Abstract:
A display apparatus includes: a video processor which performs calibration; a signal generator which generates a signal; and a controller which controls the signal generator to generate an analog signal corresponding to a predetermined direct current voltage when performing the calibration, and controls the video processor to convert the analog signal into the digital signal and to adjust the digital signal to have a same value as a reference value. The signal input for calibration is achieved in a board controllable by a microcomputer, so that the board itself can automatically perform the calibration with regard to various kinds of signals without connection of an external device.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority from Korean Patent Application No. 10-2009-0051594, filed on Jun. 10, 2009 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
       BACKGROUND OF INVENTION 
       [0002]    1. Field of Invention 
         [0003]    Apparatuses and methods consistent with the present invention relate to a display apparatus and method, and more particularly, to a display apparatus and method in which signals input for calibration are generated by a circuit board controllable by a microcomputer, so that the circuit board itself can automatically perform the calibration with regard to various kinds of signals without connection of an external device. 
         [0004]    2. Description of the Related Art 
         [0005]    A display apparatus performs analog to digital conversion (ADC) calibration to adjust gain and offset levels of each channel input in order to decrease physical scattering of the offset and the gain for sampling each channel (three channels of R, G and B or three channels of Y, U and V) at the ADC. 
         [0006]      FIG. 1  is a block diagram for explaining the existing calibration operation. 
         [0007]    A personal computer (PC) signal generator  110  generates R, G and B patterns as standard signals (0mV˜700mV). A digital television (DTV) signal generator  120  generates Y, U and V patterns as standard signals. In this case, the PC signal generator  110  and the DTV signal generator  120  are placed outside of a display apparatus  100 . 
         [0008]    The display apparatus  100  performs the calibration with reference to the patterns output from the PC signal generator  110  and the DTV signal generator  120 . For example, the detailed calibration to a PC signal is performed as follows. 
         [0009]    During the calibration, a black pattern for adjusting the offset, and a white pattern for adjusting the gain are needed. If a signal having a standard level of 0mV˜700mV is input from the PC signal generator  110 , the display apparatus  100  obtains digital sampling minimum and maximum values for the black and white patterns. The display apparatus  100  adjusts the offset of the ADC in order to set the digital sampling minimum value to a target minimum value of “0.” Then, the display apparatus  100  ascertains the digital sampling value for the black pattern again, and sets the adjusted value of the offset if the digital sampling minimum value for the black pattern satisfies the target minimum value. 
         [0010]    Further, the display apparatus  100  adjusts the gain of the ADC so as to set the digital sampling maximum value to a target maximum value of “255.” Then, the display apparatus  100  ascertains the digital sampling maximum value for the white pattern again, and sets the adjusted value of the gain if the digital sampling maximum value for the white pattern satisfies the target maximum value. 
         [0011]    Such adjustments of the offset and the gain are performed according to the respective channels (e.g., R, G and B channels or Y, U and V channels). 
         [0012]    Conventionally, when the calibration is performed to the PC signal and the DTV signal, a calibration line is connected to a PC D-sub cable and a DTV component jack is connected to the display apparatus and timing and patterns prepared for a PC mode and a DTV mode are applied to the PC signal generator and the DTV signal generator, respectively. When the PC signal and the DTV signal are output from the PC signal generator and the DTV signal generator, the display apparatus performs the calibration with regard to the corresponding signal. After calibration is completed, the D-sub cable and the DTV component jack are disconnected from the display apparatus, thereby completing the calibration process. 
         [0013]    Thus, it is necessary for someone to directly connect the external device to the display apparatus. Further, an adapter board has to be added to a signal cable in order to perform the calibration, but the adapter board causes signal distortion (e.g., overshoot and undershoot), thereby deteriorating the quality of the calibration. 
       SUMMARY OF THE INVENTION 
       [0014]    The present invention provides a display apparatus and method in which signals input for calibration are generated by a circuit board controllable by a microcomputer, so that the board itself can automatically perform the calibration with regard to various kinds of signals without connection of an external device. 
         [0015]    An aspect of the present invention provides a display apparatus including: a video processor which performs calibration; a signal generator which generates a signal; and a controller which controls the signal generator to generate an analog signal corresponding to a predetermined direct current (DC) voltage when performing the calibration, and controls the video processor to convert the analog signal into a digital signal and to adjust the digital signal to have a same value as a reference value. 
         [0016]    The predetermined DC voltage may include at least one of DC voltages representing black and white. 
         [0017]    The controller may control the video processor to adjust gain and/or offset of the digital signal on the basis of an analog signal corresponding to the DC voltage representing the black and/or the white. 
         [0018]    The predetermined DC voltage may include at least one of a minimum voltage and a maximum voltage in a waveform of the analog signal. 
         [0019]    The signal generator may generate an analog signal corresponding to the predetermined DC voltage by a pulse width modulation (PWM) method. 
         [0020]    The controller may control the video processor to finish the calibration if the digital signal is adjusted to have the same value as the reference value, but perform the calibration again if the digital signal is adjusted not to have the same value as the reference value. 
         [0021]    The controller may control the video processor to output a message of failed calibration if the calibration is repeated equal to or more than a previously set number of times. 
         [0022]    Another aspect of the present invention provides a display method including: generating an analog signal corresponding to a predetermined DC voltage; converting the analog signal into a digital signal to be compared with a reference value; and adjusting the digital signal to have a same value as the reference value to perform calibration. 
         [0023]    The predetermined DC voltage may include at least one of DC voltages representing black and white. 
         [0024]    Gain and/or offset of the digital signal may be adjusted on the basis of the analog signal corresponding to the at least one of DC voltage voltages representing black and white. 
         [0025]    The predetermined DC voltage may include at least one of a minimum voltage and a maximum voltage in a waveform of the analog signal. 
         [0026]    An analog signal corresponding to the predetermined DC voltage may be generated by a pulse width modulation (PWM) method. 
         [0027]    The calibration may be finished if the digital signal is adjusted to have the same value as the reference value, but the calibration may be performed again if the digital signal is adjusted not to have the same value as the reference value. 
         [0028]    A message of failed calibration is output if the calibration is repeated equal to or more than a previously set number of times. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0029]    The above and/or other aspects of the present invention will become apparent and more readily appreciated from the following description of the exemplary embodiments, taken in conjunction with the accompanying drawings, in which: 
           [0030]      FIG. 1  is a block diagram for explaining conventional calibration; 
           [0031]      FIG. 2  is a block diagram illustrating a configuration of a display apparatus according to an exemplary embodiment of the present invention; 
           [0032]      FIGS. 3A and 3B  are diagrams illustrating waveforms of R, G and B pattern signals, and Y, U and V pattern signals, respectively; 
           [0033]      FIG. 4  is a flowchart of performing calibration according to an exemplary embodiment of the present invention; and 
           [0034]      FIG. 5  is a flowchart of performing calibration according to another exemplary embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0035]    Exemplary embodiments of the present invention will be described in detail with reference to accompanying drawings so as to be easily realized by a person having ordinary knowledge in the art. The present invention may be embodied in various forms without being limited to the embodiments set forth herein. Descriptions of well-known parts are omitted for clarity, and like reference numerals refer to like elements throughout. 
         [0036]      FIG. 2  is a block diagram illustrating a configuration of a display apparatus according to an exemplary embodiment of the present invention. 
         [0037]    A display apparatus  200  according to an exemplary embodiment of the present invention may include, but is not limited to, a digital TV, a desktop computer, a notebook computer, a monitor, etc. Further, an electronic device may be used as the display apparatus  200  according to an exemplary embodiment of the present invention as long as it can display an image and perform analog to digital conversion (ADC). 
         [0038]    The display apparatus  200  according to an exemplary embodiment of the present invention may include a signal generator  210 , a video processor  220  and a controller  230 . 
         [0039]    The signal generator  210  generates a signal. Specifically, the signal generator  210  may generate an analog signal corresponding to a predetermined DC voltage. In this exemplary embodiment, the predetermined DC voltage may include at least one of DC voltages representing black and white. For example, the predetermined DC voltage may include at least one of 0.1V representing black and 0.6V representing white. According to another exemplary embodiment, the predetermined DC voltage may include at least one of a maximum voltage and a minimum voltage in a waveform of the analog signal. For example, the predetermined DC voltage may include at least one of a minimum voltage of 0mV and a maximum voltage of 700mV. 
         [0040]    Further, the signal generator  210  generates R, G and B pattern signals in the state that the display apparatus  200  operates in a PC mode, and generates Y, U and V pattern signals in the state that the display apparatus  200  operates in a DTV mode. 
         [0041]    In this case, the signal generator  210  may output the generated analog signal to the video processor  220 . 
         [0042]    The signal generator  210  may generate an analog signal corresponding to a predetermined DC voltage by a pulse width modulation (PWM) method. The signal generator  210  may include a PWM port  215 . 
         [0043]    The video processor  220  may perform calibration. Specifically, the video processor  220  converts the analog signal output from the signal generator  210  into a digital signal, and adjusts the digital signal to have the same value as a reference value. According to an exemplary embodiment of the present invention, the video processor  220  may adjust an offset and/or a gain of the digital signal on the basis of the analog signal corresponding to the DC voltage representing black and/or white. 
         [0044]    The video processor  220  may include a three-channel ADC chip  222  and a scaler  224 . The three-channel ADC chip  222  converts the analog signals input according to channels into 8-bit digital signals having values of 0˜255. The values of the converted digital signals may be stored in an internal register (not shown) of the scaler  224 . The scaler  224  adjusts the values stored in the internal register to be equal to the reference value. 
         [0045]    Meanwhile, the video processor  220  finishes the calibration when the value of the digital signal is equal to the reference value, but performs the calibration again if the value of the digital signal is not equal to the reference value. 
         [0046]    Further, the video processor  220  may output a message of failed calibration if the calibration is performed equal to or more than a preset number of times. This message may be output in the form of at least one of an on screen display (OSD) and a voice. 
         [0047]    The video processor  220  may be provided by, for example, but not limited to, a liquid crystal display (LCD), an organic light emitting diode (OLED), a plasma display panel (PDP), etc. 
         [0048]    The controller  230  may control the signal generator  210  to generate the analog signal corresponding to a predetermined DC voltage when performing the calibration. When the display apparatus  200  operates in the PC mode, calibration for the PC signal is needed. On the other hand, when the display apparatus  200  operates in the DTV mode, calibration for the DTV signal is needed. Thus, the controller  230  controls the signal generator  210  to generate the R, G and B pattern signals when the display apparatus  200  operates in the PC mode, and the Y, U and V pattern signals when the display apparatus  200  operates in the DTV mode. 
         [0049]    Also, when performing the calibration, the controller  230  may control the video processor  220  to convert the analog signal generated by the signal generator  210  into the digital signal and to adjust the digital signal to have the same value as the reference value. Specifically, the controller  230  compares the reference value stored in a storage unit  235  with the value of the converted digital signal stored in the internal register of the scaler  224 . Then, the controller  230  controls the video processor  220  to adjust the converted digital signal to have the same value as the reference value. 
         [0050]    According to an exemplary embodiment of the present invention, the reference values may be set with values obtained by converting the analog signals corresponding to the DC voltages representing black and white into the digital values. For example, the reference values may be set by a value (e.g., 0X01) obtained by converting 0.1V representing black into a digital value, and a value (e.g., 0X06) obtained by converting 0.6V representing white into a digital signal. In this case, the controller  230  may control the video processor  220  to adjust the gain and/or the offset of the digital signal on the basis of the analog signal corresponding to the DC voltage representing black and/or white. 
         [0051]    According to another exemplary embodiment of the present invention, the reference values may be set with values obtained by converting the minimum and maximum voltages in the waveform of the analog signal into the digital signals. For example, the reference values may be set by a value (e.g., 0X00) obtained by converting the minimum voltage of 0mV into a digital signal, and a value (e.g., 0X67) obtained by converting the maximum voltage of 700mV into a digital signal. 
         [0052]    Meanwhile, the controller  230  may control the video processor  220  to finish the calibration when the digital signal is adjusted to have the same value as the reference value, but perform the calibration again if the digital signal is adjusted not to have the same value as the reference value. 
         [0053]    Further, the controller  230  may control the video processor  220  to output a message of failed calibration if the calibration is performed equal to or more than a preset number of times. 
         [0054]      FIG. 3A  is a diagram illustrating waveforms of R, G and B pattern signals and  FIG. 3B  is a diagram illustrating Y, U and V pattern signals. 
         [0055]    In the case of the calibration for the PC signal, as shown in (a), the R, G and B pattern signals have a level of 0mV˜700mV with respect to the ground, and this level is used in performing the calibration. 
         [0056]    In the case of the calibration for the DTV signal, as shown in (a), the Y pattern signal has a level of 0mV˜700mV with respect to the ground, and this level is used in performing the calibration. However, as shown in (b), the U and V pattern signals have an intermediate level (128 digital) of 350mV, and this level is used in performing the calibration. 
         [0057]    Thus, the calibration is independently performed in the PC mode and the DTV mode. 
         [0058]      FIG. 4  is a flowchart of performing calibration according to an exemplary embodiment of the present invention. 
         [0059]    According to an exemplary embodiment of the present invention, a predetermined DC voltage generated by the signal generator  210  may include at least one of DC voltages representing black and white. In this case, the reference value previously set to adjust the gain and the offset may be set with a value obtained by converting an analog signal corresponding to the DC voltage representing black and white into a digital signal. 
         [0060]    The display apparatus  200  generates an analog signal corresponding to the DC voltages representing black and/or white in order to perform the calibration (S 401 ). For example, the display apparatus  200  may output the DC level of 0.1V representing black and the DC level of 0.6V representing white through the PWM port. The display apparatus  200  converts the generated analog signal into the digital signal (S 402 ). 
         [0061]    The display apparatus  200  compares the value of the converted digital signal with the previously stored reference value (S 403 ). For example, the previously stored reference value may be set with a value (e.g., 0X01) obtained by converting 0.1V representing black into a digital signal and with a value (e.g., 0X06) obtained by converting 0.6V representing white into a digital signal. 
         [0062]    The display apparatus  200  determines whether the value of the converted digital signal is equal to the previously stored reference value (S 404 ). If it is determined that the value of the converted digital signal is equal to the previously stored reference value (S 404 -Y), the display apparatus  200  finishes the calibration (S 408 ). In this case, the display apparatus  200  outputs a message of completed calibration, and informs a user that the calibration is successful. 
         [0063]    If it is determined that the value of the converted digital signal is different from the previously stored reference value S 404 -N), the display apparatus  200  adjusts the gain and the offset of the digital signal (S 405 ). When adjusting the offset, the display apparatus  200  adjusts a digital code converted from 0.1V representing black to be equal to the reference value. When adjusting the gain, the display apparatus  200  adjusts the digital code converted from 0.1V representing black and the digital code converted from 0.6V representing white to be equal to the reference value. 
         [0064]    The display apparatus  200  determines whether the calibration is repeated equal to or more than a predetermined number of times (S 406 ). If it is determined that the calibration is repeated equal to or more than a predetermined number of times (S 406 -Y), the display apparatus  200  outputs a message of failed calibration in the form of the OSD (S 407 ). In this case, the message of the failed calibration may be output together with a circuit board check message. 
         [0065]    If it is determined that the calibration is repeated less than a predetermined number of times (S 406 -N), the display apparatus  200  returns to the operation  5404 , thereby repetitively performing the calibration. 
         [0066]    Thus, the display apparatus according to an exemplary embodiment of the present invention internally and directly generates an analog signal corresponding to a predetermined DC voltage, thereby performing the calibration. Accordingly, the display apparatus can perform the calibration by itself even through it does not store any certain pattern for the calibration. 
         [0067]      FIG. 5  is a flowchart of performing calibration according to another exemplary embodiment of the present invention. 
         [0068]    In this embodiment, a predetermined DC voltage generated by the signal generator  210  may include at least one of a minimum voltage and a maximum voltage in the waveform of the analog signal. 
         [0069]    In this case, a reference value previously set to adjust gain and offset may be set with a value obtained by converting the minimum and maximum voltages in the waveform of the analog signal into a digital signal. 
         [0070]    The display apparatus  200  generates an analog signal corresponding to the minimum voltage and/or the maximum voltage in the waveform of the analog signal so as to perform the calibration (S 501 ). For example, the display apparatus  200  may output a minimum DC voltage of 0mV and a maximum DC voltage of 700mV through the PWM port. 
         [0071]    The display apparatus  200  converts the generated analog signal into the digital signal (S 502 ). 
         [0072]    The display apparatus  200  compares the value of the converted digital signal with the previously stored reference value (S 503 ). For example, the previously stored reference value may be set with a value (e.g., 0X00) obtained by converting the minimum voltage of 0mV into a digital signal and with a value (e.g., 0X67) obtained by converting the maximum voltage of 700mV into a digital signal. 
         [0073]    If it is determined that the value of the converted digital signal is different from the previously stored reference value (S 504 -N), the display apparatus  200  adjusts the gain and the offset of the digital signal (S 505 ). When adjusting the offset, the display apparatus  200  adjusts a digital code converted from the minimum voltage of 0mV to be equal to the reference value. When adjusting the gain, the display apparatus  200  adjusts the digital code converted from the minimum voltage of 0mV and the digital code converted from the maximum voltage of 700mV to be equal to the reference values, respectively. 
         [0074]    As described above, manpower and specific equipment are not separately needed for calibration, and the calibration is easily performed with regard to various kinds of signals such as high definition multimedia interface (HDMI)/PC/component (Comp)/audio &amp; video (AV) signals or the like. 
         [0075]    Also, the display can perform the calibration by itself at its initial operation, and there is no separate process of connecting calibration lines. 
         [0076]    Although a few exemplary embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.