JPS6093412A - Condensing slab-shaped lens array - Google Patents

Abstract

PURPOSE:To assemble plural rod lenses with a desired precision by using a condensing slab-shaped lens, which has a required gradient of refractive index only in the thickness direction or one direction, as a unit lens body. CONSTITUTION:Plural prismatic slab-shaped lenses 1 having a length (c) <=1/4 pitch are prepared as one slab-shaped lenses, and a long-width slab-shaped lens 4 which has a refractive index gradient 2' similar to the above only in the direction of a thickness (d), a width (e), and the length (c) <=1/4 pitch is prepared. The width (b) of prismatic slab-shaped lenses 1 is equal to the thickness (d) of the long-width slab-shaped lens 4. Plural prismatic slab-shaped lenses 1 and one long-width slab-shaped lens 4 are assembled between two supporting plates 5a and 5b so that directions of respective refractive index gradients 2 and 2' are orthogonal to each other and exit light end faces 1b of prismatic slab-shaped lenses 1 and an incident light end face 4a of the long-width slab-shaped lens 4 face and contact with each other. A slab-shaped lens array L1 constituted in this manner has the width (e) and a length (f) <=1/4 pitch.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a light-condensing slab-like lens array used in an image forming optical system of an electronic copying machine.

In recent years, with the miniaturization of electronic copying machines, rod lens arrays (rod lens arrays) in which rod-shaped condensing lenses having a refractive index distribution that gradually decreases from the center of the rond to the periphery have become available. A microlens array) is used as an imaging optical system. In this rod lens array, rod lenses whose length is greater than or equal to % of the meandering period (pitch) of the light rays in the lens are stacked in two or three stages, and the required number of these stacked lenses are stacked in one direction. It is constructed by arranging the

By the way, the quality of the projected image of the optical system by the rod lens array in which a large number of rod lenses are arranged vertically and horizontally is influenced to a large extent by the quality of the arrangement of the rod lenses.

However, in conventional lens arrays, the external shape of the rod lenses used as unit microlenses was cylindrical, so there was a problem in that it was extremely difficult to assemble multiple rod lenses with the required accuracy. Ta.

The present invention has been made in view of these conventional problems, and by using a light-concentrating slab-like lens having a required refractive index gradient only in the thickness direction or in one direction as a unit lens body, the above-mentioned problems can be solved. The purpose is to solve problems.

The present invention will be explained below based on the drawings. Figures 1 to 7
The figure shows an embodiment of the present invention.

Here, as previously disclosed in Japanese Patent Application No. 58-16109, the present inventor has proposed a method for manufacturing a slab-like lens (1) having a refractive index gradient (2) only in the direction of daylight a as shown in FIG. invented. As shown in FIGS. 2 and 3, this slab-like lens (1) has a required refractive index distribution in the thickness direction where the refractive index gradually decreases from the center line toward both sides. However, it has a flat and uniform refractive index in the width direction.

FIGS. 4(3), 4(B), and 4(C) show the optical characteristics of such a slab-like lens (1). That is, the lens body (1)
The diverging light (3a) emitted by the point light source (3) from one end surface (1a) is condensed again in the direction of thickness a at the output light end surface (1b) by its refractive index distribution (2).
Since it continues to diverge in the width direction, at the output light end face (1b), it becomes a straight light beam (3b) with a certain width. This invention uses such a slab-like lens as a unit lens body, It is constructed by assembling a plurality of lenses with the required dimensions in the required manner.As shown in Figure 5, one of the slab-shaped lenses is first constructed using the lens shown in Figure 1 whose length C is less than the pitch. A prismatic slab lens as shown (
A plurality of pieces of 1) are prepared, and correspondingly, as shown in FIG.
A long slab-like lens (4) having a width e and a length C of % pitch or less is prepared. The width of the prismatic slab lens (1) is the long width slab lens (4)
The thickness d in is the same dimension. The plurality of prismatic slab-like lenses (1) and one long-width slab-like lens (4) have their refractive index gradients (2) (2)' in directions orthogonal to each other, and 2 so that the output light end surface (1b) of the prismatic slab lens (1) and the input light end surface (4a) of the long slab lens (4) are in contact with each other.
It is assembled between two support plates (5m) (5b). The support plate (5m) (5b) is made of glass or plastic, and its length f is less than % pitch. Incidentally, a light absorbing agent is applied to the peripheral side surfaces of the prismatic slab lenses (1) to prevent stray light. The long slab lens (4) is located at each portion facing the prismatic slab lens (1).
) constitute a pair of combined lens bodies, but since the refractive index of the lower slab-like lens (4) is uniform in the width C direction, the long width of the unit is It is constructed as a form.

FIG. 7 shows a slab-like lens array L1 constructed in this manner, which has a width of C and a length of f, which is less than the pitch. As shown in FIG. 8, the light-condensing slab-like lens array Lm used in the imaging optical system of an electronic copying machine, etc., is made by stacking two of the above lens arrays LI and L, and having a total width of C. The length g is configured to be greater than or equal to % pitch and less than % pitch. In this way, there are two lens arrays LIL.

The reason why these are stacked to form one light-concentrating slab-like lens array La is that the slab-like lens has a refractive index gradient in only one direction, so it does not have a refractive index distribution (
In the e-direction of a long slab lens (4) etc., the light diverges and loses brightness, so in order to prevent this, the length of each lens array LI L2 is shortened and these are stacked. The overall length is the required length. Therefore, if there is no need to take brightness loss into consideration, an optical system can be constructed using one lens array L shown in FIG. 7 with a length f of % to % pitch.

Next, the effect will be explained.

Each of the prismatic slab lenses (1) and the corresponding parts of the long slab lenses (4) are as follows:
Since the refractive index gradients are set in directions perpendicular to each other, the combined lens body of the two exhibits the same lens effect as a rod lens. Therefore, the light-condensing slab-like lens array La has almost the same image-forming optical function as a conventional rod lens array, and the light-concentrating slab-like lens array La can be moved in the direction of the arrow X in FIG. This allows characters and figures on the original paper surface (not shown) to be imaged as real images on the photosensitive paper surface, allowing electronic copying and
It can be used as an imaging optical system in a machine. And when used as such an imaging optical system,
Each slab-like lens (1)..., (4) has a rectangular outer shape, so its optical axis etc. are accurately assembled with the required accuracy, allowing accurate imaging optical action. This allows an extremely good projected image to be obtained.

Next, FIG. 9 shows another embodiment of the present invention.

In this embodiment, a plurality of long-width slab-like lenses (4) as shown in FIG. Sag is %~
% pitch two-dimensional planar array. The refractive index gradient between the arrays located above and below (2)
' directions are arranged in directions perpendicular to each other.

Regarding the operation, it is possible to form a two-dimensional projected image similar to that when the light-condensing slab lens arrays t and a are moved in the X direction in a stationary state.

Next, a manufacturing example will be explained.

A porous glass plate obtained by acid treatment of phase-separated glass with a thickness of 4 rran and a width of 60 m and a length of 70 m is mixed with 1 part of water.
Cs No 3 was stuffed into the pores of the porous body by immersing it in a solution containing 12 (l) of CsNOx per 00 at a temperature of 100°C for 24 hours, and then into an aqueous solution containing 40 vol/l of ethanol. Unstuffing was performed by immersing the glass plate at a temperature of 70°C for 20 minutes.Then, this glass plate was immersed in an ethanol solution at 0°C for 3 hours to precipitate the dopant in the pores, and then kept at room temperature for 24 hours to remove the ethanol. Further, this glass plate was heat treated at a temperature of 900°C for 6 hours to collapse the pores and the thickness was 3.
A transparent glass plate with a width of 6 m and a length of 60 m was obtained.

Next, cut out both sides of the glass plate with a width of 2 tones from the outside in the width direction, and then cut out the top and bottom ends of the glass plate with a width of 2.5 cm from the outside in the length direction, so that the thickness is 3.6 mm, the width is 50 m, and the length is 55++ m.
A glass plate was obtained. This glass body was a slab-like lens having a refractive index distribution only in the thickness direction. This plate-shaped lens body was cut into a length of 25cm, and a width of 56++m4.
It was made into a long slab-like lens with a length of 6 fields and 25 square meters. on the other hand,
A prismatic slab-like lens is made by cutting it into pieces with a width of 3.6m and a thickness of 3.6m+ and a length of 25mm, and the directions of the refractive index distributions of a plurality of these and the long-width slab-like lens are orthogonal to each other. A slab-like lens array as shown in FIG. 7 was produced by stacking the lenses in the same direction.

As detailed above, according to Jin's invention, a pair of slab-shaped lenses having a required refractive index gradient only in the thickness direction or one direction are arranged such that one slab-like lens is arranged in a direction in which the directions of the refractive index gradients are orthogonal to each other. A combined lens body is formed by bringing the output light end face of the shaped lens into contact with the input light end face of the other slab-like lens, and a plurality of the combined lens bodies are arranged to form a slab-like lens array. Therefore, it is easy and accurate to assemble multiple slab lenses with the required accuracy.
The effect is that the lens array can provide an extremely good projected image.

[Brief explanation of drawings]

1 to 8 show examples of the light-condensing slab lens array according to the present invention. FIG. 1 is a perspective view of a prismatic slab lens, and FIG. The refractive index distribution curve in the width direction, Fig. 3 is the refractive index distribution line in the width direction of the same slab-like lens as above, Fig. 4 (5) (B)
(C1 is a diagram for explaining the condensing characteristics of the slab-shaped lens in Figure 1, Figure 5 is a perspective view for explaining the assembly process, and Figure 6 is a perspective view of the long slab-shaped lens. , FIG. 7 is a perspective view of a light-condensing slab-like lens array, and FIG. 8 is a perspective view showing a light-concentrating slab-like lens array for an electronic copying machine constituted by two of the above-mentioned light-concentrating slab-like lens arrays. , No. 9
The figure is a perspective view showing another embodiment of the invention. 1: Prismatic slab lens la, 4a: Incident light end face 1b: Outgoing light end face 2.2':
Refractive index gradient 4: Long width slab-like lenses 5a, 5b: Support plates Ll, La: Light-condensing slab-like lens array Lb:
Two-dimensional Blenner-shaped condensing slab lens array Fig. 1 Fig. 4 Fig. 5 Fig. 8

Claims (1)

[Claims] A pair of light-condensing slab-like lenses having a required refractive index gradient only in the thickness direction or in one direction, and an output light end face of one of the slab-like lenses in a direction in which the directions of the refractive index gradients are orthogonal to each other; 1. A light-condensing slab-like lens array, characterized in that a combined lens body is formed by bringing the incident light end face of the other slab-like lens into contact with each other, and a plurality of the combined lens bodies are arranged.