JPH0534840A - Lighting device - Google Patents

Abstract

PURPOSE:To make uniform the lengthwise light quantity distribution of the lighting device and to hold the total quantity of light at a lighted position constant at all times regardless of the position of a moving reflecting means. CONSTITUTION:A linear light source 1 is arranged and fixed and a reflecting umbrella 2 which is parallel to the light source 1 is provided so as to collimate the luminous flux B of the light source 1 into parallel light D in the width direction; and a light shield reflecting umbrella 5 which prevents the luminous flux from the light source 1 from crossing the direct parallel light D is provided in parallel to the light source 1 opposite the reflecting umbrella 2 across the light source 1, flank reflecting umbrellas 3 and 3' which have opposite reflecting surfaces are arranged opposite at right angles to the light source 1, and a scanning reflecting umbrella 4 which is movable is provided between the flank reflecting umbrellas 3 and 3' so as to guide the parallel light of the reflecting umbrella 2 and the reflected luminous flux of the flank reflecting umbrellas 3 and 3' to the lighted position 7a on a document in a slit shape.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illumination device used in an optical system such as a copying machine or an image reader,
The present invention relates to an illumination device of the type in which a light flux from a fixed light source is guided to a predetermined illumination position by a reflecting means that moves.

[0002]

2. Description of the Related Art FIGS. 8 and 9 show a conventional lighting device (Japanese Patent Publication Sho 53).
No. 41976). Reference numeral 100 is a fixed point light source, and 101 is a rotating parabolic mirror. 103
Is a scanning reflection shade as a moving reflection means, and is a rotating parabolic mirror 1
It is parallel to 01.

In the above structure, the light flux from the light source 100 is collimated by the rotating parabolic mirror 101 into the parallel light A, and is then condensed by the scanning reflection shade 103 moving along the parallel light A, and the original platen glass 104. The illumination position of the upper original 105 is illuminated in a slit shape.

[0004]

However, in the above-mentioned conventional example, since the point light source 100 is used as the fixed light source, the light source 1 starts from the central portion a of the rotating parabolic mirror 101.
The distance from the end b of the rotating parabolic mirror 101 to the light source 100 is longer than the distance to 00. Therefore, at the illumination position, the central portion is brighter than the end portions with respect to the width 200 to 300 mm in the longitudinal direction, resulting in nonuniform light amount distribution.

Therefore, in order to use the above-mentioned illumination device as an optical system for a copying machine or the like, a large amount of light in the central portion of the parallel light flux must be discarded and adjusted to the end portion, resulting in poor illumination efficiency.

On the other hand, in this type of light source,
In order to use a power of 00 watts to emit light from a small area of the filament portion, the size of the light source is 10
There is no technology that can reduce the diameter to 2 mmφ or less to secure a life of about 0 hours. Therefore, since the light source also has a finite size, even if it is collimated, it cannot be a perfect parallel light beam in the width direction Y and has a diverging or converging property.

Then, the light quantity of the light beam applied to the scanning reflection shade 103 at the scanning start position indicated by the dotted line in FIG. 8B and the light flux applied to the scanning reflection shade 103 at the scanning end position indicated by the solid line. The light intensity of the different. As a result, there is a drawback that the total amount of light at the illumination position fluctuates according to the movement of the scanning reflection shade 103.

An object of the present invention is to solve the above-mentioned problems, and an object thereof is to provide an illuminating device which can make the light amount distribution in the longitudinal direction of the illuminating position uniform and keep the total light amount of the illuminating position constant at all times. ..

[0009]

In order to achieve the above object, the present invention has a linear light source fixedly arranged, and in order to collimate the luminous flux of the light source into parallel light in the lateral direction, a first light source parallel to the light source is provided. One reflection means is provided, and at a position facing the first reflection means while sandwiching the light source, a light shielding means that can prevent the light flux from the light source from directly intermingling with the parallel light is provided in parallel with the light source,
At least two side reflection means having opposing reflection surfaces are arranged perpendicularly to the light source, and the parallel light of the first reflection means and the reflected light flux of the side reflection means are guided in a slit shape to a predetermined illumination position. The moving reflecting means is movably provided between the two side reflecting means.

[0010]

According to the present invention based on the above structure, since the light source is linear, the luminous flux is dispersed and emitted in the longitudinal direction, and if the wattage is the same, the filament diameter can be made smaller than that of the point light source. It is possible to reduce the collimation error when collimating parallel light in the lateral direction using the means.

On the other hand, regarding the light quantity distribution in the longitudinal direction, even if the light source is a linear light source arranged with a light source interval of about 10 to 20 mm, the ripple disappears and is smooth if it is separated from the arranged line by about 50 to 100 mm. It has a wide distribution.

Further, by providing the side surface reflecting means,
The light amount distribution can be made flat without any change in the light amount in the longitudinal direction. By doing so, it is not necessary to discard the light amount in the central portion, so that it is possible to effectively use the luminous flux even for the light source of the same total luminous flux.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. Figure 1
(A) and (B) are a front view and a plan view showing a first embodiment of the present invention. Reference numeral 1 denotes a light source in which a plurality of fixed light emitting points are arranged in a line (a diffused (frosted) light is applied to a tube wall surface of such a light source is used as a halogen lamp for illuminating an original in a copying machine or the like). , The luminous flux B emitted therefrom is the first reflection means, that is, the reflection shade 2 having the parabolic cylindrical surface 2a.
The light is condensed within the width in the lateral direction h by (or an elliptic cylindrical reflecting shade having a light collecting property in consideration of the size of the filament).

Since the reflection shade 2 is provided in parallel with the light source 1 and has no light-collecting power in the longitudinal direction R, it diverges as shown in FIG. Since it is surely returned to the inside of the required width in the longitudinal direction R by the side reflection means, that is, the side reflection shades 3 and 3 ', the light flux B is totally in the box-shaped region inside the lateral width h and the longitudinal width H. Will be trapped.

The light beam B thus confined is moved by the moving reflection means, that is, the scanning reflection shade 4, which moves below the original platen glass 6 in parallel with the original platen glass 6, that is, in the direction of arrow E. A predetermined irradiation position 7a of the original 7 on the image 6 is irradiated in a slit shape. Then, the scanning reflector 4 moves from the scanning start position shown by the dotted line to the scanning end position shown by the solid line, thereby illuminating the entire document 7.

In the drawing of this embodiment, the width of the side reflection shades 3 and 3'is made wider than the width h of the scanning reflection shade 4 up to just below the original platen glass 6 to indicate that the scanning reflection shade 4 is formed. This is to prevent the light flux from escaping from the width H in the longitudinal direction even during the light flux travels from the original to the original 7 so that the illumination efficiency in the longitudinal direction and the light amount of a single portion are not reduced.

At this time, the light amount distribution of the slit-shaped light beam B in the longitudinal direction R is at a light amount pitch at an interval corresponding to the filament pitch up to a position extremely close to the light source 1 (a distance about twice the filament interval). Although unevenness is detected (Fig. 2 (a)), unless the divergent light from the filament has a light distribution with extremely strong directivity, these side reflection shades 3, 3 '
By making the distance between the virtual image of the filament and the filament located at the end substantially equal to the filament pitch, it is possible to obtain a uniform distribution at a distance twice or more the filament distance from the light source 1.

Therefore, by setting the scanning start position beyond the position where the filament pitch unevenness disappears,
From the scanning start position to the scanning end position, it is possible to obtain a flat and almost equal level light amount distribution as shown in FIGS. 2 (b) and 2 (c). Therefore, the light amount distribution in the longitudinal direction at the illumination position 7a can be made uniform.

In this figure, reference numeral 5 is a light shielding member for preventing the light flux B emitted from the light source 1 from directly hitting the scanning reflection shade 4 or the original 7 without passing through the quadric curved surface reflection shade 2. Is. In addition, since the light-shielding member uses the surface on the light source 1 side as a reflecting surface and returns it to the vicinity of the light source position, the light flux B directed toward the fixed quadric curved cylindrical reflection shade 2 can be increased. In the specification, it will be referred to as a "shading reflection shade".

In FIG. 1 (B), the luminous flux spreading from each filament in the longitudinal direction R is traced and drawn for only four arbitrary rays, but in reality, it is the same for all filaments. It is not drawn in order to avoid the complexity of the figure.

3A and 3B show a second embodiment. In this embodiment, the light source 1 is an example of a completely linear light source. Unlike the multi-filament light source (halogen lamp for OA) shown in the first embodiment, such a linear light source does not have a segment ripple as shown in FIG. Start position is light source 1
It has the advantage of being close to

As such a light source, there are an LED array and those shown in FIGS. 4 (A) and 4 (B). The light source 1 has a cylindrical rod 50 and a main light source 51 arranged outside an opening 52 on one end side of the rod 50. The other end side of the rod 50 is closed by a reflection plate 53, and the reflection plate 5 is formed on the inner peripheral surface of the rod 50. Further, the rod 50 is provided with a slit T along the longitudinal direction, and a linear diffusion portion Q is formed on the opposite side of the slit T.

In the above structure, the light flux of the main light source 51 enters the rod 50 through the opening 52, travels back and forth while being totally reflected by the reflector 5, and the light flux hitting the diffusing portion Q is emitted from the slit T. is there.

In such a light source, the substrate for the LED array is integrated with the light source, and in the light source 1 shown in FIG. 4, the reflection plate 5 forming the slit T is integrated with the light source. Incidentally, FIG. 7 shows a third embodiment in which the reflector is divided into 2, 2 '.

By the way, since the light beam B is eclipsed by the light shielding / reflecting plate 5 in the vicinity of the optical axis surface of the reflection shade 2 of the first and second embodiments, the light beam in the vicinity cannot be effectively used. Therefore, an example of effectively utilizing the luminous flux is shown in FIGS.
Shown in.

In FIG. 5 (A), the reflecting shades 2 and 2'are divided, a fixed curved reflecting shade 2 "is provided behind the reflecting shades 2 and 2 ', and a plane mirror 12 is provided below it. After passing through the reflection shades 2 and 2 ′, the light flux of the light source 1 is collimated perpendicularly to the parallel light D by the fixed curved reflection shade 2 ″ and is changed in the same direction as the parallel light D by the plane mirror 12. Note that FIG. 5B shows an example in which the plane mirror 12 is provided above and the fixed curved surface reflection shade 2 ″ is provided below it.

FIG. 6A shows a fourth embodiment. This is an example in which only the reflection shade 2 in the upper half of FIG.
If there is a margin in the amount of light, this structure may be used. This example can realize a compact illumination system in the thickness direction (vertical direction in the figure) as compared with the first, second and third embodiments.

FIGS. 6 (B) and 6 (C) show a fifth embodiment having a plurality of scanning reflection shades 4. FIG. 6 (B) is composed of two scanning mirrors 4, 4 ', and (C) is four scanning mirrors.
4'and 4 "are divided into three parts to prevent the shadow of the cut and paste of the original from appearing with 5: 5 illumination. In the case of (C), the system can be thinned by using three pieces. The method of dividing the scanning reflector 4 for such 5: 5 illumination is as follows.
Although it is possible in the first to fourth embodiments, it is particularly effective in the first and second embodiments that do not use the light flux near the symmetry plane including the optical axis of the curved cylindrical surface.

[0029]

Since the present invention is configured as described above, the light quantity distribution in the longitudinal direction at the illumination position can be made uniform, and the total light quantity at the constantly illuminated position is independent of the position of the moving reflection means. Can be kept constant.

[Brief description of drawings]

FIG. 1A is a front view of the first embodiment, and FIG. 1B is a plan view of the same embodiment.

2A to 2C are graphs showing the light amount distribution in the longitudinal direction of the first embodiment.

3A is a front view of the second embodiment, and FIG. 3B is a plan view of the same embodiment.

FIG. 4A is a plan view of the light source of the second embodiment, and FIG. 4B is a sectional view of the light source of the same embodiment.

5 (A) and 5 (B) are sectional views in which the third embodiment is developed.

FIG. 6A is a sectional view of a fourth embodiment, FIGS.
Is a sectional view of the fifth embodiment.

FIG. 7 is a sectional view of the third embodiment.

8A is a plan view of the conventional example, and FIG. 8B is a front view of the conventional example.

FIG. 9 is a perspective view of a conventional example.

[Explanation of symbols]

 1 Light Source 2 Reflector 3, 3'Side Reflector 4 Scanning Reflector 5 Light-Shielding Reflector B Luminous D Parallel Light

Claims (1)

Claim: What is claimed is: 1. A linear light source is fixedly arranged, and in order to collimate the luminous flux of the light source into parallel light in the lateral direction, a first reflecting means parallel to the light source is provided, and the light source is A light-shielding device, which can prevent the light flux from the light source from directly intermingling with parallel light, is provided parallel to the light source at a position facing the first reflecting device, and at least two side surface reflecting devices having opposing reflecting surfaces are provided as the light source. Is arranged perpendicularly to the first reflecting means, and the parallel light beam of the first reflecting means and the reflected light flux of the side reflecting means are guided to a predetermined illumination position in a slit shape, so that the moving reflecting means can be moved between the two side reflecting means. A lighting device characterized by being provided.