WO2007105760A1

WO2007105760A1 - Liquid crystal image display device and liquid crystal image display method

Info

Publication number: WO2007105760A1
Application number: PCT/JP2007/055110
Authority: WO
Inventors: Hirotsugu Yamamoto
Original assignee: The University Of Tokushima
Priority date: 2006-03-15
Filing date: 2007-03-14
Publication date: 2007-09-20
Also published as: JP5087774B2; JPWO2007105760A1

Abstract

[PROBLEMS] Encrypting of a liquid crystal display and a limit of an observation region are to be put into practice. [MEANS FOR SOLVING THE PROBLEMS] An encrypting liquid crystal panel (30) for displaying encrypted data and a decoding key liquid crystal panel (40) for displaying decoding key data are disposed in pixel-to-pixel correspondence to each other. An encrypting means (80) generates encrypted data of video image data based on a visual decoding type encryption in accordance with a polarizing light rotating angle change of a polarizing light rotating element for each pixel, a decoding key generating means (90) generates decoding key data set for the polarizing light rotating angle for decoding the video image data in accordance with the polarizing light rotating angle of the encrypted data for each pixel, and the encrypting liquid crystal panel (30) displays the encrypted data. The decoding key liquid crystal panel (40) displays the decoding key data and overlaps the encrypted data and the decoding key data for each pixel, so that a proper polarizing light rotating angle corresponding to the video image data is given to each pixel, light passing through a pixel of the encrypting liquid crystal panel and its corresponding pixel of the decoding key liquid crystal panel reconstructs a video image only given in the observation region.

Description

Specification

Liquid crystal image display device and liquid crystal image display method

Technical field

TECHNICAL FIELD [0001] The present invention relates to a liquid crystal image display device and a liquid crystal image display method in which image data displayed on a liquid crystal display screen is encrypted, and more specifically, to a liquid crystal image display device of a visual decryption type encryption using polarized light. And a liquid crystal image display method.

Background art

[0002] In recent years, with the development of mobile computing environments, usage forms for performing work using information terminals such as personal computers in public transportation institutions such as trains and airplanes have become widespread. Under such circumstances, the information displayed on the screen is accidentally or intentionally viewed by an unspecified number of people not intended by the user, raising the risk of leakage of confidential information such as companies! /

[0003] On the other hand, terminals that are installed in public places and connected to a display (for example, terminals of financial institutions and terminals installed in public offices) are expected to increase the security for similar security. Is done.

[0004] As described above, security technology for maintaining confidentiality of information and preventing leakage is important. In order to ensure security, various encryption technologies are being developed for communication, and personal authentication technologies are being developed for connection and access to information. On the other hand, the power that requires some kind of protection for the image information that is finally displayed on the screen through these procedures is not progressing in this field. For example, even if connection is established through communication encryption or personal authentication, it may be seen from the surroundings when it is displayed on the screen. On the other hand, the leakage electromagnetic wave of the image signal transmitted from the computer or the like to the monitor may be intercepted, and the image information may be acquired and reproduced.

[0005] For example, as a technique for preventing leakage of information contained in image data displayed on a liquid crystal display such as a computer or a mobile phone, a filter sheet for limiting the viewing angle is attached to the surface of the liquid crystal display. A method for limiting the visible space is known. In addition, directional image display, Norrax Noria, patterned phase difference film Methods such as 3D-LCD (polarized glasses or no glasses), integral, super multi-view, volume display, holography application, etc. are also being studied.

[0006] Further, Patent Document 1 discloses a liquid crystal image display device capable of limiting the viewing angle.

In this liquid crystal image display device, as shown in FIG. 1, a driving liquid crystal panel 1 is disposed on the observer side (upper side of the figure), and on the opposite side (lower side of the figure) of the driving liquid crystal panel 1 to the observer. The compensation liquid crystal panel 2 is laminated on the driving liquid crystal panel 1. One polarizing plate 3 and 4 is disposed on the viewer side and the non-viewer side of these liquid crystal panels, respectively. A driving circuit 5 for applying a driving voltage is connected to the driving liquid crystal panel 1 via an electrode (not shown), and a viewing angle is changed to the compensating liquid crystal panel 2 via a transparent electrode (not shown). Compensation voltage application circuit 6 for applying a voltage for the purpose is connected. The driving liquid crystal panel 1 has a transmissive or transflective pixel structure and displays an image. The compensation liquid crystal panel 2 can apply a voltage independently of the driving liquid crystal panel 1. In addition, by appropriately dividing the electrodes of the compensation liquid crystal panel 2, the viewing angle characteristics corresponding to the usage environment and the content to be displayed can be selectively selected in each part of the display surface of the same liquid crystal image display device. Can be displayed

[0007] In these methods, by limiting the viewing angle, only the user himself / herself can normally browse from a specific position, and information displayed on the display screen cannot be viewed from other positions and angles. Can prevent side effects from being seen.

Patent Document 1: JP 2005-265930 A

Patent Document 2: JP 2001-274971 A

Patent Document 3: Japanese Translation of Special Publication 2005—517218

Non-Special Reference 1: Han- Yen Tu, Chau- Jern Cheng and Mao- Ling hen; Optical image encryption based on polarization encoding by liquid crystal spatial light modulators; J ournal of Optics A: Pure and Applied Optics; 2004; 6 ; pp.524-528. <http://www.iop.org/EJ/abstract/1464-4258/6/6/005>

Disclosure of the invention

Problems to be solved by the invention

However, the liquid crystal image display device inherently includes image data. Therefore, the above method cannot counter eavesdropping by intercepting leaked electromagnetic waves.

On the other hand, a printed material using visual decryption secret sharing is known (Patent Document 2). Image encryption using the visual decryption secret sharing method involves printing image data divided into a plurality of dot patterns that look only like noise on a transparent film and overlaying the transparent film. The image is restored. However, this method uses a plurality of pixels to express a single point, so there is a problem that the resolution, brightness, and contrast are halved.

Further, Non-Patent Document 1 discloses a proposal for encrypting a black-and-white binary image such as a character displayed on a liquid crystal display using the visual decryption secret sharing method. As shown in FIG. 2, this liquid crystal display has two liquid crystal layers 7 and 8, which are used for an input signal and a decryption key, respectively. As shown in FIG. 3, the liquid crystal layer is divided into two directions, vertical and parallel, with respect to the input signal liquid crystal layer 7 and the decryption key liquid crystal layer 8, and these liquid crystal layers are overlapped to overlap the liquid crystal layer. Decode by exclusive OR (XOR) using phase lag. As a result, the image information itself can be encrypted by visual decryption encryption using polarized light, which is one of the optical encryption technologies. For this reason, even if a leaked electromagnetic wave is intercepted, it cannot be reproduced unless there is decryption information because it is encrypted image data. However, this method can only be applied to black and white binary images, and has a problem that it cannot decode multi-tone images such as gray scale and full color display.

On the other hand, Patent Document 3 discloses a liquid crystal display in which a liquid crystal layer of a liquid crystal display is divided into two, and encryption and decryption are performed by polarization rotation of a liquid crystal cell. This liquid crystal display has the power to achieve cell-by-cell encryption at the polarization rotation angle, but cannot restrict the observation area. There was a problem!

[0012] The present invention has been made in view of such problems. The main object of the present invention is to realize a liquid crystal-type image display device and a liquid crystal that realizes visual decryption of an encrypted image and restriction of a viewing angle at the same time, and has excellent contrast even when a high-resolution multi-valued image is encrypted. It is in providing a formula image display method.

Means for solving the problem In order to achieve the above object, a first liquid crystal image display device according to the present invention is a liquid crystal image display device capable of displaying given image data in gradation, and the image data is converted into a visual decryption type encryption. An encryption means for encrypting based on / under, a decryption key generation means for generating decryption key data for decrypting encrypted data encrypted by the encryption means, and a pixel structure, and polarization rotation for each pixel An encryption liquid crystal panel for displaying encrypted data generated by the encryption means, an encryption operating voltage application means for driving a polarization rotation element of the encryption liquid crystal panel, and a pixel structure. The pixel pitch is smaller than that of the encryption liquid crystal panel, each pixel has a polarization rotation element, and the decryption key liquid crystal panel for displaying the decryption key data generated by the decryption key generation means, and the decryption key LCD panel for keys And a decryption key operating voltage applying means for driving the polarization rotation element, and the encryption liquid crystal panel and the decryption key liquid crystal panel are spaced apart from each other by a predetermined distance and are arranged to correspond to each pixel. The encryption unit generates encryption data obtained by encrypting the image data based on the visual decryption type encryption by changing the polarization rotation angle of the polarization rotation element for each pixel, and the decryption key generation unit includes the decryption key generation unit for each pixel. Decryption key data in which the polarization rotation angle for decrypting the image data is set according to the polarization rotation angle of the encryption key data is generated, and the encryption liquid crystal panel is driven by the encryption operation voltage applying means to generate the encryption data. Is displayed, and the decryption key operating voltage applying means drives the decryption key liquid crystal panel to display the decryption key data. By superimposing the encryption key data and the decryption key data for each pixel, the image data is displayed. The appropriate polarization rotation angle was given to each pixel, and light that passed through the corresponding pixels of the encryption liquid crystal panel and the decryption key liquid crystal panel was given to the observation surface only in the observation region. The image can be reconstructed. As a result, multi-tone display image data such as color and gray scale can be encrypted and displayed for each pixel, so that information leakage can be effectively prevented. In particular, since the restored image data itself is not directly displayed on the liquid crystal panel, information cannot be obtained even if the display data itself is intercepted. For example, even if image restoration is attempted by intercepting leaked electromagnetic waves, Since only encrypted data can be displayed and the contents cannot be confirmed, it is possible to ensure effective security against such eavesdropping. In addition, by limiting the viewing angle, it is possible to limit the field of view and observation area, and effectively prevent side-viewing and rear-side force snooping. In addition, the second liquid crystal image display device has a cryptographic liquid crystal panel power having a first cryptographic liquid crystal layer having a predetermined pixel pitch and an aperture ratio, and a pixel pitch and an aperture ratio substantially equal to the first cryptographic liquid crystal layer. And a second encryption liquid crystal layer spaced apart from the first encryption liquid crystal layer by a certain distance and arranged so as to overlap, and the encryption means transmits the encryption data for the first encryption liquid crystal layer. The first encryption data and the second encryption data for the second liquid crystal are divided, and the first encryption data is supplied to the first encryption liquid crystal layer and the second encryption data is supplied to the second encryption liquid crystal layer. The encryption data can be configured to be encrypted through the encryption liquid crystal layer and the second encryption liquid crystal layer. As a result, by setting the interval between the first encryption liquid crystal layer and the second encryption liquid crystal layer, the pixel pitch, and the aperture ratio, the observation area where the decoded image can be observed can be limited three-dimensionally. It can effectively deal with snooping from the side or from behind.

[0015] Further, the third liquid crystal image display device includes a decryption key liquid crystal panel force, a first decryption key liquid crystal layer having a predetermined pixel pitch and an aperture ratio, and a pixel pitch substantially equal to the first decryption key liquid crystal layer. And a second decryption key liquid crystal layer that is spaced apart from the first decryption key liquid crystal layer by a certain distance, and is decrypted by the decryption key generating means. The key data is divided into first decryption key data for the first decryption key liquid crystal layer and second decryption key data for the second decryption key liquid crystal, and the first decryption key data is divided into the first decryption key data. By applying the second decryption key data to the second decryption key liquid crystal layer, the encrypted data is decrypted via the first decryption key liquid crystal layer and the second decryption key liquid crystal layer. Can be configured. As a result, by setting the installation interval, the pixel pitch, and the aperture ratio of the first decryption key liquid crystal layer and the second decryption key liquid crystal layer, the observation area in which the decrypted image can be observed can be viewed three-dimensionally. It can be limited, and can effectively deal with snooping from the side or from behind.

[0016] Furthermore, the fourth liquid crystal image display device is a liquid crystal image display device capable of displaying gradation of given image data, and the image data is encrypted based on visual decryption encryption.暗号 encrypting means, decryption key generating means for generating decryption key data for decrypting the encrypted data encrypted by the encrypting means, and a backlight light source disposed on the side opposite to the observation surface side A first polarizing plate disposed on the observation surface side, a second polarizing plate disposed away from the first polarizing plate and having a polarization direction orthogonal or parallel to the first polarizing plate, and the first polarizing plate And a liquid crystal panel having a polarization rotation element disposed between the second polarizing plates and having a pixel structure, Each pixel has a polarization rotation element and is arranged so as to overlap with the first polarizing plate, and includes an encryption liquid crystal panel for displaying encrypted data generated by the encryption means, a pixel structure, and a pixel pitch. It is smaller than the encryption liquid crystal panel, has a polarization rotation element for each pixel, and is arranged to match the encryption liquid crystal panel for each pixel to display the decryption key data generated by the decryption key generation means. Decryption key liquid crystal panel, encryption operating voltage application means for driving the polarization rotation element of the encryption liquid crystal panel, and decryption key operation voltage application means for driving the polarization rotation element of the decryption key liquid crystal panel And the encryption liquid crystal panel and the decryption key liquid crystal panel are arranged so as to be separated from each other by a certain distance and correspond to each pixel, and the encryption means has a polarization rotation angle of the polarization rotation element for each pixel. The encryption key data is generated by encrypting the image data based on the visual decryption type encryption by changing the degree, and the decryption key generating means generates the image data according to the polarization rotation angle of the encrypted data for each pixel. Decryption key data in which the polarization rotation angle for decryption is set is generated, the encryption liquid crystal panel is driven by the encryption operation voltage applying means to display the encryption data, and the decryption key operation voltage application means is used to display the decryption key data. The LCD panel is driven to display the decryption key data, and an appropriate polarization rotation angle corresponding to the image data is given to each pixel by superimposing the encryption key data and the decryption key data for each pixel. Thus, light that has passed through the corresponding pixels of the encryption liquid crystal panel and the decryption key liquid crystal panel through the first and second polarizing plates passes through the knock light source to the observation surface side, and only in the observation region. Give The reconstructed image can be configured. In addition, by limiting the viewing angle, it is possible to limit the viewing range and observation area, and effectively prevent side-viewing and side-viewing.

Furthermore, the fifth liquid crystal image display device can be configured such that there are three or more encryption liquid crystal panels and decryption key liquid crystal panels in total. As a result, it is possible to further enhance security by enciphering the encryption key.

[0018] Further, the sixth liquid crystal image display device has the encrypted data generated by the encryption means.

Can be configured to change over time. This makes it more difficult to decrypt encrypted data that changes over time.

Furthermore, the seventh liquid crystal image display device can change the encryption key pattern for each frame constituting the moving image in displaying the moving image. As a result, the encryption key is further captured. Security can be increased.

Furthermore, the eighth liquid crystal image display device is a liquid crystal image display device capable of displaying given image data in gradation, and the image data is encrypted based on visual decryption encryption.暗号 Encrypting means, a backlight light source disposed on the opposite side of the observation surface side, a first polarizing plate disposed on the observation surface side, and a first polarizing plate disposed apart from the first polarizing plate. A second polarizing plate having a polarization direction perpendicular or parallel to the plate, and disposed between the first polarizing plate and the second polarizing plate, having a pixel structure, and having a polarization rotation element for each pixel, and the first polarizing plate And an encryption liquid crystal panel for displaying the encrypted data generated by the encryption means, and an encryption operation voltage applying means for driving the polarization rotation element of the encryption liquid crystal panel, A phase difference plate arranged so that the polarization rotation angle is different for each pixel; And encryption means generates encrypted data obtained by encrypting the image data for each pixel according to the polarization rotation angle for each pixel of the retardation plate based on the visual decryption encryption, and performs the encryption operation. The encryption liquid crystal panel is driven by voltage application means to display the encrypted data, and the encryption data is superimposed on a phase difference plate for each pixel, so that the polarization rotation angle corresponding to the image data is changed for each pixel. Only in the observation area of the light force that passes through the corresponding pixels of the encryption liquid crystal panel and the decryption key liquid crystal panel through the first and second polarizing plates to the observation surface side through the backlight light source. A given image can be configured to be reconstructable. As a result, multi-gradation display image data such as color or gray scale can be encrypted and displayed for each pixel, so that information leakage can be effectively prevented. In particular, since the restored image data itself is not displayed directly on the liquid crystal panel, information cannot be obtained even if the display data itself is intercepted. For example, even if image restoration is attempted by intercepting leaked electromagnetic waves, it is encrypted. However, since only data can be displayed and the contents cannot be confirmed, it is possible to ensure effective security against such eavesdropping.

Furthermore, the ninth liquid crystal image display device can include a plurality of retardation plates. The polarization rotation element using the phase difference plate can be freely attached and detached, and the number of layers can be changed according to the situation.

[0022] Further, in the tenth liquid crystal image display device, the retardation plate can be detachably configured. As a result, it is possible to replace the phase difference plate with a pattern having a different polarization rotation angle or to change the phase difference plate. Security can be further enhanced by changing the number of sheets.

Furthermore, the eleventh liquid crystal image display device is a liquid crystal image display device capable of displaying given image data in gradation, and encrypts image data based on visual decryption encryption. And a decryption key generation means for generating decryption key data for decrypting the encrypted data encrypted by the encryption means, and a pixel structure, each pixel having a polarization rotation element and encryption A liquid crystal panel for encryption for displaying encrypted data generated by the means, a means for applying an encryption operating voltage for driving a polarization rotation element of the liquid crystal panel for encryption, and a pixel structure. A decryption key liquid crystal panel for displaying the decryption key data generated by the decryption key generation means, and a decryption key operating voltage application means for driving the polarization rotation element of the decryption key liquid crystal panel. LCD screen for encryption And the decryption key liquid crystal panel are spaced apart from each other by a certain distance and correspond to each pixel, and the pixel pitch of each corresponding pixel of the decryption key liquid crystal panel is relatively smaller than that of the encryption liquid crystal panel. As shown, the displayed decryption key data pattern is reduced, or the encryption key data pattern is enlarged, and the encryption means changes the polarization rotation angle of the polarization rotation element for each pixel to change the image data. Encrypted encrypted data is generated based on the visual decryption type encryption, and the decryption key generating means sets a polarization rotation angle for decrypting the image data for each pixel according to the polarization rotation angle of the encrypted data. The set decryption key data is generated, the encryption liquid crystal panel is driven by the encryption operation voltage application means to display the encryption data, and the decryption key operation voltage application means drives the decryption key liquid crystal panel. The decryption key data is displayed and the encrypted data and the decryption key data are overlapped for each pixel, so that an appropriate polarization rotation angle corresponding to the image data is given to each pixel, and the encryption is performed on the observation surface side. The light that has passed through the corresponding pixels of the liquid crystal panel for decryption and the liquid crystal panel for decryption key can be configured to reconstruct an image given only within the observation region. As a result, multi-gradation display image data such as power and gray scale can be encrypted and displayed for each pixel, so that information leakage can be effectively prevented. In particular, since the restored image data itself is not displayed directly on the liquid crystal panel, information cannot be obtained even if the display data itself is intercepted. For example, even if image restoration is attempted by intercepting leaked electromagnetic waves, it is encrypted. Since only data can be displayed and the contents cannot be confirmed, it is effective against such eavesdropping. Security can be secured. In addition, by limiting the viewing angle, it is possible to limit the viewing range and observation area, and effectively prevent side-viewing and side-viewing. In particular, the decryption key data pattern and the encryption data pattern without changing the pixel pitch of the decryption key liquid crystal panel and the encryption liquid crystal panel in a node-like manner can be reduced and enlarged to reduce the relative pixel pitch. Changes can be implemented in software, and the spatial observation area can be limited at a lower cost.

Furthermore, the twelfth liquid crystal image display method includes an encryption means for encrypting image data based on visual decryption encryption, a backlight light source disposed on the side opposite to the observation surface, A first polarizing plate disposed on the surface side, a second polarizing plate disposed apart from the first polarizing plate and having a polarization direction orthogonal or parallel to the first polarizing plate, the first polarizing plate, and the second polarizing plate A liquid crystal panel having a polarization rotator disposed between polarizing plates, having a pixel structure, having a polarization rotator for each pixel, and being disposed so as to overlap the first polarizing plate. The encryption liquid crystal panel for displaying the encryption data generated in step 1 has a first encryption liquid crystal layer having a predetermined pixel pitch and an aperture ratio, and a pixel pitch and an aperture ratio substantially equal to the first encryption liquid crystal layer. With a certain distance from the first encryption liquid crystal layer In addition, a cryptographic liquid crystal panel having a second cryptographic liquid crystal layer arranged so as to overlap with each other, and a pixel structure, the pixel pitch is smaller than that of the cryptographic liquid crystal panel, and a polarization rotation element is provided for each pixel. A decryption key liquid crystal panel for displaying the decryption key data generated by the decryption key generation means, and a polarization rotation element of the encryption liquid crystal panel. And a decryption key operation voltage application means for driving the polarization rotation element of the decryption key liquid crystal panel, and can provide gradation display of the given image data. A liquid crystal image display method for displaying image data on a liquid crystal image display device, wherein the encryption means changes the polarization rotation angle of the polarization rotation element for each pixel based on the visual decryption encryption. In addition to generating encrypted encrypted data, the substantially encrypted data is divided into first encrypted data for the first encrypted liquid crystal layer and second encrypted data for the second liquid crystal, and a decryption key generating means is provided for each pixel. And generating a decryption key data in which the polarization rotation angle for decrypting the image data is set according to the polarization rotation angle of the encrypted data, and the encryption liquid crystal panel by the encryption operation voltage applying means. In order to drive and display the cipher key data, the first cipher data is given to the first cipher liquid crystal layer, the second cipher data is given to the second cipher liquid crystal layer, and decryption is performed by means of applying the decryption key operating voltage. Driving the key liquid crystal panel to display the decryption key data, and by superimposing the encryption key data and the decryption key data for each pixel, an appropriate polarization rotation angle corresponding to the image data is obtained from the pixel. The light that passes through the corresponding pixels of the encryption liquid crystal panel and the decryption key liquid crystal panel through the first and second polarizing plates enters the observation area.て It is possible to reconstruct a given image only. As a result, multi-tone display image data such as color and gray scale can be encrypted and displayed for each pixel, so that information leakage can be effectively prevented. In particular, since the restored image data itself is not displayed directly on the liquid crystal panel, information cannot be obtained even if the display data itself is intercepted. For example, even if image restoration is attempted by intercepting leaked electromagnetic waves. Since only encrypted data can be displayed and the contents cannot be confirmed, it is possible to ensure effective security against such eavesdropping. In addition, by limiting the viewing angle, it is possible to limit the viewing range and the observation area, and effectively prevent side-viewing and rear-viewing.

Furthermore, the thirteenth polarization operation type image display device is a polarization operation type image display device capable of displaying gradation of given image data, and encrypts image data based on visual decryption encryption. And a decryption key generating means for generating decryption key data, a pixel structure, a polarization rotator for each pixel, and the encryption means generating the encryption data encrypted by the encryption means The encryption panel for displaying the encrypted data and the pixel structure, the pixel pitch is smaller than that of the encryption panel, each pixel has a polarization rotation element, and the decryption key generated by the decryption key generation means A decryption key panel for displaying the key data, the encryption panel and the decryption key panel are spaced apart from each other at a fixed distance and correspond to each pixel. Pixel Each time the polarization rotation angle of the polarization rotator is changed to generate encrypted data obtained by encrypting the image data based on the visual decryption type encryption, the decryption key generation means also applies the polarization of the encrypted data to each pixel. Generates decryption key data that sets the polarization rotation angle for decrypting image data according to the rotation angle, displays the encrypted data on the encryption panel, and displays the decryption key data on the decryption key panel. , The encrypted data and the decryption key data for each pixel. By superimposing the data, an appropriate polarization rotation angle corresponding to the image data is given to each pixel, and the optical power observation that has passed through the corresponding pixels of the encryption panel and the decryption key panel on the observation surface side is observed. An image provided only within a region can be configured to be reconstructable. With the above configuration, it is possible to encrypt the video signal to be expressed by adding the polarization rotation angle based on the visual decryption secret sharing method, and to improve the security against leakage and interception of image data. Furthermore, it is possible to limit the observation area by correspondence of the pixel position of the encrypted data, and to set the image data to be visible only at the observation position limited to a specific distance, for viewing from the side or behind. On the other hand, security can be increased. By using polarized light, multi-gradation can be expressed, and high-definition display with increased expressive power compared to conventional encrypted image display devices can be realized.

Furthermore, in the fourteenth polarization operation type image display device, a liquid crystal can be used as a polarization rotation element. As a result, encryption can be easily performed for each pixel.

Furthermore, the fifteenth polarization operation type image display device is a retardation plate in which a polarization rotation element is patterned. As a result, it is possible to realize field-of-view restriction and encryption at low cost.

Furthermore, in the sixteenth polarization operation type image display device, the encryption liquid crystal panel and the decryption key liquid crystal panel can be combined to be 3 or more. As a result, the security can be further enhanced by enciphering the encryption key.

[0029] Further, the seventeenth polarization calculation type image display method is a polarization calculation type image display method for displaying image data on a polarization calculation type image display device capable of displaying gradation of given image data. Based on the visual decryption-type encryption, encrypted data is generated by encrypting the polarization rotation angle of the polarization rotation element for each pixel, and the approximate encryption data is converted to the first encryption data for the first encryption layer. Then, the data is divided into second encryption data for the second encryption layer, and further, decryption key data in which the polarization rotation angle is set for decoding the image data according to the polarization rotation angle of the encryption data for each pixel is generated. In order to display the encrypted data on the encryption panel for displaying the process and the encrypted data, the first encrypted data is given to the first encrypted layer and the second encrypted data is given to the second encrypted layer. On the other hand, decryption key data Displaying the decryption key data on a decryption key panel for displaying data, and by superimposing the encryption key data and the decryption key data on a pixel-by-pixel basis, The polarization rotation angle is given for each pixel, and the encryption panel and the decryption key panel correspond to each other through the first polarizing plate arranged on the observation surface side and the second polarizing plate arranged on the opposite surface side. The light power that has passed through the pixels can be reconstructed only in the observation area. As a result, multi-gradation display image data such as color and gray scale can be displayed in an encrypted manner for each pixel, so that information leakage can be effectively prevented. In particular, since the restored image data itself is not displayed directly on the liquid crystal panel, information cannot be obtained even if the display data itself is intercepted. For example, even if image restoration is attempted by intercepting leaked electromagnetic waves, Since only encrypted data can be displayed and the contents cannot be confirmed, it is possible to ensure effective security against such eavesdropping. Furthermore, by setting the installation interval, pixel pitch, and aperture ratio of the first and second encryption liquid crystal layers, the observation area where the decoded image can be observed can be limited in three dimensions, and the lateral direction can be limited. It can effectively respond to sneak peeks from behind or sneak peeks of backward power.

The invention's effect

[0030] According to the liquid crystal image display device and the liquid crystal image display method of the present invention, visual decryption of an encrypted image and restriction of the viewing angle can be realized at the same time, and deterioration in resolution and luminance can be reduced. In particular, compared to conventional privacy protection filters attached to liquid crystal displays such as personal computers and mobile phones, the use of an algorithm that implements visual decryption encryption using polarized light not only limits the viewing angle. Even if leaked electromagnetic waves are intercepted by video signal encryption, image data cannot be constructed, and security can be further strengthened. In addition, the observation position can be limited three-dimensionally by left and right and depth, and it is possible not only to see the side but also from behind, and to deal with not only data leakage in the middle but also information leakage at the final output stage. it can.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the embodiments described below exemplify a liquid crystal image display device and a liquid crystal image display method for embodying the technical idea of the present invention, and the present invention is a liquid crystal image display device and a liquid crystal display device. The formula image display method is not specified as follows. Further, the present specification by no means specifies the member shown in the claims as the member of the embodiment. Especially the form of implementation Unless otherwise specified, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in the embodiments are merely illustrative examples that are not intended to limit the scope of the present invention. . Note that the size, positional relationship, and the like of the members shown in each drawing may be exaggerated for clarity of explanation. Further, in the following description, the same name and reference numeral indicate the same or the same members, and detailed description will be omitted as appropriate. Furthermore, each element constituting the present invention may be configured such that a plurality of elements are constituted by the same member and a plurality of elements are shared by one member, and conversely the function of one member is a plurality of members. It is a matter of sharing and realizing.

[0032] The present inventors applied a visual decoding type secret sharing method to a display as a countermeasure against a snooping of a liquid crystal image display device such as a liquid crystal display, and displayed a screen with white and black dot patterns; Research on a device that restores an image by overlaying a transmission mask and a decoding mask with a shading pattern was repeated (see Fig. 11 and Fig. 12). With this technology, the image itself displayed on the screen is encrypted, so even if a leaked electromagnetic wave is intercepted, it looks like a mere noise and information can be concealed. Furthermore, by adjusting the size of the mask and the installation distance with respect to the screen, the observation area where the image is restored can be limited. However, this method has a problem in that resolution, brightness, and contrast are reduced because a plurality of pixels are used to display one light spot. In order to solve this problem, the present inventors have intensively studied the visual decoding type secret sharing method using polarized light and have come up with the present invention.

The liquid crystal image display device has a configuration in which a polarization rotation element, that is, a liquid crystal layer is sandwiched between two polarizing plates. The polarization rotation element is divided into a plurality of layers, and the image data is restored by superimposing the plurality of layers for each pixel. The liquid crystal layer divided into a plurality of layers functions as a set of an encryption liquid crystal panel and a decryption key liquid crystal panel, and these alone cannot reproduce image data, but image data can be reproduced by combining them. As a result, the target image is recognized by the user's eyes, but the image signal itself displayed on the liquid crystal layer remains encrypted and is not decrypted as data. Even if this is intercepted by some means, image data cannot be constructed. This effectively eliminates electronic wiretapping using leaked electromagnetic waves.

In addition, the configuration for reproducing image data by combining a plurality of layers is a liquid crystal layer. In addition, it can be realized by a combination of a liquid crystal layer and a retardation plate. In other words, if the liquid crystal layer is used, it can be set to an arbitrary polarization rotation angle, but if all the data of each layer is intercepted, there is a risk that it will be decoded, but the polarization pattern is encrypted in the retardation plate. A configuration using a hardware decryption panel that provides a rotation angle increases security because it cannot be decrypted using only electronic information. Further, since it is only necessary to add a physical phase difference plate, there is an advantage that the hardware configuration can be simplified and an inexpensive encryption key can be realized. In this way, by using a part of the polarization rotation element as a retardation plate pattern, it is possible to further reduce the possibility that the image signal to the polarization rotation element is intercepted and restored. If a plurality of retardation plates are used, restoration can be made more difficult. For example, when multiple people have a phase difference plate, the decoded data can be visually recognized only while each person brings the phase difference plate and installs, and information access can be physically restricted. Furthermore, an image display device can be configured with only a retardation plate.

(Viewing angle control)

[0035] Furthermore, side-viewing can be prevented by intentionally narrowing the viewing angle and limiting the observation region. The observation area is three-dimensionally determined by the installation interval of the polarization rotation elements of each layer, the pixel pitch, and the aperture ratio. When viewed from within the observation area, the target image is recognized, but when viewing from the observation area, the pixels of the polarization rotation elements in each layer are displaced, so that a normal image is not recognized. As a result, it is possible to prevent sneaking from seeing in an oblique direction from the surroundings.

[0036] Furthermore, not only the viewing angle is limited, but also the distance from the liquid crystal image display device can be limited. As a result, it is possible to prevent an act of peeping by expanding the distant force. In this way, secret sharing by using multiple key images for decryption keys can be used to improve secrecy.

[0037] In this specification, for convenience, it is called an encryption 'decryption key', but since it is actually secretly distributed, both are equivalent and the encryption and decryption keys can be interchanged. Displaying the decryption key data on the decryption key liquid crystal panel indicates not only the decryption key data itself but also display data generated based on the decryption key data (for example, an inversion pattern of the decryption key data). You can also In image encryption by secret sharing, information is distributed to multiple images, and each image is called a “shared image”. In this specification, share At least one of the images is “encryption” and at least one is “decryption key”. Especially when moving images are targeted, “encryption” can be changed for each screen or frame. The “decryption key” can use a single pattern or a plurality of patterns. Of course, you can change the decryption key for each screen. In particular, when encrypting a video, if the random number sequence that is the key for generating the encryption is fixed, that is, if the pattern of the encryption data that is the key is fixed, by storing the encryption data sent by the information sender, There is a possibility that encryption data as a key is estimated. Therefore, when displaying a moving image, security can be enhanced by encrypting based on a unique random number sequence for each frame. In this case, it is preferable to use a liquid crystal as a polarization rotation element rather than a retardation plate.

Hereinafter, a liquid crystal image display device according to an embodiment of the present invention will be described with reference to FIG. A liquid crystal image display device 100 shown in FIG. 4 includes a knocklight light source 10, a first polarizing plate 20, an encryption liquid crystal panel 30, a decryption key liquid crystal panel 40, and a second polarizing plate 50. This liquid crystal image display device 100 is of a transmissive type in which the backlight emitted from the light source 10 for backlight passes through the polarizing plates 20 and 50 and the liquid crystal panels 30 and 40 and is not passed through. In addition, the liquid crystal image display device 100 employs an active matrix method, and can display gradations of image data such as full color and gray scale. However, it is also possible to adopt a reflection type that does not use a knocklight or a transflective type that uses a backlight and reflected light in combination.

(Light source for backlight 10)

[0039] The knock light source 10 is preferably a CCFL (Cold-Cathode Fluorescent Lamp) or LED (Light-Emitting Diode) that is generally used as a backlight for liquid crystals. Available.

(First polarizing plate 20, second polarizing plate 50)

The polarizing plate has a bias in the vibration direction of light, and is a filter that extracts light oscillating in a certain direction from natural light oscillating in all directions. There are two types of polarization of light: linearly polarized light and circular / elliptical polarized light. Elements that change to linearly polarized light are called polarizers. Linearly polarized light is often converted to circular or elliptical polarized light by a phase difference plate or the like. It is called a circularly polarized plate or an elliptically polarizing plate.

As shown in FIG. 5, the first polarizing plate 20 and the second polarizing plate 50 are polarizing filters whose polarization directions are perpendicular to each other. As shown in FIG. 5, in the liquid crystal image display device, the first and second polarizing plates 20 and 50 are arranged orthogonally, and light passing through the polarizing plate on one side is polarized on the opposite side according to the alignment state of the liquid crystal. The display is controlled by changing the alignment state of the liquid crystal depending on the voltage. That is, in the state where no operating voltage is applied to the liquid crystal, the liquid crystal is twisted so that it is aligned with the polarization direction of the polarizing plates arranged orthogonally, and the incident light of one polarizing plate is twisted by the liquid crystal, and the other polarization Can pass through the board. That is, it can be in the ON state. On the other hand, when the operating voltage is applied to the liquid crystal by the operating voltage applying means to align the liquid crystal, the light is not twisted, and the light incident from one polarizing plate cannot pass through the other polarizing plate and is turned off. . The OFF state represents black without light emission. In this way, the liquid crystal functions as a shirt and controls on / off of light emission. Furthermore, by using a color filter, colorization and multi-valued image can be realized. In this example, 256 gray scale display is possible.

(Encryption LCD panel 30, Decryption key LCD panel 40)

The liquid crystal panel includes an encryption liquid crystal panel 30 for displaying encryption key data and a decryption key liquid crystal panel 40 for displaying decryption key data. Each liquid crystal panel has a polarization rotation element for each pixel. Each liquid crystal panel is installed such that the corresponding positions of the pixels provided in the polarization rotation elements of the encryption liquid crystal panel 30 and the decryption key liquid crystal panel 40 are matched.

As the liquid crystal panel, twisted nematic liquid crystal, super twisted nematic liquid crystal, parallel-arranged nematic liquid crystal, or the like can be used as appropriate. The liquid crystal alignment in the liquid crystal panel can change the polarization state and optical rotation direction of incident light such as vertical alignment, parallel alignment (uniaxial alignment), antiparallel alignment, twist alignment, hybrid alignment, etc. All liquid crystal display modes that can change the degree of change in the polarization state and optical rotation direction of the incident light by applying a voltage to can be used.

[0044] In particular, in the case of hybrid alignment, since it has no threshold value characteristic, the liquid crystal alignment changes moderately and forcefully with respect to voltage application, the birefringence can be easily adjusted, and the viewing angle can be controlled. accuracy It can be done well. Further, when the twisted orientation is adopted, the display can be performed by changing the optical rotation, so that a display with a high contrast ratio can be obtained and the display quality can be improved. Furthermore, in the case of parallel alignment (uniaxial alignment) and vertical alignment, it is easy to analyze the alignment state, and it is easy to optimize the optical characteristics design and the applied voltage of the decryption key liquid crystal panel 40 and encryption liquid crystal panel 30. The viewing angle can be easily controlled.

As the liquid crystal material in the encryption liquid crystal panel 30, any liquid crystal material can be used as long as it has birefringence and the alignment direction can be changed by an electric field. For the above-described polarizing plate, when a voltage is applied to the liquid crystal layer, the polarization plane of rotation sometimes rotates by 90 °, and the transmission direction of the polarizing plate is orthogonal and transmits light (normally white). Also, any of the types (normally black) in which the transmission direction of the polarizing plate is parallel and does not transmit light can be used.

As the liquid crystal material in the decryption key liquid crystal panel 40, any liquid crystal material can be used as long as it has birefringence and the orientation direction can be changed by an electric field. The liquid crystal alignment in the decoding key liquid crystal panel 40 can change the polarization state and optical rotation direction of incident light such as vertical alignment, parallel alignment (uniaxial alignment), antiparallel alignment, twist alignment, and hybrid alignment. In addition, all liquid crystal display modes that can change the degree of change in the polarization state and optical rotation direction of incident light by applying a voltage to the panel can be used.

[0047] In particular, when the decryption key liquid crystal panel 40 is in a hybrid orientation, the voltage dependence does not have a threshold characteristic, so that the liquid crystal orientation gradually changes with voltage application, and the birefringence is adjusted. And viewing angle control can be performed with high accuracy. Furthermore, the hybrid alignment is particularly suitable in that it does not respond to the application of voltage existing near the transparent electrode interface of the encryption liquid crystal panel 30, compensates for the influence of liquid crystal molecules, and widens the viewing angle.

(Encryption operation voltage application means 60, Decryption key operation voltage application means 70)

[0048] The encryption liquid crystal panel 30 and the decryption key liquid crystal panel 40 are connected to the encryption operation voltage application means 60 and the decryption key operation voltage application means 70, respectively, and are polarized light included in the liquid crystal panel. An operation voltage for driving the rolling element is applied and driven. This operating voltage application means constitutes a liquid crystal drive driver that drives by controlling ONZOFF and gradation independently for each pixel. Further, the encryption operation voltage application means 60 and the decryption key operation voltage application means 70 are connected to the encryption means 80 and the decryption key generation means 90 that control the respective operations.

(Encryption means 80)

[0049] The encryption means 80 generates encryption key data based on image data input from the outside. Based on the generated image data, the encryption operation voltage applying means 60 is controlled, and the liquid crystal of the encryption liquid crystal panel 30 is driven to perform ONZOFF control.

In order to display desired image data on the liquid crystal image display device, a polarization rotation angle is given to the polarization rotation elements of the corresponding pixels of the encryption liquid crystal panel 30 and the decryption key liquid crystal panel 40. The polarization rotation angle is given at a random ratio for each pixel. Thus, image data can be reproduced by combining the encryption liquid crystal panel 30 and the decryption key liquid crystal panel 40. On the other hand, since only the data before decoding remains in each liquid crystal panel, even if these data are acquired by leaked electromagnetic waves or the like, the image data will not be reproduced.

(Decryption key generation means 90)

[0051] Decryption key generation means 90 generates decryption key data corresponding to the encrypted data. By superimposing the encrypted data and the decryption key data, the correct rotation angle of the polarization plane for expressing the original image data can be obtained.

[0052] In the above example, it is difficult to perform decryption by using an encryption pattern in which the polarization rotation angle is changed for each pixel. Furthermore, the encryption pattern is not fixed, but can be changed with time, for example. For example, when displaying a moving image on a liquid crystal image display device, it is possible to make decryption more difficult by changing the encryption pattern for each frame.

(Visual decryption encryption)

In the present embodiment, the visual decryption secret sharing method (visual decryption encryption) is adopted as the encryption technique. Secret sharing is a secret management method in which secret information is distributed over multiple keys, and access to the secret information is permitted only after a certain number of keys are available. There is an effect to reduce. Visual decryption encryption is a secret sharing scheme This is a new type, an encryption technique proposed by Naor and Shamir in 1994 that distributes secret information to multiple encrypted images. The conventional visual decryption type encryption has a problem that the image quality is degraded because one pixel is composed of a plurality of pixels (for example, 4 pixels), and the resolution, brightness, and contrast are inferior. On the other hand, in this embodiment, a polarization-type visual decryption type encryption using rotation of the polarization plane is constructed, and the image data to be kept secret is distributed to the encryption key data and the decryption key data. Prevents loss of resolution, brightness, and contrast.

This situation will be described with reference to FIG. Figure 6 shows (a) backlight, (b) first polarizing plate 20,

(c) The encryption liquid crystal panel 30, (d) the decryption key liquid crystal panel 40, (e) the second polarizing plate 50, and (f) the output light pattern. Of these, (b) the first polarizing plate 20 and (e) the second polarizing plate 50 indicate the polarization transmission direction, and (c) the encryption liquid crystal panel 30 and (d) the decryption key liquid crystal panel 40 are polarized. The rotation of the surface is shown. Here, for explanation, it is assumed that a binary image is displayed with a block pattern of 4 pixels, and image data to be displayed in the pattern shown in (f) is input. (B) The first polarizing plate 20 and (e) the second polarizing plate 50 are fixed in the polarization directions orthogonal to each other. (C) The encryption liquid crystal panel 30 and (d) the decryption key liquid crystal panel 40 each have a polarization rotation angle pattern of 0 and 90 ° as shown in FIG. After passing through these two LCD panels, the left half of the four pixels is 90 ° and the right half is zero. As a result, in the left half, (a) the light incident on the polarizing plate from the backlight (b) passes through (c) the liquid crystal panel 30 for encryption and (d) the liquid crystal panel 40 for decryption key. (F) The left half of the output light pattern is “bright”. On the other hand, in the right half, no light is transmitted and it is “dark”. In this way, by controlling the polarization rotation angle of the liquid crystal panel, encryption is performed for each pixel to ensure the security of information display.

In the above example, for simplicity, it goes without saying that it is possible to take intermediate values such as forces ± 45 °, 30 °, etc. with the polarization rotation angle of the pixel being either 0 or 90 °. In particular, as shown in Fig. 4, the use of an arbitrary polarization rotation angle can further improve the accuracy of the encryption key.

[0056] Next, based on FIG. 4, a state in which optical computation is performed with the polarization-type visual decryption encryption will be described. In this liquid crystal image display device 100, the polarization rotation element is a super twisted nematic liquid crystal, It is assumed that the polarization rotation angle of each liquid crystal panel can be controlled from 0 to 180 ° and 256 gradations. In addition, the encryption liquid crystal panel 30 and the decryption key liquid crystal panel 40 are arranged in three dimensions in a one-dimensional direction so that the pixels overlap each other. The polarization rotation angle of the encryption liquid crystal panel 30 is set to 60 °, 10 °, and 45 ° to the left force, while the polarization rotation angle of the decryption key liquid crystal panel 40 is set to 30 °, 80 °, and 45 ° from the left. As a result, the polarization obtained by transmitting through the second polarizing plate 50 is 90 ° in all three pixels, so that the light is transmitted and is 1 or “bright” or ON. Note that the same effect can be obtained by using 270 ° in addition to a total of 90 ° by optical calculation.

[0057] On the other hand, even if the liquid crystal panel 30 for encryption and the liquid crystal panel 40 for decryption key are misaligned, the obtained data is encrypted data and decryption key data that is not the image data itself, and is temporarily intercepted. Even so, image data cannot be restored by itself. Therefore, since complete image data does not exist in the liquid crystal image display device, even if this data is intercepted, information is not leaked and security can be improved.

In the example of FIG. 4, the decryption key liquid crystal panel 40 is disposed under the encryption liquid crystal panel 30. However, the present invention is not limited to this configuration, and the decryption key liquid crystal panel is disposed over the encryption liquid crystal panel. By doing so, the same effect can be obtained.

Further, in addition to the encryption liquid crystal panel and the decryption key liquid crystal panel being constituted by one sheet, it is also possible to constitute these by a plurality of liquid crystal panels. For example, as in the modification shown in FIG. 7, the encryption liquid crystal panel 30 is composed of a first encryption liquid crystal layer 31 and a second encryption liquid crystal layer 32, and the polarization rotation element of the first encryption liquid crystal layer 31 and The cipher data is constructed by superimposing the polarization rotation element of the second encryption liquid crystal layer 32. The encryption means 80 distributes the encrypted data to the first encryption liquid crystal layer and the second encryption liquid crystal layer. As a result, it becomes more difficult to decrypt with the data of each liquid crystal layer, and security can be improved.

Similarly, the decryption key liquid crystal panel can be formed of a plurality of layers. FIG. 8 shows an example in which the decryption key liquid crystal panel 40 is composed of a first decryption key liquid crystal layer 41 and a second decryption key liquid crystal layer 42. In this case, the decryption key generation means 90 distributes the decryption key data to the first decryption key liquid crystal layer and the second decryption key liquid crystal layer, and constructs the decryption key data by superimposing them. this Even with the configuration, it is possible to improve security by making it difficult to decode only the data of each liquid crystal layer.

As described above, by configuring the liquid crystal panel with a plurality of liquid crystal layers, the accuracy of encryption is increased, and decryption is difficult and security can be improved. However, if a large number of liquid crystal layers are provided, the amount of light is reduced. Therefore, the number of liquid crystal layers and the like are appropriately determined according to the luminance required for the liquid crystal used.

(Polarization rotation angle)

[0062] Next, the total number of combination patterns of encryption keys is calculated based on the possible value of the polarization rotation angle. In the liquid crystal image display device according to FIG. 8, when the polarization rotation element is a super twisted nematic liquid crystal, it is assumed that each layer can control the polarization rotation angle of 0 to 180 ° and 256 gradations. If the polarization rotation angle at a certain pixel when displaying using a general liquid crystal display is 0 s, the polarization rotation angle when the liquid crystal image display device according to FIG. 8 is used can be expressed as follows.

[0063] [Equation 1]

s i n (0 s) = | s i n (0 d + 0 m 1 + 0 m 2) |

Θ s Polarization rotation angle required for display target (◦ ~ 90 °)

Θ d: Polarization rotation angle displayed as encrypted data (0 to 1800 °)

0 m 1: Polarization rotation angle by the LCD panel 1 for decryption key (0 to 180 °)

0 m 2: Polarization rotation angle by the LCD panel 2 for decryption key (0 to 180 °)

[0064] In the above equation 1, in (Φπι1 + Φπι2 + Φ (1), Φπι1 · Φπι2 takes a free value, and Φ (1 is 180 ° Because it exists, 256X256X2 = 131072 ways.

(When 0s = 3O °, there are six possible values of Φπι1 + Φπι2 + Φ (1): 30 °, 150 °, 210 °, 330 °, 390 °, 510 °.)

[0065] By using the polarization-type visual decryption encryption in this way, one pixel of the secret image can be expressed by one pixel of the encryption liquid crystal panel and the decryption key liquid crystal panel, so there is no deterioration in resolution. An effect of improving the contrast of the image after decoding can be obtained.

(Viewing angle control)

In the above example, the encryption liquid crystal panel 30 and the decryption key liquid crystal panel 40 are arranged so that the corresponding pixels coincide with each other. For encryption LCD panel 30 and decryption key A wide viewing angle can be secured by placing the liquid crystal panel 40 close to each other. On the other hand, it is desirable to intentionally narrow the viewing angle in order to prevent snooping from the surroundings. As a method for limiting the viewing angle, the pitch of the liquid crystal layer is changed between the encryption liquid crystal layer and the decryption key liquid crystal layer, and the distance between the encryption liquid crystal panel 30 and the decryption key liquid crystal panel 40 is constant. By limiting the viewing angle by separating the distance, the viewing range can be limited.

This example will be described with reference to FIG. In this example, by separating the encryption liquid crystal panel 30 and the decryption key liquid crystal panel 40, the rotation angle of the polarization plane can be correctly obtained in the front area. On the other hand, in the right region, the pixels are viewed as being shifted due to the spacing between the liquid crystal panels, and as a result, the encryption liquid crystal panel 30 and the decryption key liquid crystal panel 40 do not form a correct pixel combination. As a result of adding different rotation angles of the polarization plane, it cannot be visually recognized as normal image data. Similarly, even in the left area, the image is visually recognized with a shifted pixel and cannot be visually recognized as correct image data. As a result, the correct image data can be visually recognized only at the front position, and as a result, the viewing angle is limited, the vertical and horizontal forces cannot be correctly recognized, and the presence of a nearby position force can be prevented.

(Dummy image display)

[0068] Further, in the above example, the image data is designed to be reproduced only in the front of the liquid crystal image display device, and a normal image is displayed in a region outside the visual field range (left and right regions in FIG. 9). It is configured so that it cannot be displayed. Here, as a modified example, a normal image can be displayed at the front position, and different images can be intentionally displayed in the left and right areas. For example, in a liquid crystal display that displays a personal identification number, a dummy number that is not a personal identification number is intentionally displayed in the right region or the left region, and a person who has seen it can be disturbed. In addition, a dummy number is set as a special notification number, and when this number is entered, an alarm is issued as there is a possibility that a person who has seen the sneak is likely to be present, or a process such as reporting to the department to be operated is performed. Let's try to detect such people.

[0069] Further, in addition to the configuration for reproducing the image data in the front, as another modified example, the image data can be intentionally reproduced at a position that is slightly shifted in the vertical and horizontal directions. For example, correct image data can be displayed only in the right region in FIG. 9, and dummy image data can be displayed in the front and left regions. As a result, the image seen from the front It is possible to perceive the act of snooping by believing that it is data.

(Phase difference plate 45)

[0070] In the above example, the! / ヽ deviation between the encrypted data and the decryption key data is also set using the liquid crystal panel capable of controlling the polarization rotation angle. In this configuration, there is an advantage that the encryption pattern can be changed for each pixel and for each time. On the other hand, using two LCD panels requires two LCD drivers. One LCD panel can be used together for compensation, etc., and can reduce the burden on hardware. Multiple LCDs and their drive circuits are required, which complicates the circuit and reduces costs. Become high.

On the other hand, by providing a decoding pattern corresponding to the decoding key data on the phase difference plate having a fixed polarization rotation angle, a visual decoding type encryption can be realized without increasing the number of liquid crystal panels. This example will be described based on FIG. 10 showing a liquid crystal image display device according to Embodiment 2 of the present invention. A liquid crystal image display device 200 shown in FIG. 10 includes a knocklight light source 10, a first polarizing plate 20, an encryption liquid crystal panel 30, a retardation plate 45, and a second polarizing plate 50. The same members as those in FIG. The liquid crystal image display device 200 shown in this figure includes a phase difference plate 45 in place of the decryption key liquid crystal panel 40. The phase difference plate 45 is a phase difference film that compensates for the phase difference generated by the liquid crystal (for example, prevention of coloring). Some retardation films have an optical compensation function for widening the viewing angle. In the present embodiment, the viewing angle can be determined according to the purpose of use, and a retardation film can be used for the adjustment.

Since the phase difference plate 45 is used as a decryption key panel, a polarization rotation angle is set for each pixel. The polarization rotation angle is not uniform, and it is difficult to read the code by arranging it differently for each pixel. On the other hand, the encryption unit 80 generates an encryption pattern in which the polarization rotation angle is adjusted for each pixel of the image data in accordance with the pattern of the polarization rotation angle for each pixel provided in the decryption key panel. As a result, the encryption data generated according to the encryption pattern is displayed on the encryption liquid crystal panel 30. When the phase difference plate 45 is overlapped with the encryption liquid crystal panel 30 and observed from the observation surface side, the encryption liquid crystal panel is displayed. And the light passing through the corresponding pixels of the phase difference plate 45 reconstruct the image given only within the observation region, that is, the decoded image data can be visually recognized. [0073] The polarization rotation angle of the phase difference plate 45 cannot be physically changed and is fixed. However, by making the phase difference plate 45 detachable from the liquid crystal image display device, it is possible to physically change the encryption pattern by preparing and replacing the phase difference plate 45 with different polarization rotation angles. The

[0074] If a plurality of phase difference plates 45 can be attached, the number of layers of the phase difference plate 45, that is, the decryption panel can be changed, and not only the encryption pattern but also the accuracy of encryption can be changed depending on the intended use and purpose. Can also be changed. As described above, a display capable of reproducing intermediate colors that are not binary images by XOR operation and limiting the observation area is realized.

(Visual decryption encryption)

[0075] Hereinafter, the principle of realizing both the encryption of the display image and the restriction of the observation area by the visual decryption encryption will be described. FIG. 11 is an explanatory diagram showing a state where a monochrome image is encrypted. Here, each of the black and white pixels constituting the secret image to be encrypted is expressed by a combination of pixels composed of 2 × 2 auxiliary pixels! Since the pixel value is determined by the combination of the display image and the decryption key data, only the display image or the decryption key data does not leak any secret image information. Figure 12 shows an example of cipher pattern constructed using this method. Copying the decryption key data pattern onto a transparent sheet such as an OHP sheet and overlaying it on the display image yields a decrypted image. Decryption does not require any computation. By reducing the size of the decryption key panel and placing the image display surface power at a fixed distance as shown in Fig. 13, the viewing position corresponding to the pixel power ^ 1 of the display pixel and the decryption key panel is limited. Therefore, it is possible to limit the observation area of the display simultaneously with the encryption of the display image. The example in FIG. 13 shows an example in which image information is distributed and encrypted in two images. One of the two images is a decryption mask, the other is a display image, and depending on the pitch of the decryption mask and the installation distance. The observation position can be limited. This configuration has the effect of limiting the viewing distance beyond simply limiting the viewing angle.

(Restriction of observation area)

[0076] The encrypted image is decrypted by observing from a viewpoint position in which the auxiliary pixel of the decryption key panel and the auxiliary pixel of the display image have a one-to-one correspondence. As shown in Fig. 14, the pitch of the decryption key panel is reduced compared to the pixel pitch of the display image, and a certain distance from the image display surface is obtained. Install a panel for decryption keys at a distance. The pitch of the auxiliary pixel on the decryption key panel is P, the pitch of the auxiliary pixel on the display screen is P, the distance from the display screen to the observation position is Z, and the display screen

D E

In terms of surface power, when the distance to the decryption key panel is Z, it is necessary to install the decryption key panel at a position where the following relationship of 2 is established.

[0077] [Equation 2]

P P D = 1 ∑ E

The configuration of FIG. 14 can deal with multi-tone images and color images. However, in the state shown in Fig. 14, there is only one observable position depending on the pitch and the arrangement interval. In other words, the observation area is too limited, and there is only one position where the secret image can be observed without missing pixels and without crosstalk. Therefore, since it is necessary to enlarge the observation area, a black area is introduced around the light emitting part of the display image. Here, Fig. 15 and Fig. 16 show the configuration in which the aperture ratio is introduced to obtain the observation region. In these drawings, FIG. 15 shows a region without a chip and FIG. 16 shows a region without a crosstalk. Here, if the aperture width is W and the pitch is P, the aperture ratio a can be obtained by a = WZP. In Figs. 15 and 16, the aperture width of the auxiliary pixel of the display image is W, the aperture ratio is a, and the auxiliary pixel of the decryption key panel

D D

The width of the observation area is obtained with W as the aperture width and a as the aperture ratio. The width V of the area where the entire pixel can be seen is determined from the ray connecting the aperture of the encryption panel and the auxiliary pixel of the display image as shown in Fig. 15.

In other words, the following equation 3 holds.

[0079] [Equation 3]

V "= P. P _M (a M-a _D ) / (P.-PM)

Further, as shown in FIG. 16, the width V of the region where crosstalk does not occur is as follows.

cx

[0081] [Equation 4]

V «, = PBPMC 2-a _d -a M) / CP _B -PM)

[0082] Since the width of the observation area is limited by two types of conditions: crosstalk and pixel loss, the right sides of Equations 3 and 4 must be equal to maximize the observation region width. As a result, a = 1 is obtained, and the aperture ratio of the auxiliary pixel of the decryption key panel is 1. It can be seen that this is the optimum condition. The depth of the observation area is limited as shown in Equation 5 below.

[Equation 5]

V d, = 2 P MZ ECN-1) C a M- a _D ) (P _D _ P _M )

/ {(N-1) ² (P _D -PM) ^2- (a _D P _B -a MPM) ² ]

[0084] [Equation 6]

V _{0 I} = 2 P _M ∑ _E (N-1) (2-a — a M) CPB— PM)

/ [(N-1) ² (P _B -P MJ ² -[(2-a _D ) P-a MPM]

[0085] According to the first-order approximation of 1 ^ -1), the condition that the right sides of Equation 5 and Equation 6 are equal is a = 1. When the aperture ratio of the auxiliary pixel is set to 1, the right side of Equations 3 and 4 is 0, but by reducing the aperture ratio of the auxiliary pixel in the display image, the observation area shown in Equations 3 and 4 is used. Both have the effect of expanding. Or P to P

The observation area is enlarged by approaching D. From Equation 2, this means that the decryption key panel is brought closer to the image display surface, which is consistent with the fact that the observation area is not limited by close contact. Even if the aperture ratio of the displayed image is limited by the specifications of the actual nodeware, the observation area can be adjusted by the pitch and installation distance of the decryption key panel. As described above, an observation area can be derived geometrically, and a design guideline for realizing an observation area of a desired size can be obtained.

Even when the pattern of the decryption key panel is fixed, different images can be displayed by setting the polarization rotation angle (X, y) according to the pixel value of the secret image. However, in terms of security, the risk of estimating the key pattern increases by accumulating a large number of display images and analyzing the appearance frequency. In the case of moving image display, it is desirable that the key pattern changes for each frame in the implementation mode shown in FIG.

[0087] As described above, the liquid crystal image display device can simultaneously realize the limitation of the viewing angle and the decryption of the encrypted image data by using the rotation of the polarization plane by the liquid crystal, and the data itself is intercepted. Security can be increased against risks. In addition, there is an advantage that the observation area can be restricted simultaneously with the encryption of the display image.

[0088] It should be noted that a mode in which the encryption key is canceled and the image data is displayed as it is, and if necessary, viewing is performed. It can also be set to adjust the field angle. In other words, by configuring the viewing angle control and Z or ON / OFF of the encryption key to be switchable, it is possible to use them according to the purpose of use and application.

(Prototype liquid crystal image display device)

Example

Next, a liquid crystal image display device was created, and an observation image in the observation region was observed, thereby demonstrating a polarization operation by stacking liquid crystal panels. Here, a structure in which the liquid crystal panel from which the polarizing film on the output side is removed and the liquid crystal panel from which the polarizing film on the incident side is removed is laminated, that is, a polarizing film, a liquid crystal panel, a liquid crystal panel, and a liquid crystal display having a polarizing film structure. Was made. The manufactured multilayer LCD panel is shown in Fig. 18, as a screen display example, a color sample display example on a black background is shown in Fig. 19, and a color sample display example on a white background is shown in Fig. 20, respectively. Here, the distance between the two liquid crystal panels is lcm. As shown in Fig. 19 and Fig. 20, the screen display example shows that when the polarization rotation angle in the background liquid crystal panel is 0 ° (black if the liquid crystal panel is single), each pixel displayed in the foreground is The light intensity increases monotonously with respect to the pixel value. On the other hand, if the polarization rotation angle of the background liquid crystal panel is 90 ° (white if the liquid crystal panel is single), the light intensity decreases monotonously with respect to the pixel value of each pixel displayed on the foreground liquid crystal panel. did. Table 1 shows the relationship between these colors, that is, the relationship between the background or foreground color displayed on the laminated liquid crystal panel and the observed color. From Table 1, when the polarization rotation angle in the background liquid crystal panel is set to 0 °, the color displayed in the foreground is observed as it is, and when the polarization rotation angle in the background liquid crystal panel is set to 90 °, it is displayed in the foreground. Complementary colors were observed, confirming the color change due to the rotation of the polarized light and the multi-gradation display principle.

[0090] [Table 1] In the background LCD panel In the background LCD panel

Polarization rotation angle Polarization rotation angle

0. When set to 90 °

Foreground color Observed color Foreground color Observed color

White white white village

Yellow Yellow Yellow R

Red red red cyan

Magenta magenta magenta green

冃 '冃 Yellow

Cyan cyan cyan red

Green green green magenta

Sato Sato Sato White

FIG. 21 shows an example of an encrypted image subjected to encryption that enables decoding based on polarization as image data to be displayed on the liquid crystal display. Each pixel is expressed in white and black. For comparison, the result of decoding this image based on the conventional intensity calculation (white: transmission, black: shading) is also shown in FIG. In addition, FIG. 23 shows the result displayed on the laminated liquid crystal panel in which the polarization rotation angle is added (white: polarization rotation angle 90 °, black: polarization rotation angle 0 °).

From these figures, in the liquid crystal image display device, when an image in the observation region, that is, a decrypted image visually recognized in the front, is compared with an image visually recognized outside the observation region, encryption and decryption keys are obtained. Since both polarized light was used, it was confirmed that white was displayed brightly in the observation area. In particular, in the conventional method shown in FIG. 22, the white part of the decoding result “TU” character is expressed in black and white random dots (grain pattern), whereas the decoding according to this embodiment shown in FIG. As a result, white Z black was determined for each pixel, and it was confirmed that the contrast of the white part and the black part was improved. Furthermore, Fig. 24 shows the liquid crystal display observed from outside the observation area. In Fig. 24, (a) shows the upper force of the observation area, (b) shows the view from below, (c) shows the right force, and (d) shows the view from the left. . As shown in these figures, the “TU” character that is the decoding result is not visible outside the observation area. From these results, it was confirmed that the effectiveness of decryption by adding the rotation angle of the polarization plane and the limitation of the observation area can be realized.

[0093] By using the secret sharing method in this way, secret data is distributed into n pieces (n is 2 or more) of encrypted data, and k pieces (k is 2 or more and n or less) are superimposed. Thus, encryption can be performed so that the secret data is decrypted. Decryption can be made more difficult by distributing the encrypted data to a plurality of sheets. In addition, the secret data is distributed to multiple encrypted data There is no distinction in operation function. That is, the encryption key layer for displaying the encryption key data and the decryption key layer for displaying the decryption key data can be arbitrarily set. For example, a polarization rotation element that displays encrypted data transmitted from an information sender is used as an encryption layer, and a polarization rotation element that displays encryption data held by a user is used as a decryption key layer. Can be the encryption layer, and the transmission data side can be the decryption key layer.

In the secret sharing method, secret data is distributed to a plurality of pieces of encrypted data based on a random number sequence unique to each user. At this time, a part of the plurality of sheets can be used as decryption data serving as a decryption key. For example, when secret data is distributed over two pieces of encrypted data, one piece of encrypted data is owned by the user and the other is held by the information sender. For any confidential data, the information sender can configure the encrypted data to be communicated so that it can be decrypted by the encrypted data held by the user. In addition, when distributing secret data to three or more encrypted data, a combination of one encrypted data and two decryption data, or two encrypted data and one decryption data to be communicated Combinations are possible. When there are two or more pieces of decryption data, a plurality of keys can be entered so that decryption can be performed only when a plurality of users bring the decryption data. On the other hand, when there are multiple pieces of encrypted data to be communicated, access to the encrypted data can be achieved by using multiple servers with different access privileges or by transmitting the encrypted data using different communication paths. This can be more restrictive than when using encrypted data. If this is used, it can be suitably applied to applications that require the approval of multiple observers for information access.

Industrial applicability

In the above example, the example applied to the liquid crystal image display device has been described, but a polarization calculation type image display device other than the liquid crystal can also be used. For example, a retardation plate, a magneto-optic spatial light modulator, an electro-optic spatial light modulator, etc. can be used.

Brief Description of Drawings

FIG. 1 is a cross-sectional view showing a configuration of a conventional liquid crystal display device.

FIG. 2 is a cross-sectional view showing a configuration of another conventional liquid crystal display device.

FIG. 3 is a schematic diagram for explaining a state where encryption using polarized light is realized by exclusive OR of two-dimensional planes. FIG. 4 is a cross-sectional view showing a liquid crystal image display device according to an embodiment of the present invention.

[5] FIG. 5 is a perspective view showing the alignment direction of the first polarizing plate and the second polarizing plate and the light transmitting state.

[6] FIG. 6 is a schematic diagram for explaining a state in which encryption is performed using a pattern of a polarization rotation angle. [7] FIG. 7 is a cross-sectional view showing a liquid crystal image display device according to a modification of the present invention.

FIG. 8 is a cross-sectional view showing a liquid crystal image display device according to another modification of the present invention.

FIG. 9 is a cross-sectional view showing a liquid crystal image display device according to still another modification of the present invention.

FIG. 10 is a cross-sectional view showing a liquid crystal image display device according to Embodiment 2 of the present invention. [11] It is an explanatory diagram showing a state of encrypting a binary image.

[12] It is an explanatory diagram showing a state of limiting the observation region.

[13] FIG. 13 is an explanatory diagram illustrating visual decryption encryption.

14] It is an explanatory diagram showing the relationship between the pitch of the decryption key panel and the installation distance.

圆 15] An explanatory diagram showing a region where the secret image is decoded and observed without missing pixels 圆 16] An explanatory diagram showing a region where the secret image is decoded and observed without crosstalk

FIG. 17 is an explanatory diagram showing a state of decryption of polarization encryption by stacking liquid crystal panels.

FIG. 18 is a perspective view showing a laminated liquid crystal panel of a liquid crystal image display device according to an example.

FIG. 19 is an image diagram showing a display example of a color sample on a black background displayed in FIG.

20 is an image diagram showing a display example of a color sample on the white background displayed in FIG.圆 21] It is an image diagram showing an example of visual decryption encryption.

[22] FIG. 22 is an image diagram showing a decryption result by strength calculation, which is a conventional visual decoding type encryption.

圆 23] It is an image diagram for visually recognizing the decoding result according to the embodiment of the present invention from within the observation region. 圆 24] It is an image diagram for visually recognizing the decoding result according to the embodiment of the present invention also for the observation region external force. 00, 200 ... Liquid crystal image display device

1 ... Drive LCD panel

2 .... Compensation LCD panel

3 ··· Polarizer on the observer side

4 · Polarizer on the non-observer side

5 ... Drive circuit

6 ... Compensation voltage application circuit

7 ··· Input signal liquid crystal layer

8. Decryption key liquid crystal layer

10 '' Knock light source for firewood

20 '-1st polarizing plate

30 ···· Crystal LCD panel

31 ····· 1st encryption liquid crystal layer

32 · '-Second encryption liquid crystal layer

40 'LCD key for decryption key

41 · 'Liquid crystal layer for first decryption key

42 · 'Liquid crystal layer for second decryption key

45 · '' · Phase plate

50 · '-2nd polarizing plate

60 · '-means for applying encryption operating voltage

70 · '-Decryption key operating voltage application means

80 'encryption means

90 '' Decryption key generation means

Claims

The scope of the claims

A liquid crystal image display device capable of displaying gradation of given image data, and encryption means for encrypting the image data based on visual decryption encryption;

Decryption key generation means for generating decryption key data for decrypting the encrypted data encrypted by the encryption means;

An encryption liquid crystal panel having a pixel structure, having a polarization rotation element for each pixel, and displaying encryption data generated by the encryption means;

An encryption operating voltage applying means for driving the polarization rotation element of the encryption liquid crystal panel;

A decryption key liquid crystal having a pixel structure, having a pixel pitch smaller than that of the encryption liquid crystal panel, having a polarization rotation element for each pixel, and displaying the decryption key data generated by the decryption key generation means A panel,

A decryption key operating voltage application means for driving the polarization rotation element of the decryption key liquid crystal panel;

With

The encryption liquid crystal panel and the decryption key liquid crystal panel are arranged so as to be separated from each other by a certain distance and correspond to each pixel,

The encryption unit generates encryption data obtained by encrypting image data based on visual decryption encryption by changing a polarization rotation angle of a polarization rotation element for each pixel, and the decryption key generation unit includes: Generate decryption key data in which the polarization rotation angle for decrypting the image data is set for each pixel according to the polarization rotation angle of the encrypted data,

The encryption liquid crystal panel is driven by the encryption operating voltage application means to display the encryption data, and the decryption key liquid crystal panel is driven by the decryption key operation voltage application means to thereby generate the decryption key data. Is displayed and an appropriate polarization rotation angle corresponding to the image data is given to each pixel by overlapping the encrypted data and the decryption key data for each pixel. A liquid crystal image display device configured to be able to reconstruct an image given only in a light power observation region that has passed through a corresponding pixel with a liquid crystal panel for a decryption key. [2] The liquid crystal image display device according to claim 1,

The encryption liquid crystal panel is

A first encryption liquid crystal layer having a predetermined pixel pitch and an aperture ratio;

A second cryptographic liquid crystal layer having a pixel pitch and an aperture ratio substantially equal to the first cryptographic liquid crystal layer, spaced apart from the first cryptographic liquid crystal layer by a certain distance, and disposed so as to overlap. ,

The encryption means divides encrypted data into first encrypted data for the first encrypted liquid crystal layer and second encrypted data for the second liquid crystal,

By providing the first encrypted data to the first encrypted liquid crystal layer and the second encrypted data to the second encrypted liquid crystal layer, respectively, the encrypted data is transmitted via the first encrypted liquid crystal layer and the second encrypted liquid crystal layer. A liquid crystal image display device, wherein the data is encrypted.

[3] The liquid crystal image display device according to claim 1 or 2,

The decryption key liquid crystal panel comprises:

A first decryption key liquid crystal layer having a predetermined pixel pitch and aperture ratio;

The second decryption key liquid crystal having a pixel pitch and an aperture ratio substantially equal to those of the first decryption key liquid crystal layer, spaced apart from the first decryption key liquid crystal layer by a certain distance, and arranged so as to overlap. Layers,

Have

The decryption key generating means divides the decryption key data into first decryption key data for the first decryption key liquid crystal layer and second decryption key data for the second decryption key liquid crystal;

By providing the first decryption key data to the first decryption key liquid crystal layer and the second decryption key data to the second decryption key liquid crystal layer, respectively, the first decryption key liquid crystal layer and the second decryption key are provided. A liquid crystal image display device configured to decrypt encrypted data via a liquid crystal layer.

[4] A liquid crystal image display device capable of gradation display of given image data,

Encryption means for encrypting image data based on visual decryption encryption, decryption key generation means for generating decryption key data for decrypting encrypted data encrypted by the encryption means, A backlight light source disposed on the opposite side of the observation surface;

A first polarizing plate disposed on the observation surface side;

A second polarizing plate disposed apart from the first polarizing plate and having a polarization direction orthogonal or parallel to the first polarizing plate;

A liquid crystal panel having a polarization rotation element disposed between the first polarizing plate and the second polarizing plate,

A liquid crystal panel for encryption that has a pixel structure, has a polarization rotation element for each pixel, and is arranged so as to overlap with the first polarizing plate, and displays encrypted data generated by the encryption means. When,

A pixel structure having a pixel pitch smaller than that of the encryption liquid crystal panel, a polarization rotation element for each pixel, and a pixel rotation unit arranged to match the encryption liquid crystal panel for each pixel; A decryption key liquid crystal panel for displaying the decryption key data generated by the key generation means;

With

The encryption liquid crystal panel is driven by the encryption operating voltage application means to display the encryption data, and the decryption key liquid crystal panel is driven by the decryption key operation voltage application means to thereby generate the decryption key data. Is displayed and an appropriate polarization rotation angle corresponding to the image data is given to each pixel by overlapping the encrypted data and the decryption key data for each pixel. An image in which light that has passed through the corresponding pixels of the encryption liquid crystal panel and the decryption key liquid crystal panel through the first and second polarizing plates is given only to the observation surface through the backlight light source only within the observation region. A liquid crystal image display device, characterized in that it can be reconstructed.

[5] The liquid crystal image display device according to any one of claims 1 to 4,

A liquid crystal image display device comprising three or more of the encryption liquid crystal panel and the decryption key liquid crystal panel.

[6] The liquid crystal image display device according to any one of claims 1 to 5,

The liquid crystal image display device characterized in that the encrypted data generated by the encryption means changes over time.

[7] The liquid crystal image display device according to any one of claims 1 to 6,

A liquid crystal image display apparatus, wherein a moving image is displayed by changing an encryption pattern for each frame constituting the moving image.

[8] A liquid crystal image display device capable of gradation display of given image data,

Encryption means for encrypting image data based on visual decryption encryption;

A backlight light source disposed on the opposite side of the observation surface;

A first polarizing plate disposed on the observation surface side;

It is arranged between the first polarizing plate and the second polarizing plate, has a pixel structure, has a polarization rotation element for each pixel, is arranged so as to overlap the first polarizing plate, and is generated by the encryption means. An encryption LCD panel for displaying encrypted data;

A phase difference plate arranged so that the polarization rotation angle is different for each pixel;

With

The encryption means generates encrypted data obtained by encrypting image data based on visual decryption encryption for each pixel according to the polarization rotation angle for each pixel of the retardation plate, and The encryption liquid crystal panel is driven by the activation operating voltage applying means to display the encrypted data, and the encryption data is overlapped with the phase difference plate for each pixel, so that the polarization rotation angle corresponding to the image data is displayed. Is obtained for each pixel, and light that has passed through the corresponding pixels of the encryption liquid crystal panel and the decryption key liquid crystal panel through the first and second polarizing plates to the observation surface side through the backlight light source is observed region. A liquid crystal image display device, characterized in that an image given only inside can be reconstructed.

[9] The liquid crystal image display device according to claim 8,

A liquid crystal image display device comprising a plurality of the retardation plates.

[10] The liquid crystal image display device according to claim 8 or 9,

A liquid crystal image display device, wherein the retardation plate is configured to be detachable.

[11] A liquid crystal image display device capable of gradation display of given image data,

A decryption key liquid crystal panel having a pixel structure, having a polarization rotation element for each pixel, and displaying the decryption key data generated by the decryption key generation means;

With

The pixel pitch force for each corresponding pixel of the decryption key liquid crystal panel The displayed decryption key data pattern is reduced or the encrypted data pattern is reduced so as to be relatively smaller than the encryption liquid crystal panel. Magnify, The encryption unit generates encryption data obtained by encrypting image data based on visual decryption encryption by changing a polarization rotation angle of a polarization rotation element for each pixel, and the decryption key generation unit includes: Generate decryption key data in which the polarization rotation angle for decrypting the image data is set for each pixel according to the polarization rotation angle of the encrypted data,

The encryption liquid crystal panel is driven by the encryption operating voltage application means to display the encryption data, and the decryption key liquid crystal panel is driven by the decryption key operation voltage application means to thereby generate the decryption key data. Is displayed and an appropriate polarization rotation angle corresponding to the image data is given to each pixel by overlapping the encrypted data and the decryption key data for each pixel. A liquid crystal image display device configured to be able to reconstruct an image given only in a light power observation region that has passed through a corresponding pixel with a liquid crystal panel for a decryption key.

A first polarizing plate disposed on the observation surface side;

A liquid crystal panel for encryption that has a pixel structure, has a polarization rotation element for each pixel, and is arranged so as to overlap with the first polarizing plate, and displays encrypted data generated by the encryption means. Because

A second cryptographic liquid crystal layer having a pixel pitch and an aperture ratio substantially equal to those of the first cryptographic liquid crystal layer, spaced apart from the first cryptographic liquid crystal layer by a certain distance, and disposed so as to overlap. LCD panel for

A pixel structure having a pixel pitch smaller than that of the encryption liquid crystal panel, a polarization rotation element for each pixel, and a pixel rotation unit arranged to match the encryption liquid crystal panel for each pixel; For displaying the decryption key data generated by the key generation means A decryption key LCD panel;

A liquid crystal image display method for displaying image data on a liquid crystal image display device capable of gradation display of given image data,

The encryption means generates encryption data obtained by encrypting image data based on visual decryption encryption by changing the polarization rotation angle of the polarization rotation element for each pixel, 1 divided into the first encryption data for the encryption liquid crystal layer and the second encryption data for the second liquid crystal,

The decryption key generating means generating decryption key data in which a polarization rotation angle for decrypting image data is set for each pixel in accordance with a polarization rotation angle of the encrypted data; and applying the encryption operating voltage Means for driving the encryption liquid crystal panel to display the encrypted data, the first encryption data on the first encryption liquid crystal layer and the second encryption data on the second encryption liquid crystal layer. And providing the decryption key operating voltage applying means to drive the decryption key liquid crystal panel and displaying the decryption key data, and superimposing the encryption key data and the decryption key data for each pixel, An appropriate polarization rotation angle corresponding to the image data is given to each pixel, and the liquid crystal panel for encryption and the liquid crystal panel for decryption key are passed through the first and second polarizing plates to the observation surface side through the backlight light source. Corresponding with The liquid crystal image display method which light passing through the element, characterized in that the re-construct an image that is given only in the observation area.

A polarization operation type image display device capable of displaying gradation of given image data, and encryption means for encrypting the image data based on visual decryption encryption;

An encryption panel having a pixel structure, having a polarization rotation element for each pixel, and displaying encryption data generated by the encryption means; A decryption key panel that has a pixel structure, has a pixel pitch smaller than that of the encryption panel, has a polarization rotation element for each pixel, and displays the decryption key data generated by the decryption key generation means When,

With

The encryption panel and the decryption key panel are spaced apart by a certain distance and arranged to correspond to each pixel,

The encrypted data is displayed on the encryption panel, the decryption key data is displayed on the decryption key panel, and the encryption key data and the decryption key data are overlapped for each pixel, so that the appropriate data corresponding to the image data is displayed. A polarization rotation angle is given for each pixel, and on the observation surface side, light that has passed through corresponding pixels of the encryption panel and the decryption key panel is reconstructed only in the observation area. A polarization-calculated image display device characterized by being configured.

[14] The polarization calculation type image display device according to claim 13,

A polarization operation type image display apparatus, wherein the polarization rotation element is a liquid crystal.

[15] The polarization operation type image display device according to claim 13,

A polarization operation type image display device, characterized in that the polarization rotation element force is a S-patterned retardation plate.

[16] The polarization operation type image display device according to any one of claims 13 to 15, wherein the encryption panel and the decryption key panel include three or more in total. Display device.

[17] A polarization calculation type image display method for displaying image data on a polarization calculation type image display device capable of displaying gradation of given image data,

Based on the visual decryption-type encryption, the encryption data is generated by encrypting the polarization rotation angle of the polarization rotation element for each pixel, and the approximate encryption data is converted into the first encryption data. The first encryption data for the encryption layer and the second encryption data for the second encryption layer are divided, and the polarization rotation angle for decrypting the image data in accordance with the polarization rotation angle of the encryption key data for each pixel. Generating set decryption key data; and

In order to display the encrypted data on the encryption panel for displaying the encrypted data, the first encrypted data is displayed on the first encrypted layer, and the second encrypted data is displayed on the second encrypted layer. On the other hand, displaying the decryption key data on the decryption key panel for displaying the decryption key data;

Including

By superimposing the encryption data and the decryption key data for each pixel, an appropriate polarization rotation angle corresponding to the image data is given to each pixel, and the first polarizing plate disposed on the observation surface side and the opposite surface side Polarization calculation type characterized in that the optical power that has passed through the corresponding pixels of the encryption panel and the decryption key panel through the second polarizing plate arranged in the image can be reconstructed only in the observation area Image display method.