JPH0365924A - Optical element - Google Patents

Abstract

PURPOSE:To execute the switching of optical paths with a simple construction at a high speed by providing transparent electrodes for transmission and transparent electrodes for reflection opposite to a transmission surface exclusive of reflectors on the outside surface of a 1st polarizing plate and applying voltages to the transparent electrodes for transmission or the transparent electrodes for reflection. CONSTITUTION:This optical element consists of a liquid crystal 1 which rotates the plane of polarization of transmitted light by 90 deg. by a twisted structure in the absence of an electric field and the 1st polarizing plate 2 and 2nd polarizing plate 3 provided with polarizing filters 2a, 3a on the outside surfaces of transparent glass 2b, 3b holding the liquid crystal 1 therebetween. The plural reflectors 4 are provided apart specified intervals on the outside surface of the 1st polarizing plate 2. The transparent electrodes 5 for transmission opposite to the respective reflectors 4 are provided on the inside surface of the 2nd polarizing plate 3 and the transparent electrodes 7 for reflection are provided opposite to the transmission surface 6 exclusive of the reflectors 4 on the inside surface of the 1st polarizing plate 2. The reflection and transmission of light are freely switched by impressing the voltages to the transparent electrodes 5 for transmission or the transparent electrodes 7 for reflection at this time. The switching of light is executed at the high speed with the simple construction in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an optical element using liquid crystal, and can be used in optical systems of copying machines, laser printers, etc., or optical path switching mechanisms of cameras.

<Prior art> Conventionally, for example, a movable mirror is provided to switch the optical path to the viewfinder and shutter of an eye reflex camera, and the mirror is mechanically moved to switch between transmission and reflection as necessary. It is done by

<Problems to be Solved by the Invention> However, in the above-mentioned conventional technology, there are problems in that the mirror moving mechanism is complicated, the switching operation is slow, and a large driving force is required during the operation.

In view of the above, the present invention has a simple structure for switching the optical path.
Moreover, the object is to provide an optical element that can perform high-speed processing.

<Means for Solving the Problem> As shown in FIG. 1.2, the means for solving the problem according to the present invention comprises a liquid crystal 1, a first polarizing plate 2 and a second polarizing plate 3 whose polarization planes are orthogonal to each other with the liquid crystal 1 in between. In the optical element, a plurality of reflectors 4 are provided on the outer surface of the first polarizing plate 2 at regular intervals, and a plurality of reflectors 4 for transmission are provided on the inner surface of the second polarizing plate 3 facing each reflector 4. A transparent electrode 5 and a reflective transparent electrode 7 are provided facing the transmitting surface 6 of the inner surface of the first polarizing plate 2 other than the reflector 4, and the transparent electrode 5 for transmitting or the transparent electrode 7 for reflecting Reflection and transmission of light can be switched freely by applying a voltage.

<Function> In the above means for solving the problem, when a voltage is applied only to the transparent electrode 5 for transmission, as shown in FIG. No light can pass through the second polarizing plate 3, which has orthogonal polarization planes, and is reflected by the reflector 4, and the polarization plane is 90° due to the liquid crystal l.
The rotated and parallel light passes through the second polarizing plate 3, and transmitted light is obtained from the transmitting surface 6.

Furthermore, when a voltage is applied only to the reflective transparent electrode 7, as shown in FIG. It reaches the body 4 and is reflected.

If this optical element is utilized in a copying machine capable of copying in both the scanning forward and backward scanning directions of the optical system as shown in FIG. 3, a compact optical system can be constructed.

That is, if the optical element according to the present invention is used in the E mirror, which is the second mirror 16 shown at 14 in FIGS. 3 and 4, the light 20 from the inverted lens system will be transmitted as shown in FIG. By reflecting the light 2I from the vertical lens system as shown in FIG. 2(b), two types of optical paths can be formed using the -2 optical elements.

<Example> Hereinafter, an example of the present invention will be described based on the drawings. 1st
The figures are cross-sectional views of the optical element of the present invention, FIGS. 2(a) and 2(b).
3 is a schematic diagram of the optical system of a copying machine to which the optical element of the present invention is applied, FIG. 4 is a sectional view taken along line A-A in FIG. 3, and FIG. 6 is a sectional view taken along line CC in FIG. 4, and FIG. 6 is a sectional view taken along line CC in FIG.

As shown in FIG. 1.2, the optical element of the present invention comprises a liquid crystal 1 that rotates the polarization plane of transmitted light by 90' in the absence of an electric field due to a twisted structure, and transparent glasses 2 b and 3 that sandwich the liquid crystal 1.
It consists of a first polarizing plate 2 and a second polarizing plate 3 with polarizing filters 2 a and 3 a provided on the outer surface of the first polarizing plate 2 , and a plurality of reflectors 4 are arranged at two regular intervals on the outer surface of the first polarizing plate 2 . A transparent electrode 5 for transmission is provided on the inner surface of the second polarizing plate 3, facing each reflector 4, and a transparent electrode 5 for transmission is provided on the inner surface of the second polarizing plate 3, facing the transmitting surface 6 other than the reflector 4 among the inner surfaces of the first polarizing plate 2. A transparent electrode for reflection 7 is provided, and by applying a voltage to the transparent electrode for transmission 5 or the transparent electrode for reflection 7, reflection and transmission of light can be freely switched.

The reflector 4 is an aluminum film in which aluminum is vapor-deposited in stripes on the first polarizing plate 2, and a stripe-shaped reflective surface is formed on the outer surface of the first polarizing plate 2. The inner surface of the first polarizing plate 2 is made of ITO (Indium Tin).
A common transparent electrode 8 made of (Oxide) is provided.

The transparent electrode 5 for transmission and the transparent electrode 7 for reflection are IT
A first lead wire 9 is connected to the transparent electrode 5 for transmission, and a second lead wire 1O is connected to the transparent electrode 7 for reflection. IO is connected to a power source (not shown).

The first polarizing plate 2 and the second polarizing plate 3 are arranged facing each other so that the surfaces having transparent electrodes are spaced apart from each other by a predetermined distance and their polarization planes are perpendicular to each other.
An optical element is formed by filling the .

In the above configuration, first, to explain the function of the optical element, when a voltage is applied only to the transmission transparent electrode 5, as shown in FIG. 2(a).
As shown in FIG. 1, the liquid crystals 1 are aligned in the direction of the electric field (direction perpendicular to the electrode plane) by the action of the electric field, and there is an alignment part 1 in which the plane of polarization does not rotate.
a is formed on the front surface of the reflector 4. Therefore, the light transmitted through the first polarizing plate 2 cannot pass through the second polarizing plate 3 whose polarization planes are perpendicular to each other, and no light reaches the reflector 4 and is reflected. 90'
When rotated, the polarization plane of the light that reaches the second polarizing plate 3 becomes parallel, and the light is transmitted from the first polarizing plate 2 through the transmission surface 6 .

Furthermore, when a voltage is applied only to the reflective transparent electrode 7, as shown in FIG. The light reaches the reflector 4 and is reflected. The reflected light that has passed through the second polarizing plate 3 is further rotated by 90 degrees by the liquid crystal 1 and becomes parallel to the first polarizing plate 2, thereby obtaining reflected light.

Next, a copying machine to which the optical element of the present invention is applied will be explained. This copying machine is capable of copying in both forward and backward directions by switching the optical system, and is designed to improve copying speed. The mirror base of is scanned and exposed at a speed ratio of 2:l.

As shown in FIG. 3, the optical system includes a lens 11 that forms an inverted image, a mirror unit 12 that rotates the image of the lens 11 by 180 degrees, a first mirror 13 fixed to the main body of the copying machine, and A photosensitive drum 15 is disposed in the reflection direction of the second mirror 13 and the second mirror 14.

The mirror unit 12 is an optical system using an optical element according to the present invention.
Mirror 16, F mirror 17, G mirror 18, H mirror ■
It consists of four 45° mirrors. The optical path in this mirror unit 12 will be explained based on FIG. 4. Here, the X direction is the direction from the back to the front of the paper, and the Y and X directions are as shown. The light passing through the lens 11 and heading in the X direction is input to the E mirror 16, and the E mirror 1
6 reflects in the -YX direction, and the F mirror 17 reflects in the -Z direction.
reflected in the X direction, reflected in the X direction by the G mirror 18, reflected in the X direction by the H mirror 19, and then reflected in the second mirror 1.
It is output in the direction of 4.

Here, the optical element of the present invention is used for the second mirror 14 and the E mirror 16, and when used, it operates as follows.

That is, during forward scanning, the transmission transparent electrodes 5 of the E mirror 16 and the second mirror 14 are driven.

Then, the light from the lens 11 will pass through the transmission surface 6 of the E mirror 6, as shown in FIG. The light passes through, and an inverted lens system optical path 20 is formed, forming an inverted image on the drum 15.

Further, during backward scanning, the reflective transparent electrodes 7 of the E mirror 16 and the second mirror 14 are driven. Then, the light from the lens 11 is transmitted to the E mirror 16 as shown in FIG. 2(b).
The light image is reflected at 180 degrees and passes through the mirror unit 12.
An erect lens system optical path 21 is formed in which the light is rotated by .degree. and output and reflected by the second mirror 14, thereby forming an erect image on the drum 15.

At this time, the second mirror 14 is placed closer to the mirror unit 12 than the first mirror 13 in order to compensate for the increase in the optical path length of the mirror unit 12.

In this way, since an inverted image or an erect image can be switched and recorded on the drum 15, reciprocating copying becomes possible.

Note that by providing the stripes of the reflector 4 perpendicular to the scanning direction, the striped optical images are averaged and a normal latent image is obtained.

FIG. 7 shows another embodiment in which the optical element of the present invention is applied to a single-lens reflex camera. FIG. 7 is a schematic diagram of an optical system in a single-lens reflex camera showing another embodiment.

The optical system of the camera of this embodiment has a convex lens 1 as shown in the figure.
2, a mirror 23 using the optical element of the present invention, a reflecting mirror 24 that guides the light reflected by the mirror 23 to the finder, and a shutter 25.

The mirror 23 switches the optical path of the output light from the convex lens 22 to the finder side and the shutter 25 side. That is, by driving the transparent electrode 5 for transmission, the light passes through the mirror 23 and is guided to the shutter 25, and by driving the transparent electrode 7 for reflection, the light is reflected by the mirror 23 and guided to the finder.

Therefore, the optical element according to the present invention can switch between transmission and reflection of light using the liquid crystal, and can switch optical paths at high speed with a simple structure.

It should be noted that the present invention is not limited to the above embodiments, and it goes without saying that many modifications and changes can be made to the above embodiments within the scope of the present invention.

For example, the present invention is not limited to the copying machine and camera of this embodiment, but may be applied to other devices that require switching of optical paths.

<Effects of the Invention> As is clear from the above description, according to the present invention, in an optical element comprising a first polarizing plate and a second polarizing plate whose polarization planes are perpendicular to each other with a liquid crystal in between, the outer surface of the first polarizing plate is A plurality of reflectors are provided at regular intervals, a transparent electrode for transmission is provided on the inner surface of the second polarizing plate, facing each reflector, and a transmitting surface other than the reflector is provided on the outer surface of the first polarizing plate. A transparent electrode for reflection is provided opposite to the transparent electrode for reflection, and when a voltage is applied to the transparent electrode for transmission or the transparent electrode for reflection, the alignment of the liquid crystal changes, so that reflection and transmission of light can be switched freely. This structure has an excellent effect in that the optical path can be switched at high speed.

[Brief explanation of drawings]

Figure 1 is a sectional view of the optical element of the present invention, Figures 2 (a) and (b).
) is a diagram showing its operating state, FIG. 3 is a schematic diagram of the optical system of a copying machine to which the optical element of the present invention is applied, FIG. 4 is a sectional view taken along line AA in FIG. 3, and FIG. FIG. 6 is a cross-sectional view taken along line CC in FIG. 4. 1: liquid crystal, 2: first polarizing plate, 3: second polarizing plate, 4: reflector, 5: transparent electrode for transmission, 6: transparent surface, 7: transparent electrode for reflection.

Claims (1)

[Claims] In an optical element consisting of a liquid crystal and a first polarizing plate and a second polarizing plate sandwiching the liquid crystal, a plurality of reflectors are provided at regular intervals on the outer surface of the first polarizing plate, and a plurality of reflectors are provided at regular intervals on the outer surface of the first polarizing plate, and A transparent electrode for transmission is provided on the inner surface of the first polarizing plate to face each of the reflectors, and a transparent electrode for reflection is provided to face the transmission surface other than the reflector on the outer surface of the first polarizing plate, and the transparent electrode for transmission or An optical element characterized in that reflection and transmission of light can be switched freely by applying a voltage to a transparent reflective electrode.