by 90 °. In this case, the integrated lens CL1 uses the periphery of the cylinder. That is, in FIG. 6, the portion occupied by the imaging lens 4 from the state where the entire portion displayed as the illumination unit LU1 and the second illumination unit LU2 is viewed as the LED1, LL1, CA1, CA2, and CL1 shown in FIG. Is excluded. The integrated lens CL1 having such a configuration has a shape as shown in FIG.

By adopting this configuration, it is not necessary to shift the illumination unit LU shown in FIG. 4 so as to completely disengage from the imaging lens in the vertical direction, and they may be arranged so as to overlap each other when viewed from the front.
Note that both the first and second illumination units LU1 and LU2 may be installed, but either one may be used. This is determined by the balance between the amount of light required and the cost.

Here, another method for reducing the illuminance unevenness on the irradiation target region K will be described.
The luminous flux from one light source LED1 is divided by a plurality of cylinders. FIG. 7 shows an example of three divisions. The display of the irradiation range in FIG. 7 shows a case where the integrated lens CL1 is removed. When the integrated lens CL1 is inserted, if the focal length of the integrated lens CL1 is made to coincide with the distance a to the illumination target surface 2, the sub optical axes cut out by the respective cylinders coincide with each other in the illumination target surface. The range of M illuminated by the cylinder is made to coincide with the illumination target area K, which is the same as the contents described in FIG.

The illuminance distribution when the integrated lens CL1 is inserted is as shown in FIGS. FIG. 8A shows the intensity distribution of the light beam emitted from the rotating parabolic mirror PR and entering each of the cylinders m1, m2, and m3, and when it reaches the illumination target surface 2, FIG. Thus, the luminous flux from m1 irradiates the entire illumination target area K as in m1 ′. Similarly, the light beam from m2 is irradiated as m2 ', and the light beam from m3 is irradiated as m3'. Thus, it can be seen that m1 to m3 cut by the condenser lens CA1 are inverted with the optical axis being line symmetric and each irradiates the entire illumination target region K.
FIGS. 8B and 8D show four cases as representatives when the number of cylinders constituting the condenser lens CA1 and the illumination lens CA2 is an even number. The correspondence relationship between m and m ′ is the same as in the case of FIGS.
As a result, even if the distribution of irradiation through the respective cylinders is biased, the sum is almost constant in any part of the entire illumination target area K, and illuminance unevenness hardly occurs.

Here, a modification is shown.
The width m of one cylinder constituting the cylinder array can be 1 mm to several mm.
Even if the integrated lens CL1 is removed, the deviation on the illumination target surface 2 is only the unit. FIG. 7 shows the illumination range when the integrated lens CL1 is removed. As the range M irradiated by one cylinder, only the overlapping portion of the areas irradiated by the cylinders is captured in the imaging region (illumination target region K). In this case, the light beam that is wasted in the main scanning direction can be obtained by multiplying the area of the cylinder by the width of the cylinder, and one object of the present invention to irradiate the reading area uniformly is as follows. Can be achieved. This is particularly effective when the number of cylinders is small.

FIG. 9 shows a three-dimensional view of main optical components used in the method and apparatus described so far or the method and apparatus described below.
FIG. 9A shows a cylinder array used for the condenser lens CA1 and the illumination lens CA2 in FIGS.
FIG. 9B shows a cylinder array CA used for the illumination lens in FIG.
FIG. 9C shows a single cylinder which is a component of FIG. Although the length ratio is different, the integrated lens CL1 in FIGS. 1 and 7 also has this shape.

FIG. 9D shows the peripheral portion cut out by removing the vicinity of the optical axis of the cylinder of FIG. 9C. The integrated lens CL1 shown in FIG. 6 uses this shape.
FIG. 9E is a cylinder used as the focusing lens CL2 and has a shape obtained by combining FIG. 9C.
FIG. 9F is a parabolic mirror used instead of the focusing lens CL2 and can be approximated by a concave mirror. This is the parabolic mirror PM on the first traveling body 3 shown in FIG.

  In FIG. 9 (G), when the focal length of the cylinder of FIG. 9 (C) is short and large, it becomes thicker and heavier. To solve this problem, prisms are arranged in the same way as the Fresnel lens. It is thinned. The curvature of each prism-shaped part is basically the same as the curvature of the corresponding position from the center of the original cylinder, but may be approximated by a straight line. Further, since the angle of each prism can be adjusted by correcting the aberration corresponding to the so-called spherical aberration of the normal convex lens, this shape can improve the performance optically.

  FIG. 9H shows the cylinder shown in FIG. 9D made Fresnel. For the same reason as in FIG. 9G, the optical performance can be better than that in FIG. 9D, and can be used instead of the integrated lens CL1 in FIG. This will be referred to as a prism array PA again.

Here, the method of making the light beam emitted from the light source LED1 into parallel light will be described in more detail.
FIG. 10 is generally referred to as a cannonball type, and the tip portion covered with a transparent resin with the center of the light emitting surface of the LED as the optical axis is a convex lens (also referred to as a hood lens).
The position and shape of the convex lens are determined by a trade-off between the utilization rate of the luminous flux and the parallel light conversion rate. In FIG. 10, the range from the center of the light emitting surface of the LED to the critical angle θ with respect to the surface of the hood lens is defined as the size D of the hood lens, and the focal length of the hood lens is defined as f.

  If the focal length f is reduced, the curvature of the hood lens is reduced and the size D of the lens is also reduced. As a result, the angle α at which the luminous flux radiated from the LED is taken becomes small, and the luminous flux that cannot be collimated increases, so that the light utilization efficiency decreases.

  Therefore, the focal length f of a certain size is necessary, but the maximum value is naturally determined by the refractive index of the resin used if the range up to the critical angle θ described above is the size D of the hood lens. . In addition, the light beam emitted from the central part of the LED can be made into completely parallel light in principle. However, since the LED has an area, the light beam emitted from a portion (point) slightly off the center is from the same position. Although the radiation vector becomes parallel light, it becomes a light flux having a certain inclination from the optical axis.

  As for the inclination, the luminous flux from the end becomes the largest. Therefore, the light flux of the entire hooded LED becomes a light flux having a certain angular distribution. In the side view (B), the reason for cutting in the z-axis direction is to increase the arrangement density when a plurality of lines are arranged in the main scanning direction. This part is also a part where the degree of parallelism deteriorates, and it is assumed that the arrangement density is increased and arranged even at a slight sacrifice of the light flux to be captured. The rotating paraboloid mirror described later shows a state of cutting in the z-axis direction, but the reason is the same.

  In FIG. 11, the center of the light emitting surface of the light source LED is placed at the focal position of the rotary parabolic mirror, and is filled with transparent resin up to that position. In principle, the light beam emitted from the center of the light emitting surface of the LED becomes completely parallel light. The light emitting surface of the LED has an area, and the emitted light flux has almost the same radiation vector at any location (point), and the intensity thereof is also the same. A portion deviated from the center deviates from the focal position of the paraboloid of revolution. The light beam emitted therefrom is not parallel light with respect to the optical axis of the rotary parabolic mirror, but is emitted as a light beam having an inclination from the optical axis.

  As a result, the luminous flux emitted by either method has a vector other than parallel light, and both methods reduce the angle of the light source LED with respect to the size of the lens and the size of the parabolic mirror. If the size of the LED is determined, the size of the lens or parabolic mirror can be increased. However, there is a limit due to the relationship between the luminous efficiency and the overall size.

  FIG. 5 shows the light distribution characteristics of a practical rotary parabolic mirror. The vector intensity at the center is strong, and the half-value angle with respect to it is about ± 5 °. The shell-shaped light distribution characteristics are almost the same in the vicinity of the center.

  Here, referring back to FIG. In FIG. 4, since there is a distance from the illumination unit LU to the folding mirror C, a component having a large angle (shown in FIG. 5) emitted from the illumination unit LU enters the folding mirror B.

Further, a part of this component returns to the original state when entering the folding mirror A, and a part thereof also enters the imaging lens 4. As a result, as described above, it causes black float.
In order to avoid this, as described above, the illumination optical axis of the illumination unit LU may be separated from the reading optical axis of the imaging lens 4, but as a result, the apparatus becomes large, and a method for solving this problem Is shown below.

FIG. 12 shows a method for improving the parallelism by inserting a tapered lot immediately after the LED with the hood lens shown in FIG. 10 is emitted. 12 (A) and 12 (B) are the same as FIG. 10 and are based on the focal position when the center of the light emitting surface of the light source LED is the optical axis of the hood lens (the focal position is at the center of the light emitting surface of the LED). The state where the emitted light beam becomes parallel light is shown.
FIG. 12C shows the state of the luminous flux emitted from the end of the light emitting surface of the LED with the same hood lens. On the optical axis of the cone, the entrance is D1 and the exit is D2 (D1 <D2). The case where the lot (bar) of the transparent body (glass or resin) of the shape which cut out the part by L is shown is shown. The taper angle θ of the taper lot is
θ = tan ⁻¹ [(D2−D1) / (2 × L)]
It becomes.

  The radiation vector emitted from the edge of the light emitting surface of the LED with the hood lens at the entrance of the lot is the same as the radiation vector emitted from the center, but after passing through the hood lens because the radiation position is different, 12 is output as parallel light having a constant inclination α with respect to the optical axis. Note that the light beam is refracted when entering the entrance of the tapered lot (this refraction is good for this purpose, but on the contrary it is bad and cancels out), but it is slight. Ignore and explain.

The light beam emitted from the lens hood enters the taper lot and reaches the wall surface at a critical angle or more, so it is totally reflected. However, the taper angle θ of the taper lot enters at an angle α with respect to the optical axis. Is reflected by β, and the tilt angle with respect to the optical axis becomes small.
The relationship is β = α−θ / 2 and the degree of inclination is improved.

In this figure, the ratio of the diameter D and the length L of the lot is shown to be small for the sake of explanation, but the length L is actually a length of several tens to several tens mm while the diameter D is several mm. For this reason, this reflection may occur a plurality of times, in which case the degree of improvement increases.
If the taper lot enters the taper lot at an angle of θ or less, or the angle β of the light beam reflected by the wall surface of the lot becomes θ or less, then the light beam is emitted from the exit as it is without being reflected on the wall surface of the taper lot. . As a typical example, the light beam indicated by * in FIG. 12 (C) is a light beam emitted on the optical axis shown in FIG. 12 (A), and passes through the tapered lot from the entrance to the exit as parallel light. To do.

Specifically, when θ = 2 °, the reflection is improved by 1 ° with one reflection. The luminous flux with a large angle at the entrance of the taper lot has an increased number of reflections, and the luminous flux from the exit has been improved accordingly. As a result, it can be seen that light beams having the light distribution characteristics as shown in FIG. 5 are concentrated and output at a small angle as shown in FIG. 13, and the parallelism is remarkably improved.
FIG. 12D shows a modified example in which the parallelism is improved by the taper lot. This is a diagram for improving the parallelism of the light beam from the rotary parabolic mirror instead of the bullet-type LED shown in FIG. 12C, and has the same effect with the same principle.

  Another embodiment of improving the parallelism using a tapered lot will be described. In FIGS. 14A and 14B, the transparent resin hood of the light source LED has a flat tip, and a convex lens is attached to the entrance on the taper lot side so that the optical axes coincide with each other. Since the focal position of the convex lens is set to the center of the light emitting surface of the light source LED, the luminous flux from the central portion of the light source LED is collimated by the convex lens portion of the tapered lot as shown in FIG. It is taken in the taper lot.

  FIG. 14B shows the behavior of the light beam emitted from the end portion of the light source LED. In the convex lens, the light beam is still parallel light but is tilted from the optical axis and taken into the tapered lot. The subsequent behavior is the same as in FIG.

  A modified embodiment using a tapered lot with a convex lens is shown in FIG. This is achieved by placing the first focal point of the spheroid mirror in the center of the light emitting surface of the light source LED and aligning the focal point of the convex lens at the entrance of the tapered lot with the second focal point of the spheroid mirror. 14 (A), the same effect as described in (B) can be obtained. Although not shown in the drawings, there are various variations such as combining a rotating parabolic mirror and a convex lens to replace the rotating ellipsoidal mirror.

  FIG. 15 shows an example in which the parallel light enhancement method described above is inserted into the illumination system. This is obtained by inserting the tapered lot described in FIG. 12 into the illumination system described in FIG. That is, the tapered lot TL is associated with each of the plurality of LEDs with lens hoods in FIG. 15, and the condenser lens CA1 is placed at the exit thereof. Since the behavior after the condensing lens CA1 is the same as that in FIG. 1, it will be omitted. However, the light beam splitting method by the condensing lens CA1 and the illumination lens CA2 is different from that in FIG. Among the methods described above, an example in which the light beam of one light source LED is divided into two is illustrated.

  When the tapered lot is used in this way, the degree of parallel light required differs between the main scanning direction and the sub-scanning direction, and the sub-scanning direction is required to be overwhelmingly high performance. That is, when incorporated in an image reading apparatus, the performance with a small vertical divergence angle described in the explanation of FIG. 4 is required.

Therefore, the cross section of the tapered lot does not necessarily have to be circular. The variation is shown in FIG. In FIG. 16, the top row is shown in the center row (A), the left side view is shown on the left side (C), and the right side view is shown on the right side (D). In addition, all common front views are shown in FIG.
That is, all the variations described below have the same shape as viewed from the front.

  (1) in FIG. 16 is the same as that described in FIG. 12, and shows a part of the cone cut out. (2) is a part of a regular quadrangular pyramid, and (3) is a part of a rectangular pyramid. (4) is a part of a cone having a circular entrance and a regular square outlet, and (5) is a part of a cone having an elliptical entrance and a rectangular exit.

  Here, FIG. 16 (6) is slightly different from (1) to (5), and the shape seen from above as a top view is a rectangle. As the front view is tapered, if the right side is a regular square, the left side is naturally rectangular. That is, when inserted into an illumination system as shown in FIG. 15, the direction in which the light source LEDs are arranged is not necessarily tapered, and the taper in the direction perpendicular to the direction (sub-scanning direction) is essential.

  Next, FIG. 17 and FIG. 18 show a light guide that integrates the plurality of tapered lots. The one shown in FIG. 17 is made by integrally molding a transparent resin as a material. This is obtained by connecting the shapes shown in FIGS. 16 (2) to (3) on the outlet side (right side surface). Here, this is again referred to as a taper plate. 16 (1) and (3) to (5) can be easily molded integrally using a transparent resin as a material.

FIG. 18 is a development view of the tapered mirror housing. This can be made of a metal plate such as bright aluminum (of course, it may be made of synthetic resin and mirror finished).
The upper plate 7 has a lower surface as a mirror surface, and the lower plate 9 has an upper surface as a mirror surface. A wedge-shaped plate (partition plate) 8 is disposed between them, and both surfaces thereof are mirror surfaces. The wedge taper angle is the same as the taper described in FIGS. Although not shown, a groove corresponding to the thickness of the partition plate is provided in the mirror surface portion of the upper plate 7 and the lower plate 9, and the partition plate is fitted. Such a structure also provides a stable housing.

The shape of the space surrounded by the mirror surface thus formed is the arrangement of those shown in FIG.
For example, a space surrounded by four sides of the partition plate 8 ₁ and 8 ₂ and the upper plate 7 and the lower plate 9, becomes exactly the same shape as FIG. 16 (6). The structure shown in FIG. 16 (6) is a light guide that forms a lot with a transparent body and uses a critical angle, but the configuration of FIG. 18 is a light guide that uses a mirror surface. This characteristic is exactly the same for the purpose of the present invention as that of the light guide made of a transparent body.

FIG. 19 shows an illumination system in which the tapered plate TP described in FIG. 17 is inserted between the light source LED1 with a convex lens and the condenser lens CA1, and the cylinder of the integrated lens is changed to the prism array PA shown in FIG. Is described. The center of the illumination target area K is the main optical axis, but since the reading unit such as an imaging lens is fixed and arranged at that position, the integrated lens is shifted so that the illumination unit can be arranged avoiding it. Yes. Furthermore, it is a prism array type in which optical performance is easily obtained.
By replacing the set from the light source LED to the integrated lens (prism array) PA with the set of the illumination unit in FIG. 6, the shift amount of the illumination unit shown in FIG. You can
Further, it can be easily understood that the taper mirror casing shown in FIG. 18 can be substituted for the taper plate shown here.

Here, the effect of the illumination unit using the light guide path having the upper and lower tapers will be described. In FIG. 20, among the contents shown in FIG. 4, the folding mirror C and the folding mirror D, which are the folding mirrors of the illumination system, are removed, and the widths of the folding mirrors A and B of the reading system are increased accordingly.
The lighting unit LU shown in FIG. 19 is used, and the mounting position seen from the top is the same as that in FIG. Thus, since the divergence angle from the illumination unit LU is reduced, the shift amount can be reduced and the number of parts can be reduced, so that the apparatus can be made thinner and the cost can be reduced.

  The imaging lens 4 is fixed to the document table, and the lengths of the reading optical axis and the illumination optical axis are kept constant while the moving speeds of the first traveling body 3 and the second traveling body 5 are differentiated between them. This is an illumination method for an image reading apparatus that reads a document on a document table, and the illumination apparatus is placed in the vicinity of the imaging lens 4, and the first traveling body 3 and the second traveling body 5 are also used for illumination. The problem of the method of guiding light to the document table was shown, and one method for solving the problem was shown. The problem here is that a light beam with a large spread angle of the light beam emitted from the illumination device enters the folding mirrors A and B on the second traveling body 5 to cause side effects.

  Therefore, another solution is shown. The configuration is such that the illumination light is not actively passed through the second traveling body 5 and the entire lighting device is placed on the first traveling body 3. Then the problem itself will disappear. In other words, it is only necessary to replace the portion illuminated by the conventional cold cathode tube. The illumination method for that is shown in FIG.

  FIG. 21A shows the main scanning direction in a top view, and illuminates the entire illumination target area. FIG. 21B is a front view showing the sub-scanning direction, and illuminates one line or several lines. FIG. 21C is a diagram for explaining the illuminance distribution in the main scanning direction, and FIG. 16D is a diagram for explaining the illuminance distribution in the sub-scanning direction.

  In FIG. 21, light sources LED1 that are reflected by the rotary parabolic mirror PR to become parallel light are arranged linearly from L1 to Ln. A cylinder array in which the individual cylinders (focal lengths f) are made to correspond to each light source LED1 in a one-to-one correspondence with each light source LED1 is arranged as an illumination lens CA.

Also, placing the side in contact with the two in parallel to each other to the edge of the illumination lens CA of the illumination lens CA across the side mirror SM _A and the side mirror SM _B to the illumination target surface 2 so that the mirror surface. This is for efficiently guiding the luminous flux emitted from the LED 1 to the illumination target surface 2. In this FIG. 21, a light beam emitting at L1, L2, L3 of the light source LED1 on the side mirror SM _A, and is reflected by a side mirror SM _B light beams emitting in Ln-2, Ln-1, Ln.

  By doing in this way, since these LED1 behaves as if it exists also outside this illuminating device, uniform illuminance distribution is obtained also in the edge part of the illumination object surface 2 similarly to a center part. Ideally, the mirror surface from the illumination lens CA to the illumination target surface 2 is a mirror surface, but in the actual configuration, there is a contact glass 6 as a document table, which is unavoidable. As a result, since the illuminance at the end of the illumination target surface 2 is slightly lowered, it is necessary to increase the width of the entire illumination device by that amount, but the amount is extremely small as compared with the case where the side mirror SM is not used.

Here, the illumination state by one light source LED is demonstrated using the light source L4 in FIG.
First, FIGS. 21A and 21C are used to describe the main scanning direction.
The luminous flux emitted from the light source L4 is reflected by PR4 (the number is not shown in the figure, but is numbered in correspondence with the number Ln of the light source LED), and the correspondence in the illumination lens CA to the substantially parallel luminous flux. Enter the cylinder.

The light beam that has passed through the cylinder is once focused at that position because the focal length of the cylinder is f, but the point after that is diffused. Here, a focusing lens CL is inserted, but this focusing lens CL functions as a parallel plate in this direction, so that it diffuses in the same manner regardless of whether or not it is included. Spread and illuminate the surface 2. The degree of spread is g, where the distance from the center position of the cylinder to the illumination target surface 2 is g.
Q = (g−f) / f
(The state of the spread is indicated by a thick broken line in FIG. 21, and is drawn approximately 6.5 times).

The illuminance distribution on the illumination target surface 2 at this time is as shown by a thick solid line in FIG. That is, the illuminance decreases as the distance from the optical axis increases with the peak on the optical axis of L4 and PR4. As a result, the illuminance distribution has a large illuminance difference depending on the location.
However, the luminous flux emitted from the adjacent L5 illuminates the illumination target surface 2 with the same illuminance distribution, although the peak position is shifted by the cylinder width m. Similarly, the illumination target surface 2 is irradiated with the luminous flux from the LEDs after L6.
Here, considering the illuminance on the optical axis of L4, a small amount of light from L1 is included, a considerable amount of light from L2 is included, and a further amount of light from L3 is irradiated. The light beam from L5 is irradiated with the same amount of light beam as the light beam from L3, and similarly, the light beam from L6 is irradiated with the same amount of light beam from L2 and from L7. As a result, it can be seen that the light emitted from L1 to L7 is superimposed and illuminated as described above.

  When this is generalized, an arbitrary point on the illumination target surface 2 is a luminous flux from LEDs of the number obtained by rounding down the number after the decimal point of Q in the above formula (6 or 7 in this figure). It is irradiated with. As a result, the illuminance distribution on the illumination target surface 2 becomes substantially flat as depicted on the right side in FIG.

  Here, the illuminance distribution is not a perfect straight line but has a slight undulation, which expresses the influence of the variation in the light amount of the light source LED. Since the light emission efficiency of the LED largely fluctuates due to a slight change in conditions at the time of manufacture, a selection process is required to prepare a plurality of LEDs with a certain light emission amount, which increases the cost. In this proposed method, the variation can be absorbed, so that the LED sorting operation can be omitted.

Next, in order to describe the sub-scanning direction, the operation in the sub-scanning direction will be described using FIGS. 21B and 21D.
The light beam emitted from the light source LED is reflected as a substantially parallel light beam as the first stage of focusing by the rotary parabolic mirror PR, and is transmitted through the illumination lens CA as parallel light. If the focusing lens CL is not inserted, the light beam reaches the illumination target surface 2 as it is as parallel light. As shown in FIG. 21D, the illuminance distribution at that time indicates the illuminance distribution from the individual LEDs and the illuminance distribution obtained by superimposing all the light beams reaching from other LEDs as solid lines. In this case, the distribution is broader than when a focusing lens CL described later is inserted.

On the other hand, when a sharp illuminance distribution is required in the sub-scanning direction, a focusing lens CL that performs the second-stage focusing is inserted. The illuminance distribution at that time is as shown by a two-dot chain line in FIG. If an intermediate distribution is required, a distribution with an arbitrary width can be obtained by setting the focal length of the focusing lens CL to be away from the position of the illumination target surface 2.
Thus, the illuminance distribution can be set both sharply and broadly on the illumination target surface 2 in the sub-scanning direction while the illuminance distribution in the main scanning direction is substantially constant.

Next, a modified embodiment of the illumination lens is shown in FIG.
Up to now, only an example in which a plurality of convex cylinders are arranged as an array as an illumination lens has been shown. However, even if a plurality of concave cylinders are arranged in an array, the emitted light beam can be similarly diffused in the main scanning direction.
As shown in FIG. 22 (A), if the focal length of each concave cylinder is f, the magnification is the same as the explanation of FIG.
Q = (g + f) / f
Can be set. Since the other behaviors are the same except that the focal positions are different, the illuminance distribution in the main scanning direction is almost the same as that shown in FIG. Further, the front view of FIG. 22B is almost the same as FIG. 21B, and the behavior in the sub-scanning direction is the same, so the illuminance distribution in the sub-scanning direction is also the same as FIG.

  In this way, even if the distance from the light source LED 1 to the illumination target surface 2 is relatively short, the focal lengths of the individual cylinders constituting the cylinder array are made as short as possible so that the illumination ranges overlap each other. By greatly increasing the degree of illuminance, unevenness in illuminance due to variations in individual light sources is averaged, and illumination with less illuminance unevenness can be achieved. In addition, since an integrated lens is not required and the cylinder array is only one illumination lens CA, the number of components is small and the configuration can be simplified.

Furthermore, another embodiment in which the entire lighting device is placed on the first traveling body is shown.
The method described in FIG. 1 requires a certain distance a from the integrated lens CL1 to the illumination target surface 2. The distance a is shortened (specifically, the distance c between the condenser lens CA1 and the illumination lens CA2 is shortened), and at the same time, the illumination target area that one unit is responsible for is narrowed. Specifically, as shown in FIG. 23, two or more illumination units LU1 and LU2 are simply arranged to share the imaging area.

  In one illumination unit LU, light beams passing through a plurality of cylinders are diffused over the entire illumination range and are combined by the integrated lens CL1, so that each illumination intensity unevenness is canceled and illumination intensity unevenness hardly occurs in the illumination range. . However, when this method is commercialized, variations in the illuminance at the end of the illumination area M occur between the illumination units LU1 and LU2 due to variations in parts processing accuracy and assembly accuracy. For this reason, in order to eliminate the uneven illuminance at the boundary portion shared by the respective lighting units LU1, LU2, it is necessary to adjust the interval between the lighting units LU1, LU2 during assembly.

  FIG. 24 shows a method for eliminating this adjustment. This is the same as in FIG. 23 in which the reading area is shared by the two illumination units LU1 and LU3, but another illumination unit LU2 is inserted between them so that the central part illuminates the boundary portion of the sharing. In this way, the illuminance that the middle illumination unit LU2 irradiates uniformly and the illuminance at the boundary between the other two illumination units LU1 and LU3 are substantially the same, and as a result, the illuminance unevenness at that portion is reduced to half.

  As a result, the unevenness in illuminance caused by variations in assembly or the like can be suppressed to a level that can be ignored, so that the device creation process is simplified. Furthermore, by placing the mirror surface SM in parallel with the position of a quarter from the end of the range illuminated by each of the first two illumination units LU1, LU3, the light flux in the quarter range is folded. Therefore, the end can be shared with the end of the illumination range M2 shared by the third illumination unit LU3 inserted in the middle.

Here, although it is a case where the illumination unit LU is three, it will generalize this.
First, the number of illumination units LU is n, the illumination target area K is divided by 2 × n, and numbers are assigned from the ends to the boundaries. Next, it can be seen that the illumination unit LU is placed on an odd boundary and the side mirrors SM are placed on both ends thereof. Here, returning to the method described with reference to FIGS. 21 and 22, it can be seen that this generalized principle applies if each light source LED is an illumination unit.
Thus, by positively superimposing the respective illumination ranges M from the plurality of illumination units, it is possible to reduce the influence of variations in the illuminance drop at the end of the illumination target region K.

FIG. 25 and FIG. 26 are examples in which the illumination method shown in FIG. 7 is placed on the first traveling body, and both are arranged according to the generalized concept described in FIG.
FIG. 25 shows a method of superimposing so that the illuminance unevenness at the boundary between the lighting units does not occur.
FIG. 26 shows a method of positively superimposing the light beams from the respective light sources based on the same concept as FIG. In FIG. 21, the illumination lens CA allocates one cylinder to the light source LED1, but in FIG. 26, a plurality of cylinders are allocated. Therefore, if the pitch between the light sources is the same and the magnification Q of the illumination lens is the same. 26, the illuminance unevenness is reduced. Further, by narrowing the interval between the two cylinder arrays (extremely, the interval may be completely eliminated and integrated), the spread angle can be increased, and the distance between the illumination lens CA2 and the illumination target surface 2 is the same. Unevenness of illuminance can be further reduced.

  A specific mounting method of the method of mounting and illuminating on the first traveling body described so far will be described. FIG. 27 shows only a front view. FIG. 27A shows an example in which the basic concept described in FIGS. 21 and 22 is mounted as it is. In the arrangement shown by the two-dot chain line, in order to avoid the vertical portion of the optical path (reading optical axis) of the reading system, the entire imaging region is irradiated obliquely. Although the purpose can be achieved even if it remains as it is, if the inclination angle θ is reduced, the size will increase in the vertical direction, so by inserting a folding mirror as shown by the solid line and holding the whole horizontally, It is possible to make the vertical direction thinner. In FIG. 27, only the example in which the focusing lens is inserted is shown. However, as described above, when the illuminance distribution is broad, it may not be inserted.

  Next, FIG. 27B will be described as this modified example. That is, the function of the converging lens CL is a parabolic mirror PM whose imaging region is a focal point (this is a parabolic mirror in which only the sub-scanning direction is focused as shown in FIG. 9F). The scanning direction is not replaced with a focusing function. In this way, since the folding mirror shown in FIG. 27A can be used, the thickness can be reduced while reducing the number of members. In FIG. 27, the reading optical axis is bent at a right angle to the left by a deflecting mirror, but it does not change the essence of the invention even if the reading optical axis is bent to the right or reversed horizontally.

  FIG. 27C shows only a front view (sub-scanning direction) in the embodiment in which the method described in FIGS. 25 and 26 is mounted. Also in this case, a focusing mirror is used instead of the focusing lens CL. Further, when it is desired to illuminate the illumination target surface broadly, a plane mirror may be used, and when the illumination target surface is desired to be in the middle, the curvature of the condensing mirror may be broadened and the focal position may be deepened.

  FIG. 27D shows only the front view (sub-scanning direction) in the embodiment in which the method described in FIGS. 23 and 24 is mounted. Also in this case, a focusing mirror is used instead of the focusing lens CL. In this case, since the distance from the integrated lens CL1 to the illumination target surface is required to some extent, the lens is folded once by the folding mirror and then focused on the illumination area by the focusing mirror. The positions of the folding mirror and the focusing mirror can be interchanged (of course, the focal length of the focusing mirror needs to be changed accordingly).

  Although the color of the illumination light has not been mentioned so far, it is not necessary to change the basic idea of the present invention even for a color image reading apparatus. Of course, if you use a white LED, you can easily see that any method can be used for color, but red (R), green (G), and blue (B) three-color chips are placed close together in one package. However, it can be easily realized even by using a common convex lens for parallelization, or using red (R), green (G), and blue (B) LEDs.

For example, in the method shown in FIG. 1, red (R), green (G), and blue (B) are stacked in three steps in the sub-scanning direction on the front view of FIG. The method shown in FIGS. 15 and 19 assigns each LED in the main scanning direction to three colors (it is convenient to assign two each because it is six LEDs in this figure). Is good).
The method after FIG. 21 is the easiest method in which the three stages are overlapped in the sub-scanning direction. However, except for the method shown in FIG. 25 and FIG. 26, a method of assigning each of the main scanning directions to three colors is also possible.

  By adopting the above configuration, light is efficiently emitted from a plurality of light source LEDs in any illumination region in the main scanning direction, so that there is an energy saving effect, a light source LED sorting process is not required, and illuminance variation is achieved. Therefore, when it is electrically corrected by the method described above, the influence of noise is reduced even in a place with low illuminance, and the image signal quality is maintained.

As described above, the reading apparatus in which the document table (contact glass), the imaging lens, and the one-dimensional imaging device are integrated is fixed, and scanning in the sub-scanning direction is realized by differential movement of the first traveling body and the second traveling body. Based on the above, an embodiment in which the lighting device of the present invention is mounted on the first traveling body has been introduced.
This system is suitable for high-speed reading because the first traveling body is only equipped with a deflecting mirror that reflects the reading light except for the illumination device. However, when the low speed is acceptable, there is a method in which the above-described reading unit (imaging lens and one-dimensional imaging device) is also mounted on the first traveling body (of course, the second traveling body is not necessary at this time). Only one traveling body is required).

  FIG. 28 shows an example in which the illumination device of the present invention is mounted on one traveling body together with the reading device. Also in this case, since the reading system is a reduction optical system, a certain distance from the document surface to the imaging lens is required. Therefore, after the image reading light from the original surface is once changed in the horizontal direction by the turning mirror, in FIG. 28, the light is turned twice by the turning mirrors M1 and M2, and then guided to the reading unit.

  Even if such a reading system is placed on the traveling body, any illumination system may be used as long as it has been described so far. In FIG. 28, the content shown in FIG. 27D is used, but the position of the focusing mirror is placed across the reading optical axis that is folded back of the reading system. By doing so, the layout is made so as not to affect the thickness of the apparatus while securing the optical path length of the illumination system to some extent.

  The present invention can be applied to an image reading apparatus and an image reading method that are included in an image forming apparatus such as a digital PPC and include a reduction optical system including a solid-state imaging device, an imaging lens, and an illumination device. The image reading apparatus according to the present invention can also be applied to a film scanner, a book original scanner, and the like that read an image from the upper side of the original table.

It is a figure explaining the basic view A of smooth illumination. It is a figure which shows the difference in the illumination intensity distribution by the difference in the number of a light emission point and a cylindrical lens. It is a figure explaining the uniformity method of illumination distribution. It is a figure explaining the solution method of the malfunction which the divergent light enters into a return mirror pair from an illuminating device. It is a typical example of the light distribution characteristic of the light beam reflected by the parabolic mirror from the LED light source. FIG. 3 is a top view of a developed side surface of the image reading apparatus. It is a figure explaining the basic view B of smooth illumination. It is a figure explaining illuminance distribution when an integrated lens is inserted. It is a figure which shows the shape of main optical components. It is an example of a setting of LED with a lens hood. It is an example of a setting of LED with a rotating paraboloid mirror. It is a figure explaining the reinforcement | strengthening A of the beam collimation by a taper lot. It is a typical example of the light distribution characteristic of the light beam reflected by the parabolic mirror from the LED light source. It is a figure explaining the reinforcement | strengthening B of light beam collimation by a taper lot. It is an example of the illuminating device which inserted the taper lot. It is a modification of the light guide formed with a transparent body. It is an example of the integrated light guide formed with a transparent resin. It is an expanded view of a taper mirror housing | casing. It is an example of the illuminating device using an integrated light guide. This is an example in which the reading optical axis and the illumination optical axis are separated. It is a figure explaining that the illumination intensity distribution on an illumination object surface becomes smooth. This is an example in which a concave cylinder array is used for the illumination lens. It is the example A which divides and illuminates an illumination object area | region using a some unit. It is the example B which shares and illuminates an illumination object area | region using a some unit. It is the example C which shares and illuminates an illumination object area | region using a some unit. It is the example D which divides and illuminates an illumination object area | region using a some unit. It is a basic example (front view) mounted on the first traveling body. It is an example which mounts an illumination unit on a traveling body with a reading unit. 1 is an overview diagram of an image reading apparatus. It is a front view of an image reading apparatus. It is a figure explaining the illuminance distribution on the original stand by the conventional illumination method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Light source LED, LL1 ... Convex lens, PR ... Rotary parabolic mirror, CA1 ... Condensing lens, CA2 ... Illumination lens, CL1 ... Integrated lens, CL2 ... Converging lens, 2 ... Irradiation object surface, 3 ... 1st traveling body , LU ... illumination unit, LU1 ... first illumination unit, LU2 ... second illumination unit, LU3 ... third illumination unit, 4 ... imaging lens, A, B, C, D ... folding mirror, 5 ... second traveling body , PM ... Parabolic mirror, E ... Plane mirror (folding mirror), 6 ... Contact glass, TL ... Tapered lot, 7 ... Upper plate, 8 ... Wedge-shaped partition plate, 9 ... Lower plate, TP ... Tapered plate, 30 ... Document setting place (document setting table), 31 ... contact glass, 32 ... document, 33 ... illumination lamp, 34 ... deflecting mirror, 35 ... reflector, 36 ... dimensional imaging device, 37 ... imaging lens, 38 ... drive transmission means , 39 Motor, 40 ... running body, 41 ... running body, 43 ... mirror, 44 ... document surface, 45 ... imaging region, 46 ... reading unit, 47 ... reading the optical axis.

Claims (3)

Scattered light from a document surface illuminated by a plurality of light sources arranged in a straight line is imaged on an image sensor by an imaging lens, and the image on the document surface is parallel to the direction in which the plurality of light sources are arranged. A one-dimensional reading is performed as a reading direction, and a two-dimensional image is read by sequentially repeating the one-dimensional reading by moving in a moving direction orthogonal to both the reading direction and a direction parallel to the irradiation optical axis of the plurality of light sources. In an illumination device for an image reading device,
A plurality of bullet-type convex lenses having a one-to-one correspondence with the plurality of light sources and outputting a light beam emitted from the light sources as parallel light, the light emitting surface of the light source being a focal position;
A condenser lens that divides the light beam output from the bullet-type convex lens in the main scanning direction and collects the light;
An irradiation lens for irradiating the light beam output from the condenser lens in the main scanning direction of the document surface;
A combination of an integrated lens that superimposes the luminous flux output from the irradiation lens on the original surface is configured as one illumination unit,
The plurality of bullet-type convex lenses are arranged such that side surfaces in the reading direction are linearly cut and adjacent side surfaces are in contact with each other,
A plurality of the lighting units are arranged in the reading direction, each of the plurality of lighting units shares an area illuminated,
Extending a pair of parallel first and second side mirrors in a direction parallel to the irradiation optical axes of the plurality of light sources,
The first side mirror is arranged such that a side in contact with the edge of the integrated lens of the illumination unit arranged at one end of the illumination unit arranged in the reading direction is a mirror surface,
The second side mirror is arranged such that a side in contact with an edge of the integrated lens of the illumination unit arranged at the other end of the illumination unit arranged in the reading direction is a mirror surface,
An illumination device, wherein a plurality of light beams output from the plurality of illumination units are superimposed on a document surface. The imaging device according to claim 1 ,
The number of the illumination units is n, the illumination target area is divided by 2 × n, and when the numbers are assigned from the end to the boundaries of the divided illumination target areas, the illumination units are arranged at odd boundary numbers, An illumination device, wherein the side mirror is arranged on a side portion outside an illumination unit arranged outside among the arranged illumination units. The imaging device according to claim 2 ,
The number of the illumination units is 3, and when the illumination target area is divided into 6, and when the numbers are assigned to the boundaries of the illumination target areas divided into 6 from the end, numbers 1 and 3 that are odd boundary numbers are assigned. And the number 5, the three lighting units are arranged,
The lighting device, wherein the side mirror is disposed outside two lighting units on both sides of the three lighting units.

Images