Writable and erasable media and handheld writing devices

Abstract

The present invention relates to a handheld writing tool for generating a visual representation on a writable and erasable passive medium. The present invention further provides an assembly of the writing tool and the medium. The writing tool comprises a sensor capable of detecting non-visible light and a data processing entity configured to induce image elements of the medium to generate the visual representation by enabling and / or disabling individual inducer entities of the tool.

Description

[Technical field]

[0001] The present invention relates to a writable and erasable medium and a device for generating visual representations on the medium based on digitally and / or electronically stored information. The present invention relates to the field of electronic paper. More specifically, the present invention provides a handheld wireless writing tool and a writable and erasable medium for generating visual representations. [Background technology]

[0002] Writable and erasable media are substrates on which a user creates visual representations (graphical or textual information), typically with the aid of a writing tool, in which the visual representations can be erased and new visual representations can be created. A blackboard can be viewed as the prototype of a writable-erasable medium, where the writing tool is chalk and the medium is erased by cleaning the blackboard with the aid of a suitable cleaning solvent, such as water.

[0003] Simple writable and erasable media exist that avoid the drawbacks of writing tools such as chalk that wear out over time and need to be replaced, and the drawback of needing a solvent to erase the media. A well-known erasable medium that allows a user to write or draw information on the medium is the Magna Doodle display, which comprises a substrate filled with a thick, opaque, white liquid containing small, dark magnetic particles. The writing device in this case is a magnet-tipped stylus. When the magnet tip is close enough to the writing surface of the display, it creates a magnetic field that exerts a force on the dark particles, which are drawn to the drawing surface to create a visual effect. For erasure, the particles are removed from the drawing surface by a magnet, in this case in the form of an eraser bar that also slides on the back of the medium. In summary, the writing tool directs energy into the display to act on the magnetic image elements, which changes the position or orientation of the magnetic image elements in the medium to create a visual effect.

[0004] The Magna Doodle display is generally used as a toy and cannot be used to display digitally stored information.

[0005] It is desirable to generate visual information from external sources on a writeable-erasable display, as well as information generated directly by the user using a writing tool. Thus, the objective is to reproduce electronically and / or digitally stored visual information on a writeable-erasable medium with reasonable time efficiency and reproducibility. Techniques for generating digitally stored visual information on a display platform can be as simple as printing on paper with an inkjet or laser printer, which allows the exact same visual information to be reproduced in a short time compared to writing one stroke at a time. However, visual information printed on paper is typically non-erasable and therefore cannot be rewritten.

[0006] Commonly used LCDs (liquid crystal displays), OLEDs (organic light emitting diode displays) and electrophoretic displays are displays that can present digitally stored information and also provide erasable functionality. Unlike printed paper, an internal addressing device, e.g. a passive matrix or active matrix driving circuit containing millions of pixel control units, is required to write visual information. To achieve a larger displayable area and display resolution, the number of pixel control units required further increases, which requires more stringent quality control in manufacturing uniformity, higher capacity of driver ICs (integrated circuits), more complex system level control, and therefore the manufacturing cost and complexity increases faster than a simple linear trend. In the context of the present invention, it is an object to provide a writable-erasable medium that can be provided without an internal addressing device, so that the above-mentioned problems for increasing the displayable area can be avoided. It is an object to provide a bistable medium, so that the addressing process is only required to change the display content. The displayable area and dimensions are preferably not limited by the number of pixel control units, and therefore there is more flexibility in the selection of the display medium format and addressing tools. The manufacturing complexity and cost of the medium must also be reduced. On the other hand, such displays still require a writing tool to generate visual representations on the medium. The writing tool can be external or the medium can be provided integrally with the writing tool.

[0007] Electronically driven writable and erasable media encompasses e-paper. Electronic paper was probably first developed in the 1970s by Nick Sheridon of the Xerox corporation. The first electronic paper, called Gyricon, consists of polyethylene spheres between 75 and 106 micrometers in diameter (U.S. Pat. No. 5,389,945; U.S. Pat. No. 5,389,945). Each sphere is composed of negatively charged black plastic on one side and positively charged white plastic on the other (so each bead is a dipole). The spheres are embedded in a transparent silicone sheet, and each sphere is suspended in a bubble of oil so that the spheres can rotate freely. The display comprises many electrodes on both sides of the silicone sheet, so that an electric field can be generated at any desired position on the sheet. Thus, the polarity of the voltage applied to each pair of electrodes determines whether the white or black side faces out, thus giving the pixel a white or black appearance.

[0008] US Patent No. 5,389,945 discloses a Gyricon e-paper display using an addressable pen wirelessly connected to a workstation. The display includes alignment marks on the sides of the display to coordinate with appropriate sensors in the pen to track pen speed and alignment. The pen further includes an array of modulation electrodes. When the addressable pen is moved relative to the display sheet and the voltages at its individual modulation electrodes in the array are switched according to pixel information in the document to be written appearing at the remote workstation, an electric field is established between the electrodes and an electrically conductive ground plane. The electric field affects the orientation of the Gyricon spheres, thus resulting in the generation of a visual representation in the e-paper. However, the voltages required to generate the electric fields required in this system are very high, making a truly wireless pen difficult to realize. Furthermore, this concept requires the presence of alignment marks at the border of the medium, which may reduce the surface available for displaying. Furthermore, this concept requires the pen to be large enough to cover the entire display laterally. In other words, this concept limits the size of the display (or e-paper) in that the e-paper is necessarily narrower than the longitudinal length of the pen. In principle, the pen needs to be guided to ensure that the sensor can capture the alignment marks.

[0009] No. 6,498,597 discloses a scroll-like flexible medium housed in a cylindrical case, the mode of operation of which is similar to that of the Gyricon material based e-paper already described for U.S. Pat. No. 5,389,945.

[0010] US Patent No. 6,806,453 discloses a handheld scanning and printing device for scanning over paper-like rewritable sheets containing bistable electrochromic dyes that are susceptible to local electric fields. A drawback of this system is that scanning of the original image is required to obtain information that allows the device to identify the position and orientation of the print head contained in the device. As a result, the image cannot be scaled and cannot be used independently with writable sheets of various sizes.

[0011] US Patent Application Publication No. 2006 / 0170981 discloses a system for writing to a bistable medium using a write head. The write head comprises a roller containing write electrodes that can induce a write voltage that addresses a corresponding pixel when in electrical contact with an electrode of the medium. This teaching requires the establishment of electrical contact and thus current flow between the write head and the medium. This makes the medium susceptible to failure due to soiling and humidity. Furthermore, a roller-based write head makes the device difficult to implement as a handheld device.

[0012] "SweepScreen: Sweeping Programmable Surfaces to Create Low-fi Displays Everywhere," by Christos Mourouzi et al., Proc. CHI 2018, discloses a handheld writing device with an array of electromagnets combined with a motion sensor to generate an image on a magnetophoretic surface. Connected via a cable to a smartphone, the device includes an optical mouse sensor to track the device's position. The paper proposes the generation of a merged photo, and a camera that automatically detects already printed parts of the image.

[0013] US Patent Application Publication No. 2020 / 0201454 discloses a large area display with an IR sensor located on the display to enable a stylus to enable localized erasure of a photo. Summary of the Invention [Problem to be solved by the invention]

[0014] The present invention achieves the above objectives. [Means for solving the problem]

[0015] The inventors achieve the objective of providing a writable-erasable medium and / or e-paper display, preferably a passive non-emissive medium, and / or a writing device, that can be used to generate visual representations based on electronically and / or digitally stored data.

[0016] It is an aim to provide a medium that does not include internal addressing systems, e.g. active or passive matrix, that require complex and costly microfabrication steps.The present invention provides a medium that offers many possibilities related to the materials used and to the realization of lightweight and / or flexible displays.

[0017] It is an object to provide a medium that can be addressed by a writing tool without imposing any constraints related to the relative and / or absolute dimensions of the medium and the writing tool.

[0018] It is also an object of the present invention to provide a handheld wireless writing tool for generating visual representations on a medium.

[0019] Additionally, it is an object to provide a writable-erasable medium that may be further adapted for use with a pen-like handheld writing tool for generating visual representations, particularly by a user moving a pen-like driver device across the surface of the medium, to provide a more intuitive operation in terms of degrees of freedom in relative printing direction and in terms of the angle between the writing tool and the medium.

[0020] In one aspect, the present invention provides a writing device adapted for generating a visual representation on a writable-erasable medium, the device comprising: - a sensor capable of detecting non-visible light, the sensor being configured to generate a signal related to two-dimensional marker information associated with the writable-erasable medium; - a plurality of inducer entities, each of the inducer entities configured to independently assume at least two states: a first state, an inducing state, and a second state, a passive state; a data processing entity configured to act on individual inducer entities to switch between a first state and a second state, the data processing entity preferably comprising: (1) based on a signal generated by a sensor and / or a visual representation generated on a writable-erasable medium; (2) taking into account the signals generated by the sensor and / or the visual representations generated on the writable-erasable medium; and / or (3) as a function of the signal generated by the sensor and / or the visual representation generated on the writable-erasable medium; a data processing entity configured to act on the inducer entity; A writing device is provided, comprising:

[0021] In one aspect, the present invention provides a writing device adapted for generating a visual representation on a writable-erasable medium, the device comprising: - a sensor capable of detecting non-visible light, the sensor being configured to generate a signal related to two-dimensional marker information associated with the writable-erasable medium; - a plurality of inducer entities, each of which is configured to independently assume at least two states, a first state being an inducing state and a second state being a passive state, and wherein when in the first state, the inducer entity is configured to direct a predetermined amount of energy in a predetermined direction; - a data processing entity configured to act on respective inducer entities to switch between a first state and a second state, the data processing entity being configured to act on the inducer entities based on a signal generated by a sensor and / or based on a visual representation generated on a writable-erasable medium; A writing device is provided, comprising:

[0022] In one aspect, the present invention provides a writing tool configured to write to, drive and / or address the writable-erasable medium of the present invention.

[0023] In one aspect, the present invention provides a writing tool configured to generate a visual representation of visual information digitally stored on the writeable-erasable medium of the present invention.

[0024] In one aspect, the invention provides a writable-erasable medium comprising a plurality of image elements that, depending on the position, configuration, orientation, and / or light absorption characteristics of the image elements in the medium, affect the reflection and / or transmission of visible light impinging on the writable-erasable medium and contribute to the generation of a visual representation. Preferably, the medium further comprises two-dimensional marker information.

[0025] In one aspect, the invention provides a writable-erasable medium capable of providing an erasable visual representation, the medium comprising a plurality of image elements that, depending on the position, configuration, orientation, and / or light absorption characteristics of the image elements, affect the reflection of visible light impinging on the writable-erasable medium and contribute to generating the visual representation, the medium further comprising two-dimensional marker information, the marker information being transparent to visible light.

[0026] In one aspect, the invention provides a writable-erasable medium configured to be written to, addressed and / or driven by a device of the invention.

[0027] In one aspect, the present invention provides an assembly comprising a writing device of the present invention and a writable-erasable medium.

[0028] Further aspects and preferred embodiments of the present invention are defined hereinbelow and in the appended claims. Further features and advantages of the present invention will become apparent to those skilled in the art from the description of the preferred embodiments set forth below. [Brief description of the drawings]

[0029] [Figure 1] FIG. 1 is a schematic diagram of a handheld device according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic top-down view of a medium according to an embodiment of the present invention, with marker codes visible and enlarged for illustrative purposes. [Diagram 3] 3 is a schematic cross-sectional view illustrating the writable-erasable medium of FIG. 2 and an inducer entity of the hand-held device of FIG. 1 operatively positioned relative to an image element of the writable-erasable medium. [Figure 4] FIG. 4 illustrates the generation of visual information in a medium according to an embodiment of the present invention. [Diagram 5] FIG. 5 is a schematic diagram illustrating the placement of individually addressable inducer entities in a handheld device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] In the following, preferred embodiments of the device of the present invention are described to illustrate the present invention without any intention of limiting the scope of the present invention.

[0031] The present invention relates to a writing device for a writable-erasable medium and to a medium which can be written by the writing device.

[0032] The term "medium" in the context of the present invention encompasses displays, screens, platforms, e-paper, and any other type of substrate that comprises a surface on which a visual representation can be displayed. Preferably, the medium comprises a generally smooth, and preferably flat and / or planar display surface. The medium may also be a flexible and / or curved medium.

[0033] The term "visual representation" encompasses graphical information including images, graphs, lines, and written information, such as letters, words, numbers, signs, text, etc. A "visual representation" is preferably visible and identifiable by the human eye and therefore reflects or emits light in the visible spectrum. A "visual representation" is preferably provided and / or present in the device of the invention in the form of electronic and / or digital data, and is generated by the device based on such data. As the invention relates to a writable and erasable medium, the visual representation generated on the medium is preferably writable and / or erasable.

[0034] The visual representations generated by the devices and / or tools of the present invention are preferably stable, semi-stable, and / or bistable. After the visual representation is generated, it preferably remains visible and / or readable for a period of time long enough to fulfill the desired purpose of the image or information medium. For example, after generation, the visual representation preferably exists for 30 seconds to 48 hours or more, preferably 1 minute to 24 hours or more, more preferably 5 minutes to 12 hours or more, and most preferably 10 minutes to 6 hours or more.

[0035] The term "writable-erasable" denotes that a visual representation can be shown and erased from the medium, e.g., cancelled or cleared, and a new, other and / or the same visual representation can thereafter be shown. The medium can be used for repeated writing and erasing, and is thus preferably rewritable and / or re-erasable. The generation of a visual representation on the medium can be considered as writing to the medium, printing to the medium, addressing the medium, and / or driving the medium, which is preferably performed by a writing tool of the present invention.

[0036] 1 illustrates an embodiment of a writing tool 10 in accordance with an embodiment of the present invention. In practice, the writing tool may also be referred to as a "writing device," an "addressing device," a "printing device," or a "driver," since the writing tool is configured to act on pictorial entities contained in a medium to generate a visual representation.

[0037] The writing tool 10 is preferably configured to use digital and / or electronic information, preferably digitally and / or electronically stored information, and to act on the medium based on that information to generate a visual representation corresponding to the medium. Due to the ability to write, erase, and rewrite digitally stored information, the medium of the present invention may also be referred to as electronic paper or e-paper.

[0038] The writing tool 10 is preferably wireless. The writing tool 10 preferably comprises a wireless communication module or unit 61. Furthermore, the writing tool preferably comprises an internal source of electrical energy, for example a battery or a solar cell (not shown).

[0039] The writing tool 10 is preferably hand-held and / or hand-held. The writing tool 10 is preferably adapted to be held in a user's hand so that the user can move and preferably slide the writing tool 10 over the medium as shown in FIG. 4 and as described in more detail herein below. Thus, the writing tool 10 preferably has a relatively light weight, for example 1 kg or less, preferably 500 g or less, more preferably 100 g or less. For example, the writing tool has a weight of 10 g to 100 g. Preferably, the writing tool can be easily operated by the average person, and preferably even by a child, and furthermore is easy to carry by the user for use at any time, for example while on the go.

[0040] Writing tool 10 may be realized in the form of an elongated bar, as shown in Figures 1 and 4, but may have any shape that makes it suitable for manual manipulation. For example, the writing tool may have an ergonomic profile that is adapted for gripping in the hand and that facilitates handheld use.

[0041] The writing tool 10 further comprises a lower, preferably substantially flat, surface 11 that is intended to be in contact with, in close proximity to, or within a predetermined maximum working distance from the media surface 35 of the media when the tool is used to write a visual representation on the media. The position of the device when it is used to write a visual representation on the media is also the "operative" and / or "operable" position of the device relative to the media. In this position, the flat lower surface 11 of the device is generally as close as possible to the upper surface 35 of the media, and surfaces 11 and 35 extend substantially parallel.

[0042] As described elsewhere herein, there may also be operable positions where the writing device is not in direct contact with the media, for example, where the writing device is spaced apart from the media and / or where the lower surface 11 of the writing device is positioned at an angle, particularly with respect to the viewing surface 35 of the media.

[0043] It is noted that the writing tool comprises a casing 12, with the internal components generally mounted within and / or retained by or within the casing. The underside 11 may be considered to be part of the casing.

[0044] The writing tool preferably comprises one or more sensors 21. The sensors are preferably suitable for capturing non-visible light, for example UV (ultraviolet) and / or infrared (IR). In an embodiment, the sensor or sensors capture exclusively UV light, exclusively IR light, or exclusively IR and UV light.

[0045] For purposes of this specification, UV light is light having a wavelength between 10 nm and 400 nm.

[0046] For purposes of this specification, IR light is light having a wavelength from 700 nm to greater than 1 mm.

[0047] For purposes of this specification, visible light is light having a wavelength from 400 nm to greater than 700 nm.

[0048] The sensor is preferably a 2D image sensor. The sensor (or several sensors) is preferably adapted to capture a two-dimensional (2D) pattern and to generate a signal related to the 2D pattern. As explained in more detail below, the 2D pattern is preferably marker information related to the medium.

[0049] In an embodiment, the sensor 21 is selected from a CMOS or CCD image sensor.

[0050] In an embodiment, the tool comprises an optical element 25. The optical element is provided to guide, direct, focus, and / or filter light reflected from the surface towards the sensor. The optical element is preferably positioned such that an image of the markers on the medium can be clearly and / or effectively captured by the sensor. The optical element may include one or more selected from the group consisting of lenses, mirrors, and optical filters. The light directed by the optical element preferably includes non-visible light reflected or emitted from the marker information associated with the medium. The optical element is preferably positioned to capture light that strikes an opening or window in the lower surface 11 that is near the media surface 35 of the medium and preferably in contact with the media surface 35 of the medium during use.

[0051] In an embodiment, the writing device preferably comprises a light source 70. Preferably, the light source emits non-visible light, preferably IR and / or UV light, more preferably exclusively IR and / or UV light. The light source 70 and optics 25 are preferably positioned on the device such that when the device 10 is operatively positioned on the surface 35 of the media (FIG. 3), the light emitted by the source 70, when reflected by the marker information 31 contained in or on the media, is directed towards the optical system 25 and guided towards the sensor 21.

[0052] Preferably, the light source and the sensor are an integral part of the writing device.

[0053] It should be noted that a light source may not be required in situations where there is sufficient light from the environment reflected by the marker information 31, such as when the device is used in the presence of direct sunlight. However, since the device is preferably configured to be operable in all situations, a light source is preferably present to ensure that sufficient light is reflected so that the sensor produces an interpretable signal in all situations.

[0054] The writing tool preferably comprises a data processing entity 60, for example comprising a microprocessor and / or CPU (Central Processing Unit) 63, and a memory 62, in particular comprising a memory for digitally stored information, such as a RAM and / or ROM memory. The information stored in the memory is preferably related to the visual representation to be displayed on the medium. The memory 62 may further be a removable memory, for example in the form of an external memory, for example a USB stick or a memory card, removably connected or inserted in the tool.

[0055] In another embodiment, the invention encompasses that digital and / or electronic data corresponding to the visual representation is communicated by wireless transmission in real time while the visual representation is being generated, and thus is not necessarily stored, or is only partially stored, in the device of the invention. The data may be transmitted, for example, from a wireless module in a workstation, or from any other source from which data may be transmitted, for example, by wireless transmission.

[0056] Preferably, the device comprises software and / or firmware for operating the device.

[0057] In an embodiment, the data processing entity is configured to determine from the signal generated by the sensor one or more selected from the group consisting of: (i) a position of the hand-held device relative to the writable-erasable medium, (ii) an orientation or angle of the hand-held device relative to the writable-erasable medium, and (iii) a position and / or orientation of one, some or all of the inducer entities associated with the writable-erasable medium, and in particular associated with an image element of the writable-erasable medium.

[0058] Preferably, the position referred to is an absolute position of the writing device with respect to the writable-erasable medium. Preferably, the position is not a relative position, i.e. a position specified with respect to a previous position of the writing device.

[0059] Since the marker information is preferably 2D information, the data processing entity is preferably configured to further determine the distance and / or angle of the writing device relative to the medium, and in particular relative to the viewing surface of the medium. Depending on the inducer entity, and the technique or energy used by the inducer entity, the image may be generated with the writing device at a distance from the surface, as long as the inducer entity and the image element are in an operable position relative to one another. However, although the sliding of the writing device 10 over the viewing surface 11 of the medium preferably involves, for example, direct physical contact between the writing device and the medium, writing and / or erasing may also be performed at other relative positions between the writing device and the medium, in particular without direct contact, with the writing device and the medium separated by a distance relative to one another.

[0060] The device preferably includes an algorithm capable of determining which inducer entities need to be enabled and / or disabled and for how long when the device is in a particular (operable) position on the medium to generate the visual representation. It can also be said that the algorithm determines which inducer entities to enable and / or disable at what point in time when the device is moved by the user over the medium (FIG. 4).

[0061] The CPU and / or device is preferably configured to use the signals received from the sensors 21 and the digital information associated with the visual representation to control inducer entities 41, 42, 43 etc. preferably provided near the lower surface 11 of the tool. Reference numeral 64 denotes a data bus and / or electrical lines for controlling the activity of the inducer entities.

[0062] The inducer entities are configured to be controlled, i.e. enabled and disabled, e.g. switched on and / or off, by the data processing entity 60. Each inducer entity may exist independently from other user entities in a first enabled and / or inducing state, and in a second passive or non-inducing state.

[0063] The device of the present invention preferably comprises a plurality of inducer entities. Preferably, the device comprises 5 to 10000 inducer entities, more preferably 7 to 5000 inducer entities, and even more preferably 10 to 2000 inducer entities. In a preferred embodiment, the device comprises 20 to 500 inducer entities.

[0064] In an embodiment, the device comprises 25 or more, preferably 30 or more, and most preferably 50 or more inducer entities.

[0065] When in an active state, the inducer entity preferably emits a predetermined amount of some form of energy in a predetermined direction, in particular adjacent to the underside 11 of the device which, in use, is near or even in contact with the media surface 35. The predetermined amount of energy is preferably suitable to enter the media and to affect image elements contained in the media and to cause the image elements to produce a response which favorably affects the light reflected or emitted by the media.

[0066] The above-described process in which an inducer entity of device 10 acts on an image element in a medium provides a writing process that is the generation of a visual representation in the medium. To generate a desired visual representation, the tool preferably activates a particular inducer entity when the particular inducer entity is at a spatial location relative to a particular image element that is used to generate the visual representation (e.g., made visible), the spatial location of which allows the inducer entity to act on the image entity and / or induce a response of the image entity, thereby generating a visual effect that contributes to the visual representation. The spatial location generally depends on the distance between the inducer entity and the image element, the relative position or orientation of the inducer entity, and the particular form of energy emitted from the inducer entity.

[0067] In accordance with the above description, the expression "a predetermined amount of energy in a predetermined direction" is generally intended to mean that when enabled, the inducer entity is configured to generate a response in one or more image elements present at a particular location in the medium, as described herein, that contributes to generating a visual representation.

[0068] When an inducer entity acts on an image element, the latter is generally altered in its position, configuration, orientation, and / or light absorption properties, thereby affecting the modulation (e.g., reflection) of visible light impinging on the medium and contributing to the generation of a visual representation.

[0069] In the context of the present invention, "a predetermined amount of energy in a predetermined direction" refers to the ability of the inducer entity, when enabled, to generate and / or modulate an electromagnetic force and / or emit electromagnetic energy in the direction of the image element. Preferably, when in an induced state, the inducer entity emits energy in one or more forms selected from a magnetic field, electromagnetic radiation waves, and an electric field.

[0070] In an embodiment, the inducer element is preferably configured to generate or regulate one or more selected from a magnetic field, an electric field, and electromagnetic radiation waves.

[0071] Preferably, the applicable magnetic fields, electric fields, and electromagnetic radiation waves are directed in such a manner and / or in such a direction to exert a force or influence on the image elements, thereby inducing a response in the image elements that contributes to generating a visual representation.

[0072] As is apparent from the above description, the image elements are selected to be responsive to the energy and / or force provided by the activated inducer element, the response of the image elements to the activated inducer element being one or more selected from a change in position, configuration, orientation, and / or light absorption properties of the image elements.

[0073] The position, configuration, and / or light absorption properties of the picture elements are varied so that a desired visual effect is produced in the medium. The response of the picture elements affects the reflection of visible light that strikes the writable-erasable medium, thereby contributing to the production of a visual representation.

[0074] It should be noted that the writing tool and medium are configured such that when writing, an enabled inducer element acts on a limited, preferably predefined, number of image elements, which are at specific locations in the medium. In general, when enabled, the energy or force emitted by the inducer element is sufficient only to induce a response in a limited number of image elements closest to the inducer element and / or which are at a specific, preferably predefined, position and / or orientation relative to the inducer element, which may be referred to as the inducer position.

[0075] In an embodiment, the inducer entity emits energy in the form of a magnetic field (or generates a magnetic field). In this case, the image elements are preferably responsive to the magnetic field. Preferably, the image elements comprise ferromagnetic and / or ferrimagnetic components.

[0076] In an embodiment, the inducer entity emits energy in the form of an electric field (or generates an electric field). In this case, the image element is preferably responsive to the electric field. Preferably, the image element is selected from a material having one or more electric charges, the material comprising one or more permanent or non-permanent electric dipoles. Non-permanent dipoles are generally materials that can be induced by an electric field to form electric dipoles. Furthermore, non-permanent electric dipoles adjust their orientation in the presence of an electric field and therefore may be used according to the present invention.

[0077] In an embodiment, the inducer entity emits energy in the form of electromagnetic radiation (or generates electromagnetic radiation), in which case the image element is preferably responsive to the electromagnetic radiation. Preferably, the image element comprises one or more selected from photochromic, photoelectrochromic, fluorescent, and / or phosphorescent components.

[0078] Preferably, in the enabled state, the energy or force provided by the inducer entity is suitable to cause the image element to produce a desired response which preferably results in a desired visual effect. As mentioned above, the visual effect is preferably stable, semi-stable and / or bistable.

[0079] For completeness, it is explained that when an inducer entity is not enabled, deactivated, or disabled, any electromagnetic force, energy, or light that may be emitted by the deactivated or disabled inducer entity, even when the inducer entity is at an operable distance or orientation relative to such image entity, is preferably not sufficient to induce a visually discernible response of the image entity in the medium. In preferred embodiments, a deactivated or disabled inducer entity does not generate one or more selected from an electric field, an effective magnetic field, as applicable, and / or does not emit electromagnetic radiation waves.

[0080] When the inducer entity emits energy in the form of a magnetic field, the inducer entity may comprise, for example, a permanent magnet and / or an electromagnet. For example, if the inducer entity comprises a permanent magnet, activation of the inducer entity may be to move the permanent magnet closer to the lower surface 11 of the device 10, so that the magnetic field emanating from the tool at the lower surface is strong enough to act on the ferromagnetic and / or ferrimagnetic image elements contained in the medium. In this configuration, the device 10 preferably comprises a mechanical system for acting on the permanent magnet, e.g., for pulling and pushing the magnet, to generate sufficient energy to act on the image elements.

[0081] The Magna Doodle display mentioned in the introduction is an example of a visual representation generated under the influence of the magnetic field of a permanent magnet.

[0082] In embodiments in which the inducer element comprises an electromagnet, the inducer element may be switched on and off simply by directing current through a coil that surrounds the core material in the electromagnet configuration.

[0083] In embodiments where the inducer entity is configured to generate an electric field acting on the image elements, the inducer elements preferably comprise electrodes that can be switched on and off. The electrodes can be provided in the form of an array. An example of an image element that responds to an electric field can include the Gyricon e-paper display system, which is based on spherical beads with a surface charge that gives each bead a dipole moment. The manufacture of such beads is described in US Pat. No. 6,097,531. The beads are provided in oil-filled capsules, and the beads can rotate in response to the electric field. Depending on the rotational position, the beads can expose a particular color, black, or white, to the viewing surface of the medium.

[0084] In an embodiment in which the inducer entity is configured to generate electromagnetic radiation waves that act on the image element, the inducer element preferably comprises a light source, and the image element preferably comprises one selected from photochromic, photoelectrochromic, fluorescent, and / or phosphorescent materials. Thus, when illuminated by the light source of the inducer element, the image element changes and / or exhibits a desired color characteristic. For example, the image element may change or emit color depending on the wavelength of light impinging on the image element. An exemplary document disclosing a photochromic medium is JP2004-258474.

[0085] For purposes of this specification, black and white are considered colors.

[0086] In this example, it should be noted that the size of each image element is not particularly limited, since the image elements can be selected from molecules and particles. Depending on the desired resolution, it is preferable to include image elements that are relatively small, preferably close to the border of what the human eye can distinguish as an independent entity. In an embodiment, the image elements of the present invention have a maximum dimension within the range of 0.5 nm (for molecules) to 1.5 mm, preferably 1 nm to 1 mm, and even more preferably 5 nm to 0.5 mm.

[0087] When the image elements are particles, e.g. ferromagnetic or ferrimagnetic particles and / or particles with a permanent or non-permanent dipole moment and / or with an electric charge, the size of the particles is preferably selected from nano- and microparticles, preferably in the range of 1 nm to 200 μm, preferably 0.5 μm to 100 μm, most preferably 1 μm to 50 μm. In an embodiment, the particles have an average size of 1 μm to 10 μm.

[0088] As will be appreciated herein, the response of one image element to an enabled inducer entity may not be sufficient to cause a change in the medium that is noticeable to the human eye. Thus, an enabled inducer entity will generally generate responses in multiple image elements, as shown in Figure 3. It should be noted that one skilled in the art may adjust the response generated by the inducer entity in the image elements of the medium by adjusting the amount of energy emitted, e.g., the magnitude of the magnetic and / or electric field and / or the strength of the electromagnetic radiation.

[0089] The present invention further provides a medium 20 configured to display a visual representation 50 when addressed or driven by a writing tool 10 (FIG. 4).

[0090] In a preferred embodiment, medium 20 includes marker information, which is preferably 2D marker information.

[0091] The 2D marker information is preferably provided in the form of a plurality of marker images or codes 31, 32, ... as shown in Figure 2. The marker images or codes 31, 32 may for example be provided in the form of a QR code or in the form of any other suitable 2D representation, image, sign or shape.

[0092] Preferably, the marker information is provided on a transparent support 30. Preferably, the transparent support provides at least a portion of the viewing surface 35 of the medium. Preferably, the transparent support with the two-dimensional marker information is an integral part of the medium. In an embodiment, the support provides the viewing surface of the medium.

[0093] In an embodiment, marker information, e.g., an image or code, is dispersed across a surface 35 of the writable-erasable medium, which surface 35 corresponds to or at least partially overlaps with a viewing surface 35, and a visual representation is provided on and / or through the viewing surface 35 that is viewable to a user of the medium.

[0094] In a preferred embodiment, the marker information 31, 32, ... is permanent and / or independent of the navigable image elements 81, 82.... Preferably, the marker information, e.g., an image or code, is not generated or induced during use of the tool. Preferably, the marker information remains unchanged and / or the same for a given medium, preferably over the life of the medium.

[0095] In the embodiment shown in Figure 2, the marker information, particularly images or codes, are arranged together in an array and / or in rows and columns across the viewing surface, with the lines and / or rows preferably forming an array. Preferably, adjacent images or codes in an array are spaced a constant distance apart. In other words, the distance from one code to the next in the same line and / or row of the array preferably remains constant.

[0096] Preferably, the marker density per unit length is equal to or greater than the density per unit length of addressable image pixels (or other image units, dots, patches, etc. (see references 85, 86 and description of FIG. 3)) on the medium. The density of markers on the medium determines the quality of images that the writing tool and medium system can produce.

[0097] In a preferred embodiment, each marker code and / or image is asymmetric. This also preferably applies to the 2D aspects of the marker code. Preferably, the marker code and / or image does not contain an axis of symmetry in the 2D surface on which it is provided.

[0098] In a preferred embodiment, each marker code and / or image is unique within a particular writing medium. Each marker code and / or image preferably includes a unique asymmetric image that cannot be moved to be congruent with any other marker code and / or image, even when the marker code and / or image is rotated (mentally). This is preferably true for the 2D aspect of the marker code. Thus, a given geometric 2D arrangement (e.g., a QR code) appears only once in each medium, and thus the position and orientation of the writing tool in the medium can be specified based on only one marker 31, 32, etc. In other words, any marker element 31 is completely different from any other marker element 32 in the medium.

[0099] In another embodiment, multiple marker elements captured together provide a unique 2D arrangement in the medium, and the writing tool includes one or more sensors capable of capturing multiple marker elements simultaneously or within a relatively short period of time, for example when the writing device is stationary or in motion.

[0100] FIG. 3 shows selected components and media obtained from a writing tool in accordance with an embodiment of the present invention to illustrate the principles of operation.

[0101] In the embodiment shown, medium 20 includes a top surface 35, which is also the display surface of the medium through which the visual representation is displayed and viewable by a user of the medium. In the embodiment shown, top surface 35 is the top surface of a transparent substrate 30, which is preferably transparent to visible light, but need not be transparent to IR and UV light.

[0102] The marker information 31, 32, ... is preferably provided on the substrate 30. According to this embodiment, the marker information is provided directly on the viewing surface 35 of the medium.

[0103] In one embodiment (not shown), the marker information is provided on the underside of a transparent substrate, with an opposing top side of the substrate providing the viewing surface 35 of the media. In this embodiment, the bottom side of the transparent substrate is preferably oriented toward the inside of the device, while the top side is oriented outward. In such an embodiment, or even in other cases, the substrate 30 is also transparent to light emitted by the writing tool light source 70 (FIG. 1) and to non-visible light (e.g., UV, IR) that is reflected from the marker information 31, 32, ... and captured by the sensor 21.

[0104] The marker information may be printed or engraved onto the substrate 30, preferably a transparent substrate.

[0105] The marker information 31, 32, ... is preferably transparent to visible light, but preferably reflects and / or absorbs non-visible light. Preferably, the marker information reflects or emits non-visible light, e.g. UV and / or IR light. Most preferably, the marker information reflects or emits exclusively UV and / or IR light.

[0106] As can be understood in view of Figures 1 and 3, when the writing tool 10 is moved over the medium, the sensor 20 of the writing tool 10 generates signals related to the light reflected and / or emitted by the marker information. These signals are interpreted by the data processing entity 60, for example by an algorithm contained in the data processing entity, in order to determine the position and orientation of the writing tool on the display surface of the medium and thus also the specific positions and / or orientations of the inducing entities 41, 42, 43... on the medium and in particular the relative positions of the inducing entities with respect to the image entities 81 or sections 85, 86 contained in the medium. Based on the information related to the visual representation generated on the medium, the writing tool 10, and in particular the data processing entity 60, activates and / or deactivates the inducing entities 41, 42 at the right time and / or when they are in the right position in order to activate the image element 81 or the image elements provided in the section.

[0107] 3, the inducer entities 41, 42 are electromagnets that, when switched on, generate a magnetic field 90 that penetrates into the medium 20 containing image elements 81 in the form of ferromagnetic and / or ferrimagnetic particles. In the embodiment shown, these ferromagnetic and / or ferrimagnetic particles are dark or black and are attracted towards the viewable display surface 31 under the influence of the magnetic field 90. As they do so, they displace the white or clear particles 82 to produce colored, dark or black spots on the viewable surface.

[0108] In another embodiment, the ferromagnetic and / or ferrimagnetic particles may move across a clear or white, preferably semi-permeable, substrate, which may be substantially immobile.

[0109] In the embodiment shown in Fig. 3, the image elements 81, 82 are provided within spatially defined and / or confined compartments, cavities, unit blocks, image dots and / or pixels 85, 86. The compartments preferably provide and / or define individually addressable image dots or units. Preferably, the size of the compartments is constant and / or the density of the compartments (number of compartments per unit length) over a distance is constant in the medium.

[0110] One purpose of the partition is to limit the lateral spatial movement of the image elements over long distances, which may result in a non-uniform spatial distribution of the image elements at longer distance scales. The lateral walls can ensure that the amount of image elements within the dimensions of the partition is constant, and therefore the achievable color contrast of the image dots can be guaranteed. In the case of media that do not include lateral walls, the image elements may accumulate excessively in certain localized areas due to the magnetic field attraction, resulting in some areas not containing image elements, and as a result, the image quality of the generated visual representation is also reduced.

[0111] In Fig. 3, the underside 11 of the writing tool 10 is shown not to be in direct physical contact with the substrate 30 of the medium. The tool 10 may comprise spacing maintaining elements (not shown), for example mounted at some positions on the underside 11 of the device, to maintain the underside 11 at a predefined, preferably constant, distance away from the upper surface of the medium. Such spacing maintaining elements may be provided by rolling balls or sliding elements comprising a low friction material that favors sliding of the device over the medium. In another embodiment, the underside 11 of the device 10 slides directly over the upper surface of the medium, over the substrate 30 and / or over the markers 31, 32.

[0112] In another embodiment, the lower surface 11 is away from the substrate 30 within a maximum design working distance where the inducer entities 41, 42 can still address the image element 81, and the lower surface is not necessarily parallel to the substrate 30. According to this embodiment, the distance information between each inducer and the corresponding addressing image element 81 is calculated by a stored algorithm based on the deformation of the marker image captured by the image sensor 21. For example, when the writing tool 10 is away from the media surface 35, the captured marker image is smaller than the marker image when the writing tool 10 is closer to the media surface 35. When the lower surface 11 of the tool 10 is not parallel to the media surface 35, the captured marker image shows a smaller dimension in the direction where the writing tool is more inclined to the surface 35. This embodiment can be applied, for example, to an embodiment in which the inducer element emits energy in the form of electromagnetic radiation waves, which are suitable for inducing a response in the image element even when the writing device is at a defined working distance away from the media.

[0113] 4 illustrates the generation of a visual representation 50 (text in this example) by using a writing device 10 and preferably manually sliding the device over a display surface 35 of a medium 20. The inducer entities 41, 42 of the writing device are shown only diagrammatically. While a data processing entity in the device 10 locates the device over the medium, the device activates the inducer entities 41, 42, which act on image entities of the medium as they move over the medium 20 to generate the visual representation 50.

[0114] In this configuration, the advantage is that the writing device 10 is completely free-floating or freely movable and is not connected to any other base station and device. The device does not require markers provided on the side frame of the device and does not require any specific starting point provided anywhere on the medium or its frame. The driver device 10 can therefore have any shape size or form, in particular a maximum width L that can be smaller than any one of the respective sides 28, 29 of the medium 20. Furthermore, using the device of the invention the writing process can be arbitrarily started at any position of the medium. Information related to the size of the writable surface medium can for example be coded in the marker information or can be entered as an input by the user into the writing device.

[0115] Furthermore, in contrast to the writable-erasable media described in the prior art, the devices of the present invention do not require an initial reading or scanning step in which the visual representation is first read before it can be reproduced on the media.

[0116] Thanks to the multiple inducers, the writing tool is configured to write or print on consecutive and / or contiguous areas of the medium when the device moves in a writing mode relative to the medium (FIG. 4). As the user moves the device 10, areas of the medium that have already been written to may be at least partially covered again by the device. In other words, areas covered by a device that is manually moved by the user over the medium when writing a visual representation may overlap and / or certain areas may be repeatedly covered by the device in writing one visual representation and / or in one writing process (as opposed to erasing and then rewriting, in which the same areas are logically covered again).

[0117] In a preferred embodiment, the device includes and / or uses algorithms and / or computer code that cause the device to store areas, pixels, dots, sections, etc. of the medium that have already been written to, avoiding reprinting the same areas, pixels, dots, sections, etc., respectively. In this manner, the writing process can be performed at optimal resolution and without loss of information in the visual representation. Such algorithms and / or codes are particularly useful when the writing device comprises many inducers that may cover very small distances as described with reference to FIG. 5.

[0118] The media of the present invention is preferably writable and erasable, so that any visual representation 50 created may be erased by the action of the writing device 10. The erasure mechanism depends on the system of image elements and inducer entities used. For example, if the image elements are responsive to electric fields, then an electric field with the opposite polarity to the field used to create the visual representation may be used to erase the visual representation.

[0119] Erasing of writable-erasable media responsive to a magnetic field may be accomplished by a permanent magnet moved behind the media. More generally, a permanent magnet may be used to attract image elements in a direction opposite to that induced by the writing device. In embodiments where the image elements comprise permanent magnets with different colors on either side or different sides of the pole, erasure may be accomplished by flipping the image elements using a permanent magnet or electromagnet with the opposite polarity. If the writing device comprises an electromagnet, the polarity of the magnet may be reversed by changing the direction of the current flowing through the coil wire of the electromagnet, and the writing device may also be used to erase the visual representation. In embodiments where the image elements are more ordered and / or clustered as they contribute to the image, a permanent magnet may disperse the image elements.

[0120] If the image element is responsive to electromagnetic radiation, and particularly if the image element is a photochromic material, erasure may be achieved by irradiating the medium with light suitable for reversing the color change caused by the light emitted by the inducer entity.

[0121] Where the imaging element is a photoelectrochromic material, erasure may be achieved by electrical means, for example by providing electrodes and applying an electrical potential suitable for removing photogenerated electrons from the photoelectrochromic material.

[0122] In some embodiments, the medium may further comprise electrodes provided specifically for erasure.

[0123] In Figures 1, 3 and 4, the inducer entities 41, 42... of the writing tool are shown forming a linear array, one inducer entity next to another on a straight line. Of course, the writing tool is not limited to such an arrangement and the inducer elements may be located in the writing tool in any desired manner. It should be noted that there is preferably a predetermined, and in one embodiment a constant, distance between each inducer entity and its nearest neighbor. According to this embodiment, there is preferably a predetermined constant distance between the inducer entities.

[0124] In an embodiment, the inducer entities of the writing tool are preferably spaced apart by a given minimum distance. This ensures that the response generated by one inducer entity does not spread into the field for the action of another inducer entity. For example, referring to FIG. 3, the distance between inducer entities 41 and 42 is selected such that when inducer entity 42 is enabled (as shown) but entity 41 is not enabled, inducer entity 42 does not generate responses in image elements closer to inducer entity 41. In FIG. 3, the enabled inducer entity 42 is far enough away from inducer entity 41 so as not to induce noticeable responses in image entities present in section 85. On the other hand, since the inducer density per unit length value reflects the DPI (dots per inch) of the printed image, the distance between adjacent inducers must be close enough to achieve a suitable image quality of the generated visual representation.

[0125] In embodiments where the guiding method is implemented using a magnetic field, the writing tool may comprise an array of electromagnets, preferably in different possible forms such as rod-shaped or U-shaped or variations thereof. In another embodiment where the guiding method uses a magnetic field, the writing tool may comprise an array of actuators including permanent magnets, in which case each actuator may move a permanent magnet back and forth towards or away from the media.

[0126] In embodiments in which the induction method is performed using an electric field, the writing tool may comprise an array of electrodes made from a conductive material.

[0127] In embodiments in which the directing method is performed using electromagnetic radiation, the writing tool may include an array of independently controlled light sources, such as an array of lasers, an array of laser diodes, an array of light emitting diodes (LEDs), or an array of organic light emitting diodes (OLEDs). In another embodiment in which the directing method is performed using electromagnetic radiation, the writing tool may include one or more light sources and a spatial light modulation method, such as a light source including an array of liquid crystal light valves, or a light source including a digital micromirror device (DMD).

[0128] FIG. 5 is a plan view of the underside 11 of the writing tool 10 according to another embodiment, showing an arrangement of inducer entities 41, 42, 49, etc. on parallel lines 52, 52, 53. The inducer entities on each of these lines are shown to be offset by a distance (d) along the respective line relative to the inducer entities on adjacent lines. This particular arrangement of inducer entities within the writing tool 10 allows for the generation of a more accurate, higher resolution visual representation, taking into account the smallest possible physical spacing (S) between two inducers. When the inducers are configured in a 1D array, there is a maximum inducer density per unit length due to the size of the inducer itself. Thus, the image quality of the printed visual representation is limited by the density of the inducers. The configuration in FIG. 5, or others similar based on the same concept, can be implemented to increase the image quality based on the same inducer size. During the printing process, the writing tool moves in principle along a direction perpendicular to its long axis, so that the distance (d), which is the projected length of the inducer spacing on the long axis, defines how close two dots can be printed to reproduce the visual representation. The distance (d) can in principle be any value less than (S) but greater than 0. In embodiments where the distance (d) is still greater than the distance between any two adjacent markers 31, 32 and / or the distance between adjacent pixels of the visual representation with the desired DPI, an algorithm that causes the writing tool 10 to store already printed pixels of the visual representation concomitant with multiple movements of the writing tool 10 over the same area of ​​the medium can complete the writing with an acceptable minimum loss of information in the visual representation.

[0129] Although some preferred embodiments of the present invention have been described above and specifically illustrated, it is not intended that the present invention be limited to such embodiments. As described in the following claims, various modifications may be made to the embodiments without departing from the scope and spirit of the present invention. Below, examples of the present invention are disclosed. These examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

Claims

1. A handheld writing device (10) suitable for generating a visual representation (50) on a writable-erasable medium (20), said handheld writing device (10) comprising: a sensor (21) capable of detecting non-visible light, said sensor (21) being configured to generate a signal related to two-dimensional marker information (31, 32) associated with said writable-erasable medium; a plurality of inducer entities (41, 42, ...), each of said inducer entities configured to independently assume at least two states: a first state, an inducing state, and a second state, a passive state, and wherein when in said first state, said inducer entity is configured to direct a predetermined amount of energy in a predetermined direction; a data processing entity (60) configured to act on each of the inducer entities (41, 42, ...) to switch between the first state and the second state, the data processing entity (60) being configured to act on the inducer entities based on the signal generated by the sensor (21) and on the visual representation generated on the writable-erasable medium; A handheld writing device (10) comprising:

2. the predetermined amount of energy is adapted to act on image elements (81) of the writable-erasable medium with the handheld writing device (10) operatively disposed over the writable-erasable medium, and to cause the image elements (81) to change their position, configuration, orientation, and / or light absorption characteristics, thereby affecting the reflection of visible light impinging on the writable-erasable medium (20) and contributing to the generation of the visual representation; A handheld writing device (10) according to claim 1.

3. a light source (70) configured to emit electromagnetic radiation waves that are reflected or absorbed by the two-dimensional marker information (31, 32) to provide the invisible light that can be detected by the sensor (21); A handheld writing device (10) according to claim 1 or claim 2.

4. said data processing entity: (i) the location of the handheld writing device on the writable-erasable medium; (ii) the orientation or angle of the handheld writing device relative to the writable-erasable medium; and (iii) the position and / or orientation of one, some, or all of the inducer entities relative to the writable-erasable medium, and in particular relative to image elements of the writable-erasable medium; configured to identify from the signal generated by the sensor one or more selected from the group consisting of: A handheld writing device (10) according to claim 1 or claim 2.

5. The two-dimensional marker information (31, 32) is transparent to visible light. A handheld writing device (10) according to claim 1 or claim 2.

6. The two-dimensional marker information (31, 32) is provided on a transparent support (30). A handheld writing device (10) according to claim 1 or claim 2.

7. the two-dimensional marker information (31, 32) includes a plurality of two-dimensional marker images or codes, the marker images or codes being dispersed across a surface (35) of the writable-erasable medium, the surface (35) at least partially corresponding to or overlapping a viewing surface on which the visual representation (50) is provided; A handheld writing device (10) according to claim 1 or claim 2.

8. the marker images or codes form an array and / or are arranged in rows and columns; A handheld writing device (10) according to claim 7.

9. the two-dimensional marker information (31, 32) comprises a plurality of two-dimensional marker images or codes, each of which is unique within a particular writable-erasable medium and / or each of which is asymmetric, such that the signal generated by the sensor when capturing invisible light reflected from or emitted from the two-dimensional marker information can be preferably analyzed by the data processing entity to determine position and / or orientation information relating to the handheld writing device relative to the writable-erasable medium, and in particular any one or more of the position information (i) to (iii) in claim 4; A handheld writing device (10) according to claim 1 or claim 2.

10. When the inducer entities (41, 42, ...) are in the induced state, they emit energy in one or more forms selected from a magnetic field, an electric field, and an electromagnetic radiation wave. A handheld writing device (10) according to claim 1 or claim 2.

11. Where applicable, the magnetic field, the electromagnetic radiation, and the electric field are oriented to exert a force or influence on an image element (81) thereby causing the image element to produce a response that contributes to the generation of the visual representation, the response preferably being selected from a change in position, a change in configuration, a change in orientation, and / or a change in light absorption properties of the image element. A handheld writing device (10) according to claim 10.

12. In the induced state, the inducer entities (41, 42, ...) (1) a magnetic field, wherein the imaging element (81) is responsive to the magnetic field generated by the activated inducer entity, and wherein the imaging element preferably includes a ferromagnetic and / or ferrimagnetic component; (2) an electric field, wherein the image element (81) is responsive to the electric field generated by the activated inducer entity, and wherein the image element preferably comprises one or more selected from one or more charged components and / or components forming a permanent or non-permanent inducible electric dipole; (3) Electromagnetic radiation, wherein the image element (81) is responsive to light emitted by the activated inducer entity, and wherein the image element preferably comprises a photochromic and / or photoelectrochromic component; emits energy in the form of A handheld writing device (10) according to claim 10.

13. an optical element (25), preferably comprising one or more lenses, mirrors, and / or filters, configured to guide invisible light reflected or emitted from the two-dimensional marker information toward the sensor (21); A handheld writing device (10) according to claim 1 or claim 2.

14. A writable-erasable medium (20) capable of providing an erasable visual representation (50), the writable-erasable medium (20) comprising a plurality of image elements (81), the image elements contributing to the generation of the visual representation by influencing the reflection of visible light impinging on the writable-erasable medium (20) depending on the position, configuration, orientation, and / or light absorption characteristics of the image elements, the writable-erasable medium (20) further comprising a transparent support (30) and two-dimensional marker information associated with the support, the two-dimensional marker information being transparent to visible light. A writable and erasable medium (20).

15. the two-dimensional marker information (31, 32) comprises a plurality of two-dimensional marker images and / or codes, the marker images and / or codes being dispersed across a surface (35) of the writable-erasable medium, the surface (35) corresponding to or at least partially overlapping a viewing surface on which the visual representation is provided and / or through which the visual representation is visible to a user of the writable-erasable medium; 15. The writable erasable medium of claim 14.

16. The marker images and / or codes form an array and / or are arranged in rows and columns on the support (30) and / or across the viewing surface; 16. The writable and erasable medium according to claim 14 or 15.

17. The two-dimensional marker information (31, 32) includes a plurality of two-dimensional marker images and / or codes, each of which is unique within a particular writable-erasable medium, and / or each of which is asymmetric.

16. The writable and erasable medium according to claim 14 or 15.

18. configured to display the visual representation (50) under control of a handheld writing device (10) according to claim 1 or claim 2; 16. The writable and erasable medium according to claim 14 or 15.

19. the transparent support (30) carrying the two-dimensional marker information is an integral part of the writable-erasable medium; 16. The writable and erasable medium according to claim 14 or 15.

20. A handheld writing device (10) according to claim 1 or claim 2 and a writable and erasable medium (20) according to claim 14 or claim 15, assembly.

Images