GB2410143A

GB2410143A - Display calibration cradle for portable device

Info

Publication number: GB2410143A
Application number: GB0400647A
Authority: GB
Inventors: Hassan Paddy Abdel Salam
Original assignee: Individual
Current assignee: Individual
Priority date: 2004-01-13
Filing date: 2004-01-13
Publication date: 2005-07-20
Also published as: GB0400647D0

Abstract

A cradle 1 for recalibrating the unevenness in the output of a display due to pixel degradation is disclosed. The cradle (fig. 1) may comprise a light sensing device 2 and contacts 13 for electrical connection with a portable device 11. Alternatively (fig. 2) the cradle may comprise light reflection means to reflect light from the device display 12 onto an optical sensor 2 in the device. Calibration electronics may be mounted either in the cradle or portable device, and the cradle may have multiple sensors (fig. 4). The cradle may also be used to recharge the batteries of the device. The portable device may be a phone, hand-held computer, camera or game console.

Description

DOCKING STATION 24 10 143

FIELD AND BACKGROUND OF THE INVENTION

The present invention applies to cradles or docking stations for rechargeable portable devices that have a display, such as mobile phones and palm-held computers.

Such portable devices contain batteries that need to be charged many times during the useful life of the device.

An emerging type of display being considered for mobile phones and palmheld computers is the OLED display.

OLED displays are subject to uneven degradation of the pixels during the service life of the display. The uneven degradation results in images in which the pixels are not matched with each other.

An OLED display can have, for example, red, green and blue pixels. The different colors can degrade at different rates from each other. For example the emission intensities of the red pixels may degrade at a faster or slower rate than the emission intensities of the green pixels, thus altering the fidelity of color rendering of the pixels as the pixels age. Furthermore, the pixels of a given color, for example green, may degrade at different rates from each other, causing a displayed image to be uneven even if the image is all just green.

SUMMARY OF THE INVENTION

An object of the present invention is to reduce unevenness in the monochrome or color matrix display of a portable hand-held device.

According to an embodiment of the invention a cradle for a portable device, the portable device having a rechargeable battery and a display, includes at least one optical element provided for re-calibrating the display.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG.1 illustrates schematically a cradle according to one embodiment of the invention.

FIG.2 illustrates schematically a cradle according to another embodiment of the invention.

FIG.3 illustrates schematically a cradle according to a further embodiment of the invention.

FIG.4 illustrates schematically a cradle according to an embodiment of the invention wherein the portable device is a palm-held computer.

Fig. 5 illustrates schematically a cradle according to another embodiment of the invention.

DESCRIPTION

FIG. 1 illustrates a cradle 1 comprising a light-sensing device 2. Lightsensing device 2 receives light from a portable device 11 that has a matrix display 12, and that has a rechargeable battery that is not shown. The portable device 11 may, for example, be a mobile phone and display 12 may be an OLED matrix display. The rechargeable battery receives recharging energy from cradle 1 via some of a set of contacts 13. A cable 4 receives power for recharging the battery and delivers the power to cradle 1.

Before, during or after recharging of portable device 11, while it is on cradle 1, devices 1 and 11 interact via one or more of contacts 13 so that display 12 is caused to emit light. The output of sensor 2, detecting the emitted light, is measured and used for calibrating the display 12, so that display 12 can be corrected for any uneven degradation of its OLED pixels. Sensor 2 is shown mounted in a reflector cup 3. The OLED pixels can be energised and measured each in turn.

Sensor 2 may consist of one photocell or several photocells. Sensor 2 may comprise a red, a green and a blue photocell.

Sensor 2 can be replaced with a digital camera, in which case cup 3 can be made non-reflective. Using a camera at position 2 as the light sensor enables many pixels to be measured individually and simultaneously, but the cost of sensing becomes higher.

FIG. 2 illustrates another arrangement for cradle 1. In this case rechargeable portable device 11 has attached to it a light sensing device 2. Light from display 12 is directed to light sensing device 2 by reflectors 5 incorporated in cradle 1 for calibration.

FIG. 3 illustrates yet another arrangement for cradle or docking station 1. In this case rechargeable portable device 11 has attached to it a light sensing device 2 and light from display 12 is directed to light sensing device 2 by an optical fibre bundle 6 incorporated in cradle 1 which guides light from display 12 to sensor 2.

FIG.4 illustrates a cradle according to an embodiment of the invention wherein the rechargeable portable device is a palm-held computer. In this case several sensors 2 are provided in hollow 14 of cradle 1. The several sensors 2 can be connected in parallel.

Fig. 5 illustrates a cradle according to another embodiment of the invention wherein recargeable portable device 11 comprises a digital having a camera-lens 15. Device 11 is elongate in the direction into the paper. Electrical contacts under device 11, not shown, charge the batteries of device 11 using energy derived from cable 4. In this case the camera in device 11, having lens 15, serves as the optical sensor for calibration of display 12. The camera is arranged during calibration, initiated for example by device 11 or by cradle 1, to take one or more pictures of display l2, via mirrors 17a -17d and convergent close-up lens 16. Mirrors 17a -17d and close-up lens 16 are parts of cradle 1. Display 12 may have a length, measured into the paper, nearly equal to the length of device 11. Cradle 1 includes locating means, not shown, for positioning device 11 correctly. Device 11 can in this case be, for example, a digital camera or a combined digital camera/handheld computer, or a combined digital camera/games device.

In each of the arrangements discussed, display 12 may be a color OLED display, in which case the display may have red, green and blue pixels. A problem with red, green and blue OLED pixels is that each of the three colors degrades at a different rate from the other two, causing the color rendering of the display to deteriorate with use. The arrangements of the present invention overcome or ameliorate the problem of the color rendering changing with time. The light intensities of the red, green and blue pixels can be kept matched by the arrangements described with reference to the drawings even if the red, green and blue pixels degrade at markedly different rates from each other.

From time to time the system comprising cradle 1 and portable device 11 corrects for unevenness that has developed in the display 12. Correction can be by a calibration process supervised by cradle 1 or by device 11 involving measuring the light output of the display and recording correction parameters dependent on the measurements in a memory provided in device 11. The recorded information is subsequently referred to by device 11 for correcting the drives to the pixels when device 11 is being used off its cradle 1.

For each of the arrangements of FIGS. 1-5 a cable for providing the power for recharging the batteries of device 11 can be connected to either cradle l, as illustrated in FIG. 1, or to device 11.

For each of the arrangements of FIGS. 1-5, display 12 can be an OLED display or it can be any other type of display.

In the arrangements relying on sensors 2 each pixel can be individually calibrated in turn, by energising it and recording the corresponding output from sensor 2. To improve the sensitivity of light detection the pixel can be driven by a modulated signal, in which case the output of sensor 2 is fed to a circuit selective to the modulation.

Furthermore, instead of just one pixel being energized, sets of pixels can each be energized simultaneously and calibrated. A set of simultaneously energized pixels may, for example be a 2x2 or a 4x2 matrix, or a 4x1 array.

To correct for just the different rates of color degradation in a display 12 that uses red, green and blue pixels for example, the calibration can rely on turning on and measuring all the red pixels as one operation turning on and measuring all the green pixels as another operation, and turning on and measuring all the blue pixels as a further operation. Alternatively, if the optical sensor is an ROB sensor, all the pixels of the display can be energized and measured as one operation, and the red, green and blue outputs of the sensor used for correcting for the different rates of color degradation.

For each of the arrangements of FIGS. 1-5, the light measurements can be analyzed for calibration by electronics that are in cradle 1 and/or in device 11. s

Claims

What is claimed is: 1. A cradle for a portable device, the portable device

having a rechargeable battery and a display, wherein the cradle includes at least one optical device provided for re-calibrating the display from time to time during the lifetime of the portable device.
2. A cradle according to claim 1 wherein the cradle charges said battery.
3. A cradle according to claim 1 wherein the optical device comprises a light-sensor.
4. A cradle according to claim 2 wherein the optical device comprises a light-sensor.
5. A cradle according to claim 1 wherein said optical device comprises reflector means provided for directing light from said display towards a part of said portable device.
6. A cradle according to claim 1 wherein said optical device comprises means provided for channelling light from said display towards a part of said portable device.
7. A cradle according to claim 1 wherein said display has pixels of a first nominal color, the pixels of the first nominal color degrading at different rates from each other; wherein said portable device includes memory storing correction information derived with the aid of said optical device, the correction information being used for re-matching the pixels of the first nominal color.
8. A cradle according to claim 2 wherein said display has first, second, and third pixels of first, second, and third colors, respectively; the first, second, and third pixels degrading at different rates from each other; and wherein said portable device includes memory storing correction information derived with the aid of said optical device, the correction information being used for re-matching the first, second, and third pixels.
9. A cradle according to claim 2 wherein said optical device comprises a plurality of light-sensing elements.