Method for calibrating a light-opaque display

Abstract

Method (100) for calibrating a light-opaque display (201) in an electronic reading device (200), wherein the electronic reading device (200) comprises a controllable arrangement of light elements (203) for illuminating the light-opaque display (201), comprising: Controlling (101) the controllable arrangement of light elements (203) with a plurality of different control signals in order to illuminate the light-opaque display (201) with different illumination light; detecting (103) the plurality of color spectra reflected by the light-opaque display (201) as a result of controlling the controllable arrangement of light elements (203) with the plurality of different control signals; Selecting (105) a reflected color spectrum from the plurality of reflected color spectra; and Storing (107) the control signal associated with the selected reflected color spectrum in a memory (205) of the electronic reader (200) in order to calibrate the light-opaque display (201).

Description

[0001] The present invention relates to an electronic reading device, in particular an electronic book reading device, with a light-reflective display.

[0002] US 2010 / 0 002 027 A1 discloses an operating method for an illuminated display, in which the display comprises a backlit display screen and a plurality of matrix-like arranged luminous elements which illuminate the back of the display screen, and a control device sets colors of a light emitted by each luminous element in particular differently depending on a display content displayed by the display screen.

[0003] The published patent application WO 2013 / 056 012 A1 shows a device for calibrating a lighting unit.

[0004] The published patent application US 2014 / 0 063 853 A1 shows a light-emitting device.

[0005] Electronic reading devices are used to reproduce reading content, for example book content, and usually include a flat display that allows the reading content to be shown.

[0006] Electronic reading devices typically use opaque or light-reflective displays, which, when illuminated, reflect a display light that represents the current reading content. A light source is typically used to illuminate the opaque display from the front.

[0007] For electronic reading devices, the color spectrum and thus the color temperature of the reflected display light are particularly important. A white, uniform light is generally preferred, but this places particularly high demands on the quality of the light sources used, such as LEDs, and their spectral purity.

[0008] In the production of electronic reading devices, the light elements to be used are therefore sorted from a batch of light elements in order to select light elements with the most similar luminous properties, especially with the most similar color spectra, and thus to minimize differences between the displays of different reading devices. However, this increases the manufacturing costs of electronic reading devices.

[0009] US 2013 / 0 088 522 A1 discloses a calibration method for a light-transparent display, in which the display comprises several groups of light-emitting diodes illuminating the display and a control device sets a strength of a control current for each group depending on a stored calibration value assigned to the respective group in order to achieve a uniform color temperature.

[0010] It is therefore the object of the present invention to create a more production-efficient concept for illuminating light-opaque or light-reflective displays in electronic reading devices. This object is achieved by the features of the independent patent claims. Advantageous further developments are the subject of the dependent patent claims, the description, and the figures.

[0011] The present invention is based on the finding that the above object can be achieved by using a plurality of light elements which emit light in different color spectra and thus with different color temperatures, for example blue, red or white light, to illuminate the display.

[0012] In contrast to light-transparent or colored displays used in mobile phones, electronic reading devices use light-opaque or light-reflective displays, which reflect display light when illuminated from the front.

[0013] In order to obtain a uniform color spectrum of the display light reflected by the display in response to the illumination, the display and thus the arrangement of light elements are calibrated for each electronic reading device. For this purpose, a control signal specific to the respective arrangement of light elements of an electronic reading device is determined. This control signal includes, for example, voltages, currents, or pulse widths for controlling the light elements in the arrangement of light elements. This signal is used to obtain a desired color spectrum of the display light reflected by the opaque display. If the selected control signal is applied to the arrangement of light elements, the arrangement of light elements as a whole emits an illuminating light with a color spectrum, which illuminates the opaque display.The illumination light is reflected by the opaque display, resulting in reflected light with the reflected color spectrum. The color spectrum of the illumination light and the color spectrum of the reflected display light can be identical or at least have identical spectral components.

[0014] In this way, the desired color spectrum can be achieved even with lighting elements whose luminous properties are subject to series variation. This advantageously avoids the costly selection of the lighting elements to be used.

[0015] According to a first aspect, the invention relates to a method for calibrating a light-opaque display in an electronic reading device, wherein the electronic reading device comprises a controllable arrangement of light elements for illuminating the light-opaque display, with controlling the controllable arrangement of light elements with a plurality of different control signals in order to illuminate the light-opaque display with different illumination light, detecting the plurality of color spectra reflected by the light-opaque display as a result of controlling the controllable arrangement of light elements with the plurality of different control signals, selecting a reflected color spectrum from the plurality of reflected color spectra, and storing the control signal associated with the selected reflected color spectrum in a memory of the electronic reading device,to calibrate the light-opaque display.

[0016] The control signal is related to the selected reflected color spectrum, for example, when the light elements, when controlled by the control signal, illuminate the electronic display with illuminating light having a color spectrum that includes the reflected color spectrum or that produces the reflected color spectrum of the reflected display light.

[0017] This advantageously avoids the inefficient pre-sorting of light elements to be used, and allows the use of light elements with different luminous properties and even from different batches. The control signal is therefore specific to the respective electronic reader and depends on the luminous properties of the light elements installed behind the respective electronic reader.

[0018] According to one embodiment, the controllable arrangement of light elements comprises a light element matrix with differently colored light elements, wherein the control signals comprise different electrical quantities, in particular current and / or voltage values, for controlling the light element matrix. The light element matrix can, for example, comprise rows and rows of light elements that can be controlled row by row and row by row. The control signal can therefore be composed of different sub-control signals and, for example, have different voltages assigned to different columns and / or different rows of the light element matrix.

[0019] According to one embodiment, the arrangement of light elements comprises light-emitting diodes configured to emit light in different color spectra, in particular blue, red, yellow, or white light, to obtain the illumination light. By controlling the light elements with the control signal, they each emit light in different color spectra, resulting in the entire color spectrum, which is, for example, a white spectrum with a blue or red tint. When the light-opaque display is illuminated with such an illumination light, a reflected display light is generated that has light components from the color spectrum of the illumination light and thus a desired color spectrum.

[0020] According to one embodiment, selecting the reflected color spectrum comprises comparing the detected color spectra with a reference color spectrum, and the selected color spectrum is more similar to the reference color spectrum than another reflected color spectrum. The reference color spectrum may, for example, be a white spectrum that may have a green or red tint. The selected color spectrum is more similar to the reference spectrum than another reflected color spectrum, for example, if a difference between the selected color spectrum and the reference color spectrum is smaller than a difference between the other color spectrum and the reference color spectrum.

[0021] The reflected color spectra, for example, are assigned to different reflected display lights, each of which is created when illuminated with different illumination lights. The different illumination lights are created when the light elements or the arrangement of the light elements are exposed to different control signals.

[0022] According to one embodiment, in the step of storing, a further control signal is stored in the memory, which corresponds to a further reflected color spectrum, wherein the further reflected color spectrum has a higher blue component or a higher red component than the selected reflected color spectrum.

[0023] This advantageously ensures that the electronic reading device can provide different, standardized display lights with, for example, different standardized color spectra and, if necessary, also intensities.

[0024] According to one embodiment, during the storing step, a further control signal is stored in the memory, which corresponds to the reflected color spectrum with a different light intensity. This advantageously ensures that the standardized color spectrum can be provided with different light intensities. The different light intensities arise when the opaque display is illuminated with illumination lights of different intensities.

[0025] According to one embodiment, the control signal and the further control signal are assigned to different times of day or ambient brightness levels. This advantageously ensures that the coloration of the reflected color spectrum of the light reflected by the opaque display can be varied depending on the time of day. For example, in the morning, a reflected color spectrum can be set whose color corresponds to 7,700 Kelvin. At midday, however, a reflected color spectrum can be set whose color corresponds to a value of 6,500 Kelvin. In the evening, however, a reflected color spectrum can be set whose color corresponds to 5,400 Kelvin. According to one embodiment, different ambient brightness levels can be taken into account by using different light intensities.

[0026] According to one embodiment, the reflected color spectra are different white spectra. The different white spectra differ, for example, in a red or blue component, so that they can be used at different times of day.

[0027] According to one embodiment, in the storing step, information about the selected reflected color spectrum is stored with the control signal. This advantageously ensures that different control signals can be assigned to different color spectra of the reflected display light. In this way, for example, a user of the electronic reading device can, by entering the desired color of the reflected display light, automatically select the associated control signal, which is applied to the light elements in order to set the desired color, i.e., color spectrum, of the reflected display light.

[0028] According to one embodiment, in the step of detecting the reflected color spectra, reflected light intensities are detected, and the control signal that effects a predetermined light intensity in the selected reflected color spectrum is selected. Advantageously, the control signal can be used not only to achieve spectral color compensation, but also to compensate for the scattering of light intensities of the light elements.

[0029] According to one embodiment, the invention relates to a method that is carried out in a manufacturing step of the electronic reading device. In general, the invention thus also relates to the manufacture of an electronic reading device with the additional step of calibrating a light-opaque display of the electronic reading device according to the first aspect.

[0030] According to a further aspect, the invention relates to an electronic reading device with a light-opaque display for displaying a reading content by reflected display light, a controllable arrangement of light elements for illuminating the light-opaque display in order to effect the reflected display light, a memory in which at least one control signal for controlling the arrangement of light elements is pre-stored, which control signal is assigned to a predetermined color spectrum of the reflected display light, a controller which is designed to read the control signal from the memory and to control the arrangement of light elements with the control signal for illuminating the light-opaque display in order to obtain the reflected display light with the predetermined color spectrum.

[0031] The controller may, for example, comprise a driver, which may be a software driver that outputs the control signal and activates or controls the light elements in order to control the light-opaque, reflective display.

[0032] The predetermined color spectrum may, for example, correspond to the color spectrum that was set during the manufacture of the electronic reading device as explained above.

[0033] According to one embodiment, a further control signal corresponding to a further reflected color spectrum is stored in the memory, and the reflected color spectrum and the further reflected color spectrum are assigned to different usage parameters, in particular different times of day, ambient brightness, or color spectra of the ambient light. This advantageously ensures that different color spectra of the reflected display light can be automatically adjusted depending on different usage parameters. For example, fluctuations in the color spectrum of ambient light can also be compensated for in order to maintain a desired color spectrum of the display light reflected by the display.

[0034] According to one embodiment, the controller has a sensor for detecting the usage parameter, in particular a time of day sensor or an ambient brightness sensor or a color sensor for detecting the color spectrum of the ambient light.

[0035] According to one embodiment, the light-opaque display is an e-paper display.

[0036] According to a further embodiment, the invention relates to the electronic reading device according to one of the preceding claims, which is an electronic book reading device.

[0037] Further embodiments of the present invention will be described with reference to the accompanying drawings, in which: Fig. 1 is a flowchart of a method for calibrating a light-opaque display; Fig. 2 a diagram of an electronic reader; Fig. 3a to 3c reflected display light with different color spectra; and Fig. 4 a flow diagram of a method for producing a light-opaque display of an electronic reading device.

[0038] Fig. 1 shows a method 100 for calibrating a light-opaque display in an electronic reading device. The method comprises controlling 101 a controllable arrangement of light elements, which the electronic reading device comprises for illuminating the light-opaque display, with a plurality of control signals in order to illuminate the light-opaque display with different illumination light. The control of the arrangement of light elements with different control signals preferably occurs sequentially, and electrical quantities representing the control signals are applied to the light elements to illuminate them. Examples of electrical quantities are voltages, currents, or pulse widths in the case of pulse-width modulated control of the light elements.

[0039] The method further includes detecting 103 the plurality of color spectra reflected by the light-transparent display in response to the illumination. Each reflected color spectrum represents a color of a display light reflected by the display as a result of illumination with the respective illumination light.

[0040] The method further comprises selecting 105 a reflected color spectrum from the plurality of reflected color spectra and storing 107 the control signal associated with the selected reflected color spectrum in a Fig. 1 memory of the electronic reading device (not shown) to calibrate the light-transparent display. To retrieve the selected reflected color spectrum, the stored control signal can be read from the memory and used to control the light elements, which then generate an illumination light that illuminates the electronic display and produces a reflected display light that exhibits the selected reflected color spectrum.

[0041] To select 105 the reflected color spectrum, the reflected color spectra are compared, for example, with a reference color spectrum, and the color spectrum that is most similar to the reference color spectrum or that has the smallest difference from the reference signal is selected.

[0042] To detect 103 the respective reflected color spectrum, the respective reflected display light can be detected, and the color of the reflected display light can be determined. To determine the color of the reflected display light, known methods for determining the color or color spectrum of light can be used.

[0043] The color spectrum of the reflected display light defines the color and thus the color temperature of the reflected display light. If the color spectrum contains more blue components, the color temperature of the reflected color spectrum is cooler. If, on the other hand, the reflected display light contains more red components, the color temperature of the reflected display light is warmer.

[0044] According to one embodiment, the reflected color spectra represent white display light with different colorations caused by different blue or red components.

[0045] Fig. Figure 2 shows an electronic reading device 200 according to one embodiment. The electronic reading device 200 has a light-transparent, reflected display 201 and a controllable arrangement of light elements 203, for example, light-emitting diodes, in particular organic light-emitting diodes.

[0046] The electronic reading device 200 further comprises a memory 205 in which at least one control signal for controlling the arrangement of light elements 203 is pre-stored and which is assigned to a predetermined color spectrum of the reflected display light of the light-opaque display 201.

[0047] The electronic reading device 200 further comprises a controller 207, which is designed to read the control signal from the memory 205 and to apply or control the arrangement of light elements 203 with the control signal in order to illuminate the light-opaque display 201 with illumination light, which causes the reflected display light with the predetermined color spectrum.

[0048] According to one embodiment, the target control signal stored in the memory 205 is associated with a predetermined color spectrum and a usage parameter, for example a specific user profile.

[0049] The controller 207 can, for example, implement a driver for controlling the light elements 203 with the control signal, which can be a hardware driver or a software driver. The light elements 203 are thus supplied with a control signal that is assigned to the light elements 203 and with which, for example, series scattering of light elements is compensated in order to obtain the desired reflected color spectrum despite, for example, series-related fluctuations in the respective emitted color spectrum.

[0050] The light elements 203 can, for example, be located behind or in a Fig. 2 and / or a light-guiding plastic or a light-guiding layer of the light-opaque display 201, which at least partially cover the light-opaque display 201. This arrangement allows a uniform and even distribution of the light over the entire surface of the light-opaque display 201 to be achieved.

[0051] According to one embodiment, the display 201 can be enclosed by a housing frame of a housing. In this case, the light elements can be arranged in the housing frame and emit light toward the light-opaque display 201.

[0052] The light elements 203 can be functionally combined to form a light matrix, and furthermore, the light elements 203 can each emit light in a different color. For example, one of the light elements 203 can emit white light, while another can emit red light, i.e., light with a red spectral component, or blue light, i.e., light with a blue spectral component. Mixing the spectral components thus results in colorations of the white light that differ, for example, in their blue or red components. In this way, it is possible to adjust the desired reflected white light.

[0053] The stored calibrating control signal can thus be regarded as a standard control signal that is read out from the memory 205 as standard and used to control the light elements 203.

[0054] According to one embodiment, the memory 205 is provided to provide control signals for controlling the controllable arrangement of light elements 203, wherein the control signals are assigned to different color spectra of the reflected display light and to different usage parameters. The controller 207 is configured to read a control signal assigned to a specific usage parameter from the memory 205 and to control the arrangement of light elements 203 with the read control signal to illuminate the light-opaque display 201 in order to obtain a color spectrum of the reflected display light assigned to the specific usage parameter.

[0055] The usage parameters are assigned, for example, to different times of day or ambient brightness levels. For example, a color spectrum can be selected in the morning that features white light with a higher blue component than a color spectrum selected at midday or in the afternoon. Different ambient brightness levels can also result in different light intensities of the reflected display light and thus of the illumination light emitted by the light elements 203.

[0056] By taking into account a color spectrum of the ambient light, the color spectrum of the illumination light generated by the light elements 203 can be adjusted such that, by superposition, an overall color spectrum of the light incident on the display 201 is established which corresponds to the desired color spectrum of the reflected display light.

[0057] To record the usage parameters, the electronic device 200 may, for example, comprise a sensor 209, which is optional.

[0058] According to one embodiment, the usage parameters can be entered, for example, by a user. For this purpose, the electronic reading device 200 can have a user interface 211 with which the user can select the desired color, ie

[0059] The user interface 211 can be a graphical user interface, for example, in which the user can select a color, ie, a color spectrum. The user interface 211 can also be an actuating element with which the user can set the desired color, ie, the desired color spectrum.

[0060] According to one embodiment, the light elements 203 are configured to emit white light in different wavelength ranges, i.e., with different color spectra. In this way, by mixing the respective emitted light, the color temperature of the display light reflected by the display 201 can be adjusted, for example, depending on the color temperature of daylight or the user's selection.

[0061] In Fig. 3a to 3c show the reflective, light-opaque display 201 when controlled differently by different control signals.

[0062] In Fig. 3a, for example, a reflected display light 301 is set, which has a color temperature of, for example, 7,700 Kelvin. Such a light can be set, for example, in the morning.

[0063] In Fig. 3b shows a reflected display light 303 which has a warmer color temperature than that shown in Fig. 3. The color temperature of the indicator light 303 can be, for example, 6,500 Kelvin. Such a light is suitable, for example, for use around midday.

[0064] In Fig. Figure 3c shows the opaque, reflective display 201 with a display light 305 whose color temperature is, for example, 5,400 Kelvin. Such a display light appears warmer due to the red shift and is therefore suitable for use in the evening hours.

[0065] Fig. 4 shows an example of a method 400 for producing the light-opaque display 201 of the electronic reading device 200 and for providing a driver for controlling the light-opaque display 201.

[0066] The method 400 comprises the provision 401 of LEDs, which can be subject to strong fluctuations in intensity and color temperature. In conventional displays, these fluctuations can lead to a deviation of the display color from a target color. Conventional production processes therefore employ time-consuming and costly selection processes to group LEDs into different color categories, with the goal of installing LEDs with the most uniform color tone and light intensity possible. Such methods can be dispensed with in the present method 400. The LEDs can originate from at least one batch and, for example, can only be roughly pre-sorted before provision 401, which can simplify the manufacturing process and reduce production costs.

[0067] The method 400 for producing the light-opaque display 201 further comprises installing 403 the light-emitting diodes behind and / or in a diffusing screen or a light-guiding layer, whereby a uniform and even distribution of the light over the entire surface of the light-opaque display 201 can be achieved.

[0068] After installation 403, the process 100 for calibrating the light-opaque display, which is described in Fig. 1, is carried out to calibrate the light-opaque display 201 with the built-in LEDs, which may be subject to fluctuations in intensity and color temperature.

[0069] After calibration, the driver of the controller 207 is provided 405, whereby the driver can be a hardware driver or a software driver. List of reference symbols 100 Calibration Procedures 101 Control 103 Capture 105 Select 107 Save 200 electronic readers 201 light-opaque display 203 Light element 205 storage 207 Control 209 Sensor 211 User interface 301 reflected indicator light 303 reflected indicator light 305 Indicator light 400 manufacturing processes 401 Providing LEDs 403 Install 405 Providing a driver

Claims

[1] Method (100) for calibrating a light-opaque display (201) in an electronic reading device (200), wherein the electronic reading device (200) comprises a controllable arrangement of light elements (203) for illuminating the light-opaque display (201), comprising: Controlling (101) the controllable arrangement of light elements (203) with a plurality of different control signals in order to illuminate the light-opaque display (201) with different illumination light; detecting (103) the plurality of color spectra reflected by the light-opaque display (201) as a result of controlling the controllable arrangement of light elements (203) with the plurality of different control signals; Selecting (105) a reflected color spectrum from the plurality of reflected color spectra; and Storing (107) the control signal associated with the selected reflected color spectrum in a memory (205) of the electronic reader (200) in order to calibrate the light-opaque display (201). [2] Method (100) according to claim 1, wherein the controllable arrangement of light elements (203) comprises a light element matrix with differently colored light elements (203), wherein the control signals comprise different electrical quantities, in particular current and / or voltage values, for controlling the light element matrix. [3] Method (100) according to claim 1 or 2, wherein the arrangement of light elements (203) comprises light-emitting diodes which are designed to emit light in different color spectra in order to obtain the illumination light. [4] The method (100) of any preceding claim, wherein selecting (105) the reflected color spectrum comprises comparing the detected color spectra with a reference color spectrum, and wherein the selected color spectrum is more similar to the reference color spectrum than another reflected color spectrum. [5] Method (100) according to one of the preceding claims, wherein in the step of storing (107) a further control signal is stored in the memory (205) which corresponds to a further reflected colour spectrum, wherein the further reflected colour spectrum has a higher blue component or a higher red component than the selected reflected colour spectrum. [6] The method (100) of claim 5, wherein in the step of storing (107) a further control signal is stored in the memory (205) corresponding to the reflected color spectrum with a different light intensity. [7] Method (100) according to claim 5 or 6, wherein the control signal and the further control signal are assigned to different times of day or ambient brightness. [8] Method (100) according to one of the preceding claims, wherein the reflected color spectra are different white spectra. [9] Method (100) according to one of the preceding claims, wherein in the step of storing (107) an indication of the selected reflected color spectrum is stored with the control signal. [10] Method (100) according to one of the preceding claims, wherein in the step of detecting (103) the reflected color spectra, reflected light intensities are detected, and wherein the control signal is selected which causes a predetermined light intensity in the selected reflected color spectrum. [11] Method (100) according to one of the preceding claims, which is carried out in a manufacturing step for producing the electronic reading device (200). [12] An electronic reading device (200), comprising: a light-opaque display (201) for displaying a reading content by reflected display light (301, 303, 305); a controllable arrangement of light elements (203) for illuminating the light-opaque display (201) to effect the reflected display light (301, 303, 305); a memory (205) in which at least one calibrating control signal selected in a method according to one of claims 1 to 11 is pre-stored for controlling the arrangement of light elements (203), which is associated with a predetermined color spectrum of the reflected display light (301, 303, 305); a controller (207) which is designed to read the control signal from the memory (205) and to control the arrangement of light elements (203) with the control signal for illuminating the light-opaque display (201) in order to obtain the reflected display light (301, 303, 305) with the predetermined color spectrum. [13] Electronic reading device (200) according to claim 12, wherein a further control signal corresponding to a further reflected color spectrum is stored in the memory (205), and wherein the reflected color spectrum and the further reflected color spectrum are assigned to different usage parameters, in particular different times of day, ambient brightness or color spectra of the ambient light. [14] Electronic reading device (200) according to claim 13, wherein the controller (207) comprises a sensor (209) for detecting the usage parameter, in particular a time of day sensor or an ambient brightness sensor or a color sensor for detecting the color spectrum of the ambient light. [15] Electronic reading device (200) according to one of claims 12 to 14, wherein the light-opaque display (201) is an e-paper display. [16] An electronic reading device (200) according to any one of claims 12 to 15, which is an electronic book reading device.

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