Abstract:
The invention relates to electronic devices, in particular consumer electronic devices, including an electrophoactive display, as well as to electronic document reading devices, sometimes called e-readers, such as electronic books. We describe an electronic device including an electroactive display and a light to illuminate said display, wherein said display has a viewing surface, and wherein said light is configured to illuminate said display from in front and to one side of an edge of said viewing surface, across said viewing surface and through a front-most surface of said display.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of United Kingdom Patent Application No. 0702350.0, filed Feb. 7, 2007, which is incorporated in its entirety by reference herein. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to electronic devices, in particular consumer electronic devices, including an electrophoretic display, as well as to electronic document reading devices, sometimes called e-readers, such as electronic books. 
     2. Description of the Related Art 
     A number of techniques are known for illuminating LCD display panels, including some techniques which rely on guiding illumination within a light guide plate. Examples can be found in U.S. Pat. No. 5,739,887, U.S. Pat. No. 6,791,635, U.S. Pat. No. 6,343,868 and U.S. Pat. No. 6,734,929. A similar light guiding principle is also described in U.S. Pat. No. 5,118,138 for illuminating pages of a conventional book. Other techniques for illuminating the pages of a conventional book, generally involving a lamp on an arm, are described in U.S. Pat. No. 7,163,306, WO 87/05266 and U.S. Pat. No. 3,823,312. 
     By contrast, embodiments of the invention relate to electronic reading devices with a self-contained light source, but which do not use an LCD display panel but which instead employ an electroactive display, such as a reflective bistable display (for example an electrophoretic or other like displays), which presents special problems and opportunities. This is because such a display can be flexible, and hence can have a curved configuration, and also because it can be difficult to effectively guide light within such a display. 
     SUMMARY OF THE INVENTION 
     According to a first aspect of the invention there is therefore provided an electronic device including an electroactive display and a light to illuminate said display, wherein said display has a viewing surface, and wherein said light is configured to illuminate said display from in front and to one side of an edge of said viewing surface, across said viewing surface and through a front-most surface of said display. 
     In preferred embodiments of the electronic device the viewing surface of the electroactive display has a concave curvature (from a viewer&#39;s perspective). Then, preferably, the display is illuminated through a front (viewing) surface of the display by a stripe of illumination, preferably substantially along a complete edge of the viewing surface and directed across the viewing surface. Advantageously the light may be built into a spine of the device, in particular when the device comprises an electronic document reading device. 
     Preferably the illumination of the viewing surface of the display is substantially uniform; preferably the curvature of the viewing surface is chosen to provide such substantially uniform illumination. The precise details of the curvature may, in embodiments, depend upon the uniformity of the illumination across the stripe and/or directionality (conversion/divergence) of the illumination and/or the curvature, more particularly the variation in curvature, of the viewing surface with distance from the illuminating stripe. This may be modelled, for example, in a computer aided optical design system. In embodiments a (vertical) cross-section along a (horizontal) line through the viewing surface may have the form of a conic section such as circle, ellipse, parabola, or hyperbola. 
     In embodiments the light comprises a light source which may be at least partially behind the viewing surface of the display, in combination with an optical system such as a mirror or prism and/or light guiding optical system, to direct illumination from the light source onto the viewing surface from the front of the viewing surface. Additionally or alternatively the light may comprise a plurality of LEDs (light emitting diodes) which may be white and/or coloured. For example in embodiments a plurality of LEDs may be mounted in front of the viewing surface of the display (at least where the display meets the spine), facing the display and, preferably, provided with a light-diffusing window. 
     In some preferred embodiments the device has two electroactive displays mounted on a central support or spine (which may be an integral part of one of the displays), and in this case preferably the light is able to illuminate each of the electroactive displays either simultaneously or sequentially, for example in the case of an electronic reader page-by-page as the document is read. 
     In embodiments, in particular electronic reader embodiments, the light is capable of changing colour (here the reference to a colour includes white), for example by including LEDs of different colours. The device may then include a system to control a colour of the light, in particular in co-ordination with information displayed on the device. Thus in some preferred embodiments mood lighting may be provided in which the colour of the illumination is changed in co-ordination with an emotional content of the reading matter, for example scary/thrilling, romantic, funny, happy and the like. Information for use by a document reading device for controlling the illumination colour may be provided as metadata in association with document text data, for example annotating the text. 
     In a related aspect the invention provides an electronic document reading device comprising at least one page attached to a spine, wherein said page has a viewing surface which is curved towards a viewer of the page, and wherein said at least one page is illuminated through the front of said viewing surface from in front of an edge of said curved viewing surface, in particular from said spine. 
     In some preferred embodiments the electronic document reading device has two pages, one attached to each side of the spine, each being illuminable from the spine. Thus preferably the spine includes an illumination source and a window, in a device with two pages, a window for each page, the window having the form of a stripe along the spine in front of the viewing surface where the page is attached to the spine. In this way illumination from the illumination source may be directed through the window onto the viewing surface of the page or pages. 
     The device may be configured to selectively illuminate one of the pages currently being read, either manually, for example by means of a user control, or automatically, for example in co-ordination with page turning, say, in response to a page turn event. In embodiments the device may include a manual and/or automatic colour control system to change a colour of the illumination. As mentioned above such a system may be configured automatically to change the illumination colour in accordance with an emotional content of the displayed material. 
     In a related aspect the invention provides a method of illuminating an electroactive display of an electronic device, the method comprising: configuring the display such that a viewing surface of the display has a concave curvature in one direction, from a viewing side of the display; and illuminating said viewing surface along said direction through a front surface of said display. 
     In another aspect the invention provides an electronic book having a clamshell configuration, with first and second physical pages hinged at a spine to enable said clamshell to be opened and closed, each said page having a front surface bearing an electronic display which, when said clamshell is closed, is on the inside of said closed clamshell, the rear surfaces of said physical pages providing respective front and rear surfaces of said electronic book when said clamshell is closed, and wherein when said clamshell is closed said front and rear surfaces of said electronic book taper towards an edge of said book opposite said spine. 
     Preferably a part of said electronic book opposite the spine, when the book is closed, has an overall three-dimensional shape which is generally wedge-shaped. 
     In embodiments the wedge-shape of the electronic book facilitates insertion of the book into a bookshelf at reduced risk of damage, in particular where the bookshelf is full. In preferred embodiments the clamshell comprises two physical pages hingedly mounted either directly to one another or to an intermediate spine, to allow the pages of the book to be opened and closed. In preferred embodiments a thickness of a physical page tapers away from the hinged mounting, thus contributing to the overall wedge shape when the book is closed. In embodiments each page includes an electronic display with connections along two edges to provide row column drive signals. Preferably neither of these two edges are adjacent the tip of the wedge, again for improved robustness. Optionally one or both corners of a physical page adjacent the tip of the wedge (at the top and the bottom) may be pointed or reinforced. 
     In a further aspect the invention provides an electronic document reading device having two physical pages each with an electronic page display, said physical pages being hingedly mounted at a spine in a clamshell configuration, said electronic page display being on an inside surface of said reading device when said clamshell is closed, and wherein said reading device includes an external display viewable from the outside of said device when said clamshell is closed. 
     Preferably the device includes a user control accessible from the outside of the device when the clamshell is closed, and control electronics coupled to the user control and to the external display to enable a user to selectively display information relating to an internal state of the device on the external display when the clamshell is closed. In embodiments the user control comprises a wheel mounted on the spine. The external display may either be horizontal, across the rear of a physical page or vertical, for example along the spine. The displayed information may comprise, for example, one or more items of information from the following: titles of books stored within the device, authors of books stored within the device, books from a selection stored within the device such as a favourites list, top ten list, most recently read list and the like, information on remaining battery life, information identifying how far a user is through a currently read book such as a current page number (bookmark(s)), and the like. 
     In embodiments the control electronics may be configured to change a function of the user control according to whether the book is open or closed. For example when closed the user control may provide information as described above; when open the user control may provide a page-select or page-turn function, either forwards and/or backwards. 
     In another aspect the invention provides an electronic document reading device having two physical pages each with an electronic page display, said physical pages being hingedly mounted at a spine in a clamshell configuration, said reading device further comprising control electronics coupled to memory for storing one or more documents to be read, coupled to said electronic page displays for displaying selected pages of a said document to be read, and coupled to a user control for changing said selected displayed pages, and wherein said user control comprises a thumb paddle towards a base of said spine. 
     In some preferred embodiments the thumb paddle is movable laterally in two orthogonal directions and also incorporates a push-control (vertical movement) to provide a convenient multi-function user interface. 
     The invention still further provides an electronic document reading device having two physical pages each with an electronic page display, said physical pages being hingedly mounted at a spine in a clamshell configuration, said electronic page displays being on an inside surface of said reading device when said clamshell is closed, wherein each of said electronic page displays has a display surface with a concave curvature in one direction on said display surface, and wherein said clamshell is openable such that a cross-section through said two display surfaces approximates a conic section. 
     As mentioned above, preferred embodiments incorporate an illumination source to provide substantially uniform illumination of a majority, preferably substantially all, of an electronic page display. 
     As previously mentioned, for embodiments of a device/book as described above the display preferably comprises a reflective display medium, in particular an electroactive display medium, sometimes referred to as e-ink or e-paper, such as an electrophoretic display. However embodiments of aspects of the invention may alternatively employ other display media, for example an organic LED display medium or a liquid crystal display medium. 
     As previously mentioned, in preferred embodiments the display is curved; this is facilitated by using a backplane fabricated on a flexible substrate such as PET (polyethylene terephthalate). In preferred embodiments this backplane comprises an active matrix backplane including a plurality of thin film transistors (TFTs) configured to implement pixel drive circuitry for the electroactive display. The active matrix backplane is preferably fabricated using a solution deposition technique, preferably employing organic semiconducting material, although alternatively solution-deposited inorganic semiconductor materials such as CdSe nanoparticle material may be employed. 
     According to a still further aspect of the invention there is provided an electronic reader having two pages attached to a central spinal region, each of said pages incorporating a display, said spinal region incorporating a light source to illuminate said displays from the side of each page such that a substantially uniform distribution of light is provided across each said display. 
     Preferably the two pages form front and back covers of the electronic reader. In embodiments, the electroactive display comprises a reflective bistable display, such as an electrophoretic display. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other aspects of the invention will now be further described, by way of example only, with reference to the accompanying figures in which: 
         FIGS. 1   a  to  1   d  show, respectively, a perspective view of a first embodiment of an electronic document reading device according to the invention, in an open configuration, an end view of the device of  FIG. 1   a  showing curvature of the display surfaces of the device in said open configuration, a vertical cross-section through a curved electrophoretic display for the device of  FIG. 1   a , and a perspective view of a second embodiment of an electronic device according to the invention; 
         FIGS. 2   a  to  2   d  show, respectively, first and second example optical arrangements for illuminating the electronic pages of the device of  FIG. 1   a , a schematic ray diagram for illumination of open pages of an electronic book, and a similar diagram illustrating partially closed pages; 
         FIGS. 3   a  and  3   b  show first and second views of a device similar to that shown in  FIG. 1   a  in a closed configuration; 
         FIG. 4  shows an example configuration of connectors to an electrophoretic display of the device of  FIG. 1   a;    
         FIG. 5  shows a rear, perspective view of the device of  FIG. 1   a ; and 
         FIG. 6  shows a block diagram of a control system for the device of  FIG. 1   a.    
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     We will describe an electronic document reading device (“electronic reader”) comprising pages incorporating electronic displays, with an integrated light source to produce a uniform distribution of illumination across each page. 
     Referring to  FIG. 1   a , this shows an embodiment of an electronic document reading device  100  having a pair of pages  102   a, b  each with an electronic display region  104   a, b , in preferred embodiments provided by an electroactive display such as a reflective bistable display, here an electrophoretic display. The pages  102  are each attached to a central spine  106 , for example in the form of a column. In some preferred embodiments each page can be rotated individually about the central spine; optionally a stop may be provided to limit the opening angle of the two pages. An end view of the open device is shown in  FIG. 1   b ; preferably the electronic displays form a smooth curve when the device is open. 
     In embodiments the spine  106  is provided with a pair of windows  108 , one of which  108   b  is shown in the perspective view of  FIG. 1   a . Each of these windows provides illumination for the corresponding electronic display, for example window  108   b  for display  104   b  (the device of  FIG. 1   a  is symmetrical in this respect). The spine  106  includes a light source which emits a stripe of light through a window  108  such that the electronic display area  104  is substantially uniformly illuminated, in particular because the electronic display surface is curved, as shown more clearly in  FIG. 1   b.    
     As shown in  FIG. 1   a , preferably the window providing illumination is just in front of an edge of the display  104 . In this way the illumination passes through a front-most surface of the electrophoretic display  104 . To position the windows just in front of the edges of the displays  104  a region  106   a  of the spine  106  comprising the windows  108  may be provided with a stop so that when the pages  104  are open the windows are correctly positioned. Additionally or alternatively region  106   a  of the spine  106  may be arranged so that the windows  108  are symmetrically positioned with respect to the pages  104  for a range of angular openings of pages  104 , for example by a spring attached to each hinge of the pages  104   a, b  (in  FIG. 1   a  hinges  110   a, b  of page  104   b  and hinges  112   a, b  of page  104   a ). 
       FIG. 1   c  shows a vertical cross section through a part of an electronic display  104  according to a preferred embodiment of the invention As mentioned above, in preferred embodiments the display medium is a reflective display medium, in particular an electrophoretic display medium  120 . This is laminated to an active matrix backplane comprising a flexible substrate  122  such as PET (polyethylene terephthalate) or PEN (polyethylene naphthalene) on which is fabricated a thin layer of organic active matrix pixel driver circuitry  124  for electrophoretic display  120 . 
     Preferred electrophoretic displays are used. Preferably the display and substrate are sandwiched between a pair of moisture barriers  126   a, b , for example of polyethylene and or Aklar™, a fluoropolymer (polyfluorotrifluoroethylene-PCTFE). 
     Typical approximate thicknesses for each layer of the display  104  are in the region of 200 μm, although the active matrix circuitry is thinner, for example around 5 μm and moisture barrier  126   b  can be thinner than barrier  126   a  if it incorporates a metallic moisture barrier such as a layer of aluminium foil (since barrier  126   b  does not need to be transparent). Optionally a front panel, for example of perspex, may be provided over (in front of) moisture barrier  126   a , although in embodiments this is not necessary and, generally speaking, it is desirable to keep the overall thickness of the display low. 
     In preferred embodiments the active matrix pixel driver circuitry  124  comprises transistors fabricated using solution-deposition based processes, preferably patterned by techniques such as direct-write printing, laser ablation or photolithography. We have previously described full details of such processes in the applicant&#39;s earlier patent applications including, in particular, WO 01/47045, WO 2004/070466, WO 01/47043, WO 2006/059162, WO 2006/056808, WO 2006/061658, WO 2006/106365 and PCT/GB2006/050265 all hereby incorporated by reference in their entirety. 
     Referring again to  FIGS. 1   a  and  1   b , the structure of the display illustrated in  FIG. 1   c , in particular the use of a flexible substrate and solution-deposition based, preferably organic electrophoretic display driver circuitry facilitates imparting a curve to the electronic display area, as illustrated, which in turn facilitates the above-described method of illumination. 
       FIG. 1   d , in which like elements to those of  FIG. 1  are indicated by like reference numerals, illustrates that a similar illumination technique can be employed with an electrophoretic display with concave curvature in an electronic device with, in embodiments, only a single illuminated electrophoretic display. Such a device may comprise, for example, an electronic organiser (PDA), mobile phone or some other consumer electronic device, typically of the small, hand-held type. 
     Referring now to  FIGS. 2   a  and  2   b , these illustrate example optical arrangements for the spine  106  of the electronic document reading device  100  of  FIG. 1   a  showing, in particular, vertical cross-sections through spine  106 . 
     In the example of  FIG. 2   a  two sets of LEDs  200   a, b  each extending in a longitudinal direction along the spine  106  provide light to illuminate respective electronic displays  104   a, b  via reflectors  202   a, b  and diffusing windows,  108   a, b . Optionally the optical system may also include one or more lenses. In  FIG. 2   b  a single row of LEDs  201  provides light for both electronic display  104   a, b  and, in this example, the LEDs are positioned higher so that no reflectors are needed. As described above, in both cases the light through windows  108   a, b  preferably provides substantially uniform illumination over the majority, preferably all of a display area of an electronic display  104 . The angle at which the pages are open may be adjusted by a user to achieve a substantially uniform illumination and/or a stop may be positioned so that the pages, when fully open, are substantially uniformly illuminated. (Here references to substantially uniform illumination refer to illumination, which to a user, appears approximately even over more than 70%, 80% or 90% of the display area in the absence of other illumination). 
     Referring now to  FIG. 2   c , this shows a schematic ray diagram illustrating illumination of curved display surfaces  104   a, b . In the illustrated example the electronic displays approximate a surface with a defined radius of curvature R and the eyes  210  of the user are at a distance d, typically around 30 cm although potentially in a range of, for example, 10-50 cm. (An example monochrome display may have a resolution of, say, 100-250 pixels per inch, for example 150-170 pixels per inch). Light source  204  is preferably a diffuse light source (for example a light source employing a diffusing window) such that for any point on the display surface some light rays emitted from the light source (dashed lines) hit the eyes  210  of the user. The radius of curvature R is selected such that for a specific reading distance d the display appears most uniform. The optimum radius of curvature for a given reading distance and light source may be determined by straightforward optical engineering, in a manner well known to those skilled in the art. If the user decides to vary the reading distance he or she may adjust the opening angle α between the two display surfaces to achieve optimum illumination conditions, as shown in  FIG. 2   d.    
     Generally the radius of curvature of the display is chosen to be similar to the reading distance. This helps to give the reader the feeling of being immersed in the reading experience, and to create a comfort zone between him/her and the electronic book. The skilled person will appreciate that more complex curvatures, for example not involving a single radius of curvature, may also be employed. For example optical engineering software may be employed to optimise brightness and/or uniformity of the illumination, allowing the curvature or more generally the shape of the surface to vary to achieve this. Optionally additional lighting may be employed to further improve brightness and/or uniformity of the illumination. Example side lighting techniques used in the LCD industry are described in the background prior art acknowledged in the introduction to the application, in particular U.S. Pat. No. 5,739,887, U.S. Pat. No. 6,791,635 and U.S. Pat. No. 6,343,868. These describe transmissive LCD panels and flat, rigid glass displays but the inventor has recognised that the techniques described therein may be adapted to a reflective, curved display, in particular by mounting a light-guiding film on the surface of the display. 
     As previously mentioned, preferably the light source, more particularly a window, is positioned at the edge of each side of the spine  106 , where the spine meets the display, in a strip down each side of the spine. Alternatively a light source may be mounted on a page  102 , more particularly on a strip of surround of the electronic display  104  between the electronic display and the spine. Depending upon the curvature of the pages, provided the illumination is relatively low profile the pages  102  may still be closed. Less preferably a light source for illuminating the curved surface of the display may be provided along an outer edge of a page  102 , again preferably in the strip between the electronic display area and the edge of the page. In such embodiments the pages may be inhibited from closely closing although in embodiments this may be tolerable. 
     In embodiments of the device the sets of LEDs  200 ,  201  may be configured to provide illumination of more than one colour (here a colour including white), for example by using bi- or multi-colour LEDs and/or by alternating LEDs of different colours longitudinally along the spine  106 . Mood lighting may then be provided, for example allowing a user to select a preferred colour for illuminating the display. For example green light is thought to improve concentration whilst red light is generally considered preferable for use in dim/night lighting conditions. In embodiments such a mood lighting feature may be turned on or off according to the desire of the user. 
     Additionally or alternatively the device may be configured to provide intelligent lighting, more particularly lighting that it is able to change light colour and/or intensity according to the “mood” of the displayed material. In a simple implementation the light colour and/or intensity may be determined based upon a page number of the displayed document, changing as the user scrolls through the pages. For example an orange glow across a display may be employed to represent a morning scene and dark blue lighting may be used, for example, to represent an evening or twilight scene. In a similar way, red light, say, may be used for a happy scene and blue light for a sad scene, and so forth. 
     Referring now to  FIG. 3 , this shows the device with the pages in a closed position. The back surfaces of the pages  102  effectively provide front and rear covers for the electronic book. In a fully closed position the pages  102   a, b  touch along their respective peripheral edges parallel to the spine, in embodiments leaving a gap between the pages when the device is closed. The curve of the outer surfaces of the pages (front and rear covers) between the spine and the closed edges facilitates easing the electronic reader into position between other items such as conventional books on a shelf. Optionally one peripheral corner of the device may be reinforced, pointed or curved to aid insertion between such other items; this corner may then lead the placement of the electronic book onto a shelf. In embodiments the device includes an external electronic display, preferably a further electrophoretic display.  FIG. 3   b  illustrates an example of an electrophoretic display  300  running down the spine of the electronic book; more details of such an external electrophoretic display are given below. 
     Continuing to refer to  FIG. 3 , and also referring again to  FIG. 1   b , when open the two pages (attached to the spine) have an overall generally crescent shaped cross-section. Thus, as can be seen, preferably the thickness of each page tapers away from the spine towards the edge of the page opposite the spine. For example in embodiments the thickness of a page decreases from around 10 mm near the spinal region to approximately 4 mm at the edge furthest from the spinal region. This change in width provides the user with the impression that the electronic document reading device is thinner than it actually is. This taper, together with the curvature of a page, results in the outer surface of a page having a slightly greater curvature than the inner, display surface of a page. In embodiments the inner, display surface of a page has a curvature such that tangents to the surface at opposite edges of the display surface include an angle of approximately 150°, which may be referred to as a “curvature” of approximately 30°. Generally, however, the curvature may vary substantially from 5° 10°, 15° or 20° to 40°, 50° or more; in still other embodiments the display surface may be substantially flat. The curvature may be selected for example by routine experiment to obtain a perceived illumination which is sufficiently uniform. 
     The differing curvatures of the front and back surfaces of a page creates a region  114  between these front and back surfaces in the vicinity of the spine  106 . This region may be used, for example, for the control electronics and/or a rechargeable power supply such as a rechargeable battery and/or for one or more user controls. It is particularly convenient, however, to use one or both of regions  104  to house one or more external connectors for the device, such as a USB port connector and/or an edge connector or similar for the control electronics/power supply. 
     Referring now to  FIG. 4 , this shows a view from above of a portion of an electronic document reading device  100  of the type shown in  FIG. 1   a , illustrating a preferred configuration of flexible connectors  116 , such as TCPs (tape carrier packages) between the organic active matrix backplane (as shown in  FIG. 1   c ) and associated control electronics for the device, described below. As shown the connectors  116  are preferably positioned along an upper and inner edge of the electronic display  104 , providing additional protection when the device, in the form of an electronic book, is inserted into a bookshelf in a direction shown by arrow  118 . Thus, as illustrated, row connectors for the display are positioned adjacent the spine  106  and column connectors at the top edge of display  104 , although in other embodiments the column connectors may be positioned along the bottom edge of display  104 . Such configurations help to increase the overall robustness of the device. 
     Referring now to  FIG. 5 , this shows a view of a rear of the device  100 , illustrating an additional “external” electrophoretic display  130  which is preferably provided on an external surface of the device so that the display is visible when the device is closed, for example along the spine (as shown in  FIG. 3   b ) or as shown in  FIG. 5  on a rear surface of one of the pages  102 . Display  130  may indicate a variety of information, for example a selected document/publication currently being read, a remaining amount of battery life, a page or bookmark position, and the like. Preferably an additional user control is provided on the exterior of the device. Ergonomically a scroll wheel  132  on the spine has been found to be particularly advantageous. This may be used to scroll through items on display  130  and/or a menu of publications stored within the device and the like. 
     In some embodiments the electronic book  100  incorporates a sensor to determine whether the book is open or closed and in response to this, changes one or more functions of spine wheel  132 . Thus, for example, when the book is open wheel  132  may be employed to turn pages forwards and/or backwards through the publication currently being read. 
     Referring again to  FIG. 1   a , preferred embodiments of the electronic book  100  also incorporate a thumb paddle  134 . The location of paddle  134  at the base of the spine  106  facilitates one-handed operation of the device while holding the device in the same hand or reading. In embodiments thumb paddle  134  provides a joystick-type function with lateral movement in two orthogonal directions; preferably it also provides a push-button function. In embodiments paddle  134  combines a plurality of push-button functions selectable by selecting a degree of inward pressure on the control  134 ; such a function may be provided whether or not any additional joystick-type function is implemented (and if a joystick-type function is not implemented the control need not have a “paddle” shape). 
     Referring now to  FIG. 6 , this shows example electronic control circuitry  600  suitable for an electronic document reading device of the type shown in  FIG. 1   a . The control circuitry  600  comprises a controller  602  including a processor, working memory, and non-volatile programme memory. The controller  602  is also coupled to non-volatile data memory  608 , such as Flash memory, for storing data for a plurality of electronic documents for display, and other data such as mood data, bookmark data (for example identifying a current page) and the like. The controller  602  receives user input from the thumb paddle  134  and the spine wheel  132  as well as, in embodiments, from a book open/closed sensor  604 . The controller  602  is also coupled to display interfaces  606   a  for the respective electrophoretic displays  104   a, b ; optionally these may be touch-sensitive as described in our co-pending international patent application PCT/GB2006/050220, hereby incorporated by reference in its entirety. Preferably the controller  602  is also coupled to an external electrophoretic display  130  via a further display interface  606   b . An external interface  610  is provided for interfacing with a computer such as laptop  614  to receive document data and, optionally, to provide data such as user bookmark data, user read list/book preference data and the like. The interface  610  may comprise a wired, for example USB, and/or wireless, for example Bluetooth™ interface and, optionally, an inductive connection to receive power. The latter feature enables embodiments of the device to entirely dispense with physical electrical connections. A rechargeable power source  612  such as a rechargeable battery is preferably used to provide an internal power supply; this may be recharged via interface  610 . 
     The controller  602  is also coupled to page illumination LEDs  200 ,  201  or a similar illumination source. Preferably the controller is able to control the page illumination on and off, for example in response to the book being opened and shut. In embodiments user and/or automatic control of page illumination intensity and/or colour may also be provided to control the page illumination, for example as previously described. 
     The programme memory of controller  602  stores processor control code for implementing electronic book functions. In particular to implement mood page illumination control an example procedure may sense operation of a user control such as thumb paddle  134  (step  6050 ) and in response read a new page of the currently read document from non-volatile memory  608  (step  6052 ). The procedure may then read mood data associated with the currently read document page from the non-volatile memory  608  (step  6054 ) and then write the updated page information to the page display and control the page illumination LEDs in accordance with the mood data for the current page (step  6056 ). Some particularly advantageous techniques for updating pages of an electronic document reading device are described in our co-pending international patent application number PCT/GB2006/050235, hereby incorporated by reference in its entirety. 
     No doubt many other effective alternatives will occur to the skilled person. For example although some preferred embodiments of the device employ LED illumination many other types of illumination may be employed including, but not limited to one or more incandescent bulbs, an electroluminescent panel (ELP), one or more cold cathode fluorescent lamps (CCFL) or (less preferably) hot cathode fluorescent lamps. In general, however, semiconductor-based light emitters are preferable because of their low power consumption. 
     The skilled person will understand that references to a document are to be interpreted broadly and include (but are not limited to): newspapers, books, emails, attachments, web pages, mark up language documents, written music, written computer programs, images, and other graphical representations, for examples comics. An electronic book as described above may also incorporate other functions, for example a calculator, an organiser, a game such as chess and the like. 
     The skilled person will understand that a document reading device of the type described above is not restricted to documents in any particular language such as English and may, for example, be used with languages with different script reading and/or page turning directions, such as Arabic, Chinese and (sometimes) Japanese. 
     The skilled person will also understand that a document reading device of the type described above is not restricted to electrophoretic displays. Other like electroactive or reflective bistable displays may be used instead. 
     It will be understood that the invention is not limited to the described embodiments and encompasses modifications apparent to those skilled in the art lying within the spirit and scope of the claims appended hereto.