Patent Publication Number: US-6714190-B2

Title: Image display control method and apparatus, and display apparatus

Description:
FIELD OF THE INVENTION 
     This invention relates to an image display control method and apparatus for outputting an image display signal to a display apparatus to display an image on the apparatus, and to the display apparatus. 
     BACKGROUND OF THE INVENTION 
     In a known display apparatus having a display controller and a display unit, image quality (indicating the quality of a displayed image being changed by adjusting color, brightness and contrast, and the like) can be adjusted upon receiving a signal sent from a wireless controller (utilizing an infrared light) or the like. With such an apparatus, the color adjustment of the displayed image usually is performed using a dedicated image processing circuit and the like. 
     In a case where the adjustment of the image quality such as brightness and contrast of a displayed image is performed, control can be performed independently for each of the colors R, G, B. However, in a case where the adjustment of the image quality such as chromaticity or hue of displayed image is performed, it is required that each pixel be calculated using all three of the R, G, B data. This leads to greater hardware load and to an increase in the scale of the hardware. 
     SUMMARY OF THE INVENTION 
     Accordingly, an object of the present invention is to provide an image display control method and apparatus, as well as a display apparatus, in which implementation of adjustment functions is shared by a display controller and display unit in accordance with the type of image quality adjustment indication designated, thereby preventing a decline in image quality and making it possible to adjust the image quality of a displayed image. 
     Another object of the present invention is to provide an image display control method and apparatus, as well as a display apparatus which has a display unit and a display controller for controlling display by outputting an image signal and a synchronizing signal to the display unit, wherein among image quality adjustments that have been designated, adjustment of brightness, contrast and color temperature of a displayed image is performed by the display unit and image quality adjustments other than these are performed by the display controller, whereby an increase in the scale of hardware is suppressed and designated image quality adjustments can be performed efficiently. 
     According to the present invention, the foregoing objects are attained by providing an image display control apparatus for outputting an image signal to a display unit to display an image on the display unit, comprising: input means for inputting an image quality adjustment designation for designating adjustment of image quality of an image displayed on the display unit; determination means for determining whether the image quality adjustment designation input by the input means designates an image quality adjustment that is to be performed by the display unit; command transmitting means for converting an image quality adjustment designation, which the determination means has determined designates an image quality adjustment to be performed by the display unit, to a command and transmitting the command to the display unit; image processing means for processing an image signal to thereby execute image quality adjustment and outputting processed image signal; and output means for outputting, to the display unit, the processed image signal produced by the image processing means by executing an image quality adjustment other than that of the image quality adjustment designation that the determination means has determined is to be performed by the display unit. 
     According to the present invention, the foregoing objects are attained by providing an image display control method for outputting an image signal to a display unit to display an image on the display unit, comprising: an input step of inputting an image quality adjustment designation for designating adjustment of image quality of an image displayed on the display unit; a determination step of determining whether the image quality adjustment designation input at the input step designates an image quality adjustment that is to be performed by the display unit; a command transmitting step of converting the image quality adjustment designation, which the designating step has determined designates an image quality adjustment to be performed by the display unit, to a command and transmitting the command to the display unit; an image processing step of executing an image quality adjustment other than that of the image quality adjustment designation that the determination step has determined is to be performed by the display unit; and an output step of outputting, to the display unit, an image signal an image signal processed at the image processing step. 
     Further, the present invention provides a display apparatus having a display controller and a display unit for displaying an image based upon an image signal from the display controller, wherein the display controller comprises: input means for inputting an image quality adjustment designation for designating adjustment of image quality of an image displayed on the display unit; determination means for determining whether the image quality adjustment designation input by the input means designates an image quality adjustment that is to be performed by the display unit; command transmitting means for converting an image quality adjustment designation, which the determination means has determined designates an image quality adjustment to be performed by the display unit, to a command and transmitting the command to the display unit; image processing means for processing an image signal to thereby execute image quality adjustment; and output means for outputting, to the display unit, a signal produced by the image processing means by executing an image quality adjustment other than that of the image quality adjustment designation that the determination means has determined is to be performed by the display unit; 
     and the display unit comprises: command analyzing means for analyzing the command that has been transmitted by the command transmitting means; and image quality adjusting means for adjusting displayed image quality in accordance with the image quality adjustment designation that is based upon the command analyzed by the command analyzing means. 
     It is preferred that if an image signal in the present invention contains R, G, B signals and each of the R, G, B signals can be processed independently to thereby execute the designated image quality adjustment, then a determination is made to the effect that the designated image quality adjustment is to be performed by the display unit. 
     It is preferred that if the display unit has an image quality adjustment function, then a determination is made to the effect that the designated image quality adjustment is to be performed by the display unit. 
     It is preferred that if the designated image quality adjustment is an adjustment of brightness, contrast or color temperature, then a determination is made to the effect that the designated image quality adjustments to be performed by the display unit. 
     It is preferred that if the designated image quality adjustment is a change of chromaticity or hue or emphasis of contour, then a determination is made to the effect that the image quality adjustment is to be performed by image processor of the display controller. 
     It is preferred that the display unit has a display panel which includes surface-conduction type of emission devices. 
     It is preferred that the display unit include a CRT. 
     It is preferred that the image quality adjustment designation be made by an infrared signal from a wireless controller. 
     It is preferred that the display unit analyze a command that has been transmitted to it and perform the image quality adjustment, which is based upon the analyzed command, by changing pulse width of a display driving signal. 
     It is preferred that the display unit analyze a command that has been transmitted to it and perform the image quality adjustment, which is based upon the analyzed command, by changing driving current of a display driving signal. 
     It is preferred that the display unit analyze a command that has been transmitted to it and perform the image quality adjustment, which is based upon the analyzed command, by changing number of pulses of a display driving signal. 
    
    
     Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principle of the invention. 
     FIG. 1 is a block diagram illustrating the construction of an image display apparatus according to a first embodiment of the present invention; 
     FIG. 2 is a diagram useful in describing the content of processing executed by a digital image processing unit in a controller according to this embodiment; 
     FIG. 3 is a flowchart illustrating processing executed by a controller in the image display apparatus according to the first embodiment; 
     FIG. 4 is a diagram useful in describing the connection between a display panel and X, Y drivers according to this embodiment; 
     FIG. 5 is a diagram useful in describing output signals of the X and Y drivers; 
     FIG. 6 is a perspective view illustrating an example of a display panel according to this embodiment; 
     FIG. 7 is a schematic view illustrating an example of a vacuum treatment apparatus having functions for measuring and evaluating characteristics of electron emission elements according to this embodiment; 
     FIG. 8 is a graph showing an example of the relationship among emission current, element current and element voltage in a surface-conduction type of emission device according to this embodiment; 
     FIG. 9 is a diagram useful in describing an example in which contrast is adjusted by changing the pulse width of modulated pulses conforming to the bright level of an image signal; 
     FIG. 10 is a diagram useful in describing an example in which contrast is adjusted by changing the driving current of modulated pulses conforming to the bright level of an image signal; 
     FIG. 11 is a diagram useful in describing an example in which brightness is adjusted by adding offset pulses onto modulated pulses conforming to the bright level of an image signal; 
     FIG. 12 is a block diagram illustrating the construction of an image display apparatus according to a second embodiment of the present invention; 
     FIG. 13 is a block diagram illustrating the construction of an image display apparatus according to a third embodiment of the present invention; 
     FIG. 14 is a block diagram illustrating the construction of an image display apparatus according to a fourth embodiment of the present invention; 
     FIG. 15 is a flowchart illustrating processing executed by a controller of the image display apparatus according to the fourth embodiment; 
     FIG. 16 is a block diagram illustrating the construction of an image display apparatus according to a fifth embodiment of the present invention; 
     FIG. 17 is a flowchart illustrating processing executed by a display unit of the image display apparatus according to the fifth embodiment; 
     FIG. 18 is a block diagram illustrating the construction of an image display apparatus according to a sixth embodiment of the present invention; 
     FIG. 19 is a flowchart illustrating processing executed by a controller of the image display apparatus according to the sixth embodiment; and 
     FIG. 20 is a flowchart illustrating processing executed by a display unit of the image display apparatus according to the sixth embodiment. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. 
     First Embodiment 
     FIG. 1 is a block diagram illustrating the construction of a display apparatus according to a first embodiment of the present invention. The display apparatus includes a controller  100  and a display unit  200  such as a flat-panel display. The controller  100  receives a video signal, processes the signal and outputs the processed image signal to the display unit  200 , and the display unit  200  accepts the image signal sent from the controller  100  and displays the image represented by the image signal. 
     The construction of the controller  100  will be described first. 
     The controller  100  includes a CPU  101  for controlling the operation of the controller  100 . The CPU  101  executes various processing for control in accordance with a control program that has been stored in a program memory  101   a . The controller  100  further includes a wireless-control receiver  102  for receiving infrared light from a wireless controller (not shown) operated by an operator, extracting data contained in the infrared light and outputting the extracted data to the CPU  101 . As a result, the CPU  101  analyzes the data and controls a digital image processor  103  and a digital interface (I/F) transmitter  105  in dependence upon the results of analysis. A look-up table  104  stores various data referred to when image processing is executed by the digital image processor  103 . It should be noted that the image processing executed by the digital image processor  103  includes processing for functions such as enlargement interpolation, reduction and calculation for image quality adjustment. The details will be described in detail later with reference to FIG.  2 . The digital interface transmitter  105  transmits an image signal, which has been processed by the digital image processor  103 , to the display unit  200  together with the synchronizing signals of the image signal. It also sends the display unit  200  a command conforming to the results of analysis of the wireless-control data by the CPU  101 . 
     Examples of the video signal input to the controller  100  are an NTSC television signal or the like or a digital signal such an RGB signal, and there may be more than one path on which the video signal enters the controller. 
     The construction of the display unit  200  will be described next. 
     The display unit  200  includes a CPU  201  for controlling the overall operation of the display unit  200 , and a display panel  202 . According to this embodiment, the display panel  202  is a flat-panel display having electron emission devices arrayed in the form of a matrix, for example, and phospors which emit light in response to electrons emitted from the electron emission devices. A Y-driver  203  drives the scanning-direction (row direction) wires of the display panel  202  and an X-driver  204  drives the column-direction wires of the display panel  202  in dependence upon one line of image data that has been stored in a line memory  205 . A digital interface (I/F) receiver  206  receives an image signal, command and synchronizing signals sent from the digital interface transmitter  105  of the controller  100 , applies the command and synchronizing signals to the CPU  201 , drives the Y-driver  203  in conformity with the synchronizing signals and outputs the image signal to the line memory  205 , where the image signal is stored. It should be noted that the line that connects the digital interface transmitter  105  and receiver  206  is a digital-interface dedicated line on which commands and image signals are transmitted as serial data. An adjustment value set by a user operating the wireless controller is stored in a non-volatile memory (not shown) of the CPU  101  in the controller  100  and in a non-volatile memory (not shown) of the CPU  201  in the display unit  200 . 
     FIG. 2 is a diagram useful in describing the image processing functions of the digital image processor  103  of controller  100 . 
     The image processing functions of the digital image processor  103  include functions relating to brightness, contrast, chromaticity, hue, color temperature and contour emphasis, and the units for implementing these functions are serially connected. Each type of control is executed based upon a control signal from the CPU  101 . FIG. 2 illustrates each type of image processing, the content of the processing, the calculation formulae in the case of RGB data and the processing concept. As these types of processing are all well known, a detailed description thereof is omitted. 
     FIG. 3 is a flowchart illustrating processing executed by the CPU  101  of the controller  100  according to the first embodiment of the present invention. The program for executing this processing is stored in the program memory  101   a . It should be noted that the processing illustrated by the flowchart assumes that the controller  100  has already recognized the type of display unit  200  connected to it. 
     Step S 1  of the flowchart calls for the CPU  101  to determine whether a signal has been received by the wireless-control receiver  102 . If a signal has been received, control proceeds to step S 2 , at which the CPU  101  determines whether the ID contained in the wireless-control signal matches a wireless-controller ID capable of being received by the controller  100 . If the two do not match, control returns to step S 1  without execution of any further processing. If a match is obtained, however, control proceeds to step S 3 , at which designation information contained in the wireless-control signal is analyzed. This is followed by step S 4 , at which the CPU  101  determines whether the designation made by the wireless controller is designation of a brightness, contrast or color-temperature adjustment. If such is the case, adjustment information is stored in the memory of the CPU  101  and control proceeds to step S 6  because it is judged that the adjustments are to be made by the display unit  200 . Here a command is created based upon the designation signal from the wireless-control receiver  102  and is transmitted to the display unit  200  via the transmitter  105 . 
     If it is judged at step S 4  that the designation from the wireless controller is a designation relating to chromaticity, hue or contour emphasis, control proceeds to step S 5  by reason of the fact that execution of these adjustments by the controller  100  is appropriate. The designation information is stored in the memory (not shown) of the CPU  101  and a command is output to the digital image processor  103  to cause the digital image processor  103  to execute the designated image processing. 
     FIG. 4 is a block diagram showing the construction of the display panel  202  according to this embodiment. The display panel  202  includes electron emission devices  401 . Numeral  402  denotes a row wire selected from among row wires connected to the output of the Y-driver  203 . Pulse-width modulated signals conforming to the image signal enter the display panel  202  from the X-driver  204 . 
     FIG. 5 is a timing chart illustrating examples of waveforms of voltage signal (−7 V) applied to a selected row wire and of modulated signals output from the X-driver  204 . Here a pulse-width modulated signal indicating a bright level “7” is applied to a column wire X 1  and a pulse-width modulated signal indicating a bright level “0FFh” is applied to a row wire X 2 . 
     FIG. 6 is a schematic view showing an example of the display panel  202  according to this embodiment. A portion of the panel is cut away in order to illustrate the internal structure thereof. 
     As shown in FIG. 6, the display panel  202  includes an electron-source substrate  71  on which a plurality of electron emission devices  74  are arrayed; a rear plate  81  to which the electron-source substrate  71  is secured; and a face plate  86  obtained by forming a phosphor film  84  and a metal back  85 , etc., on the inner surface of a glass substrate  83 . The rear plate  81  and face plate  86  are secured to a support frame  82  using a material such as frit glass having a low melting point. The electron emission devices  74  correspond to the electron emission device  401  of FIG.  4 . Row wires  72  and column wires  73  are connected to respective ones of a pair of element electrodes of the electron emission devices  74 . 
     An envelope  88  is constructed by the face plate  86 , support frame  82  and rear plate  81 . Because the rear plate  81  is provided mainly for the purpose of increasing the strength of the electron-source substrate  71 , it can be dispensed with if the substrate  71  per se has enough mechanical strength. More specifically, the support frame  82  may be affixed directly to the substrate  71  and the envelope  88  may be constructed by the face plate  86 , support frame  82  and substrate  71 . By placing support members (not shown) referred to as spacers between the face plate  86  and rear plate  81 , the envelope  88  constructed will having sufficient strength to resist atmospheric pressure. 
     FIG. 7 is a schematic view illustrating an example of a vacuum treatment apparatus for measuring and evaluating the characteristics of the electron emission device  74  according to this embodiment. 
     As shown in FIG. 7, the apparatus includes a vacuum vessel  55  and an exhaust pump  56 . The electron emission device  74  described above is disposed within the vacuum vessel  55 . More specifically, shown in FIG. 7 are substrate  1101  on which the electron emission device is placed; element electrodes  1102 ,  1103 ; an electrically conductive thin film  1014 ; an electron emission portion  1015 ; a power supply  51  for applying an element voltage Vf to the electron emission device  74 ; an ammeter  50  for measuring an element current If that flows through the electrically conductive thin film  1014  between the element electrodes  1012 ,  1013 ; an anode electrode (which corresponds to the metal back  85  mentioned earlier)  54  for capturing the emission current Ie emitted from the electron emission portion  1015  of the element  74 ; a high-voltage power supply  53  for applying voltage to the anode electrode  54 ; and an ammeter  52  for measuring the emission current Ie emitted from the electron emission portion  1015  of the element  74 . By way of example, measurement can be performed by adopting 1 to 10 kV as the range of voltage applied to the anode electrode  54  and adopting 2 to 8 mm as distance H between the anode electrode  54  and electron emission device  74 . 
     Equipment such as a vacuum gauge (not shown) necessary for performing measurements under vacuum conditions is provided within the vacuum vessel  55  so that measurement and evaluation can be made under the desired vacuum conditions. The exhaust pump  56  comprises ordinary high-vacuum equipment such as a turbo-pump or rotary pump, and ultra-high-vacuum equipment such as an ion pump and the like. The entire vacuum treatment apparatus in which the electron-source substrate  1011  has been placed can be heated to about 250° C. by a heater, not shown. Accordingly, using this apparatus makes it possible to carry out a process in which the electron emission portion  1015  is formed on the electrically conductive thin film  1014  and the electron emission portion  1015  is activated to enhance the electron emission characteristic. 
     FIG. 8 is a graph showing an example of the relationship among the emission current Ie, element current If and element voltage Vf in a surface-conduction type of emission device according to this embodiment. 
     Since the emission current Ie is very small in comparison with the element current If, the units indicated in the graph of FIG. 8 are arbitrary. In addition, the vertical and horizontal axes are both linear scales. As should be evident from FIG. 8, the surface-conduction type of electron emission device according to this embodiment has the following three characterizing properties in regard to the emission current Ie: 
     (i) When an element voltage equal to or greater than a certain voltage (referred to as a threshold voltage Vth in FIG. 8) is applied to the device, the emission current Ie suddenly increases. When the applied voltage is less than the threshold voltage Vth, on the other hand, almost no emission current Ie is detected. In other words, the device is a non-linear element having the clearly defined threshold voltage Vth with respect to the emission current Ie. 
     (ii) Since the emission current Ie increases monotonously in dependence upon the element voltage Vf, the emission current Ie can be controlled by the element voltage Vf. 
     (iii) An emission charge captured by the anode electrode  54  is dependent upon the time during which the element voltage Vf is applied. In other words, the amount of electric charge captured by the anode electrode  54  can be controlled by the length of time over which the voltage Vf is applied. 
     The threshold voltage Vth of the surface-conduction type of emission device in this embodiment is 14 V. Accordingly, by applying −7 V to a selected row wire and applying a pulsed signal whose voltage value is +7 V to column wires at a pulse width that conforms to the value of the image signal (i.e., the bright-level data), as shown in FIG. 5, only electron emission devices connected to the selected row wire can be caused to emit electrons in an amount conforming to the value of the image signal. 
     Further, this adjustment of the amount of electrons emitted can be carried out not only by changing the pulse width of the pulse-width modulated signal by also changing the emission current that flows into the electron emission device. 
     FIGS. 9 to  11  illustrate an example of this. FIG. 9 illustrates a case where a pixel of bright level “7” is displayed upon having its contrast raised by about 25%. Whereas the modulated pulse width is a standard 100 ns (indicated at Xn) per one bright level, display is controlled such that the modulated pulse width is raised by 25% to 125 ns (indicated at Xn′) per bright level. 
     If the contrast of the pixel of bright level “7” is raised 25%, as shown in FIG. 10, the current value resulting from drive by the X-driver  204  is made 1.0 mA (for the color R indicated at  1100  in FIG.  10 ), which is 25% higher than the usual 0.8 mA. If the contrast of the pixel of bright level “7” is lowered 25%, the current value is made 0.64 mA (for the color B indicated at  1101  in FIG.  10 ), which is 25% lower than the usual 0.8 mA. 
     FIG. 11 illustrates an example in which brightness is adjusted by changing the number of pulses of the pulse-width modulated signal. Here the pixel of bright level “7”, is brightened by four levels by increasing the seven pulses of bright level “7” by four pulses, as indicated at  1102 , or the pixel of bright level “7” is darkened by three bright levels by reducing the seven pulses of bright level “7” by three pulses, as indicated at  1103 . 
     Thus, in accordance with the first embodiment, as described above, displayed brightness, contrast and color temperature are adjusted by the display unit and other processing is executed by the controller, which outputs the image signal to the display unit. As a result, an increase in hardware can be prevented and so can a decline in image quality. 
     Second Embodiment 
     FIG. 12 is a block diagram illustrating the construction of a display apparatus according to a second embodiment of the present invention. Components shown in FIG. 12 identical with those of FIG. 1 are designated by like reference characters and need not be described again. 
     According to the second embodiment, a controller  100   a  has an analog image processor  1200  and an A/D converter  1201  for converting an analog image signal, which has been processed by the analog image processor  1200 , to a digital signal. Based upon a designation from the CPU  101 , the analog image processor  1200  executes image processing such as chromaticity or hue adjustment, i.e., adjusts the image signal in analog fashion by changing the respective chrominance gains or by changing the fsc phase to the chrominance decoders (not shown). 
     As in the first embodiment, the second embodiment also is such that processing is executed in accordance with wireless-control information received by the wireless-control receiver  102 , and the CPU  101  determines whether the designated processing is to be executed by the controller  100   a  or by the display unit  200  and performs control upon outputting a command to the controller  100   a  or the display unit  200 . As these operations are similar to those of the first embodiment, they need not be described again. 
     Thus, in accordance with the second embodiment, chromaticity and hue, etc., can be controlled with the image signal in the form of an analog image signal. This makes it possible to simplify the circuit arrangement. 
     Third Embodiment 
     FIG. 13 is a block diagram illustrating the construction of a display apparatus according to a third embodiment of the present invention. Components shown in FIG. 13 identical with those of FIG. 1 are designated by like reference characters and need not be described again. 
     In the third embodiment, the controller  100  is the same as that of the first embodiment. This embodiment differs from the first in that a display unit  200   a  includes a CRT  1300 . 
     In the display unit  200   a , a D/A converter  1301  converts digital RGB data from the digital interface receiver  206  to an analog signal and outputs the analog signal to an electron-gun driving unit  1302 . In accordance with a synchronizing signal input from the receiver  206 , a deflection circuit  1303  deflects an electron beam output in response to a drive signal a supplied by the electron-gun driving unit  1302 . A CPU  201   a , to which a command and data received by the receiver  206  are input, controls the electron-gun driving unit  1302  in dependence upon the command to adjust the image quality of an image displayed on the CRT  1300 . More specifically, in accordance with adjustment data that has been received, the CPU  201   a  controls brightness by applying a current-value offset in the electron-gun driving unit  1302 , adjusts contrast by regulating the amplitude of the driving signal from the electron-gun driving unit  1302 , or adjusts color temperature by holding fixed the G-component drive signal of the image signal and changing the balance of the driving current values of the R and B components. 
     Other components and operations are similar to those of the first embodiment and need not be described again. Thus, the present invention can be applied and effect similar to those of the foregoing embodiment can be obtained even when the display unit employs a CRT. 
     Fourth Embodiment 
     FIG. 14 is a block diagram illustrating the construction of a display apparatus according to a fourth embodiment of the present invention. Components shown in FIG. 14 identical with those of FIG. 1 are designated by like reference characters and need not be described,again. The fourth embodiment illustrates a case in which a display unit  200   b  is not equipped with functions for adjusting brightness, contrast and color temperature, etc. 
     The controller  100  according to the fourth embodiment determines whether the connected display unit  200   b  is one having an image quality adjustment function on the basis of an exchange of data with the display unit  200   b  via the digital interface transmitter  105  and receiver  206  or based upon the signal level of a pin in a terminal for the digital interface. If it is determined that the connected display unit  200   b  does possess an image quality adjustment function, then, in a manner similar to that of the first embodiment, the controller  100  determines whether designation information entered from a wireless controller is indicative of content to be processed by the controller  100  or content to be processed by the display unit  200   b , creates the corresponding commands and executes processing in which the digital image processor  103  is instructed to execute the image quality adjustment or a command is sent to the display unit  200   b  and this is instructed to execute processing. 
     The processing described above is illustrated in the flowchart of FIG. 15, in which processing similar to that of FIG. 3 is designated by like step numbers and need not be described again in detail. 
     If it is determined at step S 4  in FIG. 15 that content is not such that is processed by the controller  100 , control proceeds to step S 11 , at which it is determined whether the connected display unit  200   b  is one having an adjustment function or not. As mentioned above, this may involve recognition based upon exchange of commands with the display unit  200   b  or may be judged by the level of a specific signal line in the interface between the transmitter  105  and receiver  206 . If the connected display unit  200   b  is one having an image quality adjustment function, then control proceeds to step S 6 , at which a command conforming to the indicated designation information is created and sent to the display unit  200   b.    
     In a case where the connected display unit  200   b  is one not provided with the image quality adjustment function, control proceeds to step S 5 . Here the digital image processor  103  executes processing relating also to brightness, contrast and color temperature, etc., as shown in FIG. 2, and transmits the results to the display unit  200   b  via the digital interface. 
     Thus, in accordance with the fourth embodiment, an image quality adjustment conforming to operation of a wireless controller by a user can be performed even in a case where a display unit devoid of an image quality adjustment function is connected to the controller. 
     Fifth Embodiment 
     FIG. 16 is a block diagram illustrating the construction of a display apparatus according to a fifth embodiment of the present invention. Components shown in FIG. 15 identical with those of FIG. 1 are designated by like reference characters and need not be described again. According to the fifth embodiment, a display unit  200   c  has a construction basically the same as that of the display unit  200  described above. However, the display unit  200   c  differs in that it is provided with a wireless-control receiver  1600  and in that the CPU  201   b  has a function for decoding designation information from a wireless controller. A program memory  201   c  stores the control program of the CPU  201   b . Unlike the CPU  101  of the foregoing embodiment, the CPU  201   a  of the controller  100   b  does not possess a function for decoding the designation information from a wireless controller. Further, a digital dedicated line between the digital interface transmitter  105  and receiver  206   a  is bidirectional. 
     FIG. 17 is a flowchart illustrating control processing executed by the CPU  201   b  of the display unit  200   c  according to the fifth embodiment. The program for executing this processing is stored in the program memory  201   c . It should be noted that the processing illustrated by this flowchart assumes that the CPU  201   b  of the display unit  200   c  has already recognized the type of the controller  100   b  connected to it. 
     Step S 21  of the flowchart calls for the CPU  201   b  to determine whether a signal has been received by the wireless-control receiver  1600 . If a signal has been received, control proceeds to step S 22 , at which the CPU  201   b  determines whether the ID contained in the wireless-control signal matches a wireless-controller ID capable of being received by the display unit  200   c . If the two do not match, control returns to step S 21  without execution of any further processing. If a match is obtained, however, control proceeds to step S 23 , at which designation information contained in the wireless-control signal is analyzed. This is followed by step S 24 , at which the CPU  201   b  determines whether the designation made by the wireless controller is designation of a brightness, contrast and color-temperature adjustment, for example, to be executed by the display unit  200   c . If such is the case, adjustment information is stored in the memory (not shown) of the CPU  201   b  and control proceeds to step S 25  because it is judged that the adjustments are to be made by the display unit  200   c . In the manner described earlier, here the output of the X-driver  204  is controlled to perform an adjustment in such a manner that the designated brightness, contrast and color temperature, etc., will be obtained. 
     If it is judged at step S 24  that the designation from the wireless controller is a designation relating to an image quality adjustment of chromaticity, hue or contour emphasis that is not processed by the display unit  200   c , control proceeds to step S 26  by reason of the fact that execution of such processing by the controller  100   b  is appropriate. This designation information is stored in the memory (not shown) of the CPU  101   b  and the designation information is converted to command data which is then sent to the transmitter  105  of the controller  100   b  via the digital interface receiver  206   a . As a result, the CPU  101   a  of the controller  100   a  accepts this command and controls the digital image processor  103  in conformity with the designated content to convert the image signal. 
     The effects obtained by the operation described above are similar to those of the first embodiment. 
     Sixth Embodiment 
     FIG. 18 is a block diagram illustrating the construction of a display apparatus according to a sixth embodiment of the present invention. Components shown in FIG. 18 identical with those of the foregoing embodiments are designated by like reference characters and need not be described again. The sixth embodiment differs in that the controller  100  and a display unit  200   d  have wireless-control receivers  102  and  1600 , respectively, and a function for decoding wireless-control information received by the respective receiver. 
     In the arrangement of FIG. 18, the outputs of the wireless-control receivers  102 ,  1600  are connected in a wired OR via a digital dedicated line. When a signal is received by either of the wireless-control receivers, therefore, the wireless-control information can be input by both the controller  100  and the display unit  200   d.    
     FIG. 19 is a flowchart illustrating processing executed by the CPU  101  of the controller  100  according to the sixth embodiment. As should be evident by referring to the flowchart of FIG. 3, the processing of FIG. 19 is exactly the same as that of FIG. 3 except for step S 4 . If the determination made at step S 4  in FIG.  19  is that the designated information is not processed by the controller  200 , no processing is executed. The other steps of FIG. 19 have already been described. 
     FIG. 20 is a flowchart illustrating processing executed by the CPU  201   b  of display unit  200   d  according to the sixth embodiment. As should be evident by referring to the flowchart of FIG. 17, the processing of FIG. 20 is exactly the same as that of FIG. 17 except for step S 24 . If the determination made at step S 24  in FIG. 20 is that the designated information is not processed by the display unit  200   d , no processing is executed. The other steps of FIG. 20 have already been described. 
     Thus, in accordance with this arrangement, if either the controller  100  or display unit  200   d  is placed at a location that cannot be reached by infrared light from a wireless controller, control can still be carried out by receiving the wireless-controller signal using the other device. 
     In each of the foregoing embodiments, the controller and the display unit are illustrated as being separate from each other. However, this does not impose a limitation upon the present invention. For example, the display apparatus may be one in which the controller and display unit are integrated into a single body. 
     The present invention can be applied to a system constituted by a plurality of devices (e.g., a host computer, interface, reader, printer, etc.) or to an apparatus comprising a single device (e.g., a copier or facsimile machine, etc.). 
     Furthermore, it goes without saying that the object of the invention is attained also by supplying a storage medium storing the program codes of the software for performing the functions of the foregoing embodiments to a system or an apparatus, reading the program codes with a computer (e.g., a CPU or MPU) of the system or apparatus from the storage medium, and then executing the program codes. 
     In this case, the program codes read from the storage medium implement the novel functions of the invention, and the storage medium storing the program codes constitutes the invention. 
     Further, the storage medium, such as a floppy disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD-R, magnetic tape, non-volatile type memory card or ROM can be used to provide the program codes. 
     Furthermore, besides the case where the aforesaid functions according to the embodiments are implemented by executing the program codes read by a computer, it goes without saying that the present invention covers a case where an operating system or the like running on the computer performs a part of or the entire process in accordance with the designation of program codes and implements the functions according to the embodiments. 
     It goes without saying that the present invention further covers a case where, after the program codes read from the storage medium are written in a function expansion board inserted into the computer or in a memory provided in a function expansion unit connected to the computer, a CPU or the like contained in the function expansion board or function expansion unit performs a part of or the entire process in accordance with the designation of program codes and implements the function of the above embodiment. 
     Thus, in accordance with the embodiments as described above, a controller and a display unit are each capable of executing image quality adjustment processing that conforms to the controller and display unit. This makes it possible to display a high-quality image without increasing the scale of the circuitry and without raising the cost of hardware. 
     The present invention is not limited to the above embodiments and various changes can be made within the spirit and scope of the present invention. Therefore, to apprise the public of the scope of the present invention, the following claims are made.