Patent Publication Number: US-10332432-B2

Title: Display device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     Korean Patent Application No. 10-2016-0031208, filed on Mar. 16, 2016, and entitled, “Display Device,” is incorporated by reference herein in its entirety. 
     BACKGROUND 
     1. Field 
     One or more embodiments described herein relate to a display device. 
     2. Description of the Related Art 
     A head-mounted display device has been proposed for use in virtual reality gaming and other applications. However, existing head-mounted display devices have drawbacks relating to size, efficiency, and performance. 
     SUMMARY 
     In accordance with one or more embodiments, a display device includes a display panel including a central region and a peripheral region; a timing controller to convert image data to converted data so that a maximum luminance of the peripheral region is less than a maximum luminance of the central region; and a data driver to generate a data signal based on the converted data and to provide the data signal to the display panel. 
     The timing controller may calculate an on-pixel ratio of the image data, generate first sub converted data by reducing first sub image data among the image data based on the on-pixel ratio and a first reference on-pixel ratio, and generate second sub converted data by reducing second sub image data among the image data based on the on-pixel ratio and a second reference on-pixel ratio different from the first reference on-pixel ratio, wherein the first sub data corresponds to the central region, the second sub data corresponds to the peripheral region, and the converted data includes the first sub converted data and the second sub converted data. 
     The on-pixel ratio may be a ratio of a driving amount when pixels in the display panel are driven based on the image data to a driving amount when the pixels are driven with a maximum grayscale value. The central region may be determined based on a viewing angle of a user to the display panel. 
     The timing controller may include a first calculator to calculate the on-pixel ratio based on the image data; a second calculator to calculate a first scaling rate based on the on-pixel ratio and the first reference on-pixel ratio and to calculate a second scaling rate based on the on-pixel ratio and the second reference on-pixel ratio; and a image converter to generate the first sub converted data by reducing the first sub image data based on the first scaling rate and to generate the second sub converted data by reducing the second sub image data based on the second scaling rate. 
     The second calculator may calculate the first scaling rate based on Equation 1 when the on-pixel ratio is greater than the first reference on-pixel ratio:
 
 ACL _ DY 1= ACL _OFF_MAX1×(OPR( N )−START_OPR1)/(MAX_OPR−START_OPR1)   (1)
 
where ACL_DY 1  denotes the first scaling rate, ACL_OFF_MAX 1  denotes a first maximum scaling rate, OPR(N) denotes the on-pixel ratio, START_OPR 1  denotes the first reference on-pixel ratio, and MAX_OPR denotes a maximum on-pixel ratio.
 
     The second calculator may output the first scaling rate equal to a reference scaling rate when the on-pixel ratio is less than the first reference on-pixel ratio. The first reference on-pixel ratio may be equal to a maximum on-pixel ratio. The display panel may include a boundary region between the central region and the peripheral region, and the image converter may reduce boundary image data corresponding to the boundary region based on the first scaling rate and the second scaling rate. 
     The image converter may calculate a third scaling rate by interpolating the first scaling rate and the second scaling rate based on location information of a grayscale value in the boundary image data and is to reduce the grayscale value based on the third scaling rate. The image converter may calculate a fourth scaling rate by interpolating the first scaling rate and the second scaling rate based on location information of a grayscale value in the image data and reduces the grayscale value based on the fourth scaling rate. 
     The image converter may calculate an additional scaling rate based on direction information of a grayscale value in the image data and reduce the grayscale value based on the fourth scaling rate and the additional scaling rate, and the direction information includes a direction in which a pixel corresponding to the grayscale value is located with a central axis of the display panel. The timing controller may include a image processor to generate the image data by shifting an input image data from an external component in a first direction. The image processor may match a central axis of an image corresponding to the input image data to a central axis of the display panel. 
     In accordance with one or more other embodiments, a display device includes a display panel including a central region and a peripheral region; and a data driver to generate a first data signal based on first sub image data corresponding to the central region and to generate a second data signal based on second sub image data corresponding to the peripheral region, wherein a second maximum grayscale voltage of the second data signal is less than a first maximum grayscale voltage of the first data signal. 
     The data driver may include a first gamma register to store the first sub image data temporally; a first gamma block to generate the first data signal based on the first sub image data; a second gamma register to store the second sub image data temporally; and a second gamma block to generate the second data signal based on the second sub image data. The display device may include a scan driver to generate a scan signal and to sequentially provide the scan signal to the display panel, the second gamma block to operate when a time point at which the scan signal is provided to the central region. 
     In accordance with one or more other embodiments, a display device includes a first display panel including a central region and a peripheral region; a timing controller to generate image data by shifting input image data from an external component in a first direction and to generate converted data by converting the image data, so that a maximum luminance of the peripheral region is lower than a maximum luminance of the central region; and a data driver to generate a data signal based on the converted data and to provided the data signal to the display panel. The central region may be determined based on an area center of the first display panel. The timing controller may shift the input image data to locate a center of an image corresponding to the image data onto a viewing axis of a user. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Features will become apparent to those of ordinary skill in the art by describing in detail exemplary embodiments with reference to the attached drawings in which: 
         FIG. 1  illustrates an embodiment of a head-mounted display device; 
         FIG. 2  illustrates an embodiment of a display device; 
         FIG. 3A  illustrates an embodiment of a display panel, and  FIG. 3B  illustrates an example of characteristics of the eyes of a user; 
         FIG. 4  illustrates an embodiment of a timing controller; 
         FIG. 5  illustrates an example of luminance controlled by the timing controller; 
         FIG. 6A  illustrates an example of a scaling rate calculated by the timing controller,  FIG. 6B  illustrates an example of grayscale values remapped by the timing controller, and  FIG. 6C  illustrates another example of grayscale values remapped by the timing controller; 
         FIG. 7  illustrates another example of luminance controlled by the timing controller; 
         FIG. 8A  illustrates another example of luminance controlled by the timing controller, and  FIG. 8B  illustrates another example of luminance controlled by the timing controller; 
         FIG. 9  illustrates an embodiment of a data driver; 
         FIG. 10  illustrates an embodiment of an operation of the data driver; 
         FIG. 11  illustrates another embodiment of a head-mounted display device; 
         FIG. 12  illustrates an example of input image data processed by the timing controller in  FIG. 4 ; and 
         FIG. 13  illustrates another example of luminance controlled by the timing controller in  FIG. 4 . 
     
    
    
     DETAILED DESCRIPTION 
     Example embodiments will be described with reference to the accompanying drawings; however, they may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey exemplary implementations to those skilled in the art. The embodiments, or certain aspects thereof, may be combined to form additional embodiments. 
     In the drawings, the dimensions of layers and regions may be exaggerated for clarity of illustration. It will also be understood that when a layer or element is referred to as being “on” another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may also be present. Further, it will be understood that when a layer is referred to as being “under” another layer, it can be directly under, and one or more intervening layers may also be present. In addition, it will also be understood that when a layer is referred to as being “between” two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present. Like reference numerals refer to like elements throughout. 
     When an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the another element or be indirectly connected or coupled to the another element with one or more intervening elements interposed therebetween. In addition, when an element is referred to as “including” a component, this indicates that the element may further include another component instead of excluding another component unless there is different disclosure. 
       FIG. 1  illustrates an embodiment of a head-mounted display device  100  (or head-mounted display system) which includes a display device  10  and a lens  20 . The head-mounted display device  100  may be mounted on the head of a user and may further include a frame (or a case) to support the display device  10  and the lens  20 . The lens  20  may be spaced from the display device  100  by a predetermined distance. The lens  20  may directly provide the eyes of the user with an image generated by the display device  10 , when head-mounted display device  100  is mounted on the user. The lens  20  may be, for example, an eyepiece (or ocular eye piece). The head-mounted display device  100  may further include lenses, a reflector, and/or optical elements forming and adjusting an optical path to the eyes of the user. 
       FIG. 2  illustrates an embodiment of the display device  10  which may be in the head-mounted display device  100  of  FIG. 1 .  FIG. 3A  illustrates an embodiment of a display panel  210  in the display device  10 , and  FIG. 3B  illustrating an example of the characteristics of the eyes of a user. 
     Referring to  FIG. 2 , the display device  10  may include a display panel  210 , a scan driver  220 , a data driver  330 , a timing controller  240 , and a power supply  250 . The display device  100  may display an image based on input image data (e.g., first data DATA 1 ) provided from an external component (e.g., a graphics card). The display device  100  may be, for example, an organic light emitting display device. The input image data may be, for example, a three-dimensional (or 3D) image data, e.g., the input image data may include left image data and right image data to generate left and right images to be respectively provided to the eyes of the user. 
     The display panel  210  may include a plurality of pixels PX, a plurality of scan lines S 1  through Sn, and a plurality of data lines D 1  through Dm, where n and m are integers greater than or equal to 2. The pixels PX may be at respective cross-regions of the scan lines S 1  through Sn and the data lines D 1  through Dm. Each pixel PX may store a data signal (e.g., a data signal provided through the data lines D 1  through Dm) based on a scan signal (e.g., a scan signal provided through the scan lines S 1  through Sn) and may emit lights based on the stored data signal. 
       FIG. 3A  illustrates an example of the display panel  210  which may include a first displaying region  311  and a second displaying region  312 . The first displaying region  311  may display a first image (e.g., a left image) for one eye of the user (e.g., for a left eye of the user). The second displaying region  312  may display a second image (e.g., a right image) for the other eye of the user (e.g., for a right eye of the user). 
     The first displaying region  311  may include a first central region Z 1  (or a first central area) and a first peripheral region Z 2  (or a first peripheral area). The first central region Z 1  may be in an area having a first radius with respect to a center point of the first displaying region  311 . The center point of the first displaying region  311  may be a center of area of the first displaying region  311 . For example, the first central region Z 1  may be a rectangular area having a first width W 1  and a first height H 1  with respect to a first central axis Y 1  (or a vertical axis) of the first displaying region  311 . The first central axis Y 1  may pass the center point of the first displaying region  311 . 
     The first peripheral region Z 2  may not overlap the first central region Z 1  and may be in an area having a radius greater than the first radius with respect to a center point of the first displaying region  311 . For example, the first peripheral region Z 2  may be an area of the first displaying region  311  except the first central region Z 1  and may be between the first width W 1  and a second width W 2 . The second width W 2  is greater than the first width W 1 . 
     The display panel  210  may further include a boundary region (or a boundary area) between the first central region Z 1  and the first peripheral region Z 2 . The first central region Z 1 , the first peripheral region Z 2 , and the boundary region may be divided conceptually. 
     The second displaying region  312  may include a second central region and a second peripheral region, which may be symmetrical with (or may correspond to) the first central region Z 1  and the first peripheral region Z 2  with respect to a central axis (e.g., a vertical axis passing a center of area of the display panel  210 ), respectively. In some example embodiments, the first central region Z 1  may be determined based on a viewing angle of the user to the display panel  210 . 
       FIG. 3B  illustrates an example of the distribution of photoreceptors in the left eye of a user. The photoreceptors may include cone cells and rod cells. Each cone cell may detect and identify brightness and colors. Each rod cell may detect relatively low light and may identify contrast or a shape of an object. 
     A first distribution curve  321  may represent a distribution of cone cells. According to the first distribution curve  321 , the cone cells (or the density or number of the cone cells) may have a maximum value at about 20 degrees (or 20 degrees of the viewing angle of the user, e.g., 20 degrees in the direction toward the ear and 20 degrees in the direction to the nose) and may be distributed in the whole retina. The second distribution curve  322  may represent the distribution of the rod cells. According to the second distribution curve  322 , the rod cells may be concentrated at 0 degrees (e.g., at a center of a retina). 
     According to the first distribution curve  321  and the second distribution curve  322 , the visual recognition ability of the user may be concentrated in the range of 20 degrees (e.g., the range of 20 degrees in the direction through the ear and 20 degrees in the direction towards the nose). The user may be insensitive to a change of the image in a range other than the range of 20 degrees. 
     For reference, the user may recognize a view having an angle greater than 20 degrees of the viewing angle (or an object in an area corresponding to an angle greater than 20 degrees of the viewing angle) by rotating the head (not the eyes). For example, the user may recognize an image in a center of a screen (e.g., an image corresponding to a range within 20 degrees of the viewing angle) and may not recognize an image at a boundary of the screen (e.g., an image in a range exceeding 20 degrees of the viewing angle, or a change of luminance at the boundary of the screen). 
     Therefore, in accordance with the present embodiment, the display device  10  (or the head-mounted display device  100 ) may reduce or minimize a reduction in quality of an image visible to the user and may reduce power consumption by reducing luminance in a range exceeding 20 degrees of the viewing angle at which the visual recognition ability of the user is relatively poor (e.g., luminance of first peripheral region Z 2 ). 
     For example, the display panel  210  (or the first display region  311 ) may display an image corresponding to a range within about 50 degrees of the viewing angle of the user when the user wears the head-mounted display device  100 . The display panel  210  (or the second width W 2  of the first displaying region  311 ) may correspond to an area having a range greater than an area having a range of 20 degrees of the viewing angle of the user. The first central region Z 1  (or the first width W 1  of the first central region Z 1 ) may be determined to correspond to the range of 20 degrees of the user viewing angle. 
     In  FIG. 3A , the display panel  210  includes the first displaying region  311  and the second display region  312 . In one embodiment, the display panel  210  may include only the first displaying region  311  and a second display panel different from the display panel  210  may include the second displaying region  312 . Thus, the display device  100  may include two display panels, instead of one display panel  210 , and may drive the two display panels independently from each other. 
     Referring again to  FIG. 2 , the scan driver  220  may generate a scan signal based on a scan driving control signal SCS. The scan driving control signal SCS may include, for example, a start signal (or a start pulse) and clock signals. The scan driver  220  may include shift registers sequentially generating the scan signal based on the start signal and the clock signals. 
     The data driver  230  may generate data signals based on a data driving control signal DCS. For example, the data driver  230  may generate the data signals in analog form based on image data (e.g., second data DATA 2 ) in digital form. The data driver  230  may generate the data signals based on predetermined grayscale voltages (or gamma voltages) from, for example, from a gamma circuit. The data driver  230  may sequentially provide the data signals to pixels in a pixel column. 
     In some example embodiments, the data driver  230  may generate a first data signal based on first sub image data (e.g., data corresponding to the first central region Z 1 ) and may generate a second data signal based on second sub image data (e.g., data corresponding to the first peripheral region Z 2 ). A second maximum value (or a second maximum grayscale voltage) of the second data signal may be less (or lower) than a first maximum value (or a first maximum grayscale voltage) of the first data signal. For example, the data driver  230  may include a first gamma block corresponding to (or to generate grayscale voltages for data corresponding to) the first central region Z 1  and a second gamma block corresponding to (or to generate grayscale voltages for data corresponding to) the first peripheral region Z 2 . The data driver  230  may generate the first data signal using the first gamma block and may generate the second data signal using the second gamma block. 
     The timing controller  240  may receive the input image data (e.g., the first data DATA 1 ) and input control signals (e.g., a horizontal synchronization signal, a vertical synchronization signal, and clock signals) from an external component (e.g., application processor). The timing controller  240  may also generate image data (e.g., the second data DATA 2 ) compensated to be suitable for the display panel  210  for displaying an image. The timing controller  240  may also control scan driver  220  and data driver  230 . 
     In some example embodiments, the timing controller  240  may generate converted data, for example, by converting the input image data to have maximum luminance of peripheral regions (e.g., the first peripheral region Z 2 ) lower than maximum luminance of central regions (e.g., the first central region Z 1 ). In one embodiment, the timing controller  240  may calculate an on-pixel ratio (ORP) of the input image data (e.g., the first data DATA 1 ) and may generate the input data (e.g., the second data DATA 2 ) by reducing (or by down scaling) the input image data based on the on-pixel ratio. The timing controller  240  may generate first sub converted data by reducing the first sub image data based on the on-pixel ratio and a first reference on-pixel ratio. The timing controller  240  may generate second sub converted data by reducing the second sub image data based on the on-pixel ratio and a second reference on-pixel ratio. 
     The on-pixel ratio may be a ratio of a number of activated pixels based on the input image data to a total number of pixels. The first sub image data may correspond to the central regions (e.g., the first central region Z 1  and/or a second central region) among the input image data. The second sub image data may correspond to the peripheral regions (e.g., the first peripheral region Z 2  and/or a second peripheral region) among the input image data. The first reference on-pixel ratio may be a reference value to be used to determine whether or not the first sub image data is reduced. The second reference on-pixel ratio may be a reference value to be used to determine whether or not the second sub image data is reduced. The first sub on-pixel ratio may be greater than the second sub on-pixel ratio. 
     In one embodiment, the timing controller  240  may generate the input data by reducing the first sub image data and the second sub image data based on different references (or based on different reference on-pixel ratios), respectively or independently from each other. For example, when the on-pixel ratio calculated by the timing controller  240  is in a specified range, the timing controller  240  may reduce only the second sub image data based on the on-pixel ratio. 
     The power supply  250  may generate and provide a driving voltage to the display panel  210  (or the pixel). The driving voltage may be power voltages to drive the pixel PX. For example, the driving voltage may include a first power voltage ELVDD and a second power voltage ELVSS. The first power voltage ELVDD may be greater (or higher) than the second power voltage ELVSS. 
     In accordance with the present embodiment, the display device  10  may convert the input image data to have a maximum luminance of the peripheral regions lower than a maximum luminance of the central regions. In addition, the display device  10  may apply (or may use) different references (e.g., the first reference on-pixel ratio and the second reference on-pixel ratio) for the first sub image data corresponding to the central regions and for the second sub image data corresponding to the peripheral regions. Furthermore, the display device  100  may determine the first and second image data (or the central regions and peripheral regions of the display panel  210 ) based on characteristics (or visual characteristics) of the eyes of a user. Therefore, the display device  100  may reduce power consumption without reducing display quality of an image which the user can recognize. 
       FIG. 4  illustrating an embodiment of the timing controller  240  in the display device  10  of  FIG. 2 .  FIG. 5  illustrates an example of luminance controlled by the timing controller  240 .  FIG. 6A  illustrates an example of a scaling rate calculated by the timing controller  240 ,  FIG. 6B  illustrates an example of grayscale values remapped by the timing controller  240 , and  FIG. 6C  illustrates another example of grayscale values remapped by the timing controller  240 . 
     Referring to  FIG. 5 , a first luminance curve  511  may represent luminance of an image displayed on the display panel  210  (or on the first displaying region  311  of the display panel  210 ) based on the input image data (e.g., the first data DATA 1 ). A second luminance curve  512  may represent luminance of an image displayed on the display panel  210  based on converted data (e.g., the second data DATA 2 ) generated by the timing controller  240 . A third luminance curve  513  and a fourth luminance curve  514  may represent luminance of an image displayed on the display panel  210  based on other converted data (e.g., the second data DATA 2 ) generated by the timing controller  240 . An example of an operation of the timing controller  240  based on the second luminance curve  512  will be described below. Also, an operation of the timing controller  240  based on the third luminance curve  513  and fourth luminance curve  514  will be described. 
     Referring to  FIGS. 4 through 6C , the timing controller  240  may include an image processor  410 , a first calculator  420 , a second calculator  430 , and an image converter  440 . The image processor  410  may generate image data (e.g., third data DATA 3 ) by converting (or by resizing) the input image data (e.g., the first data DATA 1 ) to have a resolution corresponding to a resolution of the display panel  210 . 
     For example, the resolution of the input image data (e.g., a resolution of input image data in 2-dimensional format) may be 1920*1440, and the resolution of the display panel  210  may be 2560*1440. The image processor  410  may generate left image data based on some of the input image data which correspond to a resolution of 1280*1440 with respect to one side (e.g., a left side) of the input image data. The image processor  410  may generate right image data based on some of the input image data which correspond to a resolution of 1280*1440 with respect to the other side (e.g., a right side) of the input image data. 
     For example, the input image data (e.g., input image data in 3-dimensional format) may include left input image data and right input image data. The resolution of each of the left and right input image data may be 1920*1440, and the resolution of the display panel  210  may be 2560*1440. The image processor  410  may generate left image data based on some of the left input image data which correspond to a resolution of 1280*1440 with respect to one side (e.g., a left side) of the left input image data. The image processor  410  may generate right image data based on some of the input image data which correspond to a resolution of 1280*1440 with respect to the other side (e.g., a right side) of the right input image data. 
     The image processor  410  may not convert the input image data when the input image data has a format suitable for the display device  100 . For example, the image processor  410  may convert the input image data into the image data suitable for the display device  100  (or for the head-mounted display device  10 ). 
     The first calculator  420  may calculate on-pixel ratio OPR of the image data (e.g., the third data DATA 3 ). The on-pixel ratio OPR may represent a ratio of a driving amount when pixels in the display panel  210  are driven based on grayscale values of the image data to a total driving amount when the pixels are driven based on maximum grayscale values. The first calculator  420  may calculate the on-pixel ratio OPR, for example, for each frame of the image data. 
     The second calculator  430  may calculate a first scaling rate ACL_DY 1  based on the on-pixel ratio ORP and a first reference on-pixel ratio START_OPR 1 , and may calculate a second scaling rate ACL_DY 2  based on the on-pixel ratio ORP and a second reference on-pixel ratio START_OPR 2 . The first reference on-pixel ratio START_OPR 1  may include or be based on a reference value for reducing the first sub image data described with reference to  FIG. 3A  (e.g., some of the image data corresponding to the first central region Z 1  in  FIG. 3A ). The first scaling rate ACL_DY 1  may be or include a reduction value of the first sub image data. Similarly, the second reference on-pixel ratio START_OPR 2  may a reference value for reducing the second sub image data described with reference to  FIG. 3A  (e.g., some of the image data corresponding to the first peripheral region Z 2  in  FIG. 3A ). The second scaling rate ACL_DY 2  may be a reduction value of the second sub image data. 
     Referring to  FIG. 6A , a first scaling curve  611  may represent the first scaling rate ACL_DY 1  according to the on-pixel ratio OPR and a second scaling curve  612  may represent the second scaling rate ACL_DY 2  according to the on-pixel ratio OPR. 
     According to the first scaling curve  611 , when an Nth on-pixel ratio OPR(N) is less than the first reference on-pixel ratio START_OPR 1 , the first scaling rate ACL_DY 1  may be equal to a reference scaling rate ACL_DY 0 , where N is a positive integer. The Nth on-pixel ratio OPR(N) may be an on-pixel ratio OPR calculated based on an Nth frame (or an Nth frame data) of the image data. The reference scaling rate ACL_DY 0  may be, for example, a value of 1. 
     When the Nth on-pixel ratio OPR(N) is greater than the first reference on-pixel ratio START_OPR 1 , the first scaling rate ACL_DY 1  may increase proportional to a difference between the Nth on-pixel ratio OPR(N) and the first reference on-pixel ratio START_OPR 1 . An increasing rate of the first scaling rate ACL_DY 1  (or a first gradient of the first scaling curve  611 ) may be determined based on a first maximum scaling rate ACL_DY_MAX 1 . The first maximum scaling rate ACL_DY_MAX 1  may be predetermined based on a reduction efficiency of the power consumption of the display device  10  (or the head-mounted display device  100 ). 
     In one embodiment, when the Nth on-pixel ratio OPR(N) is greater than the first reference on-pixel ratio START_OPR 1 , the second calculator  430  may calculate the first scaling rate ACL_DY 1  based on Equation 1.
 
 ACL _ DY 1= ACL _OFF_MAX1×(OPR( N )−START_OPR1)/(MAX_OPR−START_OPR1)   (1)
 
where ACL_DY 1  denotes the first scaling rate, ACL_OFF_MAX 1  denotes the first maximum scaling rate, OPR(N) denotes the Nth on-pixel ratio, START_OPR 1  denotes the first reference on-pixel ratio, and MAX_OPR denotes the maximum on-pixel ratio (e.g., a value of 1).
 
     Similarly, according to the second scaling curve  612 , when an Nth on-pixel ratio OPR(N) is less than the second reference on-pixel ratio START_OPR 2 , the second scaling rate ACL_DY 2  may be equal to the reference scaling rate ACL_DY 0 . 
     When the Nth on-pixel ratio OPR(N) is greater than the second reference on-pixel ratio START_OPR 2 , the second scaling rate ACL_DY 1  may increase proportional to a difference between the Nth on-pixel ratio OPR(N) and the second reference on-pixel ratio START_OPR 2 . An increasing rate of the second scaling rate ACL_DY 2  (or a second gradient of the second scaling curve  612 ) may be determined based on a second maximum scaling rate ACL_DY_MAX 2 . The second maximum scaling rate ACL_DY_MAX 2  may be different from the first scaling rate ACL_DY_MAX 1  and may be predetermined based on a reduction efficiency of the power consumption of the display device  10  (or the head-mounted display device  100 ). 
     Similarly to a configuration of calculating the first scaling rate ACL_DY 1 , the second calculator  430  may calculate the second scaling rate ACL_DY 2  based on Equation 2, when the Nth on-pixel ratio OPR(N) is greater than the second reference on-pixel ratio START_OPR 2 ,
 
 ACL _ DY 2= ACL _OFF_MAX2×(OPR( N )−START_OPR2)/(MAX_OPR−START_OPR2)   (2)
 
where ACL_DY 2  denotes the second scaling rate, ACL_OFF_MAX 2  denotes the second maximum scaling rate, OPR(N) denotes the Nth on-pixel ratio, START_OPR 2  denotes the second reference on-pixel ratio, and MAX_OPR denotes the maximum on-pixel ratio (e.g., a value of 1).
 
     As described with reference to  FIG. 6A , the second calculator  430  may calculate the first scaling rate ACL_DY 1  and the second scaling rate ACL_DY 2  based on the on-pixel ratio OPR, respectively. 
     Referring again to  FIG. 4 , the image converter  440  may generate converted data (e.g., the second data DATA 2 ) by reducing the image data (e.g., the third data DATA 3 ) based on the first scaling rate ACL_DY 1  and the second scaling rate ACL_DY 2 . 
     In some example embodiments, the image converter  440  may generate first sub converted data by reducing the first sub image data based on the first scaling rate ACL_DY 1 . The image converter  440  may generate second sub converted data by reducing the second sub image data based on the second scaling rate ACL_DY 2 . For example, the image converter  440  may include a first sub image converter  441  (or a first image converting unit) and a second sub image converter  442  (or a second image converting unit) and may generate the first and second sub converted data using the first sub image converter  441  and the second sub image converter  442 , respectively. 
     Referring to  FIG. 6B , a first mapping curve  621  may represent a change of a maximum grayscale value of the first sub image data according to the on-pixel ratio OPR. A second mapping curve  622  may represent a change of a maximum grayscale value of the second sub image data according to the on-pixel ratio OPR. 
     According to the first mapping curve  621 , the maximum grayscale value of the first sub image data (e.g., a grayscale value of 255) may be changed based on the first scaling rate ACL_DY 1 . For example, when the on-pixel ratio OPR (or the Nth on-pixel ratio OPR(N)) is less than the first reference on-pixel ratio START_OPR 1 , the maximum grayscale value of the first sub image data may be mapped (or be remapped, be matched, be converted, correspond) to a grayscale value of 255. Thus, the maximum grayscale value of the first sub image data may be not reduced. 
     When the on-pixel ratio OPR (or the Nth on-pixel ratio OPR(N)) is greater than the first reference on-pixel ratio START_OPR 1 , the maximum grayscale value of the first sub image data may be mapped (or be converted) to a specified grayscale value less than a grayscale value of 255 according to a reduction of the first scaling rate ACL_DY 1 . The display device  10  (or the head-mounted display device  100 ) may reduce power consumption for the first sub image data by the first maximum scaling rate ACL_OFF_MAX 1 . 
     Similarly, according to the second mapping curve  622 , the maximum grayscale value of the second sub image data (e.g., a grayscale value of 255) may be changed based on the second scaling rate ACL_DY 2 . For example, when the on-pixel ratio OPR is less than the second reference on-pixel ratio START_OPR 2 , the maximum grayscale value of the second sub image data may be mapped (or be converted) to a grayscale value of 255. 
     When the on-pixel ratio OPR is greater than the second reference on-pixel ratio START_OPR 2 , the maximum grayscale value of the second sub image data may be mapped (or be converted) to a specified grayscale value less than a grayscale value of 255 according to a reduction of the second scaling rate ACL_DY 2 . The display device  100  may reduce power consumption for the second sub image data by the second maximum scaling rate ACL_OFF_MAX 2 . 
     Referring to  FIG. 6C , a third mapping curve  631  may represent a relation between the first sub image data and the first sub converted data. A fourth mapping curve  632  may represent a relation between the second sub image data and the second sub converted data. 
     According to the third mapping curve  631 , grayscale values of the first sub image data may be remapped to grayscale values less than the grayscale values of the first sub image data. For example, grayscale values greater than a first reference grayscale value corresponding to the first reference on-pixel ratio START_OPR 1  may be reduced, but grayscale values less than the first reference grayscale value may not be reduced. 
     Similarly, according to the third mapping curve  632 , grayscale values of the second sub image data may be remapped to grayscale values less than the grayscale values of the second sub image data. For example, grayscale values greater than a second reference grayscale value corresponding to the second reference on-pixel ratio START_OPR 2  may be reduced, but grayscale values less than the second reference grayscale value may not be reduced. 
     Therefore, the display device  10  (or the head-mounted display device  100 ) may prevent the display quality of an image from being degraded by limiting a reduction of grayscale value in a low grayscale range (e.g., grayscale values less than the first reference grayscale value or less than the second reference grayscale value). 
     As described with reference to  FIGS. 4 through 6C , the timing controller  240  may calculate the on-pixel ratio OPR based on the image data (e.g., the third data DATA 3  or the first data DATA 1 ), may calculate the first scaling rate ACL_DY 1  and the second scaling rate ACL_DY 2  based on the first reference on-pixel ratio START_OPR 1  and the second reference on-pixel ratio START_OPR 2 , and may convert the image data into the converted data (e.g., the second data DATA 2 ) based on the first scaling rate ACL_DY 1  and the second scaling rate ACL_DY 2 . Therefore, the display device  10  may reduce or minimize a reduction of the display quality of an image and may also reduce power consumption by reducing luminance (or brightness) of the image corresponding to the central regions and luminance of the image corresponding to the central regions, independently (or differently). 
     In some example embodiments, the timing controller  240  (or the image converter  440 ) may gradually reduce a boundary image data based on the first scaling rate ACL_DY 1  and the second scaling rate ACL_DY 2 . The boundary image data may be between the first sub image data and the second image data. 
     Referring to  FIG. 5 , the first sub image data described above may correspond to the first central region Z 1  between a reference point (e.g., a zero point on an X axis) and a first point X 1 . The second sub image data described above may correspond to the first peripheral region Z 2  between the first point X 1  and a second point X 2 . However, when the timing controller uses the third luminance curve  513 , the second sub image data may correspond to a region between a fifth point X 5  and the second point X 2 . The boundary image data may correspond to a region (e.g., a boundary region) between the first point X 1  and the fifth point X 5 . 
     The timing controller  240  may apply a scaling rate ACL_DY differently according to the location of a certain point in the boundary region. For example, the timing controller  240  may calculate a third scaling rate by interpolating the first scaling rate ACL_DY 1  and the second scaling rate ACL_DY 2  based on the location (or location information) of the certain point and may reduce image data (or a grayscale value) corresponding to the certain point based on the third scaling rate. For example, the timing controller  240  may calculate a distance variable (or a distance ratio, a distance weight) based on the location of the certain point and may calculate the third scaling rate based on the distance variable and at least one of the first scaling rate ACL_DY 1  and the second scaling rate ACL_DY 2 . The timing controller  240  may reduce the boundary image data based on the third scaling rate. 
     In one embodiment, the timing controller  240  may calculate the third scaling rate based on Equation 3
 
 ACL _ DYF=ACL _ DY×DR    (3)
 
where ACL_DYF denotes the third scaling rate, ACL_DY denotes the scaling rate and DR denotes the distance variable.
 
     Similarly, when the timing controller  240  uses the fourth luminance curve  514 , the first sub image data may correspond to a region between the reference point (e.g., the zero point) and a third point X 3 . The second sub image data may correspond to a region between a fourth point X 4  and the second point X 2 . The boundary image data may correspond to a region (or a boundary region) between the third point X 3  and the fourth point X 4 . 
     As described with reference to  FIG. 5 , the display device  10  (or the head-mounted display device  100 ) may reduce the boundary image data based on the third scaling rate (e.g., a scaling rate calculated by interpolating the first scaling rate ACL_DY 1  and the second scaling rate ACL_DY 2 ). Therefore, the display device  10  may prevent a boundary between a central region and a peripheral region of an image (e.g., between images respectively corresponding to the first central region Z 1  and the first peripheral region Z 2 ) being visible to the user. 
       FIG. 7  illustrates another example of luminance controlled by the timing controller of  FIG. 4 . Referring to  FIGS. 5 and 7 , a fifth luminance curve  711  may be substantially the same as the first luminance curve  511  described with reference to  FIG. 5 . A sixth luminance curve  712  may be similar to the second luminance curve  512  described with reference to  FIG. 5 . However, image data corresponding to the first central region Z 1  (e.g., the first sub image data) may not be reduced according to the sixth luminance curve  712 . 
     Thus, the display device  10  may reduce only second sub image data corresponding to the first peripheral region Z 2  based on the second scaling rate ACL_DY 2  and may maintain the first sub image data. For example, the display device  100  (or the head-mounted display device  10 ) may determine the first reference on-pixel ratio START_OPR 1  described with reference to  FIG. 6A  to be equal to the maximum on-pixel ratio MAX_OPR. The first sub image data may not be changed or reduced even though the on-pixel ratio OPR is changed. 
     Thus, the display device  100  may perform no conversion operation (or no data conversion) for the first central region Z 1  in which the visual characteristics of the user are good. The reduction amount of power consumption may be less than the reduction amount of power consumption of the second luminance curve  512  in  FIG. 5 , but the display device  100  may reduce or minimize the reduction of display quality of an image seen by the user. 
       FIG. 8A  illustrates examples of luminance controlled by the timing controller of  FIG. 4 . Referring to  FIGS. 5 and 8A , eleventh through thirteenth luminance curve  811 ,  812 , and  813  may represent a luminance of an image displayed on the display panel  210  (or on the first displaying region  311  of the display panel  210 ) based on the image data (e.g., the first data DATA 1 ). In some example embodiments, the display device  100  (or the timing controller  240 ) may apply (or use) the scaling rate ACL_DY according to a location of a certain point on the display panel  210 . 
     In an example embodiment, when the certain point is in the first central region Z 1 , the display device  10  may calculate a fourth scaling rate by interpolating a reference scaling value ACL_DY 0  and the first scaling rate ACL_DY 1  based on the location (or location information) of the certain point. The display device  10  may reduce image data (or a grayscale value) corresponding to the certain point based on the fourth scaling rate. When the certain point is in the first peripheral region Z 2 , the display device  10  may calculate a third scaling rate by interpolating the first scaling rate ACL_DY 1  and the second scaling rate ACL_DY 2  based on the location (or location information) of the certain point and may reduce image data (or a grayscale value) corresponding to the certain point based on the third scaling rate. For example, when the display device  10  uses a linear interpolating manner, luminance of the image may be changed according to the eleventh luminance curve  811 . When the display device  10  uses a non-linear interpolating manner, luminance of the image may be changed, for example, according to the twelfth luminance curve  812 . 
     In an example embodiment, the display device  100  may calculate a fifth scaling rate by interpolating the reference scaling rate ACL_DY 0  and the second scaling rate ACL_DY 2  based on the location (or location information) of the certain point and may reduce image data (or a grayscale value) corresponding to the certain point based on the fifth scaling rate. Luminance of the image may be changed according to the thirteenth luminance curve  813 . 
     As described with reference to  FIG. 8A , the display device  10  (or the head-mounted display device  100 ) may reduce the image data using the third through fifth scaling rate (e.g., scaling rate calculated based on two of the reference scaling rate ACL_DY 0 , the first scaling rate ACL_DY 1 , or the second scaling rate ACL_DY 2 ). Luminance of the image may be changed (or reduced) gradually from a center of the image to a boundary of the image. Therefore, the display device  100  may prevent a reduction of display quality visible to a user, even for a second maximum scaling rate ACL_OFF_MAX 2  (e.g., even when the display  10  uses a maximum scaling rate less than the second maximum scaling rate ACL_OFF_MAX 2  described with reference to  FIG. 6A ). 
       FIG. 8B  illustrates another example of luminance controlled by the timing controller of  FIG. 4 . Referring to  FIG. 8B , a twenty-first luminance curve  821  may represent luminance of an image displayed on a first sub region of the display panel  210  based on the image data (e.g., the first data DATA 1 ). A twenty-second luminance curve  822  may represent luminance of an image displayed on a second sub region of the display panel  210  based on the image data. The first sub region may be a left region of the display panel  210  with respect to a first central axis Y 1  and may include a sixth point X 6 . The second sub region may be a right region of the display panel  210  with respect to the first central axis Y 1  and may include the first point X 1 . 
     In some example embodiments, the display device  10  (or the head-mounted display device  100 ) may calculate a weight scaling rate (or a weight) based on direction information of a certain point and may reduce the image data based on the weight scaling rate. The direction information may be a direction of the certain point with respect to a center of the display panel  210  (e.g., a left direction or a right direction with respect to the first central axis Y 1  of the first displaying region  311 ). 
     When the certain point is in the first sub region (e.g., at the sixth point X 6 ), the display device  100  may determine the weight scaling rate to be a predetermined value, e.g., 0.5. The display device  100  may calculate a converted grayscale value (e.g., a grayscale value in the converted data) by multiplying a grayscale value corresponding to the certain point, the weight scaling rate, and the third scaling rate (or the fourth scaling rate) described with reference to  FIG. 8A . Luminance at the first sub region may be changed according to the twenty-first luminance curve  821 . 
     When the certain point is in the second sub region (e.g., at the first point X 1 ), the display device  100  may determine the weight scaling rate to be a predetermined value, e.g., 1. The display device  100  may calculate a converted grayscale value (e.g., a grayscale value in the converted data) by multiplying a grayscale value corresponding to the certain point, the weight scaling rate, and the third scaling rate (or the fourth scaling rate) described with reference to  FIG. 8A . Luminance at the second sub region may be changed according to the twenty-second luminance curve  822 . 
     The weight scaling rate may be determined based on the characteristics of the eyes of the user described with reference to  FIG. 3B . Referring to  FIG. 3B , the gradient of a left region (e.g., a region in direction from zero degrees to the nose of the user) may be greater than the gradient of a right region (e.g., a region in direction from zero degrees to an ear of the user). Therefore, the display device  100  may reduce luminance of the image by determining the weight scaling rate differently according to direction information of the certain point. 
       FIG. 9  illustrates an embodiment of a data driver  230  in the display device  10  of  FIG. 2 .  FIG. 10  illustrates an embodiment of the operation of data driver  230 . Referring to  FIGS. 1, 2, 3A, and 9 , the data driver  230  may include a first gamma register  911 , a second gamma register  912 , a first gamma block  921 , and a second gamma block  922 . The data driver  230  may generate a first data signal based on the first sub image data and may generate a second data signal based on the second sub image data. 
     The first gamma register  911  may store the first sub image data temporally and may output first grayscale values of the first sub image data. 
     The second gamma register  912  may store the second sub image data temporally and may output second grayscale values of the second sub image data. 
     The first gamma block  921  may generate the first data signal based on a grayscale value and first grayscale voltages which are predetermined. The grayscale value may be one of the first grayscale values or the second grayscale values. For example, the first gamma block  921  may output a certain grayscale voltage corresponding to the one of the first grayscale values or the second grayscale values based on a first gamma curve (e.g., a gamma curve 2.2.). 
     The second gamma block  922  may generate the second data signal based on a grayscale value and second grayscale voltages which are predetermined. The second grayscale voltages may be different from the first grayscale voltages. For example, a maximum grayscale voltage of the second grayscale voltages may be 5 volts (V), and a maximum grayscale voltage of the first grayscale voltages may be 3 V. The second gamma block  922  may be operated when the scan signal is provided to the first central region Z 1 . For example, when the scan signal is provided to the first central region Z 1 , the timing controller  240  may provide the data driver  230  with a control signal to operate the second gamma block  922 . 
     Thus, the display device  100  may generate the data signal using gamma blocks different from each other for each region of the display panel  210  (e.g., for each of the central and peripheral regions), instead of converting the input image data using the timing controller  240 . An output buffer AMP may provide the first data signal and/or the second data signal to the display panel  210  (or the pixel PX in the display panel  210 ). 
     Referring to  FIGS. 9 and 10 , a first scan signal SCAN_A may be provided to the display panel  210  to control output the data signal (e.g., the second data signal) to only the first peripheral region Z 2 . The data driver  230  may provide the second data signal to the display panel using the second gamma register  912  and the second gamma block  922 . For example, the data driver  230  may provide the second data signal to all output buffers AMP using the second gamma register  912  and the second gamma block  922 , and the pixel PX in the first peripheral region Z 2  may emit light based on the second data signal based on the first scan signal SCAN_A. 
     Subsequently, a second scan signal SCAN_B may be provided to the display panel  210  to control output the data signal (e.g., the first data signal) to only the first central region Z 1 . The data driver  230  may provide the first data signal to the display panel using the first gamma register  911  and the first gamma block  921 . In addition, the data driver  230  may provide the second data signal to a remaining region except the first central region Z 1  (e.g., the pixel PX in the first peripheral region Z 2  that receives the second scan signal SCAN_B) using the second gamma register  912  and the second gamma block  922 . 
     Thus, a pixel column corresponding to the first peripheral region Z 2  may receive the second data signal from the second gamma block  922 , and a pixel column corresponding to the first central region Z 1  may alternately receive the first data signal and second data signal from the first gamma block  921  and second gamma block  922 . 
     As described with reference to  FIGS. 10 and 11 , the display device  100  may generate the data signal using the gamma blocks which are different from each other for each region of the display panel  210  (for each of central regions and peripheral region). Therefore, the display device  100  may display an image with different luminance for each region. 
       FIG. 11  illustrates another embodiment of a head-mounted display device  100 ′.  FIG. 12  illustrates an example of input image data processed by the timing controller  240  of  FIG. 4 , which may be included in the head-mounted display device  100 ′.  FIG. 13  illustrates other examples of luminance controlled by the timing controller  240  in  FIG. 4 . 
     Referring to  FIG. 11 , the lens  20  may be located apart from the display device  10  by a predetermined distance. The lens  20  may include a first lens  21  (or a left lens) and a second lens  22  (or a right lens). A focus (or a point at which a viewing axis of a left eye and a viewing axis of a right eye are crossed) of the user wearing the head-mounted display device  100 ′ may be formed at a certain point apart to the display device  10 . According to the focus, a first viewing direction of the left eye (or a first viewing axis) and a second viewing direction of the right eye (or a second viewing axis) of the user may not be perpendicular to the display device  10 . 
     An image center IC 1  (or a center point) of an image displayed on the display device  10  (or on the first displaying region  311  of the display panel  210 ) may be located at an axis perpendicular to the display device  10 , passing through the lens center LC 1 , and different from a first viewing axis. Therefore, the display device  10  may shift the image in a certain direction to match the image center IC 1  and the lens center LC 1 . Thus, the display device  10  may shift the image in the certain direction to locate the image center IC 1  on the first viewing axis formed from the lens center LC 1 . 
     Referring to  FIG. 12 , a first left image IMAGE_L and a first right image IMAGE_R may be in (or correspond to) the input image data (e.g., image data provided from an external component to the display device  10 ) and may include three sub images (e.g., first through third sub left images IL 1  through IL 3  or first through third sub right images IR 1  through IR 3 ). The first through third sub left images IL 1  through IL 3  may correspond to the first through third sub right images IR 1  through IR 3 . The first through third sub left images IL 1  through IL 3  may be, for example, the same as or substantially the same as the first through third sub right images IR 1  through IR 3 . 
     A second left image IMAGE_SL and a second right image IMAGE_SR may be in (or correspond to) converted data (e.g., the second data DATA 2  generated by the display device  10 ). The display device  10  may shift the first left image IMAGE_L in a right direction by a certain distance, so that the second left image IMAGE_SL includes the first and second sub left images IL 1  and IL 2 . Similarly, the display device  10  may shift the first right image IMAGE_R in a left direction by the certain distance, so that the second right image IMAGE_SR includes first and third sub right images IR 1  and IR 3 . 
     A third image IMAGE_U may be an image visible (or may be recognized) by the user. The third image IMAGE_U may include the second sub left image IL 2 , the first sub left image IL 1 , the first sub right image IR 1 , and the third sub right image IR 3 . The first sub left image IL 1  and the first sub right image IR 1  may overlap at a central area of the third image IMAGE_U (e.g., an area corresponding to the first sub right image IR 1 ). The second sub left image IL 2  may be visible to the left eye of the user, and the third sub right image IR 3  may be visible to the left eye of the user. Therefore, when luminance of the second sub left image IL 2  (and/or luminance of the third sub right image IR 3 ) is greatly reduced, a reduction of luminance may be recognized by the user. 
     Referring to  FIG. 13 , a thirty-first luminance curve  1310  represents luminance of an image displayed on the display panel  210  when the display device  10  generates the converted data based on a center of the display panel  210  (e.g., a first area center Y 1  and a second area center Y 2  of the display panel  210 ). A thirty-second luminance curve  1320  represents luminance of an image displayed on the display panel  210  when the display device  100  generates the converted data based on a center of the input image data (e.g., a first image center C 1  of the first left image IMAGE_L and a second image center C 2  of the first right image IMAGE_R). 
     Luminance corresponding to a boundary of the display panel  210  (e.g., an area corresponding to the second sub left image IL 2  and the third sub right image IR 3  illustrated in  FIG. 12 ) according to the thirty-second luminance curve  1320  may be greater than luminance corresponding to a boundary of the display panel  210  according to the thirty-first luminance curve  1310 . 
     Therefore, the display device  100  may prevent a reduction of luminance being visible for the user by generating the converted data based on the center of the input image data (e.g., a first image center Y 1  and a second image center Y 2  of the input image data) compared with generating the converted data based on the center of the display panel  210  (e.g., a first area center Y 1  and a second area center Y 2  of the display panel  210 ). Thus, the display device  10  may efficiently prevent a reduction of luminance from being visible for the user and reduce power consumption, for example, by the same amount. In addition, the display device  10  may improve the reduction rate of power consumption with reducing luminance, for example, by the same amount (e.g., with reducing luminance at a boundary of the display panel  210  by the same amount) 
     As described with reference to  FIGS. 11 through 13 , the display device  100  may efficiently prevent a reduction of luminance from being visible for the user and reduce power consumption by the same amount, by generating the converted data based on the center of the input image data (e.g., a first image center Y 1  and a second image center Y 2  of the input image data). 
     The methods, processes, and/or operations described herein may be performed by code or instructions to be executed by a computer, processor, controller, or other signal processing device. The computer, processor, controller, or other signal processing device may be those described herein or one in addition to the elements described herein. Because the algorithms that form the basis of the methods (or operations of the computer, processor, controller, or other signal processing device) are described in detail, the code or instructions for implementing the operations of the method embodiments may transform the computer, processor, controller, or other signal processing device into a special-purpose processor for performing the methods described herein. 
     The controllers, processors, calculators, blocks, converters, and other processing features of the embodiments described herein may be implemented in logic which, for example, may include hardware, software, or both. When implemented at least partially in hardware, the controllers, processors, calculators, blocks, converters, and other processing features may be, for example, any one of a variety of integrated circuits including but not limited to an application-specific integrated circuit, a field-programmable gate array, a combination of logic gates, a system-on-chip, a microprocessor, or another type of processing or control circuit. 
     When implemented in at least partially in software, the controllers, processors, calculators, blocks, converters, and other processing features may include, for example, a memory or other storage device for storing code or instructions to be executed, for example, by a computer, processor, microprocessor, controller, or other signal processing device. The computer, processor, microprocessor, controller, or other signal processing device may be those described herein or one in addition to the elements described herein. Because the algorithms that form the basis of the methods (or operations of the computer, processor, microprocessor, controller, or other signal processing device) are described in detail, the code or instructions for implementing the operations of the method embodiments may transform the computer, processor, controller, or other signal processing device into a special-purpose processor for performing the methods described herein. 
     The aforementioned embodiments may be applied to any type of display device, e.g., an organic light emitting display device, a liquid crystal display device, etc. The display device may be in, for example, a television, a computer monitor, a laptop, a digital camera, a cellular phone, a smart phone, a personal digital assistant, a portable multimedia player, an MP3 player, a navigation system, and a video phone. 
     Example embodiments have been disclosed herein, and although specific terms are employed, they are used and are to be interpreted in a generic and descriptive sense only and not for purpose of limitation. In some instances, as would be apparent to one of ordinary skill in the art as of the filing of the present application, features, characteristics, and/or elements described in connection with a particular embodiment may be used singly or in combination with features, characteristics, and/or elements described in connection with other embodiments unless otherwise specifically indicated. Accordingly, it will be understood by those of skill in the art that various changes in form and details may be made without departing from the spirit and scope of the present invention as set forth in the following claims.