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(11) | EP 1 868 042 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Display device |
| (57) The present invention concerns a display device (10) for visualising electronically
stored information, the display device (10) comprising a housing (12) with a visualisation
zone (14) for viewing a visual reproduction of the electronically stored information.
The display device (10) further comprises a reusable display substrate (16) for carrying
the visual reproduction; a printing unit (26) for printing a printing substance onto
a portion of the display substrate (16) in such a way as to create the visual reproduction
of the electronically stored information on the display substrate (16); and an eraser
unit (32) for removing the printing substance from the display substrate (16). Transport
means (24) are provided for transporting the display substrate (16) so as to move
the portion of the display substrate (16) from the printing unit (26) to the visualisation
zone (14) and from the visualisation zone (14), via the eraser unit (32), back to
the printing unit (26).
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BACKGROUND OF THE INVENTION
[0001] The present invention concerns a display device for displaying electronically stored information.
[0002] For years, there has been a tendency to provide more and more information in electronic form. Whether it is text, graphics, videos or sound, there is a clear increase in use of the electronic version of such material. One medium that has as yet not had a great success in being replaced by its electronic version is the book.
[0003] Indeed, electronic documents (e-books) exist but are not generally used. Such electronic documents are available for download from the Internet, often free of charge or for a small charge, and can be stored in memory. The electronic document can be stored in a portable handheld device, such as a Personal Digital Assistant (PDA), which allows visualisation of the electronic document wherever and whenever desired.
[0004] The disadvantage of such a system is that the display quality of the electronic document on the PDA is generally not sufficiently good. Indeed, the representation of the electronic document on a PDA display is usually less sharp than on a printed-paper support. This means that the reader is not able to enjoy a comfortable read of the electronic document. As a consequence, the electronic version of the traditional printed-matter has not been as widely accepted by the public as has e.g. been the case for audio material.
[0005] Another disadvantage of viewing electronic documents via PDA is the fact that the display must constantly be powered, and generally also backlit, to allow the displayed information to be viewed. The constant use of power naturally reduces the possible viewing time, causing further discomfort to the reader when the battery reaches its end.
[0006] There is thus a need for an improved device for visualising electronically stored information such as electronic documents (e-books).
[0007] It is therefore an object of the present invention to provide an improved device for visualising electronically stored information.
SUMMARY OF THE INVENTION
[0008] The present invention provides a display device for visualising electronically stored information, the display device comprising
a housing with a visualisation zone for viewing a visual reproduction of the electronically stored information;
a reusable display substrate for carrying the visual reproduction;
a printing unit for printing a printing substance onto a portion of the display substrate in such a way as to create the visual reproduction of the electronically stored information on the display substrate;
an eraser unit for removing the printing substance from the display substrate; and
transport means for transporting the display substrate so as to move the portion of the display substrate from the printing unit to the visualisation zone and from the visualisation zone, via the eraser unit, back to the printing unit.
[0009] Such a display device allows for the stored information to be displayed in printer quality, i.e. at high contrast and high resolution. Indeed, the display quality of printed matter is generally of better quality than that of an electronic display screen. It follows that, by using the present display device, the electronically stored information can be visualised with increased readability. Electronic display screens rely on power for displaying the information. While the information is displayed, the power consumption is not negligible, in particular in the case where the electronic display screen is backlit. The display device according to the present invention on the other hand only consumes power while new information is printed onto the display substrate. No power is consumed for displaying the information printed on the display substrate. This leads to considerable power consumption and hence longer battery life.
[0010] The printing substance can be erasable ink. Preferably however, the printing substance is a polarised particulate material.
[0011] The printing unit advantageously comprises a polarisation unit for creating locally polarised sections on the display substrate according to a visual representation of the electronically stored information, and an application unit for transferring the polarised particulate material onto the locally polarised sections of the display substrate. The polarisation unit may e.g. comprise a LED (light emitting diode) assembly or a laser assembly to polarise the display substrate. A laser assembly comprises a laser, a moveable mirror and a lens. With such a laser assembly, as generally known from laser printers, the laser receives information according to the information to be visualized and directs light pulses onto the display substrate via a moveable mirror and a series of lenses, thereby polarising the display substrate. In the laser printer technology, such a laser assembly is used to polarise a laser drum, which transfers toner onto the display substrate, i.e. the paper. A polarisation unit with a LED assembly basically works on the same principle that a polarisation unit with a laser assembly. However, instead of a laser, the LED assembly comprises an array of light emitting diodes to polarise the display substrate. The array of light emitting diodes is solid-state and has no moving parts. The LED bar pulse-flashes across the width of the display substrance and creates the image thereon. LED assemblies are generally considered to be more efficient mechanically than normal laser assemblies, since there are fewer moving parts. Indeed the LED assembly does not rely on an elaborate combinations of rotating mirrors and lenses that must remain in alignment through use. LED assemblies can also have faster rates of print and are generally cheaper to manufacture.
[0012] The printing unit may either create a visual representation directly on the display substrate or on an intermediate, cylindrical drum. The printing unit may comprise a cylindrical drum between the polarisation unit and the display substrate, the polarisation unit creating locally polarised sections on the cylindrical drum according to a visual representation, in negative, of the electronically stored information and the cylindrical drum transferring the locally polarised sections onto the display substrate. The use of such a cylindrical drum allows the use of a less light sensitive display substrate, which in turn allows to prolong the lifetime of the display substrate.
[0013] According to an embodiment of the invention, the particulate material is toner and the toner is carried on the display substrate in its unfixed state from the printing unit, via the visualisation zone, to the eraser unit. The use of toner as particulate material is of advantage as it is readily available and therefore comparatively cheap. Toner is indeed generally used in laser printers and comprises a pigment and fusable plastic particles. In the laser printer technology, the toner is applied onto a drum, transferred onto paper and then fixed by heating such that the plastic particles in the toner melt and fuse with the fibres in the paper. According to the present invention however, the toner is carried on the display substrate in its unfixed state. The toner is maintained on the display substrate due to the relative charges between the polarised display substrate and the charged toner.
[0014] The eraser unit preferably comprises at least one brush for removing the particulate material from the display substrate, and may further comprise a collector for collecting the particulate material removed from the display substrate. The particulate material can thereby be easily removed from the display substrate, thereby providing a clean support for further printing.
[0015] The eraser unit can further be provided with means for feeding the collected particulate material to the application unit. The particulate material recovered from the display substrate can then be used again in the printing unit for printing a new representation onto the display substrate. The recycling of the particulate material within the display device reduces the amount of printing substance needed, thereby reducing the frequency at which printing cartridges need to be replaced. This obviously reduces running costs of the display device.
[0016] According to a preferred embodiment of the invention, the display substrate is a belt arranged in a closed loop, and the transport means comprises at least two rollers carrying the belt. At least one of the rollers is preferably coupled to a motor for moving the belt. Such an arrangement provides for a continuous path of the display substrate from the printing unit to the visualisation zone and from there back to the printing unit via the eraser unit. The display substrate can be provided with new representations again and again.
[0017] Although such a continuous belt is preferred, it is not excluded to provide an arrangement wherein the display substrate is unwound from a first storage roll and fed to the printing unit and wherein it is wound onto a second storage roll after passing said visualisation zone. Once the first storage roll is empty, the transport means unwinds the display substrate from the second storage roll and winds it back onto the first storage roll. Before the display substrate is again fed to the printing unit, the printing substance is removed from the display substrate by the eraser means, which is preferably located between the visualisation zone and the second storage roll for cleaning the display substrate before it is wound onto the second storage roll.
[0018] In a preferred embodiment of the invention, the display device comprises more than one printing unit, wherein each printing unit is configured to print a differently coloured printing substance onto a portion of said display substrate. Such a display device can then be used to display coloured representations. A number of printing units can e.g. be arranged in series and the different colours are printed onto the display substrate one after the other to produce the finished colour representation.
[0019] Advantageously, the display device further comprises one or more of the following units:
➢ An image processor for receiving electronically stored information to be displayed and sending a signal to the printing unit according to the visual representation to be printed. Such an image processor may be configured as an on-board processor capable of retrieving information from a memory and converting it to a signal, which can be used to drive the printing unit.
➢ Memory means for storing the electronically stored information. The memory means can be an internal hard disk, a memory chip or a memory card reader that can be fed with memory cards.
➢ An interface for receiving electronically stored information from an external source. The display device can be fed with information from an external source such as a personal computer. The interface may be a cable connection for connecting a serial, parallel or USB cable, a radio frequency receiver, an infrared receiver. An interface in form of a card reader can also be envisaged.
➢ A control unit for controlling the printing of the visual representation onto the display substrate; and the transport of the display substrate. Such a control unit may comprise control buttons on the housing of the display device and control the printing unit and the transport means according to an input from the user.
➢ A battery for delivering power to components of the display device. It should be noted that because the display device does not continuously need power to display the representation of the electronically stored information to be viewed, power consumption is relatively low.
[0020] According to preferred embodiment, the display substrate comprises a dielectric plastic film, which is opaque, white, UV resistant and has a smooth finish.
[0021] The present invention also concerns a handheld device comprising a display device as described above. In such a handheld device, the display device can e.g. be palm sized and have a visualisation zone comparable in size to that of a PDA. Such a handheld device can be used for reading electronic books. Compared with a PDA, which is generally used nowadays for reading such electronic books, the handheld device according to the present invention would have many advantages, such as better readability due to the improved contrast, lower power consumption due to the fact that power is only used while printing and moving the display substrate.
[0022] The handheld device can also be of bigger size. A handheld device with a visualisation zone having the size of an A4 sheet of paper can e.g. be used to display reading material at seminars, lectures. A handheld device with a visualisation zone having the size of an A4 sheet of paper can e.g. be used to display newspaper material.
[0023] The present invention further concerns an information panel comprising a display device as described above. Such an information panel can have a display device with a very large visualisation zone and may be used e.g. at sporting venues or conference centres for displaying information to a large audience.
[0024] The present invention further concerns an advertisement panel comprising a display device as described above. Such an advertisement panel, which may e.g. be connected to a bus shelter, can be easily and quickly fed with new information to be displayed. The advertisement to be displayed can very easily be exchanged by simply feeding an electronically stored version of the advertisement to be displayed into the display device. This can for example be done by simply connecting a laptop computer to the display device to transfer the new information. Such transfer can even be carried out remotely, i.e. with no physical connection with the display device, e.g. via radio frequency or infrared communication. Communication between the display device and a personal computer can also be established via telephone lines, e.g. GPS, GPRS, UMTS. The installation of advertisement panels in less accessible locations thereby becomes possible. There is no need for a worker to physically go to the advertisement panel, to open up the advertisement panel and, in some cases, to climb potentially dangerous ladders. Compared to existing digital advertisement panels, the system according to the invention has the advantage that the information can be read more easily due to better contrast and higher resolution. A further advantage is the reduced power consumption due to the fact that the display device only consumes power during the actual replacement of the advertisement and that no power is needed while displaying the information.
[0025] The present invention also concerns a method for visualizing electronically stored information on a display device, wherein the method comprises the following steps:
providing a housing with a visualisation zone for viewing a visual reproduction of the electronically stored information;
providing a reusable display substrate;
printing, at a printing unit, a printing substance onto a portion of the display substrate in such a way as to create a visual reproduction of the electronically stored information on the display substrate;
transporting the display substrate so as to move the portion of the display substrate to the visualisation zone;
displaying the visual reproduction of the electronically stored information in the visualisation zone;
transporting the display substrate so as to move the portion of the display substrate to the printing unit via an eraser unit; and
removing, at the eraser unit, the printing substance from the display substrate.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] The drawings form an integral part of the specification and are to be read in conjunction therewith. The detailed description of the invention is a nonlimiting description of one preferred embodiment of the invention.
- Fig.1:
- is a schematic perspective view of a display device according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0027] Referring to FIG.1, a display device is generally indicated at 10 and comprises a housing 12 with a visualisation zone 14. Such a visualisation zone 14 is generally a transparent window in the housing 12 allowing visual access to a support on which the information is displayed.
[0028] Within the housing 12, the display device 10 comprises a display substrate 16 on which the information is printed. To view the printed information, the display substrate 16 is moved such that the information is in alignment with the visualisation zone 14, thereby allowing visual access to the printed information through the transparent window of the housing 12.
[0029] According to a preferred embodiment of the invention, the display substrate 16 is an opaque, white, UV resistant plastic film with a smooth finish. Such a display substrate provides a good support for carrying the printed information. When printed with black ink or toner, the display substrate provides the ideal background for excellent contrast. The printed display substrate is comparable, in terms of quality of contrast, to a printed sheet of white paper.
[0030] The display substrate 16 is, according to the display device shown in Fig.1, arranged in a closed loop and tightly mounted between two rollers 18, 20, one of which 18 is coupled to a motor 22. The rollers 18, 20 and the motor 22 form a transport means 24 for moving the display substrate 16 so as to align the information to be viewed with the visualisation zone14.
[0031] The display device 10 further comprises a printing unit 26 for temporarily printing the information to be viewed onto the display substrate 16. The printing unit 26 shown in Fig.1 comprises a polarisation unit 28 for creating locally polarised sections on the display substrate 16 according to the information to be displayed, and an application unit 30 for transferring a polarised particulate material, such as e.g. toner, onto the locally polarised sections of the display substrate. With such a printing unit 26, high quality printing can be achieved, i.e. the information to be viewed, whether it is text, graphs or pictures, can be printed at very high resolution.
[0032] The polarisation unit 28 itself is not described here in detail, but may comprise a laser assembly or a light emitting diode (LED) assembly, as generally known from the laser printer technology for transferring an image of the information to be displayed onto a printing drum of such a laser printer.
[0033] The application unit 30 allows for toner to be transferred onto the display substrate 16 according to the polarised sections created on the display substrate by the polarisation unit 28. The printed representation of the information is then moved into alignment with the visualization window 14 by rotation of the rollers 18, 20. It should be noted that, unlike in the laser printer technology, the toner on the display substrate 16 remains in its unfixed state.
[0034] While the printed information is in alignment with the visualization window 14 the information can be viewed by the user. As more information is printed onto the display substrate 14, the previously printed information returns to the printing unit 26. Before the previously printed information reaches the printing unit 26, the toner on the display substrate 16 is removed by an eraser unit 32 comprising e.g. a brush. Because the toner is left in its unfixed state, it is possible to remove the toner and to thereby erase the display substrate 16. The latter can then be printed on again.
[0035] Preferably, the toner removed from the display substrate 16 by the eraser unit 32 is collected and fed back to the application unit 30. The toner can hence be used again.
[0036] The display device 10 further comprises an image processor 34 for receiving the electronically stored information and feeding a signal to the polarisation unit 28 according to the information to be printed.
[0037] The electronically stored information can be fed to the image processor 34 from a memory means 36 within the housing 12. The memory means 36 comprises an interface 38for connecting to an external storage device, such as e.g. a personal computer via serial cable or USB cable. Alternatively, the information to be printed may be fed directly from the external storage device to the image processor 34.
[0038] The display device 10 further comprises a control unit 40 for controlling the printing of the visual representation onto the display substrate 16 and for controlling the transport of the display substrate 16 by the rollers 18, 20. Information can be sent from the user to the control unit 40 via control buttons 42 accessible to the user.
[0039] A battery 44 is further arranged in the housing 12 for delivering the necessary power to the different components of the display device 10.
REFERENCE NUMERALS
1. Display device for visualising electronically stored information, said display device
comprising:
a housing with a visualisation zone for viewing a visual reproduction of said electronically stored information;
a reusable display substrate for carrying said visual reproduction;
a printing unit for printing a printing substance onto a portion of said display substrate in such a way as to create said visual reproduction of said electronically stored information on said display substrate;
an eraser unit for removing said printing substance from said display substrate; and
transport means for transporting said display substrate so as to move said portion of said display substrate from said printing unit to said visualisation zone and from said visualisation zone, via said eraser unit, back to said printing unit.
2. Display device according to claim 1, wherein said printing substance is erasable ink.
3. Display device according to claim 1, wherein said printing substance is a polarised
particulate material.
4. Display device according to claim 3, wherein said printing unit comprises:
a polarisation unit for creating locally polarised sections on said display substrate according to a visual representation of the electronically stored information, and
an application unit for transferring said polarised particulate material onto said locally polarised sections of said display substrate.
5. Display device according to claim 3 or 4, wherein said printing unit comprises a cylindrical
drum between said polarisation unit and said display substrate, said polarisation
unit creating locally polarised sections on said cylindrical drum according to a visual
representation, in negative, of the electronically stored information and said cylindrical
drum transferring said locally polarised sections onto said display substrate.
6. Display device according to any of claims 3 to 5, wherein said particulate material
is toner and wherein said toner is carried on said display substrate in its unfixed
state from said printing unit, via said visualisation zone, to said eraser unit.
7. Display device according to any of claims 3 to 6, wherein said eraser unit comprises
at least one brush for removing said particulate material from said display substrate.
8. Display device according to any of claims 3 to 7, wherein said eraser unit comprises
a collector for collecting said particulate material removed from said display substrate
9. Display device according to claim 8, wherein said eraser unit further comprises means
for feeding said collected particulate material to said application unit.
10. Display device according to any of claims 1 to 9,
wherein said display substrate is a belt arranged in a closed loop, and
wherein said transport means comprises at least two rollers carrying said belt.
wherein said display substrate is a belt arranged in a closed loop, and
wherein said transport means comprises at least two rollers carrying said belt.
11. Display device according to claim 10, wherein at least one of said rollers is coupled
to a motor for moving said belt.
12. Display device according to any of claims 1 to 11, further comprising more than one
printing unit, wherein each printing unit is configured to print a differently coloured
printing substance onto a portion of said display substrate.
13. Display device according to any of claims 1 to 12, further comprising one or more
units selected from the group comprising:
- an image processor for receiving electronically stored information to be displayed and sending a signal to said printing unit according to said visual representation to be printed;
- memory means for storing said electronically stored information;
- an interface for receiving electronically stored information from an external source;
- a control unit for controlling the printing of said visual representation onto said display substrate; and the transport of said display substrate;
- a battery for delivering power to components of said display device.
14. Display device according to any of claims 1 to 13, wherein said display substrate
comprises a plastic film.
15. Display device according to claim 13 and any of claims 3 to 13, wherein said plastic
film is a dielectric film.
16. Display device according to any of claims 14 or 15, wherein said plastic film is opaque,
white, UV resistant and has a smooth finish.
17. Handheld device comprising a display device as claimed in any of claims 1 to 16.
18. Information panel comprising a display device as claimed in any of claims 1 to 16.
19. Advertisement panel comprising a display device as claimed in any of claims 1 to 16.
20. Method for visualizing electronically stored information on a display device, said
method comprising the steps of:
providing a housing with a visualisation zone for viewing a visual reproduction of said electronically stored information;
providing a reusable display substrate;
printing, at a printing unit, a printing substance onto a portion of said display substrate in such a way as to create a visual reproduction of said electronically stored information on said display substrate;
transporting said display substrate so as to move said portion of said display substrate to said visualisation zone;
displaying said visual reproduction of said electronically stored information in said visualisation zone;
transporting said display substrate so as to move said portion of said display substrate to said printing unit via an eraser unit; and
removing, at said eraser unit, said printing substance from said display substrate.