JPH04168434A - Manuscript lighting device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a document illumination device for a device that reads image information of a document using a reading lens. This relates to a light guide type document illumination device in which illumination light from light sources arranged in a shape is guided onto the document surface through a transparent member.

(Prior art) Conventionally, point light sources as light sources are arranged in an array,
An old and well-known method is to provide a transparent member in the optical axis for illumination connecting the point light source and the reading position of the document, and to illuminate the document by utilizing total reflection of light from the side surfaces of the transparent member. 12th
The figure shows an example using a cross-sectional view. Here, 100 is a plate-shaped transparent member, 101 is a point light source, and 102
is a substrate on which a point light source 101 is fixed. The light beam 103 emitted from the point light source 101 passes through the incident end surface 110 and efficiently reaches the upper side while being totally reflected on the parallel side surface 104 in the OOO, and after passing through the exit end surface 111, the document 105 is read. Position a is illuminated. FIG. 13 shows the illuminance distribution of the document at this time.

(Problem to be Solved by the Invention) However, in this Umei method, the original 105 to be illuminated
14, the opening of the reading position a decreases rapidly as shown in FIG. 15. This is because the luminous flux 1.03 that reaches the upper part of the transparent member 100 after repeated total reflections has various directivities, and as the document 105 moves away, the illumination area rapidly expands. There is. Therefore, when such a document illuminating device is used in a conventionally well-known document reading device, the following problems specifically arise.

FIG. 16 is for explaining this.

The original reading device is original f! It is composed of an illumination unit, a reading lens 107°, an image sensor 108 such as a CCD, etc., and the optical axis 106 for illumination is arranged as shown in the figure so as not to spatially interfere with the optical axis 109 for reading of the reading lens 107. Usually placed diagonally. However, the illuminance at the reading position a of the document 105 away from the exit end surface 11 decreases as described above, and furthermore, due to the obliquely placed fist,
The peak of illuminance was shifted toward the lighting section, resulting in extremely poor efficiency. As a result, manuscript 1
As in the case where the reading position a of 05 is shifted, the output level of the image sensor 108 changes sensitively, so there is a drawback that the quality of image reading deteriorates.

In such a case, the only way to compensate for the lack of illuminance is to increase the number of light sources, which leads to a complicated structure of the device and an increase in manufacturing costs.

The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a document opening device capable of aligning the directivity of a light beam that passes through a transparent member and is directed toward a document.

Another object of the present invention is to provide a document illumination device capable of deflecting a light beam that has passed through an exit end face of a transparent member and concentrating it on a reading position of a document.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a light source that emits a luminous flux toward a document, and a plate-shaped optical axis provided in an illumination optical axis that connects the light source and a reading position of the document. A document illumination device comprising a transparent member and having an optical axis for illumination inclined at a predetermined angle with respect to an optical axis for reading through which reflected light from the document passes; The dimensions of the end surface are W, and the dimensions of the exit end surface on the document side are W! , the dimension of the first side on the optical axis side for reading is H2, and the dimension of the second side opposite to the first side is H
It is characterized in that it satisfies the following relationships: H2>2xW+W, <W2.

In addition, the above H3 and H2 Hl<82 It was set to

(Function) The function of the present invention based on the above configuration is such that the light beam emitted from the light source passes through the incident end surface of the transparent member, is totally reflected by the first and second side surfaces, and has the same directivity. Since the light passes through the exit end surface and heads toward the document in the same state, appropriate illuminance can be obtained regardless of the inclination of the optical axis of the illumination or the distance between the document and the exit end surface. The light beam reflected from the original passes through the reading optical axis.

In addition, the light flux passing through the exit end surface is concentrated at the reading position, so that the negative layer illuminance can be maintained at a high value.

(Example) Hereinafter, the present invention will be explained based on the accompanying drawings.

In FIG. 1, l is a plate-shaped transparent member, and this transparent member 1 is a single point light source such as an LED chip (illumination light that connects the light 2 and the reading position A of the original 7 on the original glass 6). shaft(
(Fig. 3) It is provided in 8. Further, this optical axis 8 is inclined at a predetermined angle with respect to the reading optical axis 9 of the reading lens 4. Further, the point light sources 2 are arranged in a line on a substrate 3 which is arranged diagonally with respect to the original glass 6.

The transparent member 1 is provided with an entrance end surface R1 facing the point light source 2 side, and an arc-shaped exit end surface R2 facing the document 7 side.
This is provided. Further, a first side surface S2 is formed on the optical axis 9 side, and a second side surface S1 is formed on the opposite side. Here, the dimensions of the transparent member 1 are as shown in FIG.
When the dimension (width) is R2, the dimension (height) of the first side surface S2 is R2, and the dimension (height) of the second side surface S1 is Hl, R2>2XW
l...(1) Wl<W!・
...The relationship (2) is satisfied, and the relationship Hl < 82, = (3t) exists.

The above formula (1) is a conditional formula for efficiently totally reflecting the light beam 10 entering the transparent member 1 at the first and second (ff11 surfaces S2.S, as shown in FIG. 9).Therefore, Conversely, R2<2Xw.

In the transparent member 1 (FIG. 8) having a shape such that

Second side S2. S, without total reflection at the exit end surface R.
2, efficiency decreases.

Also, according to equation (2), the first and second side surfaces Sa of the transparent member 1
, S1 are in a state of expanding toward the exit end surface R2 side with the optical axis 8 as the center. Figure 10 shows this (1)
, (transparent member that satisfies formula 2), and the directivity of the light beam 10 that is totally reflected by the first and second side surfaces S2.S is the directivity of the light beam 10 that is not totally reflected (center). It has the effect of aligning (becoming parallel).

Furthermore, equation (3) indicates that the exit end surface R2 is inclined with respect to the entrance end surface R1. As shown in FIG. 11, this has the effect of causing a deflection of the light beam 10 that has passed through the exit end surface R1.

Next, the operation of the above embodiment (FIGS. 1 to 4) will be explained.

The light beam 10 emitted from the point light source 2 passes through the incident end surface R1 of the transparent member 1, and also passes through the first and second side surfaces S2. S,
The directivity is aligned while being totally reflected at the exit surface R2, and the light is deflected toward the optical axis 9 by the exit end surface R2, passes through the document glass 6, and reaches the reading position A. This light beam 10 is reflected by the original 7, passes through the reading lens 4 on the optical axis 9, is guided to the light receiving element (image sensor) 5, and the image of the original 7 is read. Therefore, regardless of the inclination of the optical axis 8 with respect to the optical axis 9 or the distance between the exit end surface R2 and the document 7, the illuminance at the reading position A is at its peak as shown in FIG. It can be done. Therefore, the number of light sources can be reduced compared to the conventional method, which has the effect of contributing to simplifying the structure and reducing manufacturing costs.

Note that although FIG. 1 shows a transparent member 1 that satisfies the formulas fi1, fz) and (3), (1),
There is no problem even if it is only the +2j type, that is, the configuration shown in FIG. 10 (the deflection property is inferior).

5 to 7 show other configuration examples of the transparent member.

In FIG. 5, the exit end surface R2 is formed flat, and has only a deflection effect similar to that of a prism.

Furthermore, if the exit end surface R2 is made arcuate (concave) as shown in FIG. 6, the device can have a broader illumination distribution.Furthermore, as shown in FIG.

Second side S2. Sl may be formed into a paraboloid or a part of an ellipse, the entrance end surface R1 may be concave, or the entrance end surface R may be made close to a concentric circle with respect to the point light source 2.

(Effects of the Invention) Since the present invention is configured as described above, the illuminance at the reading position of the document can be brought to a peak state, and accurate reading operation can be performed. Further, the light source configuration requires fewer light sources than the conventional one, which can contribute to simplifying the structure and reducing manufacturing costs.

[Brief explanation of the drawing]

1 to 7 show embodiments of the present invention, FIG. 1 is a front view showing the schematic configuration of the document illumination device, FIG. 2 is a graph showing the relationship between the document in FIG. 1 and illuminance, and FIG. 3 is a perspective view of the transparent member, FIG. 4 is a front sectional view showing the dimensions of each part of the transparent member, FIGS. 5 to 7 are front sectional views showing other examples of shapes of the lighting member, and FIG. 8 - Fig. 11 is a front view showing how light passes through transparent members of various shapes, Fig. 12 is a schematic front view showing a conventional example in which a transparent member and a document are close to each other, and Fig. 13 is a front view showing how light passes through transparent members of various shapes.
FIG. 14 is a graph showing the relationship between the original and the illuminance; FIG. 14 is a schematic front view showing a conventional example in which the transparent member is separated from the original;
Fig. 5 is a graph showing the relationship between the original in Fig. 14 and the illuminance, Fig. 16 is a schematic front view of a conventional example in which the optical axis for illumination is tilted with respect to the optical axis for reading, and Fig. 17. is a graph showing the relationship between the original of FIG. 16 and illuminance. Explanation of symbols 1...Transparent member 2...Point light source (light source) 7
... Original document 10 ... Luminous flux A ... Reading position R1 ... Entrance end surface R2 ... Output end surface S2 ... First side surface S1 ... Second side surface
Hl...Dimension of the second side surface H2...Dimension of the first side surface Wl...Dimension of the incident end surface W2...Dimension of the exit end surface Fig. 1, □ Fig. 2 Cutting Ri8
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Wrinkles: Enemy: Zukatsu 2

Claims (2)

[Claims] (1) Equipped with a light source that emits a luminous flux toward the original, and a plate-shaped transparent member installed in the optical axis for illumination that connects the light source and the reading position of the original. In a document illumination device that is inclined at a predetermined angle with respect to the reading optical axis through which reflected light passes, the dimension of the incident end surface on the light source side formed in the transparent member is W_
1. When the dimension of the exit end surface on the document side is W_2, the dimension of the first side surface on the optical axis side for reading is H_2, and the dimension of the second side surface opposite to the first side surface is H_1, H_2>2×W_1 A document illumination device characterized by satisfying the relationship W_1<W_2. (2) The above H_1 and H_2 H_1<H_2 2. The document illumination device according to claim 1, wherein the document illumination device is set to .