JP2015143950A - Display device, control method for display device, and control program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent data in removable media from flowing out due to the robbery or duplication of the removable media when displaying the data by a display device by using the removable media.SOLUTION: A display device includes: equipment ID storage means for storing an equipment ID unique to a display device; password input means for inputting a password; encryption means for encrypting data in removable media by using the equipment ID and the password as a key; decryption means for decrypting the data in the removable media by using the equipment ID and the password as the key; display means for displaying the data in the removable media; and control means for encrypting the data in the removable media when displaying the data in the removable media.

Description

  The present invention relates to a display device, a display device control method, and a control program.

There is already known a signage system using a display device that stores display contents in a storage medium such as a USB memory (hereinafter, removable medium) and can always display the contents even when the administrator is not nearby. Yes. In addition, it is already known that data can be encrypted with encryption software installed in a PC or a removable medium in order to protect data of content stored in the removable medium.
USB is an abbreviation for Universal Serial Bus, and PC is an abbreviation for Personal Computer.

  In the conventional signage system, it is possible to display even if the administrator is not near the display device. For this reason, there is a problem that the removable media is stolen without being noticed by the administrator, or the contents of the removable media are copied and the display content is leaked. In addition, the data encrypted with the conventional encryption software needs to have the same encryption software installed in the display device, and there is a problem that the content cannot be reproduced if it is not installed.

Accordingly, various proposals have been made to solve this type of problem (for example, see Patent Document 1).
The invention described in Patent Document 1 is a browsing / viewing terminal device that is equipped with a removable storage medium that stores content and has a strong copy guard function even if it is a removable storage medium and does not rely on the use of passwords that are easily leaked. The purpose is to provide. The invention described in Patent Document 1 relates to an apparatus equipped with a removable storage medium that loads a browsing / viewing program from a removable storage medium, and processes the content stored in the removable storage medium by the browsing / viewing program for browsing / viewing. Patent Document 1 discloses a browsing / wearing device equipped with a removable storage medium having authentication means for verifying the correctness of the combination of the removable storage medium and the browsing / viewing terminal device, and decryption means for encrypted content stored therein. A viewing terminal apparatus is disclosed.

  However, the invention described in Patent Document 1 requires that the data encrypted with the encryption software needs to have the same encryption software installed in the display device, and otherwise the content cannot be reproduced. It has not been solved.

  Therefore, an object of the present invention is to prevent data in a removable medium from being leaked due to theft or duplication of the removable medium when displayed on a display device using the removable medium.

  In order to solve the above-described problem, the invention described in claim 1 is characterized in that a device ID storage unit that stores a device ID unique to a display device, a password input unit that inputs a password, and the device ID and the password are used as keys. Encryption means for encrypting data in the removable medium, decryption means for decrypting the data in the removable medium using the device ID and the password as a key, display means for displaying the data in the removable medium, Control means for encrypting data in the removable medium when displaying the data in the removable medium.

  ADVANTAGE OF THE INVENTION According to this invention, when displaying on a display apparatus using a removable medium, it can prevent that the data in a removable medium leak out by theft or duplication of a removable medium.

It is a block diagram concerning one embodiment. It is an example of the flowchart showing operation | movement of the display apparatus shown in FIG. It is another example of the flowchart showing operation | movement of the display apparatus shown in FIG. 6 is another example of a flowchart showing the operation of the display device shown in FIG. 1. It is a block diagram concerning other embodiments. It is an example of the flowchart showing operation | movement of the display apparatus shown in FIG.

Embodiments of the present invention will be described with reference to the drawings.
<Configuration 1>
FIG. 1 is a block diagram according to an embodiment.
In this embodiment, a projector is taken as an example. However, a projection system such as a DLP (Digital Light Processing) method, an LCD (Liquid Crystal Display) method, or a light source type such as a mercury lamp or a laser light source may be used. . Further, a display, a television receiver, or the like may be used as long as it can display removable media data, and is not limited to a projector. The scope of the present invention is not limited to the following illustrated examples.

  The projector 100 as a display device includes an I / F unit 10, a control unit 11, an audio processing unit 12, a speaker 13, a video processing unit 14, an optical unit control unit 15, an optical unit 16, a light source control unit 17, a light source 18, and an operation. Unit 19, storage unit 20, encryption unit 21, and decryption unit 22.

The I / F unit 10 is an interface for inputting / outputting various information to / from an external device. The I / F unit 10 includes, for example, a video port 101, an audio port 102, a USB port 103, a LAN port 104, and the like.
The video port 101 is a port for the I / F unit 10 to transmit / receive video / control signals and the like to / from a PC (Personal Computer) or AV (Audio Visual / Video) device, for example. The audio port 102 is a port for transmitting / receiving audio / control signals and the like. The USB port 103 is a port for transmitting / receiving data of a device connected to a USB (Universal Serial Bus) terminal. The LAN port 104 is a port for LAN (Local Area Network) connection.
With such a structure, images and data can be input / output to / from the projector 100 by connecting to an external device or a network.

  The control unit 11 includes, for example, a CPU (Central Processing Unit) 111, a ROM (Read Only Memory) 112, a RAM (Random Access Memory) 113, and the like. The CPU 111 performs control according to various processing programs stored in the ROM 112 and the storage unit 20. The ROM 112 stores a program that can be executed by the projector 100, various processing programs that can be executed by the program, data used when executing these various processing programs, data of the arithmetic processing result of the CPU 111, and the like. The RAM 113 includes a program storage area for expanding a processing program executed by the CPU 111, a data storage area for storing input / output data, a processing result generated when the processing program is executed, and the like.

The audio processing unit 12 performs processing such as volume adjustment and sound quality adjustment on the audio signal input from the I / F unit 10. The processed audio signal is output from the speaker 13 or an audio output port (not shown).
The video processing unit 14 performs various processes such as analog-to-digital conversion, determination / adjustment of resolution, adjustment of image quality such as luminance and contrast, and keystone correction on the video signal input from the I / F unit 10. The processed data is stored in a RAM 113, a buffer memory (not shown) or the like and projected via the optical unit control unit 15.
The optical unit control unit 15 performs projection by controlling the optical unit 16 based on the data input from the video processing unit 14. The light source control unit 17 controls turning on / off of the light source 18 (for example, a mercury lamp) based on an instruction from the control unit 11.
The operation unit 19 serving as a password input unit includes, for example, a cursor key, a character / number key, various function keys, a remote controller, a receiving unit that receives an instruction from a remote unit, and the like. A function associated with the received input is realized by receiving a user input from a hard key, a remote controller, or the like and transmitting the contents to the control unit 111.
The storage unit 20 is a non-volatile memory such as EEPROM (Electrically Erasable Programmable ROM), for example, and can store executable programs, various processing programs that can be executed by the programs, data used when executing these various processing programs, and the like. Remember. The storage unit 20 as the device ID storage means stores, for example, a unique ID unique to the device.
The display unit 120 includes a video processing unit 14, an optical unit control unit 15, an optical unit 16, a light source control unit 17, and a light source 18.

  Here, the unique ID is described as “unique” in the sense that the display device can be uniquely identified. Since there is a possibility that the same ID that can be specified / changed by the user such as the projector name exists, the ID assigned to each board or the ID assigned to each display device is intended. Also, it is not assumed that the user uses a unique ID. The unique ID shall be recorded at the time of product shipment at a factory. Since the display device performs encryption / decryption using a password set by the user and a unique ID recorded in advance in the device as a key, the user never uses a unique ID. It is assumed that the password is unknown to the user or cannot be changed even if it is known.

For example, the encryption unit 21 encrypts data in the USB memory connected to the USB port 103 as specific information using, for example, a device-specific ID stored in advance in the storage unit 20 or a password set by the user as a key. Turn into. The encryption method is not limited as long as it can be decrypted by the decryption unit 22. At the time of encryption, the data before encryption is stored in the storage unit 20 and deleted from the USB memory, but the security of the data in the USB memory may be secured by other methods.
The decryption unit 22 decrypts the data encrypted by the encryption unit 21 as specific information using, for example, a device-specific ID stored in advance in the storage unit 20 or a password set by the user as a key. At the time of decryption, the decrypted original data is stored in the USB memory and the encrypted data is deleted, but if the security of the data in the USB memory is secured by other methods Restore in an appropriate way. The data storage destination is not limited.

<Operation 1>
FIG. 2 is an example of a flowchart showing the operation of the display device shown in FIG.
The following embodiments are examples of the operation of the display device shown in FIG. 1, and the order may be different and is not limited.
The user connects a removable medium such as a USB memory storing data to be projected to the USB port 103 of the projector 100, and operates the operation unit 19 to start the signage mode (S101). In this example, the user explicitly starts a mode for projecting data in the USB memory called signage mode and projects the data in the USB, but the present invention is not limited to this. . The signage mode may be automatically started when the USB memory is recognized, and the subsequent processing may be performed without simply entering the signage mode when accessing data in the USB memory.

  The control unit 11 inputs a password via the operation unit 19 as a key used for encryption / decryption (S102). In this embodiment, the user is prompted to enter a password as a key used for encryption / decryption. In addition, a password set in advance in the device main body may be used, and in that case, it may be determined whether or not the input password matches the set password. Furthermore, the key used for encryption / decryption is not limited to a password, and any key can be used as long as security can be ensured.

The encryption unit 21 encrypts the data in the USB memory using the password inputted by the user and the unique ID unique to the device stored in the storage unit 20 or the ROM 112 as a key (S103). The data before encryption is taken into the storage unit 20 or the ROM 112, RAM 113, etc., and the data after encryption is placed in the USB memory. In the present embodiment, an example in which the data before encryption is arranged in the storage unit 20 and the data after encryption is arranged in the USB memory is shown. However, in S104, only the original data scheduled to be projected or being projected may be arranged in the storage unit 20, the ROM 112, the RAM 113, etc., and the original data that is not scheduled to be projected or not being projected may be deleted.
The object to be encrypted may be, for example, only the data designated by the user as the projection schedule or the scheduled data, or only the specific data designated by the user separately from the projection schedule Good.

  The projector 100 projects the target data stored in the storage unit 20 or the ROM 112, RAM 113, etc. (S104). Data is projected by any projection method. For example, there are methods such as repeatedly projecting one data, projecting all data in a specific folder repeatedly, and specifying a data display interval. If the target data cannot be decrypted normally, the projector 100 may notify that the projection is not successful, or may cause the user to input the password again and try decrypting again.

  When the projection ends, the user operates the operation unit 19 to end the signage mode (S105). It may be automatically terminated upon completion of data projection or at a designated time. The control unit 11 allows the user to input a password through the operation unit 19 at any timing before the USB memory is removed, such as when the signage mode ends or when the USB memory is removed. The password input may be skipped in consideration of the passage of time or the presence of a user or administrator nearby using a separately mounted camera or detection mechanism. The decryption unit 22 decrypts the encrypted data in the USB memory using the unique ID unique to the device stored in the storage unit 20 or the ROM 112 and the input password as keys (S109). At the time of decryption, it may be determined whether the decryption is correctly performed, and the decryption result may be notified to the user, or the password may be input again. Further, only specific data designated by the user may be decrypted.

<Operation 2>
FIG. 3 is another example of a flowchart showing the operation of the display device shown in FIG.
The basic sequence (S201-S202-S203-S204-S205-S207-S208-S209) is the same as that shown in FIG.
The control unit 11 confirms whether or not the data in the USB memory is encrypted (S203). When the data is encrypted, the decryption unit 22 decrypts the encrypted data in the USB memory by using the password input by the user and the unique ID unique to the device stored in the storage unit 20 or the ROM 112 as a key. The control unit 11 stores the decrypted data in the storage unit 20, the ROM 112, the RAM 113, or the like (S206).
When the encryption or decryption is completed, the projector 100 projects the target data stored in the storage unit 20, the ROM 112, the RAM 113, or the like (S205).
Since the subsequent steps are the same as the basic sequence, description thereof is omitted.

Here, when FIG. 6 described later is encrypted, the data is decrypted, and when the data is not encrypted, the data is encrypted, but the significance of encrypting the data after entering the password is explained. explain.
An object of the present invention is to prevent the contents of the USB from being stolen by a third party when the USB is still inserted in the display device. It is necessary to always encrypt the contents of USB while displaying. Even if the user can confirm with the password, if the contents of the USB are not encrypted, the third party can acquire the contents of the USB when the user leaves the display device. In addition, data is decrypted in S206, but this also describes that the contents of the USB remain encrypted and the decrypted data is arranged in the display device.

<Operation 3>
FIG. 4 is another example of a flowchart showing the operation of the display device shown in FIG.
The flow up to S302 is the same as in FIG.
The control unit 11 searches the USB memory for data that can be projected by the projector 100 (S303). For example, it is determined whether or not the projector 100 can project based on a file extension, a compression format, a file size, and the like. If there is data that can be projected in the USB memory (S304), the encryption unit 21 uses only the data that can be projected, and the unique ID stored in the storage unit 20 and the password set by the user. (S305). The subsequent processing is the same as in FIG.
When there is no projectable data in the USB memory (S304) and there is encrypted data in the USB memory (S307), the process is as follows. The decryption unit 22 decrypts the encrypted data in the USB memory using the password entered by the user and the unique ID unique to the device stored in the storage unit 20 or the ROM 112 as a key, and the decrypted data is stored in the storage unit 20 or the ROM 112. And stored in the RAM 113 or the like (S308). The subsequent processing is the same as in FIG.

  If there is no projectable data in the USB memory (S304), or if there is no encrypted data in the USB memory (S307), the control unit 11 cannot project the data in the USB memory. The signage mode is terminated (S309). Even if there is no projectable data in the USB memory, the data can only be projected, so the file tree in the USB memory, a list of file names, etc. may be projected without terminating the signage mode. In addition, when the data in the USB memory can be directly edited by the projector 100, S303 may be executed again after the data is edited, and if the data can be projected, the processing after S305 may be performed.

  Here, there is usually a format supported by the display device. MPEG2 video can be played but MPEG4 cannot be played, JPEG / TIFF can be displayed, but BMP cannot be displayed. Some files migrated with “Not present” in S304 may be determined as “Not present” because the content in the USB does not support the display device. Since it is encrypted data, the content is not known and it may be determined that it does not exist. For this reason, it is shown as in FIG.

Also, the password is entered in S302 and the password is entered again in S311. However, if the removable media is stolen, even if the password is entered, it cannot be decrypted unless the device ID leaks, and the password is entered again. The significance of data decoding will be described.
When you exit signage and remove the USB, you need to decrypt the contents of the USB so that it can be seen by other devices. If you don't decrypt the data by re-entering the password, the USB will remain encrypted and not visible on other devices even after you exit the signage. Since the present invention prevents theft during signage display, it is not necessary to encrypt until after the signage is finished. However, if it is automatically decrypted at the end of the signage, a third party may end the signage mode without permission and take away the USB. For this reason, password confirmation is performed at the end of signage, that is, at the time of removal.

<Configuration 2>
FIG. 5 is a block diagram according to another embodiment.
The projector 200 includes an I / F unit 10, a control unit 11, an audio processing unit 12, a speaker 13, a video processing unit 14, an optical unit control unit 15, an optical unit 16, a light source control unit 17, a light source 18, an operation unit 19, and a storage Unit 20, encryption unit 21, decryption unit 22, and position detection unit 23.
The position detection unit 23 is a system for specifying the position of a GPS (Global Positioning System) receiver, for example, and detects position information where the projector 200 is installed. The display unit 220 includes a video processing unit 14, an optical unit control unit 15, an optical unit 16, a light source control unit 17, and a light source 18. Other configurations are the same as those in FIG.

<Operation 4>
FIG. 6 is an example of a flowchart showing the operation of the display device shown in FIG.
The user connects a removable medium such as a USB memory storing data to be projected to the USB port 103 of the projector 200 as a display device, and operates the operation unit 19 to start the signage mode (S401). In this example, the user explicitly starts the mode for projecting the data in the USB memory called the signage mode and projects the data in the USB. However, when the USB memory is recognized, the signage is automatically The mode may be started. In addition, when the data in the USB memory is simply accessed, the subsequent processing may be performed without using the signage mode.

  The position detection unit 23 detects the position information of the projector 200 and stores it in the storage unit 20, the ROM 112, the RAM 113, or the like (S402). When there is position information detected last time in the storage unit 20 or the ROM 112, RAM 113, etc., it may be added whether or not the position information detected last time matches the position information detected this time. You may determine whether a process is advanced.

The control unit 11 confirms whether the data in the USB memory is encrypted (S403). When the data is not encrypted, the control unit 11 uses the position information detected by the position detection unit 23 and the unique ID unique to the device stored in the storage unit 20 or the ROM 112 as a key. Data in the memory is encrypted (S404). The data before encryption is taken into the storage unit 20 or the ROM 112, RAM 113, etc., and the data after encryption is placed in the USB memory.
In the present embodiment, an example in which the data before encryption is arranged in the storage unit 20 and the data after encryption is arranged in the USB memory is shown. However, in S405, only the original data to be projected or being projected may be arranged in the storage unit 20, the ROM 112, the RAM 113, or the like, and the original data that is not to be projected or not being projected may be deleted. The object to be encrypted may be, for example, only the data designated by the user as the projection schedule or the scheduled data, or only the specific data designated by the user separately from the projection schedule Good.
The control unit 11 confirms whether the data in the USB memory is encrypted (S403). If the data is encrypted, the decryption unit 22 uses the location information detected by the location detection unit 23 and the device-specific unique ID stored in the storage unit 20 or ROM 112 as a key to encrypt the data in the USB memory. Is decrypted. The decrypted data is stored in the storage unit 20 or the ROM 112, RAM 113, etc. (S406).

  When the encryption or decryption is completed, the projector 200 projects the target data stored in the storage unit 20, ROM 112, RAM 113, or the like (S405). Data is projected by any projection method. For example, there are methods such as repeatedly projecting one data, projecting all data in a specific folder repeatedly, and specifying a data display interval. If the target data cannot be decoded normally, the projector 200 may notify that it cannot project normally.

When the projection ends, the user operates the operation unit 19 to end the signage mode (S407). It may be automatically terminated upon completion of data projection or at a designated time. The control unit 11 detects the position information of the projector 200 through the position detection unit 23 at an arbitrary timing before removing the USB memory, such as when the signage mode ends or the USB memory is removed (S408). Detection of position information may be skipped in consideration of the passage of time, whether a user or administrator is nearby or a movement is detected by a separately mounted sensor or the like with a separately mounted camera or detection mechanism.
The decryption unit 22 decrypts the encrypted data in the USB memory using the unique ID unique to the device stored in the storage unit 20 or the ROM 112 and the position information detected by the position detection unit 23 as a key (S409). At that time, it may be determined whether or not decoding is correctly performed, and the decoding result may be notified to the user. Further, only specific data designated by the user may be decrypted.

<Effect>
Data in the removable medium is encrypted using a unique ID stored in the display device and a password set by the user. For this reason, it is encrypted during signage display, and it is impossible to decrypt the storage medium with another display device by decrypting with the unique ID of the encrypted display device using the user's password. As a result, when the removable device such as a USB memory is used for display on the display device, it is possible to prevent the data in the storage medium from leaking due to the theft or copying of the removable media. Further, a secondary object of the present invention is to prevent data from being leaked from the removable medium without encryption when storing the data in the removable medium.
Decoding is performed when the user ends the signage mode and removes the USB. The USB is encrypted only during the signage mode that is inserted into the display device. The reason is to prevent a legitimate user who is a user during signage from being stolen by a third party, and it is encrypted because it is not stolen when it is determined that it is a user by a password Is unnecessary.
That is, the data in the USB is encrypted by the display device only during the signage mode. Encrypt and decrypt using the device's unique ID and user password as keys.

  If the data in the removable media has already been encrypted, it is decrypted and displayed internally, so if the data is encrypted, it will be decrypted and displayed, so the previously encrypted data But it can be displayed.

  Since only the data that can be displayed by the display device is encrypted by encrypting only the data that can be displayed by the display device, the time until the data is encrypted can be shortened.

  Since the display device encrypts only the data scheduled to be displayed by encrypting only the data scheduled to be displayed, the time until the data is encrypted can be shortened.

  Since only the specified data is encrypted, the time until the data is encrypted can be shortened.

  Only the specified data is decrypted, and the data that is not specified remains encrypted data, so the time to decrypt the data can be shortened and the time to encrypt the data at the next use is shortened. can do.

  Since the location information is used as a key for encryption / decryption, data can be protected even when not only the removable media but also the display device is stolen together.

  Since the display device encrypts only the data scheduled to be displayed, the time until the data is encrypted can be shortened.

  Since only the specified data is encrypted, the time until the data is encrypted can be shortened. Also, only data that needs to be protected can be encrypted even if it is data to be projected.

  Only the specified data is decrypted, and the data that is not specified remains encrypted data, so the time to decrypt the data can be shortened and the time to encrypt the data at the next use is shortened. can do.

Here, in each flowchart, after signage is finished, a password is input or data is decrypted. However, after the signage is finished, the case where the removable medium is removed from the device and stored in a predetermined place will be described.
It is thought that it is a user, not a third party, who can know and enter a password. When the signage is completed, it is difficult to be stolen by a third party, so a decryption process is performed. If the decryption process is not performed, the contents of the USB will remain encrypted. Decryption requires a password for the display device and a unique ID recorded on the display device, so the contents cannot be seen in another place, that is, encrypted on a PC or other display device. become.

<Program>
The display device according to the present invention described above is realized by a program that causes a computer to execute processing. Therefore, as an example, a case where the function of the present invention is realized by a program will be described below.

For example,
In a control program readable by a computer of a display device comprising device ID storage means, password input means, encryption means, decryption means, and display means,
Computer
Procedure for storing the device ID unique to the display device in the device ID storage means,
The procedure for entering the password in the password input means,
A procedure for encryption when displaying data in the removable medium with the device ID and the password as a key in the encryption means,
A procedure for decrypting the data in the removable media with the device ID and password as a key in the decryption means,
The procedure for displaying the data in the removable media on the display means,
There is a control program of a display device for executing the above.

  Such a program may be stored in a computer-readable storage medium.

<Storage medium>
Here, examples of the storage medium include computer-readable storage media such as CD-ROM, flexible disk (FD), and CD-R, semiconductor memories such as flash memory, RAM, ROM, and FeRAM, and HDD.

  CD-ROM is an abbreviation for Compact Disc Read Only Memory. A flexible disk means Flexible Disk: FD. CD-R is an abbreviation for CD Recordable. RAM is an abbreviation for Random-Access Memory. ROM is an abbreviation for Read-Only Memory. FeRAM is an abbreviation for Ferroelectric RAM and means a ferroelectric memory. HDD is an abbreviation for Hard Disc Drive.

  The above-described embodiment shows an example of a preferred embodiment of the present invention, and the present invention is not limited thereto, and various modifications can be made without departing from the scope of the invention. is there.

DESCRIPTION OF SYMBOLS 10 I / F part 11 Control part 12 Audio | voice processing part 13 Speaker 14 Image | video process part 15 Optical unit control part 16 Optical unit 17 Light source control part 18 Light source 19 Operation part (password input means)
20 storage unit (device ID storage means)
21 Encryption Unit 22 Decryption Unit 23 Position Detection Unit 100, 200 Projector (Display Device)
101 Video port 102 Audio port 103 USB port 104 LAN port 111 CPU
112 ROM
113 RAM
120, 220 Display means

JP 2010-271771 A

Claims (12)

A device ID storage means for storing a device ID unique to the display device;
A password input means for entering a password;
Encrypting means for encrypting data in the removable media using the device ID and the password as a key;
Decryption means for decrypting data in the removable medium using the device ID and the password as a key;
Display means for displaying data in the removable media;
Control means for encrypting the data in the removable medium when displaying the data in the removable medium;
A display device comprising:   The display device according to claim 1, wherein the control unit decrypts and displays the data in the removable medium when the data is already encrypted.   3. The display device according to claim 1, wherein the control unit encrypts only data that can be displayed by the display unit.   The display device according to claim 1, wherein the control unit encrypts only data scheduled to be displayed by the display unit.   3. The display device according to claim 1, wherein the control means encrypts only designated data.   3. The display device according to claim 1, wherein the control means decodes only designated data. Position detecting means for detecting position information of the display means;
Encryption means for encrypting data in the removable medium using the device ID and the location information as a key;
Decryption means for decrypting data in the removable medium using the device ID and the location information as a key;
The display device according to claim 1, further comprising:   8. The display device according to claim 7, wherein the control means encrypts only data scheduled to be displayed by the display means.   8. A display device according to claim 7, wherein the control means encrypts only designated data.   8. A display device according to claim 7, wherein said control means decodes only designated data. Storing the device ID unique to the display device;
Entering a password;
Decrypting the data in the removable media using the device ID and the password as a key;
Displaying data in the removable media;
Encrypting the data in the removable medium with the device ID and the password as a key when displaying the data in the removable medium;
A control method for a display device, comprising: In a control program readable by a computer of a display device comprising device ID storage means, password input means, encryption means, decryption means, and display means,
The computer is
A procedure for storing a device ID unique to the display device in the device ID storage means,
A procedure for inputting a password into the password input means;
A procedure for encrypting when displaying data in a removable medium with the device ID and the password as a key in the encryption means,
A procedure for decrypting data in the removable medium with the device ID and the password as a key to the decryption means,
A procedure for displaying data in the removable medium on the display means;
Control program for display device to execute

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