GB2426829A

GB2426829A - Casing for electronic device having electrochromic layer

Info

Publication number: GB2426829A
Application number: GB0612408A
Authority: GB
Inventors: Martin Richard Layley; Moyeen Shujauddin Mufti
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 2003-06-10
Filing date: 2003-06-10
Publication date: 2006-12-06
Anticipated expiration: 2023-06-10
Also published as: GB0313388D0; GB0612408D0; GB2402750B; GB2402750A; GB2426829B

Abstract

A method of producing casing for an electronic device wherein an image is produced on the casing by applying an electrical control signal to an electrochromic layer formed within the casing.

Description

I

IMPROVEMENTS IN CASINGS FOR ELECTRONIC DEVICES

The present invention relates to casings for electronic devices, and in particular to producing images on said casings.

Consumers of electronic devices are able to personalise their equipment by applying various fixings, such as stickers, to the casings of the devices. Such electronic devices are, for example, mobile telephones, personal digital assistants, laptop computers, desktop computers or handheld computers.

Further, it is known that users of electronic devices, in particular mobile telephones, are able to choose and apply different casings to the mobile telephone in order to personalise the device. Manufacturers supply a wide range of fixed colour casings of many different designs for the consumer to choose from. However, once the consumer has chosen and purchased a casing, it is not possible to further change the look of the device unless a different casing is subsequently applied to the device.

Another example of an electronic device that can be personalised is the Apple iMac. This computer allows one to obtain a personalised device by allowing the consumer to choose the colour of the casing for the device.

However, once the consumer has chosen their preferable design for the casing, they are limited as to how to change further the appearance of the device.

It is known to have a mobile telephone device that provides a casing that changes colour when heat is applied, such as that shown in US patent No. 6,466,299. The casing includes a thermochromic liquid crystal material that responds to the heat transferred through touching the casing. This results in a temporary change to the colour of certain parts of the casing, for example around the keypad of the device, when it is touched. However, once the casing reverts back to room temperature, there is no longer any change in colour indicated on the casing. Also, this type of device is not capable of being personalised in a predefined manner.

The present invention aims to overcome or at least alleviate some or all of the aforementioned problems.

In one aspect the present invention provides a method of producing a casing for an electronic device wherein the method comprises the step of forming an electrochromic layer within the casing.

The present invention provides the advantage of having a casing for an electronic device, wherein the user can define the image on the casing in order to personalise the device. The image on the casing is changeable without having to provide a new casing. Further, in relation to battery powered portable electronic devices, minimal battery power is used in order to produce and maintain the image on the casing, thus allowing the battery to provide power to the device for as long as possible without having to recharge the battery.

It is also known to use electrochromic materials in displays of electronic devices in order to display status information about the device in a colour format. These displays have an electrical supply applied to the display in order to produce the desired status information in a visible format.

However, this electrical supply must be permanently applied to the display in order to produce the information on the display.

Specific embodiments of the present invention will now be described by way of example only, with reference to the accompanying drawings, in which: Figure Ia shows a graph depicting the neutral state of an electrochromic polymer; Figure lb shows a graph depicting the enhanced state of an electrochromic polymer; Figure 2 shows a mobile telephone device according to a first embodiment of the present invention; Figure 3 shows a mobile telephone system according to a first embodiment of the present invention; Figure 4 shows the layers making up a casing for the mobile telephone device according to a first embodiment of the present invention; Figure 5a shows a plan view of the electrochromic layer used in forming the casing of the mobile telephone device according to a first embodiment of the present invention; Figure Sb shows an exploded view of a pixel within the electrochromic layer depicted in Figure 5a; Figure 6 shows a charging circuit and bridge network for use in a first embodiment of the present invention; and Figure 7 shows a flow chart for addressing individual cells in a first embodiment of the present invention.

Figure 8 shows a mobile telephone utilising a casing according an embodiment of the present invention.

PREFERRED EMBODIMENT

Figures la and lb show how the eleetrochromic polymer used in this embodiment absorbs a different spectrum of light according to the different energy levels of the molecules within the polymer. The electrochromic polymer is a conjugated polymer wherein there are two or more double bonds alternating with single bonds. The structure of the electrochromic polymer is changed upon the application of a voltage to the polymer, which increases the energy level of the molecules.

Figure Ia shows the neutral state of an electrochromic polymer without any additional energy applied to the molecules of the polymer. The polymer in this state absorbs a very small amount of visible light radiation and so appears opaque to the human eye. Upon the application of energy to the polymer material, the absorbance spectrum of the polymer shifts, as shown in Figure lb, so that the polymer material appears to be a different colour as viewed by the human eye. This effect occurs due to the oxidation and reduction of the polymer material.

The electrochromjc material used in this embodiment provides a change in colour that is persistent, i.e. the colour is retained after the voltage applied to the material has been removed.

Known electrochromic polymer materials include EDOT, PEDOT, PXDOT and PXDOP, available from H.C. Starck at www.hcstarck.com.

Figure 2 shows a mobile telephone 201, which includes a casing 203, and a display 205 for indicating status information of the telephone. Further included are a nwnber of input keys 207 that are used for selecting options on a menu, dialling telephone numbers and inputting text for sending text messages. In this embodiment, the casing 203 of the mobile telephone 201 is not detachable from the other components making up the mobile telephone.

Figure 3 shows an example of the mobile telephone system 301 incorporated within the mobile telephone shown in Figure 2. The system includes a power supply 303, such as a battery, and a transmitting and receiving means 305 for sending and receiving data via a wireless communication channel utilising a system such as, for example, UMTS, GPRS or GSM. The device further includes a smart card 307, such as a SIM (subscriber identity module), a controller 309 and a memory storage device 311, such as an E2PROM. All the components work in conjunction with each other in order for a user to communicate with other users using other devices.

Figure 4 shows the layers used to form the casing 203 of the mobile telephone 201. The first layer is a plastic substrate 401, upon which a metallisation layer 403 is placed. The metallisation layer 403 is used to provide electrical connections to a set of polymer transistors that are formed upon a polymer transistor layer 405. The polymer transistor layer 405 is placed upon the metallisation layer 403. Upon the polymer transistor layer 405 is placed the electrochromic polymer layer 407. Finally, upon the electrochromic polymer layer 407 is placed a UV passivation layer 409.

Any suitably flexible and deformable plastic material is used for fonning the substrate 401. The metallisation layer 403 is formed from a suitably conductive material, which in this embodiment is aluminiwn. The metallisation layer 403 is deposited upon the substrate 401 using a screen print method, which is well known within the art. The metallisation layer 403 provides the tracks that connect to the various gates, drains and sources of the transistors formed in the polymer transistor layer 405. Further, the electrical connections within the metallisation layer 403 connect to a controller 309 within the mobile telephone system. The controller 309 in the mobile telephone system controls the voltage levels applied to the different electrical connections so as to control the transistors formed within the polymer transistor layer 405.

The polymer transistor layer 405 is formed from three separate layers, with each layer being formed using known polymer spinning and ink jet deposition techniques. The first polymer transistor layer provides the gate of the transistors. The second layer provides the drain. The third layer provides the source. Examples of polymer transistors are shown at www.plasticlogic.com.

The electrochromic layer 407 is then formed upon the polymer transistor layer 405 using screen printing techniques as are well known in the art. This electrochromic layer is shown in Figure 5a, and is discussed in more detail below.

Upon the electrochromic layer 407, a UV passivation layer 409 is provided in order to protect the electrochromic layer 407 from potentially damaging ultraviolet radiation. The UV passivation layer 409 is deposited using known spinning deposition techniques.

Figure 5a shows a plan view of an electrochromic layer used in this embodiment.

The electrochromic layer 407 has a series of individual pixels 501 that are arranged in columns 503 and rows 505.

Each of the pixels 501 has three individual cells (507, 509 and 511), with a different polymer material being used within each of the three cells.

The three different polymer materials are chosen so that the following colours, cyan (C), magenta (M) and yellow (Y), as used in printing, are visible when a charge is applied to the polymer materials. Without any charge applied, the polymer materials are opaque, in a neutral colour. Upon the application of a charge to each of the individual cells, a change in the materials chemical state is achieved and the polymer material changes from a neutral colour into one of the three colours discussed above depending on the polymer material.

Using the different shades of the three primary colours, cyan, magenta and yellow, it is possible to choose which colour, from a wide gamut, each pixel appears to be.

The layout of each pixel within this embodiment is repeated as shown in Figure Sb. The layout of the cells in each pixel is repeated for each pixel such that row I will have the cells in the following order C M Y, C M Y, C M Y, etc., having, directly next to it, row 2 laid out in the same order.

Each individual cell (507, 509 and 511) is controlled by an electronic circuit formed within the polymer transistor layer 405. The circuit includes a power supply, a charging circuit and a bridge network. Figure 6 shows the circuit used in this embodiment. The power supply 303 of the mobile telephone is connected to a source resistance 603. The combination of the power supply 303 and the source resistance 603 is conmion to all the individual cells within the electrochromic layer 407. Two control lines, SO and SI, are connected between the controller 309 of the mobile telephone system and the bridge network. The control lines SO and Si are used to determine the direction of charge being input across an individual cell 501. A third control line, S2, is also connected to the controller 309, and is used to alternate a capacitively charged circuit between the bridge network and the power supply 303.

The circuit for controlling individual cells will now be described in more detail. The positive terminal of the power supply 303 is connected to a first terminal of the resistor 603. The negative terminal of the power supply 303 is connected to a zero volt line. The second terminal of the resistor 603 is connected to each individual cell's charging circuit, as discussed below.

The charging circuit includes an FET transistor 609 arranged such that when a positive voltage is applied to the gate of the transistor 609 the transistor 609 is switched off. The gate of the transistor 609 is connected to the control line S2. Further, the source of the transistor 609 is connected to the second terminal of the resistor 603. The drain of the transistor 609 is connected to a first terminal of a resistor 607. The charging circuit further includes an FET transistor 611 arranged such that when a positive voltage is applied to the gate of the transistor, the transistor will switch on. The gate of the transistor 611 is connected to the control line S2. The drain of the transistor 611 is connected to the source of transistors 615 and 617, which form part of the bridge network discussed below. The source of the transistor 611 is connected to the drain of the transistor 609 and so to the first terminal of a resistor 607. The second terminal of resistor 607 is connected to a first terminal of capacitor 605. The second terminal of capacitor 605 is connected to the zero volt line.

When the control line, S2, is set to a low level, transistor 609 is switched on and transistor 611 is switched off. The voltage from the battery 303 produces a current through resistor 603, this current is supplied via transistor 609 to the RC network of resistor 607 and capacitor 605. The capacitor 605 is thus charged up. When the control line S2 is set to a high level, transistor 611 is turned on and transistor 609 is turned off. The charge within capacitor 605 is then applied to the bridge network.

The bridge network transistors (613, 615, 617 and 619) are arranged such that when a positive voltage is applied to their respective gate terminals the transistors (613, 615, 617 and 619) are switched on.

Transistors 613 and 619 have their respective drain terminals connected together, which in turn are connected to the zero volt line.

Transistors 615 and 617 have their respective source terminals connected together, which are connected to the drain of transistor 611. The source of transistor 619 is connected to the drain of transistor 615 and also to a first terminal of the electrochromic cell 507. The source of transistor 613 is connected to the drain of transistor 617, and also to the second terminal of the electrochromic cell 507. The gate connection from transistors 613 and 615 are connected to the control line SO. The gate terminals of transistors 617 and 619 are connected to the control line SI.

The bridge network transistors (613, 615, 617 and 619) are arranged such that either transistors 613 and 615 are switched on, or transistors 617 and 619 are switched on, depending on the signal level on control lines SO and Si.

With a positive voltage level on the SO line, transistors 613 and 615 are switched on, while with a positive voltage level on the Si line, transistors 617 and 619 are switched on. With this arrangement it is possible to change the direction of the charge being applied to the electrochromic cell 507.

By controlling the application of the three control lines SO, SI and S2, the amount of charge applied across the yellow electrochromic cell 507 is changed, which then changes the colour intensity of the cell. For example, when no charge is provided, the cell has a neutral colour. However, when a high charge is provided across the cell, the cell appears a yellow colour.

Each of the electrochromic cells within a pixel 501 has a certain amount of charge applied to it in order to produce the required colour intensity for that cell. The combination of the different colour intensities of the three coloured cells, cyan, magenta and yellow, provide an overall colour for that pixel. The combination of the different coloured pixels within the electrochromic layer 407 will produce a desired image.

Once the charge has been applied to the electrochromic cells, it is not necessary to constantly apply the charge unless it is a requirement that the colour intensity of the cell is to be changed, in which case a further charge will need to be applied.

Figure 7 depicts a flow chart that describes the process performed by the controller that enables an image to be updated on the casing. In this process, the present colour intensity of each cell is compared with the colour intensity required to show a new image on the casing. If the present colour intensity of the cell is less than the required colour intensity of the cell, then the appropriate charge is provided to that cell by applying the necessary control signals to the control lines SO, SI and S2. If, however, the present colour intensity of the cell is more than the required colour intensity of the cell then an appropriate amount of charge is removed from the cell in order to set the colour intensity at the correct level, for example, by reversing the charge across the cell.

The process starts at step 701, whereupon the picture map 725 of the current image formed on the casing is subtracted from the picture map 727 of the new image to be formed on the casing, as shown in step 703. The first cell is then selected at step 705. The controller determines if there is a difference in the amount of charge required for the cell to depict the new image compared with the current image, at step 707.

If there is no difference between the required charge and the current charge, then the next cell is selected at step 709. However, at step 711, if there is a difference between the required charge and the current charge for the selected cell, the controller then determines whether the charge required for the new image is more than the charge currently stored in the cell.

If the amount of charge currently stored in the cell is more than that required for the new image, then, in step 713, voltage levels are applied to the control lines SO and Si in order to reduce the amount of charge in the cell.

However, if the amount of charge currently stored in the cell is less than that required for the new image, then, in step 715, voltage levels are applied to the control lines SO and Si in order to increase the amount of charge in the cell.

At step 717, the appropriate positive or negative charge pulse is applied to the cell by triggering control line S2. The controller than checks to see if all the cells have been accessed at step 719, and if they haven't, then the process moves to step 709 to select the next cell. If all the cells have been checked, the picture map for the current image is updated at step 721, and the process stops at step 723. The current image is then stored within the casing, as shown by box 725.

Figure 8 shows an example of a mobile telephone 801, with a casing 803, display 805, keys 807 and a design 809 formed on the casing in order to personalise the telephone 801.

The image information to be depicted on the casing in this embodiment is provided via the air interface of the mobile telephone. The user of the device selects a suitable image from a catalogue of images and then requests the service provider to send the image to the mobile telephone, where it is stored in memory. This allows a user to have many different images stored in the mobile telephone, the user then being able to personalise the device with the image of their choice without the need to replace the casing of the device.

Further, within this embodiment, as the power supply of the mobile telephone is only used during the changing of the image on the casing, and so does not need to be applied to the casing permanently, the battery of the device is not drained and so lasts longer between charge cycles.

The use of polymer materials is particularly suited to mass production of relatively cheap casings for electronic devices.

FURTHER EMBODIMENTS

The invention may be applied to any electronic equipment that a user would wish to personalise. For example, mobile telephones, mobile hand held computing equipment, desktop computers, laptop computers, hand held computers and personal digital assistants.

Further, the casing of the electmnic device may be detachable from the rest of the device. There may also be a suitable electrical connection available on the casing of the device, in order to connect the casing to either a similar device, or to a computing device, which is able to transfer an image to the casing. The transfer of an image may also be carried out through a wireless communication means such as infrared, Bluetooth, or a wireless local area network.

The metallisation layer fonned as part of the casing may alternatively be made from any suitable conductive material, such as a conductive polymer.

Also, although a polymer transistor layer is used in the preferred embodiment, it will be clear that the transistors may be formed from semiconductor materials as is well known in the art.

It would also be possible to arrange the RC network such that there is one RC network for each individual pixel, row, column or even polymer layer.

Also, it would be possible to arrange a separate switching circuit for individual pixels, rows, columns or polymer layers.

Although the preferred embodiment has been described using a specific process to change the charge within the cells, it would also be possible to charge the cells in groups. For example, the cells may be charged one colour at a time, or one row/column at a time. Another alternative is to completely discharge the cells each time, and then recharge them to the required state.

Alternatively, the layout of the cells within each pixel may be of a different format, for example, adjacent pixels may be arranged such that the cells are not aligned but are offset. For example, the pixels in row 1 may be arranged such that.the cells are formed in the following colour sequence C M Y, C M Y, C M Y. Whereas the cells in the pixels below these cells, in row 2, are arranged such that the colour sequence is M Y C, M Y C, M Y C, or any other format.

It will be understood that embodiments of the present invention are described herein by way of example only, and that various changes and modifications may be made without departing from the scope of the invention.

Claims

CLAIMS: 1. A method of producing a casing for an electronic device wherein

the method comprises the step of forming an electrochromic layer within the casing.
2. The method of claim 1 wherein the method further comprises the step of foaming the electrochromic layer next to a layer of polymer transistors.
3. A casing for an electronic device wherein an image is produced on the casing by applying an electrical control signal to the casing.
4. The casing of claim 3 wherein the image on the casing remains after the electrical control signal has been removed.
5. The casing of claim 3 comprising an electrocbromic material.
6. The casing of claim 5 wherein the image is produced by applying a charge to the electrochromic material.
7. The casing of claim 6 wherein the image is updated by applying a further charge to the electrochromic material.
8. The casing of claim 6 wherein the colour of the electrochromic material is changed by applying only the difference in charge required.
9. The casing of claim 7 wherein the charge stored in the electrochromic material is removed prior to applying a further charge.
10. The casing of claim 6 wherein the charge is input into the electrochromic material through the use of transistors formed from a polymer material.
11. An electronic device with the casing of claim 3.
12. The device of claim 11 adapted to perform such that the image on the casing is produced when the casing is detached from the device.
13. The device of claim 11 adapted to perform such that the image on the casing is produced when the casing is attached to the device.
14. A casing for an electronic device as herein described with reference to the accompanying drawings.
15. A method of producing a casing as herein described with reference to the accompanying drawings.