Patent Publication Number: US-6339435-B1

Title: Device to automatically adjust video signals to a blanking level and method therefor

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from my application entitled Automatically Blanking Level of Video Signal Controlling Device and Controlling Method filed with the Korean Industrial Property Office on Dec. 26, 1997 and there duly assigned Serial No. 97-74267 by that Office. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a device to automatically adjust video signals to a blanking level and method therefor, and more particularly, to a device to automatically adjust video signals to a blanking level for accurately realizing an intended color by feeding back video signals at the blanking level stored in an Application Specific Integrated Circuit (ASIC), which stores video signals at the blanking level received in a flat display, and by generating clamp signals for accurately realizing a blanking level, and a method therefor. 
     2. Discussion of the Related Art 
     A plasma display (abbreviated to PDP hereafter), a liquid crystal display (abbreviated to LCD hereafter), and a light emitting display (abbreviated to LED hereafter), etc., are different types of flat displays. Video signals generated from a host, and horizontal and vertical synchronizing signals for synchronizing the video signals are transmitted to the PDP, e.g., and video signals are synchronized and represented in accordance with the received horizontal and vertical synchronizing signals. Video signals received by clamp signals generated from a micro-processor unit (abbreviated to MCU hereafter) are blanked, for blanking represented video signals, and represented. 
     Clamp signals generated from an MCU are adjusted at the time flat displays are produced. There is a case where the flat display is not able to correctly handle image signals of a pre-amplifier and an analog to digital convertor (abbreviated to ADC hereafter) when video signals are at the blanking level. That is, there is a case when video signals at a blanking level are not handled normally in the process of amplifying and outputting video signals at a blanking level as a transistor-transistor logic (abbreviated to TTL hereafter) level in the pre-amp, and in the process of sampling and outputting as digital signals in the ADC. In order to correct this, after the clamp signals generated from the MCU have been adjusted, the goods come to be forwarded. 
     For this reason, complexity of a manufacturing process increases and video signals cannot be easily adjusted to a blanking level because the clamp level of video signals is adjusted in the manufacturing process of the flat display, and so it is impossible to realize a precise color. 
     SUMMARY OF THE INVENTION 
     Accordingly, in order to overcome such drawbacks in the conventional art, it is therefore an object of the present invention to provide a device to automatically adjust video signals to a blanking level to realize a more precise color by a micro-processor unit (MCU) being fed back with video signals at the blanking level stored in the ASIC, which samples video signals at the blanking level received in a flat display and stores video signals converted into digital signals, and by generating clamp signals to adjust the video signals to a blanking level automatically, and method therefor. 
     Additional objects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention. 
     To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, there is provided a device to automatically adjust video signals to a blanking level, the device including: an ASIC (application-specific integrated circuit) to store blank video signals to be sampled and output as digital signals by an ADC (analog-digital converter), and to output a first control signal in accordance with the stored digital blank video signals; and the MCU to transmit a second control signal to a pre-amp, the second control signal blanking non-blanked portions in the first control signal received from the ASIC. 
     According to another aspect of the present invention, there is also provided a method for automatically adjusting video signals to a blanking level, the method including: checking the presence or the absence of video signals not at the blanking level according to a first control signals; and adjusting video signal not at the blanking level into video signals at the blanking level by generating a second control signal in the case of the presence of video signals not at the blanking level in the checking step. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other objects and advantages of the invention will become apparent and more readily appreciated from the following description of the preferred embodiments, taken in conjunction with the accompanying drawings of which: 
     FIG. 1 is a block view illustrating the constitution of the inner circuit of a flat display having a device to automatically adjust a video signal to a blanking level according to an embodiment of the present invention; and 
     FIG. 2 is a flow view illustrating a method to automatically adjust video signals to a blanking level according to an embodiment of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference will now be made in detail to the present preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures. 
     As shown in FIG. 1, a device to automatically adjust video signals to a blanking level according to an embodiment of the present invention comprises an ASIC  16  storing video signals sampled to digital signals and an MCU  12  being fed back a first control signal when video signals stored in the ASIC  16  are at a blanking level, and generating and outputting a second control signal to adjust the blanking level, and a pre-amplifier  13  receiving the second control signal output from the MCU  12 , receiving video signals (R, G, B) at the blanking level transmitted from a D-shaped connector (D-SUB)  11 , and amplifying and outputting the received video signals (R, G, B) at the blanking level according to the received second control signal, to a TTL level. 
     A method of controlling a device to automatically adjust the video signals to the blanking level above, as shown in FIG. 2, comprises a step (S 11 ) of checking whether the blanking level can be adjusted and a step (S 12 ) of reading level values of video signals (R, G, B) from the ASIC  16  if the blanking level can be adjusted in the checking step (S 11 ), a step (S 13 ) of delaying a predetermined time so as to be fed back with the first control signal according to the video signals at the blanking level in the reading step (S 12 ), a step (S 14 ) of checking whether there are video signals not at the blanking level according to the first control signal fed back after delaying for a predetermined time in the delaying step (S 13 ), a step (S 15 ) of converting non-blanked video signals (R,G,B) into the blanking level by generating the second control signal if there are video signals not at the blanking level in the checking step (S 14 ). 
     This invention will be described in more detail as follows. 
     A flat panel  17  ultimately receives video signals (R, G, B), originally generated from a host, and the horizontal and vertical synchronizing signals from the D-shaped connector  11 . To accomplish this, let us assume that the received video signals (R, G, B) are video signals (R, G, B) at the blanking level. In order to check that the video signals (R, G, B) are at the blanking level, pre-set conditions should be checked in the MCU  12  (S 11 ). That is, the MCU  12 , pre-set by a control knob (not illustrated), can perceive and check whether the video signals (R, G, B) are at the blanking level. When the video signals (R, G, B) at the blanking level are received, the pre-set conditions become activated and the MCU  12  perceives that the video signals (R, G, B) presently being received are at the blanking level. When the video signals (R, G, B) are not at the blanking level, the MCU  12  is operated again to check the whether the next video signals (R, G, B) are at the blanking level. The video signals (R, G, B) at the blanking level are sent from the D-shaped connector  11  to the pre-amplifier  13 , amplified to the TTL level in the pre-amplifier  13  according to the second control signal and output as signals having a TTL level to an ADC  15 . These video signals are output as digital video signals (R, G, B) after being sampled according to a clock sent to the ADC  15  and output from a first phase-locked loop (abbreviated to PLL here after)  14 a. The second control signal sent to the preamplifier  13  are output from the MCU  12 . The MCU  12  outputs the second control signal as well as a number of other control signals (PLL 1  CONTROL, PLL 2  CONTROL, ASIC CONTROL, OSD-CONTROL). The PLL 1  control and the PLL 2  control adjust clock cycles by locking in the clocks output from a first PLL  14   a  and a second PLL  14   b , respectively. The other control signals (ASIC CONTROL, OSD-CONTROL, or, on screen display-control) are transmitted to the ASIC  16  and an OSD IC  18  (on screen display integrated circuit), respectively. The ASIC  16 , having received the transmitted ASIC CONTROL, stores the digital signals (R, G, B) output from the ADC  15  according to the received signal ASIC CONTROL, and adjusts to output colors of the stored video signals (R, G, B) and images thereof. The video signals (R, G, B) in the ASIC  16  are stored and output according to the cycle of clocks output from the first PLL  14   a  and the second PLL  14   b.    
     The MCU  12  reads the first control signal according to the digital video signals (R, G, B) at the blanking level stored in the ASIC  16  (S 12 ). While the MCU  12  reads the video signals (R, G, B) stored in the ASIC  16 , a certain time delay occurs (S 13 ). When the video signals (R, G, B) are read after that certain time delay, the MCU  12  reads the first control signal and checks which of the signals (R, G, B) is not at the blanking level (S 14 ). When all of the signals are at the blanking level after checking, the MCU  12  checks again whether the next video signals (R, G, B) are at the blanking level. On the contrary, when not all of the signals are at the blanking level, the MCU  12  outputs the second control signal having adjusted a clamp level to correct this (S 15 ). The second control signal is transmitted to the pre-amplifier  13 . The pre-amplifier  13 , having received the second control signal, adjusts the blanking level according to the received second control signal and amplifies the video signals (R, G, B) to be output as a TTL level. 
     The video signals (R, G, B) at the output blanking level are stored in the ASIC  16  after being converted into digital video signals (R, G, B) by the ADC  15 . The digital video signals (R, G, B) stored in the ASIC  16  are transmitted to the flat panel  17 . The flat panel  17 , which receives the digital video signals (R, G, B) stored in the ASIC  16 , receives a driving power ( 9 V,  12 V) from an SMPS (Switching mode power supply)  19 . That is, the video signals (R, G, B), the blanking level of which is automatically adjusted, are displayed on the flat panel  17 . The next video signals (R, G, B), at the next blanking level, after automatically adjusting the blanking level of the current video signals (R,G,B) and displaying the same, are also adjusted and displayed according to the same process. 
     As described above, the present invention can reduce the process of adjusting video signals to a blanking level in manufacturing the flat panel. As a result, productivity can be improved. In addition, as the present invention automatically adjusts to the blanking level accurately, precise colors can be realized. 
     Although a preferred embodiment of the present invention has been shown and described, it would be appreciated by those skilled in the art that changes may be made in this embodiment without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.