DE2065737A1 - Image presenting appts. - has electronic cct. with store operating fluid crystal element - Google Patents

Abstract

The fluid crystal element is driven by the electronic circuit containing a storing stage. The former is created from a fluid crystal layer fixed between two electrodes. The circuit as well as the crystal element are carried upon the same subtrate. Space requirements are therefore very small. The transistors (T1 and T2) are cross-coupled. Transistors (T3 and T4) serve as load impedances. The latter are connected to the negative pole (-V) of a potential source via the lead (V) and a switch (6). The other pole is at a reference potential. This form of flip-slop serves as a memory cell in a matrix arrangement comprising many such.

Description

7O91-7OA / H / Elf

RCA Corporation, New York, N.Y. (V.St.A.)

Image display device with an electronic circuit and a liquid crystal element

The invention relates to an image display device with a Storage stage containing electronic circuit and with a liquid crystal element controlled by the circuit that consists of a liquid crystal layer arranged between two electrodes is formed.

The object of the invention is to provide a device with a spatial arrangement of the liquid crystal element that is as expedient as possible and the associated circuit.

The invention solves this problem by the in claim 1 marked device.

The invention has the advantage that the device can be made very compact and space-saving, and that the required electrical connections between the electrodes of the liquid crystal element and the electronic circuit are simple can be produced.

The invention is explained in more detail below using a preferred exemplary embodiment. Show it:

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Figure 1 shows the circuit diagram of an electrically and optically controllable Storage unit;

Figure 2 is a diagram showing various voltage profiles that occur in the operation of the circuit of Figure 1, reproduces;

Figure 3 is a plan view of a MOS integrated circuit design part of the circuit of Figure 1;

FIG. 4 shows a section along section line 4-4 in FIG. 3;

FIG. 5 shows the circuit diagram of a page arrangement of memory units in the manner of the circuit according to FIG. 1;

Figure 6 is a schematic representation of an electronic-optical Storage unit with the page arrangement of storage units according to FIG. 5;

FIG. 7 shows another embodiment of part of the storage unit according to Figure 6;

FIG. 8 shows a further embodiment of a part of the storage unit according to Figure 6; and

Figure 9 shows a modified * embodiment of the arrangement according to Figure 8.

In Figure 1, an electrically and optically settable bistable memory element (flip-flop) is shown. It contains the cross-coupled transistors T ₁ and T ₂ as well as the transistors T ₃ and T ₄ serving as load impedance for the transistors T and T ₂ , respectively. The transistors T- and T ₄ are connected via the line ν and a switch 6 to the negative pole -V of a voltage source, the other pole of which is connected to a reference potential point (ground)

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2 O ^r ί 'ΐ /

lies. The transistors T ₁ to T ^ are MOS field effect transistors. As shown for transistor T ₂ , each of these transistors has an emitter electrode 7, a collector electrode 8 and a gate electrode 9. The flip-flop with transistors T ₁ to T ₄ is of a known type.

The flip-flop serves as a memory cell in a matrix arrangement of a plurality of such memory cells, in which devices are provided for electrically writing an information bit into the memory cell and for reading out the information bit from the memory cell. The control device includes a with a column or bit line d _Q connected Bittreiber- and reading circuit or short bit circuits D_, a d to a bit line ₁ bit circuit D ₁ is connected with a line or a word line w _Q associated word driver W. and ■ it a word line W ₁ word driver connected _W1.

The bit line d _Q is connected to the collector (output) 10 of the transistor T ₁ and to the gate electrode 9 of the transistor T ₂ via a transistor T ₅ serving as a gate element. The transistor T ^ is gated on by a signal fed to _{its gate electrode via the word line W 0.} The bit line ä ^ is (j coupled to the collector (output) 11 of the transistor T ₂ and to the gate electrode of the transistor T ₁ via a transistor Tg serving as a gate element. The transistor T _g is gated on by a signal from the word line W _1.

The circuit according to FIG. 1 also contains a pn photodiode D, which is connected with its anode 13 to the collector 10 of the transistor T ₁ and with its cathode 14 to the silicon substrate of the transistor T ₁ . If the circuit is constructed in integrated form, the silicon substrate can also be common to the transistors T ₂ to T ₆ . A phototransistor (not shown) can also be used instead of the photodiode. The circuit is

509849/0807 _{lkl £! DcrTm}

ORIGINAL INSPECTED

also holds a light valve containing a liquid crystal LV, which is connected between the collector 10 of the transistor T. and a ground conductor G.

FIGS. 3 and 4 show a possible spatial embodiment of the electrically and optically settable memory element according to FIG. 1. The circuit is built on an n-conducting silicon substrate 20 in which areas of p + silicon are formed, which serve as emitter and collector elements of the transistors . The p + regions and the regions in between are covered with a layer 25 of silicon dioxide (SiO ₂ ), which forms an electrical insulator, and conductive gate electrodes are applied over the regions between the respective emitter and collector electrodes. Electrical conductors attached to the silicon dioxide layer contact the p + regions underneath through openings in the silicon dioxide layer.

_{The transistors T 1} to T _g shown in FIG. 1 have the same designations T ₁ to T 1 in FIG. The transistor T ₁ , as can be seen in FIGS. 3 and 4, has a p + -conducting emitter 21 at a distance from a p + -conducting collector 22. A thin silicon dioxide layer on the area between emitter 21 and collector 22 forms an insulating region over which a conductive gate electrode 11 * is attached. The bit lines d _Q and dj are attached to the top of the silicon dioxide layer 25. The ground conductor G on the silicon dioxide layer makes contact with the p + material forming the emitter 21 of the transistor T with a contact region 24 penetrating the silicon dioxide layer. The structure of the transistor T ₃ serving as load impedance is also shown both in FIG. 3 and in FIG.

The collector 22 of the transistor T ₁ is shown in Figures 3 and 4 as consisting of p + material, which extends along the n-line

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extending silicon substrate 20 bi · to a relatively large square area 22 '. The p-f material of the surface 22 * forms the anode 13 of the photodiode D in FIG The n-conducting material forms the cathode 14 of the photodiode D in FIG. 1. The large area 22 * made of p + material is visible through an opening 25 * in the silicon dioxide layer. The area 22 ' is not covered with silica since it also serves as an electrode of the light valve LV.

The upper side of the integrated circuit according to FIG. 3 is covered with λ a layer made of a liquid crystal, which is shown at 30 in the sectional illustration according to FIG. The liquid crystal still to be described is held in place by a glass plate 32 with a transparent conductive coating 34 made of, for example, tin oxide on the side in contact with the liquid crystal. The exposed side of the small glass plate 32 is provided with an opaque (light-impermeable) mask 36 made, for example, of aluminum with an opening 38 for the passage of light L ^ to and through the liquid crystal.

The bottom surface of the n-type silicon substrate 20 can with a thin n + layer 26 on which a metallic base or ground layer 28 is applied. The metallic f Ground layer 28 is through a continuous wire connection 29 with the Ground conductor G connected on top of the integrated circuit. As shown in FIG. 4, the metallic ground layer 28 has an opening 39 which is aligned with the opening 38 in the mask 3 · as well as with the area 22 * of the photodiode D covers. The opening 39 in the metallic ground layer 28 serves to ensure the complete passage of incident "light" of suitable wavelength in the infrared range through the integrated circuit allow if the state of the liquid crystal 30 allows. The opening 39 is not needed when the light valve works with light reflection. In this case, the p-conducting surface 22 'of the photodiode results in a partial light

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reflection made by attaching a partially reflective film can still be enlarged on the surface 22 '.

The liquid crystal 30 may be a mesophase nematic composition. The term "mesophase" denotes a state of aggregation which is between that of the crystalline solid and the the isotropic liquid. The common name for this physical state is "liquid crystal". The expression "Nematic" refers to a special type of liquid crystal. Compositions with a mesomorphic state (mesophase) have two "melting points". The first melting point is at Transition temperature from the crystalline solid state to the mesomorphic state, and the second melting point is at the transition temperature from the mesomorphic state to the isotropic liquid state. Located between these two temperatures the composition in the mesomorphic or crystalline liquid state, in which they both the behavior of a Liquid, in that it flows and is present in coalescing drops, as well as the behavior of a solid, in which it is optically or electrically anisotropic and has a one- or two-dimensional structural order.

Nematic liquid crystals are electrically and magnetically anisotropic. On surfaces such as glass, the nematic phase generally takes on a characteristic twisted or screwed structure that becomes visible between crossed polaroids or polarizers. It is assumed that this structure consists of many tufts in which the liquid crystal molecules have a fixed orientation. According to the tuft theory of nematic liquid crystals, the tufts are usually randomly oriented, which results in the light scattering properties and the cloudy appearance of a reasonably large volume. Each tuft 1st birefringent and has a size of about cm 1O ~ ^5th When applying an electrical or magnetic field

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des a layer of mesomorphic crystals show the Tuft the effort to move in a certain direction orientate so that the light-scattering and birefringent Change the properties of the layer. The degree of orientation depends on the size of the applied field. The light-diffusing Properties and the birefringent properties of a volume of nematic liquid crystal can therefore by a electric or magnetic field can be modulated. These properties are common to electro-optical components such as Kerr effect elements or Kerr cells, for facilities where the plane of polarization a light beam or light bundle is rotated, as well as for optical display devices in which the Degree of scattering of a passing or reflecting Light beam is modulated is useful.

As the nematic liquid crystal compositions, there are those the general formula

CH - N

in question, in which X and Y are saturated alkoxy radicals having 1 to 9 carbon atoms or saturated acyloxy radicals having two to five carbon atoms, such that when X is a saturated alkoxy radical Y is a saturated acyloxy radical and vice versa. The saturated alkoxy radical has at least 3 carbon atoms, when the saturated acyloxy radical has only two carbon atoms. The composition or the mixture can contain up to 60% by weight of p- (anisalamino) -phenyl acetate, based on the total weight of the Mixture, included. An acyloxy radical is a radical of an aliphatic ester of the general formula

R-C-O-.

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Oxygen simply bound to the carbon atom of the remainder is also bound to an aromatic Hng / for example in

; CH ₃ CO ^ J ^ - CH = N

one of the characteristic features of the compositions or mixtures is the relatively low minimum operating temperature due to the low crystal-mesomorphic transition temperatures of the members of the group of compositions mentioned. There are mixtures whose Kristal1-mesomorph-tfbergangstemperatur is below room temperature. Another feature is the wide temperature range in which the new components can be used. An example is a compound with a crystal-mesomorph transition temperature of approximately 50 ° C. and a mesomorph-isotropic liquid transition temperature of 113 ° C.

Figure 5 shows a matrix-shaped arrangement or grouping of memory units of the type shown in Figure 1. In really- Wk ness the integrated circuit arrangement 130 includes many laid out in rows and columns, memory units MU. Each of the four memory units MU shown here contains the transistors T. to T- according to Figure 1 as well as a photodiode D and a light

JL O

valve LV. All of the memory units of a given column are connected by a set of bit lines d _Q and dj to a corresponding set of bit circuits D _Q and D ₁ . The memory units of a given row are also connected to corresponding word drivers W _Q and W via word lines w_ and W.

The matrix-like circuit arrangement representing a "page" 130 of storage elements forms a conventional semiconductor memory level with random or optional access, which in the usual

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Way is controlled electrically by the processing position of a data processing or computing system. The control device contains conventional memory addressing circuits, a data register and control circuits, all of which are known and therefore need not be described here.

Instead of MOS field effect transistors with p-channel you can use the Circuit arrangement 130 also use MOS field effect transistors with M-channel or complementary MOS field effect transistors. Furthermore, the circuit can be both on a silicon substrate as well as using the silicon-on-sapphire technique.

The mode of operation of the circuit according to FIG. 1 will now be explained with reference to the signal curves according to FIG. It is assumed that the flip-flop is in the set state at time t _Q with transistor T on and transistor T _{2 off} . Since the circuit responds to an optical input signal (input light signal) L _r only when the flip-flop is in the reset state, the flip-flop must routinely be electrically reset before a light signal is applied. This takes place at time tj by applying _{a negative pulse to the bit line d Q} (FIG. 2c) and simultaneously applying _{a negative pulse to the hoard line w Q} (FIG. 2b), so that the transistor T _{5 is} gated on. The negative pulse passing through the transistor T ₅ reaches the collector 10 of the transistor T. and the gate electrode 9 of the transistor T ₂ . As a result, the transistor T ₂ becomes conductive and, through feedback between the cross-coupled transistors, the transistor T ₁ becomes non-conductive. The flip-flop is then in the reset state, _{the voltage -v being applied to the collector 10 of the transistor T 1} and to the photodiode D. The speed of the reset is achieved in that at the same time the signal 2d of the word line W ₁ and the signal 2e of the bit line ά be zugeMtet _χ. The photodiode is now charged to the voltage -v.

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In order to make the circuit sensitive to light, ie ready to respond to light, the photodiode D must be isolated so that it is prevented from being kept charged by current from any source. After the time t ₂ , no more current is supplied from the bit line d _Q via the transistor T ₅ , and the photodiode D can switch off the bias voltage -V (FIG. 2a) at a time before the time t ₂ , with the aid of the switch. to which input light can be received can be isolated. So that transistor T _{2 can} respond to a voltage change at its gate electrode, bit line dj is acted upon _{at time t 2 (T 6} : has already been _{gated from word line W 1} , FIG. 2d). As a result, the transistor T ₄ is effectively replaced as a load impedance for the transistor T ₂ by the transistor T ₆ .

If no input light signal is incident on the photodiode D during the interval between t ₂ and t ₄ , the charge of the photodiode is only slightly reduced by dissipation, as indicated by the dashed line 15 in FIG. 2f. At time t ₅ , when the -V bias is restored, the flip-flop then remains in the reset state.

If, on the other hand, _{an input light signal strikes the photodiode D after the time t 2} , the photodiode is made conductive and its charge is reduced, as indicated by the line 16 in FIG. 2f. This voltage is coupled to the gate electrode of transistor T ₂ , the conductivity of which is lowered by the corresponding voltage reduction until the threshold voltage of T _{1 is} reached _{at time t 3. The transistor T 1 is then made} conductive by the feedback effect, and the flip-flop is in the set state. The set state of the flip-flop is maintained by restoring the bias voltage -V at time t ₄ before removing voltage -v at time t ₅ from bit line d _x (FIG. 2e) and from word line W ₁ (FIG. 2d).

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The mode of operation of the circuit according to FIG. 1 has been described above described for the case that a binary light signal is directed to the photodiode D, through which, if there is a binary "1" represents that the flip-flop is set, while in the absence of an input light signal, the flip-flop remains in the O state.

The operation of the circuit according to FIG. 1 will now be described for the case that a light beam or light beam bundle is directed onto the light valve LV and is transmitted or scattered away depending on the state of the flip-flop. When the flip-flop is in the 1 state, the collector 10 ″ of the transistor T carries a voltage of 0 volts and the collector 11 of the transistor T _{2 has} a voltage of -v volts, as in the signal curves according to FIGS. 2f and 2g for the point in time t _5. In this case, there is no voltage across the liquid crystal light valve LV. The light valve LV remains transparent (translucent), and the light beam is transmitted through the light valve as an optical information signal "1".

If the flip-flop is _{in the 0 state at time t 5} , the collector 10 carries a voltage of −v volts, as indicated at 17 in FIG. 2f. This negative voltage applied to the light valve LV causes the liquid crystal to scatter or weaken an incident light beam. Depending on the electro-optical properties of the liquid crystal used, it may be desirable to increase the negative voltage at the light valve to a more negative voltage value V ₂ . For this purpose the source voltage -V is set in the interval between tg and t _? increased to a more negative value, as indicated in Figure 2a. This e more negative voltage V ₂ is applied to the light valve LV and generates a correspondingly greater scattering or attenuation of the incident light beam.

It will now be the electronic-optical storage unit with reference to FIG with the circuit arrangement 130 are described. The storage unit contains a laser 110, a polarization

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Dreher 111 and a beam deflector 112 with a deflector for the x direction and a deflector for the y direction. The laser 110 can be a conventional pulse solid-state laser that can be used with a single transverse natural oscillation and a polarized, well collimated beam generated. The polarization rotator is a common device that is under control by electrical input signals the polarization of the received Rotates the laser beam in either one or the other of two polarization directions offset by 90 °. Of the Polarization rotator 111 can be an electro-optic material such as potassium dehydrogenphosphate crystal with two electrodes. at When a suitable voltage is applied to the electrodes, the polarization of an incident beam is rotated by 90 °.

The beam deflector 112 may be a known digital light deflector that operates under the control of electrically indicated acoustic Waves works in a transparent liquid or solid medium. Or, in a known manner, it can have levels of Contain polarization rotators, each of which is followed by a birefringent crystal such as calcite (calcite).

The deflected beam (bundle of rays) from laser 110 can be one of beam paths 114 and 114 'or any other beam path follow. After reflection by a deflecting mirror 115, the deflected beam hits a polarization prism 117, the Light rays r with the polarization "reading" are reflected on mirrors 134 and 135 and on a holographic storage medium 126 and transmits light rays W with the polarization "writing" after a beam splitter 120. The beam path from the polarizing prism 117 is determined by the electrical excitation of the polarization rotator 111 for reading or writing.

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The polarization prism 117 can in a known manner from two birefringent triangular crystals of the same material, the are assembled with different orientations of their optical axes, or from a birefringent crystal plate, which is immersed in a liquid with a corresponding refractive index. The beam splitter 120 can be a partially silver-plated mirror in a known manner.

The erasable holographic storage medium 126 can consist of an approximately 5 × 10 cm thick layer of manganese bismuth on a "

oriented substrate such as mica or sapphire. By initially heating the assembly, the manganese bismuth film is formed into a single crystal form and the assembly is then subjected to a strong magnetic field which aligns all magnetic atoms with their north poles in a direction perpendicular to the surface of the film. The magnetization of elementary surface areas or surface elements of the film can be changed where optical energy from a laser hits and generates heat. This is called the Curie point record. If the recorded as in the magnetic state of the film optical pattern is a phase hologram, is a directed to the film read reference beam (read Referenzbün- m del) having a polarization rotation due to the magneto-Kerr effect reflected, whereby the optical image into an Evaluation level is generated again. Instead, the reading can also take place with the aid of magneto-optical rotation, based on the Faraday effect, of a reference beam passing through the manganese bismuth film. The read reference beam has a lower intensity than the write beam so that the recorded hologram is not destroyed. Instead, the reading reference beam can also be given such a high intensity that a destructive reading takes place. This means that the hologram is erased when the optically stored information is read.

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The beam splitter 120 reflects a portion, for example half of the received light beam and transmits the remaining part of the received light beam. The part of the received light beam passing through follows a beam path to a mirror 124 and from there to a surface element of the erasable holographic storage medium 126. This is the beam path for a reference beam W that is used to generate a hologram on the storage medium 126. The mirror 124 in the beam path of the reference beam is used to direct the reference beam at an appropriate angle, for example 30 ° or 45 °, onto the surface of the holographic storage medium 126. The portion of the light beam reflected by the beam splitter 120 is directed through lenses 121 and 122 onto an arrangement 127 of illumination holograms, each of which diverges or spreads a received narrow beam so that the "side" or circuit arrangement 130 is illuminated by binary storage units. In the vicinity of the circuit arrangement 130, a side lens 128 is switched on, which converges the spread light bundle onto a small surface element 132 of the holographic storage medium 126 o For example, the middle undeflected beam 114, which strikes an illumination hologram 129 in the arrangement 127, is directed towards the side lens 128 and circuit arrangement 130 widened conically or pyramidal and from there conically or pyramidal narrowed so that the light reaches a surface element 132 on the holographic storage medium 126. Likewise, when it strikes a hologram in the arrangement 127, the deflected light beam 114 'is widened conically or pyramidal in the direction of the side lens 128 and circuit arrangement 130 and from there ^{converges on a surface element 132 1 of} the holographic storage medium 125.

Some of the components described serve to compensate for the image reversal caused by a plane mirror. How rememberable at any given point in time the ray of light follows

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a single of the two beam paths shown or any other beam path. Furthermore, since the beam is deflected in both the x-direction and the y-direction, it can also follow a beam path which is located below or above the plane of the drawing in FIG.

The arrangement 127 of illumination holograms consists of a number of individual phase holograms, one of which in each case is illuminated by an incident light beam. When the incident light beam is undeflected and the beam- J Corridor 114 follows, the lighting hologram 129 is illuminated, and the light emerging from it illuminates the entire Area of the circuit arrangement 130. The lighting hologram 129 is constructed using the light valves in the circuit arrangement 130 as the object the illumination hologram 129 only the light valves in all discrete Storage units of the circuit arrangement 130 illuminates and no light for the spaces between the light valves is wasted. When the beam directed at the array 127 is deflected to form another single hologram 129 ' is illuminated, the circuit arrangement 130 of the individual storage units is illuminated in a corresponding manner.

The circuit arrangement 130 is an integrated arrangement of electrically and optically controllable memory units from each of which is a bistable transistor flip-flop, a photodiode, which sets the corresponding flip-flop when light is received, and a light valve, which is controlled by the state of the As already described in detail with reference to FIGS. 1 to 5, flip-flops either let through or block light became.

That passing through light valves in the circuit arrangement 130 Light is directed onto a surface element 132 of the holographic storage medium 126. That is, in the area element

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ment 132, an optical image of the page arrangement appears (circuit arrangement 130) of light valves with light points that originate from unexcited light valves and missing light points, which come from energized light valves that have scattered the incident light. By the action of the write reference beam w, a hologram of the page arrangement is generated in the surface element 132. The information contained in the hologram becomes later retrieved and retransmitted to the page array by the action of a read reference beam r. The reading reference beam r illuminates the surface element 132 and generates an optical one by reflection on the circuit arrangement 130 Image of the previously recorded side arrangement of light valves. That is, the original image of the arrangement of light valve / becomes on the arrangement of photodetectors in the circuit arrangement 130 and illuminates them. Be that way the flip-flops of the circuit arrangement 130 are simultaneously set to values which were originally in the circuit arrangement 130 represent electrically stored binary information.

Information can be stored from the holographic storage medium 126 simultaneously in all storage units MU are optically transmitted, if the photodiodes of the storage units by electrical Excitation can be activated in accordance with the signal curves according to FIG. The information stored in all storage units MU can be optically transferred to the holographic storage medium 126 at the same time at a later point in time.

As used herein, the terms "electrical writing" and "electrical reading" refer to the electrical operation of the electrical Semiconductor memory in the circuit arrangement 130. The corresponding information transfers take place between the Circuit arrangement 130 and the processing part of a data processing system. The terms "writing" and "reading" relate to optical writing (recording) or optical writing.

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Reading (playback) of the optical storage medium 126. These transmissions take place between the circuit arrangement 130 and the optical storage medium 126.

FIG. 7 shows another construction which can be provided in the device according to FIG. 6 between the arrangement 127 of illumination holograms and the holographic storage medium 126. In FIG. 7, additional lenses 138 and 139 are connected between the circuit arrangement and the storage medium 126. These additional lenses are designed and subsequently i arranged that they effectively enlarge the circuitry 130. That is, their image appears on the lens 139 in enlarged form before it is projected as a very small image onto the small surface element 132 of the storage medium 126. The optical arrangement according to FIG. 7 is also advantageous in that the light passing through the circuit arrangement 130 in both directions is collimated by the lenses 128 and 138.

The light valve described here works with a liquid crystal, which is translucent in the absence of an electric field and in the presence of an electric field Field scatters incident light. When it is electrically excited, the light valve does not need to block the incident light. The scattering of the light is sufficient to record a holographic image in the surface element 132 of the storage medium 126, as shown in Figures 6 and 7, to prevent because only an insignificant amount of the scattered light the surface element achieved. Furthermore, the storage medium 126 made of MnBi is characterized in that it is suitable for light below a given Threshold value is insensitive.

A Genjsch can also be used as the liquid crystal 30, which absorbs instead of scatters light in the presence of an electric field. The liquid crystal can have a dichromic color

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Contain substance that changes its light absorption properties in light of the wavelength supplied by the laser 110.

The light valve can instead also be constructed in such a way that instead of scattering or absorption there is a polarization rotation of the incident light. By the polarization rotation of the light through an excited liquid crystal light valve is the recording of a hologram on the holographic Storage medium 126 prevented because of the holographic recording the object beam and the reference beam must have the same polarization. When using such an electro-optical Liquid crystal light valve therefore draws the holographic storage medium through the unexcited light valve light passing through, while light passing through excited light valves with rotation of its polarization direction, is not recorded.

The optical arrangement of Figure 7 is particularly useful in conjunction with a circuit arrangement 130 using electro-optic liquid crystal light valves. The advantage arises from the fact that the light passing through the side assembly is collimated by the lines 128 and 138. The different angles at which the collimated light passes through the circuit arrangement 130 as a result of its origin from different points in the arrangement 127 of lighting holograms can be compensated by _{appropriately compensating for the voltage -V 2} (FIG. 2a) supplied to all storage units in the circuit arrangement 130 changed, or by placing the ground side of all Liehtventile LV on a corresponding tensioning carriage.

Figures 8 and 9 show optical systems for side assemblies with a liquid crystal containing Lishtventilen LV, which take place work with light transmission with light reflection. The arrangements according to FIGS. 8 and 9 differ from those previously described

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Arrangements also from _f that instead of the illumination hologram 127 with light transmission, an illumination hologram 127 'of the reflection type is used. The light valves in the circuit arrangement 130 of Figures 8 and 9 reflect light from the same side of the arrangement that receives light. FIG. 9 differs from FIG. 8 simply in that the illumination hologram 127 'and the holographic storage medium 126 have optically more effective orientations with respect to the circuit arrangement 130.

The light transmitting type of side assembly is generally preferable to the light reflecting type. When the side array is formed as an integrated silicon MOS array, as shown in Figure 4, the η-conductive silicon substrate 20 transmits about 50% of an incident infrared light beam having a wavelength of 1.1λχ at a thickness of about 0.1 mm. The laser 110 can easily be set up to provide light of this frequency. The remaining 50% of the light that does not pass through the silicon substrate 20 is absorbed in the η-conductive silicon substrate 20 and in the p-conductive silicon ** of the area 22 ', which is important for the operation of the photodiode, which has a pn junction between them Has materials, is necessary. The light transmission characteristics of the silicon under the liquid crystal 30 must therefore be matched to the light absorption characteristics of the silicon required for the operation of the congruent photodiode.

If the side arrangement instead of the silicon body technique according to FIG. 4 by the known silicon-on-sapphire technique it can work with light transmission using visible light, since sapphire is for visible light is permeable. In this case, the η-conducting and p-conducting silicon layers on the sapphire can be made so thick that one is sufficient for the correct operation of the photodiode

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de light absorption is ensured.

If the side arrangement according to FIGS. 8 and 9 is to work with light reflection, it can be designed according to the silicon body technology according to FIG. 4 and work with visible light, since the light used is reflected by the silicon instead of being transmitted. The p-conducting material of the surface 22 'of the photodiode by itself causes a reflection of approximately 30% of the incident visible light. The proportion of the reflected light can be increased in that one applies w sigkristalls before attaching the liquid-30, a partially reflective metal film on the surface 22 '.

The operation of the entire storage facility will now be described will. The circuit arrangement 130 of memory elements MU comprises a conventional, electrically and optionally accessible Semiconductor memory. Binary information is electrical in all memory units by means of conventional memory control circuits enrolled. This is usually done word by word under the control of the central processing part of a data processing system, as usual. The information electrically written into the memory units is made by the flip-flops • | stored in the storage units.

The electrically stored in the flip-flops of the circuit arrangement 130 Information is then stored as a hologram on one of the many surface elements of the holographic storage medium 126 transfer. The surface element selected in each case for the storage of the information page is determined by the amount of the x and y-deflection of the light beam from the laser 110 is determined. When the middle surface element 132 of the holographic storage medium 126 is intended to capture the holographic image of the page array is not a deflection of the laser beam by the beam deflector 112 required.

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When the page arrangement information is to be recorded on the holographic storage medium 126, the Laser beam through the polarization rotator 111 a polarization which corresponds to the writing state. When the laser beam is polarized and undeflected in the writing direction, it follows the beam path 114 directly through the polarization prism to the beam splitter 120. The part of the light beam reflected by the beam splitter 120 hits an illumination hologram in of the arrangement 127 of illumination holograms and is thereby fanned out conically (or pyramidal) so that it is the Circuit arrangement 130 illuminated by memory units.

The illumination holograms of the arrangement 127 are preferably constructed in such a way that only the light valves of the storage units be illuminated leaving out the spaces between the light valves where the light would be useless. The light valves of the circuit arrangement 130 are conditioned at this point in time in such a way that they allow the incident light to pass through depending on the state of the corresponding flip-flops of the memory units or lock.

In order to save energy, the light valves are actuated according to the status of the associated flip-flops only at the moment when the laser beam is pulsed for optical writing. The light point pattern generated by the opened and closed light valves is applied to the surface element of the holographic storage medium 126 is projected.

At the same time, the surface element 132 of the storage medium is applied 126 a holographic reference beam w directed. This reference beam is formed by that part of the beam which passes through the beam splitter 120 and the beam path via the mirror 124 to the surface element 132 of the holographic Storage medium 126 follows. By interference between the object beam from the circuit arrangement 130 and the reference beam w

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a page hologram becomes in the surface element 132 of the storage medium 126 generated. The side hologram recorded in this way remains on the manganese bismuth Spelcher medium until it is intentionally is deleted. To erase an individual page hologram on the storage medium 126, the hologram can be provided with a Light intensity that is less than the value required for Curie point writing, in the presence of a magnetic field, the strength of which is insufficient for erasing the unilluminated side holograms.

The side hologram can instead of in the surface element 132 of the holographic Storage medium 126 can also be recorded in any other selected location of the storage medium 126 by the x and y deflection of the laser beam by the beam deflector 112 is controlled accordingly.

When the information page stored as a hologram in the surface element 132 of the storage medium 126 is retrieved and used is to be, the polarization rotator 111 is excited for the reading process and the laser 110 is pulsed. The beam deflector 112 is adjusted so that it deflects the beam neither in the x nor in the y direction. The read polarization beam 114 becomes through the polarization prism 117 into the reading beam r via the mirrors 134 and 135 to the surface element 132 of the holographic Storage medium 126 is reflected. The angle of incidence of the beam on the hologram in the surface element 132 is exactly the angle of incidence of the beam w conjugated when writing the hologram.

The reading beam r impinging on the hologram is called a conical or pyramidal bundle reflected back on the photodiodes of the circuit arrangement 130. Which according to the received Light patterns generated electrical output signals from the photodiodes set the corresponding flip-flops of the relevant storage units in accordance with the hologram of the storage medium 126

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regenerated image. Thereafter, in the case of digital information recorded in the flip-flops of the circuit arrangement 130, this electrically read out word by word and used by the processing part of a data system.

The storage unit with electrical and optical access described above contains a page arrangement of storage units / in which the spatial grouping of the individual storage elements, photodiodes and light valves eliminates the optical coverage problems that occur in construction with spatially separated elements. The arrangement of the photodiodes used for reading a hologram recorded on the optical storage medium is in perfect alignment with the arrangement of the light valves originally used for recording the hologram, since the individual photodiodes and associated light valves are each arranged congruently one above the other. The performance and efficiency of the arrangement 127 of the illumination holograms can be ensured by using the side arrangement of light valves as an object together with system optics such as the side lens in the generation of the illumination hologram. Although the storage plant described above operates with holographic λ shear optics, however, the side arrangement of the memory units is also suitable for systems with conventional optics.

While above the invention in its application to a holographic storage unit was explained, the described page arrangement of storage units is also suitable for viewing or Image display devices and projection display devices and for other types of storage units and data processing systems.

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Claims (5)

Patent applications Device with an electronic circuit containing a memory stage and with a liquid crystal element controlled by the circuit, which is formed from a liquid crystal layer arranged between two electrodes / characterized in that both the electronic circuit (T ₁ to Tg) and the liquid crystal element (30) of a common substrate (20) carried »Ind. 2.) Device according to claim 1, characterized in that the substrate (20) made of semiconductor material consists. 3.) Device according to one of claims 1 or 2, characterized in that the electronic circuit arranged on the substrate (20) is an integrated circuit. 4.) Device according to one of the preceding claims, characterized in that the electrodes (22 ', 34J of the liquid crystal element and the electronic Circuit are on the same side of the substrate (20). 5.) Device according to one of the preceding claims, characterized in that there is an insulating layer (25) between at least part of the electronic circuit and the liquid crystal layer (30). B09849 / 0807 ■ iS- Blank page