SU1589248A1 - Projection device - Google Patents

Abstract

The invention relates to optical instrument making and allows the operational capabilities of projection devices to be expanded. The image of the object placed on the stage 5 is formed by lens 4 on an electrically controlled transparency 3 mounted on one end of rod 7, on the other end of which is a prism 6 placed on the optical axis of the projection lens 2. Illuminator 1 through objective 2 and deflecting the edge of the prism 6 illuminates the stage 5. The liquid-crystal reversing recording structure is used as a transparency 3. An image of an object recorded on a banner 3 is projected by lens 2 onto screen 14 when a banner 3 is inserted into the optical axis of lens 2 and a prism 6 is removed from it. 2 ill.

Description

The invention relates to optical instrumentation namely, appliances intended for audiovisual purposes.

The purpose of the invention is the expansion of operational capabilities.

Figure 1 shows a diagram of a projection device; in FIG. 2 is an electrically controlled transparency. (θ

The projection device includes a lighting system 1, consisting of a condenser with a projection lamp and a reflector, a projection lens 2, an electrically controlled transparency 3 placed in a frame 15 window in the form of a reversing recording structure such as a liquid crystal photoconductor, lens 4 for transferring the projected image with> 20 an object placed on a stage 5 mounted in the plane of the object of the lens 4, on a transparency 3 mounted in the image plane of the lens 4, as well as an optical prism 25 mu 6, set Mounted behind the projection lens 2 on the optical axis and the deflecting face, the guide of the light flux to the stage 5. Transparency 3 has two fixed positions: A - coaxial with lens 2 and illuminator 1 and B - coaxial with lens' 4, Transparency 3 and prism 6 are placed at the ends of the curved rod 7 and move synchronously.

using the handle 8.

Electrically controlled transparency 3 is a multilayer system (figure 2), enclosed between two glass substrates 9,. _t on the inside of which transparent conductive coatings are applied 10.

A photoconductor layer 11 is applied to the conductive coating 10 of one of the substrates 9, Between the layer 11 of the photoconductor and the conductive coating of the other substrate 9 is a liquid crystal layer 12, the thickness of which is determined by the dielectric spacers 13, The connection of the glass plates 9 is sealed.

The principle of operation of the banner 3 is as follows. The supply voltage applied to the transparent electrodes 10 is distributed between the layers of the photoconductor 11 and the liquid crystal 12. The resistances of the layers 11 and 12 are selected so that the applied voltage without exposure to. basically falls on the photoconductor layer 11, without changing the initial orientation of the liquid crystal molecules 12.

When projecting an image onto photoconductor 11, due to a change in its conductivity, there is a spatial redistribution of voltage between the layers of photoconductor I 1 and liquid crystal 12, as a result of which a potential relief is created on the layer 12 of the liquid crystal corresponding to the distribution of illumination on the layer 11 of the photoconductor. This relief locally controls the optical properties of the liquid crystal 12, forming a corresponding image in it. . The read light passing through the structure is modeled according to the input image.

For functioning in the proposed projection device, it is essential that the structure of photoconductor 1.1 - liquid crystal 12 has the ability? remember optical images. This ability can be realized by using a liquid crystal 12 with a bistable electro-optical characteristic as a modulating medium, for example, smectic A liquid crystals with positive dielectric constant anisotropy, in these liquid crystals there is a controlled electro-optical memory effect, the essence of which is the fact that an optically transparent homeotropic structure under the influence of a low-frequency electric field as a result of electrohydr of dynamic instability transforms into a confocal texture highly scattering light. Moreover, both states, due to the viscoelastic properties of smectics A, are quasi-stable and can persist for a sufficiently long time (more than 1 year, 1.

!

The transition from the scattering state to the transparent state is carried out as a result of a confocal homeotropic transition under the influence of a high-frequency voltage (2 kHz). The switching time from the transparent state to the scattering state, and vice versa, at control voltages of 70-100 V is less than I s.

The projection device operates as follows.

An object, for example, an image on a transparent medium that needs to be projected on screen 14, is placed on the stage 5 in front of the lens 4. A transparency of $ 3 moves to position B, Prism 6 deflects the light beam coming out of the lens 2, directing it to the stage 5 The lens 4 forms, q forms the image of the object in the plane of the photoconductor 11 of the transparency 3. After that, recording is performed by applying the appropriate voltage to the transparency 3. Then, the transparency 15 with the image recorded on the liquid crystal layer 12 is moved to position A and the recorded image is projected onto screen 14. To record another image, the previous image is erased by feeding on the banner 3 high-frequency voltage (2 kHz), after which you can repeat the recording cycle.

The proposed projection device * 25 is universal in the sense that it allows you to project on the screen 14 not only opaque (scattering) objects, but also transparent (for example, slides) placed in the frame window. The device also allows you to design on screen 14 the result of recording two or more objects by sequential registration: on a banner 3,

Claims (1)

Claim A projection device containing a lighting system located on the optical axis, a frame frame and a projection lens, characterized in that, in order to expand operational capabilities, it is equipped with an additional lens, a prism located behind the main lens, and an electrically controlled transparency in the form of a reversible recording structure consisting of a photoconductor, smecti-: ·. liquid crystal and. substrates with transparent conductive coatings, the prism and the electrically controlled transparency connected by a curved rod and mounted with the possibility of reciprocating movement perpendicular to the optical axes of the primary and secondary lenses.