U.S. patent application number 13/416190 was filed with the patent office on 2013-09-12 for techniques for protecting imaging access of electronic paper.
The applicant listed for this patent is Henryk Birecki, Omer Gila, Napoleon J. Leoni. Invention is credited to Henryk Birecki, Omer Gila, Napoleon J. Leoni.
Application Number | 20130235446 13/416190 |
Document ID | / |
Family ID | 49113911 |
Filed Date | 2013-09-12 |
United States Patent
Application |
20130235446 |
Kind Code |
A1 |
Leoni; Napoleon J. ; et
al. |
September 12, 2013 |
TECHNIQUES FOR PROTECTING IMAGING ACCESS OF ELECTRONIC PAPER
Abstract
Techniques for protecting imaging access of electronic paper are
described herein. For example, an electronic paper device with
protected imaging access includes a substrate, an e-paper surface
disposed on the substrate, a removable cover to prevent alteration
of the e-paper surface when the cover is disposed over the e-paper
surface, and a reversible locking mechanism engaging with the cover
to secure the cover in place over the e-paper surface. A method for
secure writing to e-paper is also provided.
Inventors: |
Leoni; Napoleon J.; (San
Jose, CA) ; Gila; Omer; (Cupertino, CA) ;
Birecki; Henryk; (Palo Alto, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Leoni; Napoleon J.
Gila; Omer
Birecki; Henryk |
San Jose
Cupertino
Palo Alto |
CA
CA
CA |
US
US
US |
|
|
Family ID: |
49113911 |
Appl. No.: |
13/416190 |
Filed: |
March 9, 2012 |
Current U.S.
Class: |
359/296 |
Current CPC
Class: |
G02F 1/133308 20130101;
G09F 9/372 20130101; G06K 19/077 20130101; B42D 25/415 20141001;
G02F 1/167 20130101 |
Class at
Publication: |
359/296 |
International
Class: |
G02F 1/167 20060101
G02F001/167 |
Claims
1. An electronic paper device with protected imaging access
comprising: a substrate; an e-paper surface disposed on the
substrate; a removable cover to prevent alteration of the e-paper
surface when the cover is disposed over the e-paper surface; and a
reversible locking mechanism engaging with the cover to secure the
cover in place over the e-paper surface.
2. The device of claim 1, in which the removable cover is for
prevention of alteration of the e-paper surface using an ion
head.
3. The device of claim 1, in which the cover is a transparent
window.
4. The device of claim 1, in which the reversible locking mechanism
comprises at least one cantilevered latch with a tab that engages
with an indentation in a mating component.
5. The device of claim 4, in which the reversible locking mechanism
comprises a cantilevered latch formed in the substrate and the
indentation is in the cover.
6. The device of claim 4, in which the reversible locking mechanism
comprises a cantilevered latch formed in the cover and the
indentation is in the substrate.
7. The device of claim 1, in which the locking mechanism is
mechanically actuated to release the cover.
8. The device of claim 1, in which the locking mechanism comprises
magnetic material.
9. The device of claim 8, in which the locking mechanism comprises
a plurality of magnets with varying polarities.
10. The device of claim 1, in which the locking mechanism comprises
a bistable flexural mechanism.
11. The device of claim 1, in which the locking mechanism engages
edges of the cover.
12. A card writer for secure writing to e-paper comprising: a base;
an actuator for actuating a reversible locking mechanism of a
removable cover covering an e-paper surface; and a writing head to
write to the e-paper surface.
13. The system of claim 12, in which the writing head is an ion
head.
14. The system of claim 12, in which the actuator comprises a
protrusion that mechanically engages a cantilevered latch.
15. The system of claim 12, in which the actuator comprises a
magnet.
16. The system of claim 12, in which the actuator is for
simultaneously engagement of two separate reversible locking
mechanisms of the removable cover.
17. A method for secure writing to e-paper comprising: activating
an actuator to unlock the cover; removing the cover to expose the
e-paper; altering markings on the e-paper; and replacing the cover
and locking the cover in place.
18. The method of claim 17, in which altering markings comprises
erasing current markings on the e-paper and writing new markings on
the e-paper.
19. The method of claim 17, in which activating an actuator to
unlock the cover comprises pressing the e-paper over protrusions to
disengage cantilevered latches to allow the cover to slide off the
e-paper.
20. The method of claim 17, in which activating an actuator to
unlock the cover comprises simultaneously engaging multiple latches
holding the cover in place.
Description
BACKGROUND
[0001] Electronic paper ("e-paper") is a display technology
designed to recreate the appearance of ink on ordinary paper.
E-paper reflects light like ordinary paper and may be capable of
displaying text and images indefinitely without using electricity
to refresh the image, while allowing the image to be changed later.
E-paper can also be implemented as a flexible, thin sheet, like
paper. By contrast, a typical flat panel display does not exhibit
the same flexibility, typically uses a backlight to illuminate
pixels, and constantly uses power during the display. Typical
e-paper implementations, such as electronic books ("e-books"),
include an e-paper display and electronics for rendering and
displaying digital media on the e-paper.
BRIEF DESCRIPTION OF THE DRAWINGS
[0002] The accompanying drawings illustrate various examples of the
principles described herein and are a part of the specification.
The illustrated examples are merely examples and do not limit the
scope of the claims.
[0003] FIGS. 1A and 1B are examples of applications for electronic
paper with protected access, according to one example of principles
described herein.
[0004] FIG. 2 is cross sectional diagram of an illustrative e-paper
printing system printing on e-paper with protected access,
according to one example of principles described herein.
[0005] FIGS. 3A-3I show a system and method for removing a
protective transparent cover to expose the e-paper in order to
alter the writing, according to one example of principles described
herein.
[0006] FIGS. 4A-4E show a system and method for writing to
electronic paper with protected imaging access, according to one
example of principles described herein.
[0007] FIGS. 5A-5C show examples of latching mechanisms, according
to one example of principles described herein.
[0008] FIGS. 6A-6C show an illustrative locking mechanism for
removably securing a cover over e-paper, according to one example
of principles described herein.
[0009] FIG. 7 is a flow chart of a method for writing to e-paper
with protected imaging access, according to one example of
principles described herein.
[0010] Throughout the drawings, identical reference numbers
designate similar, but not necessarily identical, elements.
DETAILED DESCRIPTION
[0011] E-paper is used in a variety of display applications such as
signage, e-books, tablets, cards, posters, and pricing labels.
E-paper has several paper-like features. For example, e-paper is a
reflective display that uses ambient light as an illumination
source. The ambient light strikes the surface and is reflected to
the viewer. The usage of pigments similar to those which are used
in printing allows the e-paper to be read at a wide range of angles
and lighting conditions, including full sunlight. The use of
ambient light also eliminates the need for illumination produced by
the device. This minimizes the energy used by the e-paper.
Additionally, the e-paper does not use energy to maintain the
image. Once the image is written, the image remains on the e-paper
for an extended period of time or until the e-paper is rewritten.
Thus, a typical e-paper primarily uses energy for changes of
state.
[0012] E-paper is typically written by generating a charge on a
surface in proximity to a layer of microcapsules that contain
charged pigment particles. The charge on the surface attracts or
repels the charged pigment particles in the microcapsules to create
the desired image. The pigment particles are stable within the
microcapsules after they are moved into position. However, a wide
variety of methods can be used to alter the image or text on the
e-paper after it has been written. This can restrict the use of
e-paper to applications that do not require the images or text to
be secure against alteration. However, the principles described
below illustrate a removable cover that prevents alteration of
e-paper using common techniques such as an electrified stylus or
corona discharge mechanisms. By preventing alteration of the
e-paper using easily accessible technology, the security of the
e-paper improves and the e-paper can be used a wider variety of
applications. The removable cover is locked into position over the
e-paper by a reversible locking mechanism. The locking mechanism
can be disengaged and the e-paper altered using a specialized tool.
The cover is then replaced and locked over the e-paper by the
locking mechanism. This allows authorized alterations but imposes a
significant technological barrier that prevents or reduces
unauthorized alterations of the e-paper.
[0013] In the following description, for purposes of explanation,
numerous specific details are set forth in order to provide a
thorough understanding of the present systems and methods. It will
be apparent, however, to one skilled in the art that the present
apparatus, systems and methods may be practiced without these
specific details. Reference in the specification to "an example" or
similar language means that a particular feature, structure, or
characteristic described in connection with the example is included
in at least that one example, but not necessarily in other
examples.
[0014] FIG. 1A shows a card 100 that includes a strip of e-paper
104. In this example, the card is a gift card or loyalty card that
can be used in retail settings. The e-paper 104 records the balance
114 available on the card to make purchases and an advertisement
that includes text 108 and a picture of the advertised product 102.
As discussed above, it may be desirable to secure the information
displayed by the e-paper against alteration. If the balance 114 has
not been secured against alteration, it cannot be relied on to
accurately communicate the balance of the card. Consequently, other
techniques such as a magnetic strip or embedded radio frequency
circuitry may be included in the card to communicate the balance of
the card.
[0015] FIG. 1A also includes an enlargement 110 of a small portion
of the e-paper 104. The enlargement 110 shows that this e-paper
implementation includes an array of embedded, spherical-shaped
microcapsules 106. The line 118, which is part of the product image
102, is created by selectively applying a charge to the e-paper
102. The charge moves the particles within the microcapsules 106.
In this example, a charge has been applied that moved dark
particles to the front of the microcapsules 106 to form the line
118.
[0016] FIG. 1B is a security card 126 that grants the card bearer
access to specific buildings for a predetermined period of time.
The card bearer's name 128 and access permissions 130, 132 are
printed on the e-paper 134. The use of e-paper 134 allows the user
and others to visually identify the information that is associated
with the card. However, if the e-paper 134 has not been secured
against alteration, the text 128, 130 and security symbol 132
cannot be relied upon and alternative techniques are employed to
communicate the identity of the card, the name of the card bearer
and the access privileges of the card bearer.
[0017] As described below, the cards 100, 126 can include a
removable cover that prevents alteration of e-paper using
techniques such as an electrified stylus, ion heads or corona
discharge mechanisms while the cover is in place. By preventing
alteration of the e-paper using easily accessible technology, the
security of the e-paper improves and the e-paper can be used in a
wider variety of applications, including applications that require
heightened security. The removable cover is locked into position
over the e-paper by a reversible locking mechanism. The locking
mechanism can be disengaged, the cover removed and the e-paper
altered using a specialized tool. This allows authorized
alterations but imposes a significant technological barrier that
prevents or reduces unauthorized alterations of the e-paper.
[0018] FIG. 2 shows an enlarged cross-section of secured e-paper
202 on a substrate 212. The cross-sectional view shows an
illustrative multilayer structure of the e-paper 202, including
microcapsules 206 sandwiched between a transparent charge receiving
layer 208 and a conductive ground layer 210. The conductive ground
layer 210 is disposed on a substrate 212.
[0019] In this example, each of the microcapsules 106 contain both
white particles 220 and black particles 224 suspended in a fluid
medium. Ambient light is transmitted through the charge receiving
layer 208, strikes the particles 220, 224 and reflects back to the
viewer 222. When white particles 220 of a microcapsule 206 are
located near the transparent charge receiving layer 208, the
microcapsule 206 appears white to a viewer 222, and when the black
particles 224 of a microcapsule 206 are located near the
transparent charge receiving layer 208 the microcapsule 206 appears
black to the viewer 222. The particles 220, 224 can be of opposite
charges. For example, the black particles 224 can be positively
charged particles and the white particles 220 can be negatively
charged particles. Various shades of gray can be created by varying
the arrangement of alternating microcapsules with white and black
particles located near the charge receiving layer 208 to produce
halftoning.
[0020] The microcapsules 206 are designed to exhibit image
stability using chemical adhesion between particles and/or between
the particles and the microcapsule surface. For example, the black
and white microcapsules 206 ideally can hold text and images
indefinitely without drawing electricity, while still allowing the
text or images to be changed later.
[0021] The structure, materials, and dimensions of the various
layers and components shown in FIG. 2 can be adapted to specific
design criteria. In one implementation, the transparent charge
receiving layer 208 can be composed of a transparent polymer and
can range in thickness from approximately 100 nm to approximately
14 .mu.m. The transparent charge receiving layer 208 can also be
composed of a material that holds charges or is porous or
semi-porous to charges and/or ions. The transparent charge
receiving layer 208 can also be composed of a first insulating
layer and second patterned conductive layer.
[0022] The microcapsules 206 can have a diameter of approximately
50 .mu.m but may also range in diameter from approximately 20 .mu.m
to approximately 100 .mu.m. The conductive ground layer 210 can be
composed of a transparent conductive material, such as indium tin
oxide, or an opaque conductive material and can have a thickness
ranging from approximately 5 nm to approximately 1 mm. In one
example, the e-paper 202 has a total thickness of approximately 100
.mu.m. The substrate 212 can be composed of an opaque or
transparent material and can range in thickness from approximately
20 .mu.m to approximately 1 mm, or the thickness can be much larger
depending on the how the e-paper 202 is used. The substrate 112 can
be composed of polyester, plastic, transparent Mylar.RTM., or other
suitable material.
[0023] A variety of other configurations may be used. For example,
the microcapsule may include black particles suspended in a white
colored fluid. The black particles can be positively charged
particles or negatively charged particles. One or more
microcapsules form a pixel of black and white images displayed on
the e-paper. The black and white images are created by placing
black particles near or away from the charge receiving layer. For
example, the microcapsules with black particles located away from
the transparent charge receiving layer reflect white light,
corresponding to a white portion of an image displayed on the
e-paper. By contrast, the microcapsules with black particles
located near the charge receiving layer, appear black to the
viewer, corresponding to a black portion of the image displayed on
the e-paper. Various shades of gray can be created using halftoning
to vary the arrangement of alternating microcapsules with black
particles located near or away from the charge receiving layer.
[0024] FIG. 2 also describes writing to the illustrative secured
e-paper 202 with a writing system 300. The writing system 300
includes a writing module 302, writing unit 304, and an erasing
unit 306. The writing unit 304 and erasing unit 306 are connected
to the same side of the writing module 302 that faces the outer
surface 308 of the charge receiving layer 208, with the writing
unit 304 suspended above the surface 308. In the example of FIG. 2,
the writing unit 304 is an ion head and the erasing unit 306 can be
an electrode that comes into close contact with, or can be dragged
along, the surface 308 in front of the ion head 304. The writing
module 302 can be moved in the direction indicated by the arrow and
the e-paper 202 can be held stationary; or the e-paper 202 can be
moved in the opposite direction and the writing module 302 held
stationary; or the writing module 302 and e-paper 202 can be moved
simultaneously. In the example shown in FIG. 2, the black particles
224 and the white particles 220 of the microcapsules 206 are
positively charged and negatively charged, respectively. The
erasing unit 306 erases any information stored in the microcapsules
206 prior to writing information with the ion head 304. As the
e-paper 202 passes under the writing module 302, the positively
charged erasing unit 306 can remove negatively charge ions attached
to the surface 308. The positively charged erasing unit 306 also
creates electrostatic forces that drive positively charged black
particles 224 away from the charge receiving layer 208 and attract
negatively charged white particles 220 toward the charge receiving
layer 208. By passing the erasing unit 306 over the charge
receiving layer 208, the information written to the e-paper 202 is
erased by positioning the negatively charged white particles 220
near the top of the microcapsules 206 and pushing the positively
charged black particles 224 to the bottom of the microcapsules 206.
Additionally or alternatively, a corona source or the ion head 304
could be used to erase prior images present on the e-paper 202.
[0025] FIG. 2 also shows an illustrative writing operation
performed by the ion head 304. The ion head 304 is designed and
operated to selectively eject ions 314 (shown as black bars) toward
the charge receiving layer 208, when a region of the e-paper 202
located beneath the ion head 304 is to be changed from white to
black. The ions 314 reach the surface 308 and remain on the surface
to create negatively charged areas 316. The negatively charged
white particles 220 are repelled and driven away from the
negatively charged areas 316 on the charge receiving layer 208,
while the positively charged black particles 224 are attracted to
the negatively charged area 316 and driven toward the charge
receiving layer 208. Thus, to a viewer 222, the positively charged
areas of the charge receiving layer 308 will appear white and the
negatively charged areas 316 will appear black.
[0026] In addition to ion heads, a number of alternative writing
devices can be used to write on the e-paper 202 or alter the
contents of the e-paper 202. One of the simplest writing devices is
a charged stylus that is manually brought into proximity with the
charge receiving surface. The tip of the charged stylus creates an
electromagnetic field which can influence the position of the
charged pigments in the microcapsules 206.
[0027] Securing e-paper 202 against unauthorized alteration by a
charged stylus, other field writing device, or ion head can result
in e-paper 202 being significantly more secure. Consequently, the
visual information conveyed by the e-paper 202 could be relied on
to a greater extent. This may reduce the need for alternative
technology to be incorporated into the card. Further, the
information conveyed by secured e-paper 202 could be used to
visually verify the information conveyed by a magnetic strip,
embedded microchip or other technology. In one example, a
transparent cover is placed over the e-paper 202 after it is
written. The transparent cover allows images on the e-paper 202 to
be viewed but prevents alteration of the e-paper 202 while it is in
place. Additionally, the transparent cover protects the e-paper
from mechanical abrasion and damage. The transparent cover can be
locked into place using a variety of methods, including those
described below. A specialized card writer is used to unlock the
transparent cover, remove it from the e-paper surface and alter the
images on the e-paper surface and then secure the transparent cover
back in place.
[0028] FIGS. 3A-3I show one example of a card with protected
imaging access. The card includes e-paper, a cover, and a locking
mechanism. In this example, the locking mechanism on the card
engages and disengages the transparent cover to restrict its
movement. If a cardholder wishes to make a purchase with the card,
the value on the e-paper display can be updated as described
below.
[0029] FIG. 3A is a perspective view of the card 100 with a
transparent cover 300 moved to the right to expose a portion of the
underlying e-paper 202. The transparent cover 300 slides in a
channel formed in the substrate 320 of the card 100. Also formed in
the substrate 320 of the card is a locking mechanism 324 that
engages a corresponding aperture 332 in the cover 300 to secure the
cover 300 in place. In this implementation, the cover 300 is
transparent or translucent and allows the e-paper 202 to be visible
when covered by the cover.
[0030] FIG. 3B shows a cross section of the card 100 along line
3B-3B. This cross section illustrates the shape of the cover 300.
The cover 300 has a lip that fits into a corresponding shape of a
channel in the substrate 320 of the card 100. In this example, the
cover 300 has an inverted "T" shaped cross-section. The cover 300
has a lip that fits into the channel of the substrate 320, which
restrains the motion of the cover but allows the cover to slide
along the length of the channel as shown in FIG. 3A. The e-paper
202 is located underneath the cover 300. As discussed above, a
locking mechanism, such as a latch, restrains the motion of the
cover 300 along the length of the channel.
[0031] FIGS. 3C-3H show a perspective cross-sectional view of the
card 100. The cross section is taken along the length of the
e-paper 202 and channel. FIG. 3C shows the substrate 320, a portion
of the channel 325, e-paper 202 on the bottom of the channel 325
and a simple locking mechanism 324. The cover has not yet been put
in place. In this example, the locking mechanism 324 is a
cantilevered beam 329 with a tab 328 formed on the end that extends
above the upper surface of the e-paper 202.
[0032] In FIG. 3D, the cover 300 has been put in place and the tab
328 on the locking mechanism has engaged with a corresponding
aperture 332 in the cover 300. The cover 300 is now securely
fastened to the substrate 320. The channel 325 and the locking
mechanism 324 prevent the cover 300 from moving and prevent writing
to the e-paper 202. Until the locking mechanism 324 is disengaged
from the aperture 332, the cover 300 cannot slide down the channel.
More than one locking mechanism 324 may be included on the card 100
to increase the level of complexity and prevent unauthorized
alteration of the e-paper 202.
[0033] FIG. 3E shows a pin 330 being inserted through a hole 326 in
the cover 300 to depress the tab 328 on top of the locking
mechanism 324 and force it out of the aperture 332 in the cover
300.
[0034] FIG. 3F shows the pin 330 pressing downward on the tab 328.
This bends the cantilevered beam 329 that supports the tab and
forces the tab out of the aperture 332 in the cover 300. This
disengages the substrate 320 from the cover 300 and the cover 300
can then slide along the channel to expose the underlying e-paper.
The exposed e-paper can then be altered as desired using any of a
number of techniques described above. After erasing/writing is
complete, the cover 300 can be slid back into place and prevent any
further alterations.
[0035] After the transparent cover 300 and substrate 320 have been
disengaged from each other, the cover 300 has freedom to move. FIG.
3G shows the transparent cover 300 slid to the right and the
e-paper 202 exposed underneath. After the e-paper 202 has been
exposed, a new balance or any other new information on the card can
be written on the e-paper 202 with methods mentioned above.
[0036] In FIG. 3H the transparent cover 300 is slid back into
position and the locking mechanism 324 reengages with the cover 300
to secure it in place.
[0037] FIG. 3I shows the card 100 after a purchase was made. The
card 100 has been rewritten as described above to show the
appropriate balance ($13.47) on the card. As discussed above, the
protective transparent cover 300 was temporarily opened to write
and then closed to protect the e-paper during regular use. When
closed, the protective transparent cover 300 protects the e-paper
not only from tampering but from mechanical abrasion and
contamination. This protects the e-paper functional layers from
damage over its lifetime. The cover, e-paper, and locking
mechanisms fit within the limited thickness of a standard credit
card form factor. The locking mechanisms described herein allow a
properly designed tool to easily open the cover while preventing
anyone without the tool from opening the card.
[0038] The difficulty in disengaging the locking mechanism(s) is
directly related to the level of security provided by the cover.
For example, if the locking mechanism is relatively simple, as
shown above, the card would provide a lower level of security than
a card that used a more complex locking mechanism. More complex
locking mechanisms can be created in a number of ways, including
increasing the number of mechanisms that engage the cover,
concealing the locking mechanism so that it is more difficult to
circumvent, creating locking mechanisms that require specialized
equipment to disengage, and creating locking mechanisms that
require a high level of precision/coordination/sequencing to
disengage. Additionally, tamper detection could be used to discover
cards that have been surreptitiously altered.
[0039] FIGS. 4A-4E show a card that incorporates a locking
mechanism with two latches and a specialized card writing device
that allows locking mechanism to be disengaged and the e-paper of
the card to be altered. FIG. 4A shows cross sectional view of the
card taken along the length e-paper and side view of the
specialized card writing device 400 which includes a base 412 and a
sliding writing head 404. The base 412 includes a cavity 414 to
receive the card. Inside the cavity 414 there are two protrusions
402 that engage the apertures 432 in the card 100. The card 100
includes two locking mechanisms 424 that are similar to those
described in FIGS. 3A-3I. However, in this example, the
cantilevered beams and tabs are formed in the transparent cover
300, not the card substrate 320. The card substrate 320 includes
two apertures 432 that pass through the bottom of the channel. The
card includes a channel that allows the cover 300 to slide when the
tabs on the cover 300 are not engaged with the apertures 432 in the
bottom of the channel.
[0040] FIG. 4B shows a perspective view of the specialized card
writing device 400 and card 100 being placed into the cavity 414 of
the base 412 so that the protrusions 402 pass into the apertures
432 and disengage the tabs. FIG. 4C shows a side view of the
specialized card writing device 400 with the card 100 placed in the
cavity 414 with the protrusions 402 pushing the tabs of the locking
mechanisms 424 in the cover 300 out of the apertures in the card
substrate 320. The sliding writing head 404 is then slid over the
base 412. FIG. 4D shows that as the sliding writing head 404 slides
over the base 412, the transparent cover 300 is also slid to the
right with it, leaving the e-paper exposed. The writing head 410 is
then in place over a portion of the exposed e-paper 202 and the
information on the e-paper can be altered as needed.
[0041] As shown in FIG. 4E, after the writing is complete the
sliding writing head 404 is moved to the left, returning the cover
300 to its original position as shown. The card 100 can then be
removed from the specialized device.
[0042] Having the tabs and flexures in the cover rather than the
substrate may have a number of advantages. For example, by
incorporating the tabs and flexures into the cover, more of the
bottom of the channel in the substrate can be covered with e-paper.
Further, the e-paper surface is not disrupted by protrusions that
extend upward. This may simplify writing to the e-paper.
[0043] The cover may be formed out of any of a number of materials.
A transparent cover may be formed using any of a number of
materials, including polycarbonate, acrylic, polyvinylchloride,
polymethylmethacrylate, biaxially-oriented polyethylene
terephthalate, polyester or other suitable transparent material.
The cover may include a number of characteristics or additives that
improve the security of the card, such as transparent fibers to
increase the mechanical strength/stiffness of the cover or a
transparent conductive layer that dissipates electrical
charges.
[0044] Although the cover has been described as transparent, it may
be opaque or translucent. For example, if there is an application
where it is not desirable for the writing on the e-paper to be seen
except by authorized persons, the e-paper may be covered by an
opaque cover. In some embodiments, the card bearer may not even be
aware that the cover exists.
[0045] FIGS. 5A-5C and 6A-6C show several additional illustrative
locking mechanisms. These locking mechanisms are given only as
examples and are not intended to be exhaustive. A variety of
locking mechanisms could be used to secure the cover according to
principles described herein.
[0046] FIG. 5A is a cross section of a card 100 showing a locking
mechanism that includes cantilevered tabs 524, 526 that are
actuated by pins 530 from both sides of the card 100. This
increases the difficulty in sliding the cover 300 without
specialized tools because the two cantilevered tabs 524, 526 need
to be actuated simultaneously and from different directions.
[0047] FIG. 5B shows the cross section of a locking mechanism that
includes a cantilevered tab 528 in the card substrate 320 that
engages a groove in the cover 300. The tab 528 includes a magnetic
material 502 on its back surface. When placed on the base of a
writing device, an electromagnet 504 in the base can be actuated to
draw the tab 528 out of the groove in the cover 300, as shown in
5C. The magnet 504 induces a magnetic field 506 that pulls the
cantilevered tab 528 with the magnetized material 502 and
disengages from the groove in the cover 300. The magnetic material
on the cantilevered tabs may be a ferrous material or a magnet. If
the magnetic material is a ferrous metal (such as iron, nickel,
cobalt, alloys) the polarity of the electromagnet is not important.
Either polarity can attract the ferrous metal and withdraw the
tab.
[0048] Where magnets are used on the cantilevered tabs, the
polarity of the electromagnets becomes important. In some
embodiments, a series of tabs with different magnetic polarities
can be used. This series of tabs could only be withdrawn by a
properly ordered series of electromagnets. The implementations
shown in FIGS. 5B and 5C may have a number of advantages including
maintaining a smooth uniform outer surface of the cover. This could
increase the robustness of the device by preventing dirt and fluids
from accessing the e-paper through the cover. Additionally, there
are no features on the upper surface to interrupt the viewing of
the underlying e-paper.
[0049] FIGS. 5B and 5C are only one example of a magnetically
actuated locking mechanism. A variety of other embodiments may be
used. For example, moving magnets or other mechanisms that are
encapsulated within the substrate could be used as locking
mechanisms.
[0050] FIGS. 6A-6C show bistable mechanisms 610 that engage the
sides of the cover 300. In this example, the bistable mechanisms
610 are curved pieces of metal wire that are supported at each end.
The bistable mechanisms have two stable positions. In FIG. 6A the
bistable mechanisms 610 are shown in a first position where they
are arched inward toward the cover 300 and hold it in place. The
ovals 620 that are superimposed over the card represent magnetic
actuators that are used to change the bistable mechanisms 610
between their stable states. In FIG. 6A, the bistable mechanisms
610 may engage apertures in the sides of the cover 300 or hold the
cover 300 in place using friction.
[0051] FIG. 6B shows the outer electromagnetic actuators,
represented by the outer shaded ovals 630, moving the bistable
mechanisms 610 to a second stable state that is arched away from
the cover 300. In this configuration the bistable mechanisms 610
have disengaged from the cover 300 so that it can slide and the
e-paper can be altered.
[0052] FIG. 6C shows the inner electromagnetic actuators,
represented by the inner shaded oval 640, moving the bistable
mechanisms 610 back to their original state to lock the cover 300
over the altered e-paper.
[0053] This approach may have a number of advantages including
using locking mechanisms that are entirely contained within the
card and using actuation that would not be apparent from inspection
of the card.
[0054] A variety of other approaches could be used. For example,
the cover could be adhered to the substrate using thermal glue. To
remove the cover, the thermal glue is heated so that its strength
and/or adhesion properties are reduced. This allows the cover to be
removed from over the surface of the substrate. The e-paper is then
altered as desired and the cover replaced. The thermal glue is then
cooled and holds the cover in place.
[0055] Additional security can be obtained by using techniques to
detect cards that may have been tampered with. These techniques may
include incorporating features on the locking mechanisms that break
if they are not properly opened or covers provide visual indication
of unusual stresses that occur when the cover is pried off or
otherwise removed without the use of a proper actuator. This would
allow detection of tampered cards at the point of use. The cards
and/or card users could be more carefully inspected and the
transaction rejected if necessary.
[0056] FIG. 7 is a flowchart that describes one method for writing
to e-paper with protected imaging access. The method includes
placing e-paper with a cover in a writing device and activating an
actuator to unlock the cover (block 710). As discussed above, the
e-paper may have a variety of sizes and shapes, including a card.
The locking mechanism may include mechanical, electrical, magnetic
or chemical locking techniques, with appropriate actuators for
disengaging the locking mechanism or mechanisms. For example, the
e-paper may be pressed over protrusions to disengage cantilevered
latches to allow the cover to slide off the e-paper. Additionally
or alternatively, the activating the actuator may include
energizing electromagnets to disengage a latch holding the cover in
place. In some implementations, multiple actuators may be needed to
unlock the cover. These actuators may be simultaneously engaged
with multiple latches or other locking mechanisms holding the cover
in place.
[0057] The cover is removed to expose the e-paper (block 715). The
markings on the e-paper are altered (block 720). Altering markings
may include erasing current markings on the e-paper and/or writing
new markings on the e-paper. The cover is replaced and locked into
place (block 725) to protect the e-paper from unauthorized
authorization. The altered e-paper can then be removed from the
writing device.
[0058] By providing protective/removable access to the e-paper
within a card (or other e-paper application), the use of the card
is separated from the writing of the card. This passively improves
the security of the card against alteration or reimaging with an
unauthorized device. The implementations and principles described
above allow separate optimization of mechanical protection of
e-paper from electrical characteristics of the e-paper. The
mechanical protection of the removable cover guards the e-paper
from abrasion and unauthorized tampering. The optimized electrical
characteristics provide improved resolution and smaller dot sizes.
The locking mechanisms that hold the cover in place can be
automatically disengaged as part of the writing process but provide
a significant barrier against tampering
[0059] The preceding description has been presented only to
illustrate and describe examples of the principles described. This
description is not intended to be exhaustive or to limit these
principles to any precise form disclosed. Many modifications and
variations are possible in light of the above teaching.
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