Patent Publication Number: US-8970604-B2

Title: State display device and display method of state display device

Description:
TECHNICAL FIELD 
     The present invention relates to a state display device which displays a state of a home electrical appliance such as an air conditioner and a display method employed by the state display device. 
     BACKGROUND ART 
     Embedded devices such as air conditioners and home electrical appliances accelerate to have multifunctionality. Then, it is difficult to operate, in a conventional way, such an embedded device only using a combination of a plurality of buttons and a liquid crystal display (such as a segment liquid crystal display) which displays fixed content directly relating to the buttons. 
     Therefore, electric apparatuses employing display devices which use general liquid crystal (so-called full-dot liquid crystal) and which includes so-called graphical user interfaces (GUIs) have been fabricated. As the GUIs, arbitrary diagrams and images are displayed in a liquid crystal screen, and multifunctionality and usability are supported by a method of switching screen displays in the liquid crystal screen from one to another or a method of adding display of a small window used for explanation in the screen. Therefore, users can easily use functions of electric devices, and accordingly, operability is improved. 
     However, in the display device of these electric devices, content to be displayed in a liquid crystal display and an operation device have considerable restrictions from the viewpoint of fabrication cost. 
     Considering cost, heat generation, and power consumption, a microcomputer used in an embedded device has low processing performance compared with that in a personal computer. As for a performance ratio thereof, a speed is 1/100 or lower compared to the microcomputer of the personal computer and a storage capacity is 1/1000 or lower of the microcomputer of the personal computer in most cases. 
     Since the full dot liquid crystal described above realizes display having a high degree of freedom by combining small luminous points, the full dot liquid crystal requires a number of instructions in order to display a single diagram. When a diagram of 1 cm square is to be rendered, for example, approximately a hundred of small luminous points should be changed, and accordingly, approximately a thousand instructions are required. 
     Most of the processing power of the microcomputer is consumed to realize a GUI process of combining such display diagrams with one another and frequently performing rendering by changing display screens from one to another, and furthermore, most of the storage capacity is consumed to perform intermediate information processing. Therefore, execution of a control application program which realizes an original function of the embedded device may be delayed. As a result, it becomes difficult to design the control application program, and accordingly, it is possible that the number of developing processes is increased. 
     To address this problem, an apparatus including dedicated hardware (graphic accelerator) used to execute part of the GUI process has been proposed (refer to Patent Literature 1, for example). 
     CITATION LIST 
     Patent Literature 
     
         
         Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2006-185195 (Page 4) 
       
    
     A processing speed of the GUI process performed using hardware is considerably faster than that performed using software. This is because the microcomputer performs processes in synchronization with a minimum unit clock on a process-by-process basis whereas the hardware performs a parallel process independently from the clock and furthermore a degree of the parallel process can be optimized. In this way, by performing the GUI process using the dedicated hardware, a main control application can occupy the processing power of the microcomputer. In a case where the GUI process is performed using the hardware, for example, when a diagram of 1 cm square is to be rendered, approximately only ten instructions are required to calculate edge points. Furthermore, when the GUI process is performed using hardware, a unit of a rendering command such as “line rendering”, “color calculation”, or the like is used. 
     However, when the GUI process is performed using hardware as described above in unit of a rendering command, processes relating to GUIs are not completely separated from the microcomputer. That is, when much information is displayed on the liquid crystal screen as diagrams or images and a display screen is switched, a rendering request is frequently generated. Therefore, the microcomputer consumes most of the processing power to perform the process regarding rendering requests. Accordingly, although execution of rendering commands can be performed independently from the microcomputer, the process regarding the rendering requests should be performed by the microcomputer, and consequently, a processing load applied to the microcomputer is heavy. 
     Conversely, it is difficult to perform all the GUI processes using the hardware. This is because, since different GUI display processes are performed for different applications or different products, dedicated hardware is required for each application or each product, and accordingly, a large burden and large cost are required. 
     SUMMARY OF INVENTION 
     Technical Problem 
     The present invention has been made to solve the problems described above, and provides a state display device which corresponds to a display device in which part of a GUI process is performed using hardware and which reduces a processing load of a microcomputer, and a display method of the state display device. 
     Solution to Problem 
     A state display device according to the present invention includes 
     a liquid crystal display unit, and 
     a rendering generation unit which generates display content to be displayed in the liquid crystal display unit, 
     wherein the rendering generation unit includes a central processing unit, a rendering processing unit, first storage means, and second storage means, 
     the first storage means is readable and writable by both the central processing unit and the rendering processing unit, 
     the second storage means is readable and writable by the rendering processing unit and readable by the liquid crystal display unit, 
     the central processing unit interprets and executes a display program and instructs the first storage means to store a rendering request based on a result of the execution, 
     the rendering processing unit includes an instruction address register which stores an instruction address serving as an address of the rendering request to be executed, and performs a series of a rendering execution process including a process of interpreting the rendering request stored in the first storage means in accordance with the instruction address, a process of calculating a coordinate and a color of a luminous point of liquid crystal when the interpreted rendering request is a rendering execution request, a process of storing the coordinate and the color obtained as the result of the calculation in the second storage means, and a process of updating the instruction address, 
     the liquid crystal display unit allows luminous points of the liquid crystal to generate color in accordance with coordinates and colors stored in the second storage means, 
     the rendering processing unit includes a start/end instruction register which stores a starting command for instructing start of the rendering execution process and an interruption factor register which stores a factor of an interruption issued to the central processing unit, and 
     the rendering processing unit starts a process in accordance with the rendering request stored in the first storage means when the starting command is stored in the start/end instruction register, terminates the process being performed in accordance with the rendering request when the rendering request specified by the instruction address is a rendering termination request, stores an termination factor in the interruption factor register, and issues an interruption to the central processing unit. 
     Advantageous Effects of Invention 
     According to the present invention, the rendering processing means performs the rendering processing process independently from the central processing unit in a period of time from when the starting command is written to the start/end instruction register to when the rendering request for requesting performance of the rendering termination process is executed. 
     Accordingly, since processes regarding a GUI are performed using hardware, a high-speed effect can be obtained. 
     Furthermore, the rendering processing unit may execute a series of rendering commands independently from the central processing unit. Therefore, the central processing unit may assign calculation resources to processes other than the processes regarding the GUI, and accordingly, a processing load applied to the central processing unit at a time of a rendering process can be reduced. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a block diagram illustrating a display device according to Embodiment 1 of the present invention. 
         FIG. 2  is a flowchart illustrating operation of the display device according to Embodiment 1 of the present invention. 
         FIG. 3  is a diagram illustrating an exemplar configuration of a rendering request region. 
         FIG. 4  is a flowchart illustrating a rendering request process shown in  FIG. 2 . 
         FIG. 5  is a flowchart illustrating a rendering execution process shown in  FIG. 4 . 
         FIG. 6  is a flowchart illustrating a rendering-range limitation updating process shown in  FIG. 4 . 
         FIG. 7  is a flowchart illustrating a rendering termination process shown in  FIG. 4 . 
         FIG. 8  is a diagram illustrating an exemplar configuration of a rendering request. 
         FIG. 9  includes diagrams illustrating exemplar display performed in response to the rendering request shown in  FIG. 8 . 
         FIG. 10  is a diagram illustrating an exemplar configuration of another rendering request. 
         FIG. 11  includes diagrams illustrating exemplar display performed in response to the rendering request shown in  FIG. 10 . 
         FIG. 12  is a diagram illustrating exemplar configurations of rendering request regions according to Embodiment 2 of the present invention. 
         FIG. 13  is a flowchart illustrating a rendering request process according to Embodiment 2 of the present invention. 
         FIG. 14  is a flowchart illustrating operation of a display device according to Embodiment 2 of the present invention. 
         FIG. 15  is a diagram illustrating content of data stored in a rendering request region  121  in a state display device according to Embodiment 3 of the present invention. 
         FIG. 16  is a diagram illustrating content of rendered data in a rendering result region  122  in the state display device according to Embodiment 3 of the present invention. 
         FIG. 17  includes diagrams illustrating a size of image data  602  and a size of a rendering range  701 . 
         FIG. 18  includes diagrams illustrating a process of repeatedly writing the image data  602  to the rendering result region  122  performed by rendering processing means  104  in the state display device according to Embodiment 3 of the present invention in detail. 
         FIG. 19  is a flowchart illustrating a procedure of repetitive rendering performed by the rendering processing means  104  in the state display device according to Embodiment 3 of the present invention. 
         FIG. 20  is a diagram illustrating a button obtained by repeatedly rendering image data in a rendering range  1101  in a state display device according to Embodiment 4 of the present invention. 
         FIG. 21  includes diagrams illustrating content of data stored in a rendering request region  121  in a state display device according to Embodiment 5 of the present invention. 
         FIG. 22  includes diagrams illustrating content of another data stored in the rendering request region  121  in the state display device according to Embodiment 5 of the present invention. 
         FIG. 23  includes diagrams illustrating content of rendering data in a rendering result region  122  in the state display device according to Embodiment 5 of the present invention. 
         FIG. 24  is a block diagram illustrating functions of a state display device according to Embodiment 6. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Embodiment 1 
     In Embodiment 1, a state display device which is incorporated in an embedded device such as an air conditioner and which displays a state of the air conditioner will be described as an example. 
       FIG. 1  is a block diagram illustrating a state display device  1  according to Embodiment 1 of the present invention. In  FIG. 1 , the state display device  1  includes central processing means  101 , rendering processing means  104 , storage means  118 , and a liquid crystal display unit  123  including a liquid crystal screen  125 . Note that the central processing means  101  and the rendering processing means  104  are preferably integrated on an identical microcomputer LSI. 
     First, the storage means  118  will be described. 
     The storage means  118  may be accessed by both the central processing means  101  and the rendering processing means  104 , and stores various programs to be executed by the central processing means  101  and the rendering processing means  104  and calculation results. The storage means  118  includes a display program region  119 , a device control program region  120 , a rendering request region  121 , and a rendering result region  122 . 
     The display program region  119  stores a display program used to perform display in the liquid crystal display unit  123 . The device control program region  120  stores a device control program used to control entire operation of the state display device  1 . The display program and the device control program are executed by the central processing means  101 . 
     The rendering request region  121  stores various rendering request to be executed by the rendering processing means  104 . In accordance with results of various calculations performed by the central processing means  101 , rendering requests are written to the rendering request region  121 . 
     The rendering result region  122  is a storage region which stores rendering data to be displayed in the liquid crystal screen  125 , and is generally referred to as a frame buffer. The rendering result region  122  includes storage spaces assigned to addresses of luminous-point coordinates of liquid crystal of the liquid crystal display unit  123 . Although a case where the rendering result region  122  corresponds to a luminous-point coordinate of the liquid crystal of the liquid crystal display unit  123  on a one-to-one basis is taken as an example in Embodiment 1, a plurality of rendering result regions may be provided for the liquid crystal display unit  123 . 
     Note that the display program region  119  and the device control program region  120  are preferably constituted by nonvolatile storage devices such as a DRAM or an SRAM, and the rendering request region  121  and the rendering result region  122  are preferably constituted by volatile storage devices such as a ROM. 
     Furthermore, the storage means  118  is preferably implemented on the microcomputer LSI on which the central processing means  101  and the rendering processing means  104  are implemented, and the microcomputer LSI preferably corresponds to a system LSI. 
     Next, the central processing means  101  will be described. 
     The central processing means  101  is constituted by a microcomputer, for example, and includes a main register  102  and a controller  100 . 
     The controller  100  executes a device control program to control the entire state display device  1  in a unit of clock, executes a display program used to perform display in the liquid crystal display unit  123 , and performs various calculation processes. 
     The main register  102  includes a data register which performs various calculation processes and an address register which specifies an address used to access the storage means  118 . However, in Embodiment 1, only a command address register  103  is shown in the drawing. 
     The command address register  103  store addresses in the storage means  118  corresponding to commands executed by the controller  100 . In  FIG. 1 , arrow marks  131  and  132  which extend from the command address register  103  to the storage means  118  represent that the command address register  103  specifies addresses of the storage means  118 . 
     Next, the rendering processing means  104  will be described. 
     The rendering processing means  104  is a logic circuit specialized for the liquid crystal display and has a function of reading from and writing to the storage means  118 . The rendering processing means  104  includes a rendering register  105  and a rendering processing unit  110 . Furthermore, the rendering register  105  includes an instruction address register  106 , a start/end instruction register  107 , an interruption factor register  108 , and a rendering address register  109 . 
     The instruction address register  106  stores an address which is in the storage means  118  and which corresponds to an instruction (hereinafter referred to as a “rendering request”) to be executed by the rendering processing unit  110 . In  FIG. 1 , an arrow mark  133  represents that the instruction address register  106  specifies an address of the storage means  118 . 
     The start/end instruction register  107  stores a starting command which instructs the rendering processing unit  110  to start a rendering process. 
     The interruption factor register  108  stores an interruption factor when the rendering processing means  104  issued an interruption signal to the central processing means  101 . 
     The rendering address register  109  stores an address in the storage means  118  to which a result of the rendering process performed by the rendering processing unit  110  is written. Note that an arrow mark  134  extending from the rendering address register  109  to the storage means  118  represents that the rendering address register  109  specifies an address included in the storage means  118 . 
     The rendering processing unit  110  includes an interpreter  111 , logic circuits with special rendering functions comprising a line rendering circuit  112 , a square frame rendering circuit  113 , a solid square rendering circuit  114 , and an image rendering circuit  115 , a rendering range limitation storage unit  116 , and a rendering availability state storage unit  117 . 
     The interpreter  111  interprets a rendering request and activates one of the line rendering circuit  112 , the square frame rendering circuit  113 , the solid square rendering circuit  114 , and the image rendering circuit  115 . Note that, in a description described below, the line rendering circuit  112 , the square frame rendering circuit  113 , the solid square rendering circuit  114 , and the image rendering circuit  115  are collectively referred to as a rendering logic circuit where appropriate. 
     The rendering range limitation storage unit  116  stores a range in which the rendering processing means  104  can perform rendering as a limitation range. That is, the rendering processing means  104  does not perform rendering in regions other than the rendering range stored in the rendering range limitation storage unit  116 . The rendering range limitation storage unit  116  includes two sorts of rendering range limitation, i.e., a request limitation  116   a  and a rendering limitation  116   b.    
     The request limitation  116   a  corresponds to a rendering limitation range specified by a rendering request. In other words, the request limitation  116   a  corresponds to a range which is a limit of rendering in accordance with a result of execution of a display program. The rendering processing means  104  does not perform rendering in regions other than the range represented by the request limitation  116   a.    
     The rendering limitation  116   b  corresponds to a rendering limitation range calculated in accordance with the rendering result region  122 . Since the rendering result region  122  corresponds to an address of a luminous point coordinate, the rendering limitation  116   b  is basically translated into a range which can be displayed in the liquid crystal screen  125  in the liquid crystal display unit  123 . 
     Note that, when a plurality of rendering result regions (frame buffers) are assigned to the liquid crystal screen  125  of the liquid crystal display unit  123 , a range which can be actually displayed in the liquid crystal screen  125  may be separately stored as a rendering limitation range. 
     Note that a first rendering range limitation of the present invention corresponds to the rendering limitation  116   b  whereas a second rendering range limitation corresponds to the request limitation  116   a.    
     The rendering availability state storage unit  117  stores information representing whether rendering has been performed on the rendering result region  122  or rendering has not been performed on the rendering result region  122 . 
     Note that first rendering availability variable and second rendering availability variable are stored in the rendering availability state storage unit  117 . 
     The liquid crystal display unit  123  includes a liquid crystal controller  126 , a display address register  124 , and the liquid crystal screen  125  and is stored in a housing not shown. 
     It is assumed that full dot liquid crystal is used in the liquid crystal display unit  123  and the full dot liquid crystal emits light at high speed in accordance with a change of a display position from an upper left side to a right side of the screen and further to a lower side with time so that a two-dimensional image is generated by an effect of an afterimage which remains in eyes. 
     The liquid crystal controller  126  is an LCD controller which performs display control of the liquid crystal screen  125  in accordance with rendering data in the rendering result region  122 . 
     The liquid crystal screen  125  has the liquid crystal which is aggregate of small luminous points and performs screen display under display control of the liquid crystal controller  126 . 
     The display address register  124  stores an address in the storage means  118  which stores luminous values and color values used to make the luminous points in the liquid crystal screen  125  emit light. The liquid crystal controller  126  obtains rendering data specified by the display address register  124  from the rendering result region  122  so as to make the luminous points of the liquid crystal screen  125  emit light. Note that an arrow mark  135  extending from the display address register  124  to the storage means  118  represents that the display address register  124  specifies an address in the storage means  118 . 
     Next, an outline of an operation of displaying a screen in the liquid crystal screen  125  will be described. 
       FIG. 2  is a flowchart illustrating an operation of the state display device  1  regarding display performed by the liquid crystal screen  125 , that is, outlines of operations performed by the central processing means  101 , the rendering processing means  104 , and the liquid crystal display unit  123 . 
     (1) Operation of Central Processing Means  101   
     (Step S 11 ) 
     The central processing means  101  executes a predetermined calculation process in accordance with a display program (in step S 11 ). Specifically, the central processing means  101  specifies a command in the display program region  119  in accordance with a command address stored in the command address register  103 . Then, the central processing means  101  interprets the specified command in accordance with content of a definition in the central processing means  101  and performs required processes including four arithmetic operations, a logical operation, data transfer, a change of an instruction address, and a change of an conditional instruction address. The central processing means  101  controls display of the liquid crystal display unit  123  using a program obtained by combining the calculations and the like with one another. Note that, although not shown in  FIG. 2 , the entire operation of the state display device  1  is controlled in accordance with a device control program. 
     (Step S 12 ) 
     The central processing means  101  writes a rendering request in the rendering request region  121  in the storage means  118  based on a result of the execution of the display program (in step S 12 ). 
     Here, an example of a configuration of a rendering request group  200  stored in the rendering request region  121  is shown in  FIG. 3 . Note that only the rendering request region  121  is in the storage means  118  shown in  FIG. 3 . 
     The rendering request group  200  includes rendering requests  201  to  206 . In  FIG. 3 , text “rendering execution”, “rendering range limitation update”, and “rendering end” in the rendering requests  201  to  206  represent types of rendering request (which will be described in detail hereinafter). Rendering processes corresponding to the types of rendering request are performed. 
     (Step S 13 ) 
     The central processing means writes a starting command to the start/end instruction register  107  in the rendering processing means  104 . The writing of the starting command serves as a trigger of start of a process performed by the rendering processing means  104 . 
     (Step S 14 ) 
     Thereafter, the central processing means performs a process of controlling another control application in accordance with the device control program. 
     (Step S 15 ) 
     When the rendering processing means  104  issued an interruption command, the central processing means performs a predetermined interruption process. Here, the central processing means may refer to the interruption factor register  108  and perform the interruption process in accordance with stored information. 
     (Step S 16 ) 
     When the process of the rendering processing means  104  is to be restarted, central processing means writes a starting command to the start/end instruction register  107 . 
     (Step S 17 ) 
     Thereafter, a process of controlling another control application is performed in accordance with the device control program. 
     (Step S 18 ) 
     When the rendering processing means  104  issued an interruption command again, the central processing means  101  performs the predetermined interruption process. 
     That is, the central processing means  101  performs the control process separately from the rendering processing means  104  in a period of time from when the starting command is written to the start/end instruction register  107  to when the rendering processing means  104  issues the interruption command. 
     (2) Operation of Rendering Processing Means  104   
     Next, operation of the rendering processing means  104  will be described. 
     (Step S 21 ) 
     When the starting command is written to the start/end instruction register  107 , a rendering request process is performed in accordance with the rendering request stored in the rendering request region  121 . 
     Here, an operation of the rendering request process shown in  FIG. 2  will be described. 
       FIG. 4  is a flowchart illustrating the operation of the rendering request process. 
     In  FIG. 4 , the rendering processing means  104  reads a rendering request specified by an instruction address stored in the instruction address register  106  from the rendering request region  121  (in step S 1201 ). Then, the rendering processing means  104  interprets the read rendering request using the interpreter  111  (in S 1202 ). Here, three types of rendering request, i.e., a rendering request “rendering execution” used to execute rendering of a line and a rectangular shape, a rendering request “rendering range limitation update” used to update the request limitation  116   a  of the rendering range limitation storage unit  116 , and a rendering request “rendering end” used to terminate the rendering process are provided. 
     The process branches in accordance with the types of rendering request (in step S 1203 ), and processes corresponding to the rendering requests are performed (in step S 1204 , step S 1205 , and step S 1206 ). 
     After the processes are terminated, the instruction address in the instruction address register  106  is updated to a next instruction address (in step S 1206 ), and the process is terminated. 
     Accordingly, when the rendering request process is performed again, a rendering request specified by the instruction address updated in step S 1206  is executed. In this way, processes corresponding to rendering requests stored in the rendering request region  121  are sequentially executed. 
     The operation of the rendering request process has been described hereinabove. 
     Next, an operation of the rendering execution process shown in  FIG. 4  will be described. In the rendering execution process, various calculation processes for performing rendering such as rendering of a line and rendering of a square frame are performed, and coordinates and colors obtained as results of the calculations are stored in the rendering result region  122 . 
       FIG. 5  is a flowchart illustrating the rendering execution process. When starting the rendering execution process, the rendering processing means  104  initializes the rendering availability state storage unit  117  (in step S 1301 ). 
     Next, it is determined whether the rendering process is terminated or not (in step S 1302 ). When the determination is affirmative, the process proceeds to step S 1308  whereas when the determination is negative, the process proceeds to step S 1303 . Here, assuming that a termination condition is not satisfied, and therefore, it is determined that the rendering process is not terminated, the process proceeds to step S 1303 . 
     In step S 1303 , a coordinate to be subjected to the rendering is calculated in accordance with the rendering request (in step S 1303 ). Then, it is determined whether the calculated rendering coordinate is in the rendering limitation  116   b  stored in the rendering range limitation storage unit  116  or not (in step S 1304 ). The fact that the calculated rendering coordinate is included in the rendering limitation  116   b  means that a graphic to be rendered, for example, can be rendered in the rendering result region  122 . This determination is made by comparing a coordinate of the calculation result of the rendering coordinate in a horizontal direction with a coordinate of the rendering limitation  116   b  in the horizontal direction and comparing a coordinate of the calculation result of the rendering coordinate in a vertical direction with a coordinate of the rendering limitation  116   b  in the vertical direction. When the determination is affirmative, the process proceeds to step S 1305  whereas when the determination is negative, the process proceeds to step S 1308 . 
     In step S 1305 , it is determined whether the rendering coordinate calculated in step S 1303  is included in the request limitation  116   a  stored in the rendering range limitation storage unit  116  or not (in step S 1305 ). A method of the determination is the same as that in step S 1304 . When the determination is affirmative, the process proceeds to step S 1306  whereas when the determination is negative, the process proceeds to step S 1308 . 
     When the rendering coordinate is included in the rendering limitation  116   b  and the request limitation  116   a , color values of the rendering coordinate included in the rendering result region  122  is changed (in step S 1306 ). Subsequently, information included in the rendering availability state storage unit  117  is changed to information representing a rendering available state (in step S 1307 ) and a next rendering coordinate is calculated (in step S 1308 ). 
     Thereafter, it is determined whether the rendering process is terminated or not (in step S 1302 ). The process from step S 1303  to step S 1308  is repeatedly performed on all coordinates of a region specified by the rendering request. For example, when a request for rendering a solid square is issued, the process from step S 1303  to step S 1308  is repeatedly performed on all coordinates included in a region of the solid square. After the process from step S 1303  to step S 1308  has been performed on the coordinates to be rendered, the rendering termination condition is satisfied (in step S 1302 ). 
     When the termination condition of the rendering process is satisfied in step S 1302 , it is determined whether the rendering availability state is an initial state or not (in step S 1309 ). When the rendering availability state stored in the rendering availability state storage unit  117  is not the initial state, the rendering availability state has been changed in step S 1307  and rendering has been performed on the rendering result region  122 . In this case, the rendering execution process is terminated (in step S 1313 ). 
     On the other hand, when it is determined that the rendering availability state is the initial state in step S 1309 , the rendering has not been performed on the rendering result region  122 . In this case, an interruption factor “out of rendering range” is set in the interruption factor register  108  (in step S 1310 ). Then, an interruption request is issued to the central processing means  101  (in step S 1311 ), and the rendering execution process is terminated (in step S 1312 ). In this case, the execution of the rendering request process itself is stopped. 
     Note that, an execution state storage, not shown, is preferably included in the rendering processing means  104  so that a determination as to whether a rendering calculation is to be interrupted is performed in step S 1312 . That is, when the execution state memory represents a developing state, the rendering calculation is interrupted whereas when the execution state memory represents completion of development, the rendering calculation is not interrupted. 
     The operation of the rendering execution process has been described hereinabove. 
     Next, a rendering-range limitation updating process shown in  FIG. 4  will be described. In the rendering-range limitation updating process, the request limitation  116   a  stored in the rendering range limitation storage unit  116  is updated in accordance with a rendering request. 
       FIG. 6  is a flowchart illustrating the rendering-range limitation updating process. 
     When starting the process, the rendering processing means  104  updates the request limitation  116   a  stored in the rendering range limitation storage unit  116  in accordance with a condition specified by the rendering request (in step S 1401 ). For example, when the rendering request represents that a rectangular region including an upper left coordinate (1, 1) and a lower right coordinate (10, 10) which are diagonally arranged is set as a rendering range, the rectangular region is stored as the request limitation  116   a.    
     The rendering-range limitation updating process has been described hereinabove. 
     Next, a rendering termination process shown in  FIG. 4  will be described. In the rendering termination process, the process performed by the rendering processing means  104  is terminated. 
       FIG. 7  is a flowchart illustrating an operation of the rendering termination process. 
     When the rendering termination process is started, the interruption factor is written to the interruption factor register  108  (in step S 1501 ). For example, when the rendering process is terminated due to generation of a “termination factor x”, the “termination factor x” is written to the interruption factor register  108 . The interruption factor written to the interruption factor register  108  may be arbitrarily determined. Although the rendering request group  200  shown in  FIG. 3  includes rendering requests  203  and  206  representing “rendering termination”, different termination factors may be stored as interruption factors. 
     Then, an interruption is issued to the central processing means  101  (in step S 1502 ) and the process is terminated. 
     The central processing means  101  performs a required interruption process in response to the issuance of the interruption, and a reason of the issuance of the interruption can be recognized with reference to the interruption factor register  108 . 
     The operation of the rendering termination process has been described hereinabove. 
     Referring back to  FIG. 2 , the operation performed by the rendering processing means  104  is continued. 
     (Step S 21  to Step S 23 ) 
     The rendering processing means  104  successively executes the rendering request processes in accordance with content of the rendering request. After the rendering termination process is performed, the operation is stopped. 
     (Step S 24  to Step S 26 ) 
     When the starting command is written to the start/end instruction register  107  again, the rendering request process is started in response to the rendering request stored in the rendering request region  121 . 
     That is, after the starting command is written to the start/end instruction register  107 , the rendering processing means  104  performs the process in response to the rendering request independently from the central processing means  101 . 
     (3) Operation of Liquid Crystal Display Unit  123   
     Next, operation of the liquid crystal display unit  123  will be described. 
     (Step S 31  and Step S 32 ) 
     The liquid crystal display unit  123  successively reads rendering data specified by display addresses of the display address register  124  from the rendering result region  122 , and obtains the coordinate values and the color values used to emit light from the liquid crystal included in the liquid crystal screen  125  so that the liquid crystal of the liquid crystal screen  125  emits light. By this, a diagram or an image is displayed in the liquid crystal screen  125 . 
     As described above, the central processing means  101  executes the display program and writes the rendering request to the storage means  118 , and in response to the rendering request, the rendering processing means  104  executes the rendering request process and writes a rendering result to the storage means  118 . Then, in accordance with the rendering result, the liquid crystal display unit  123  performs display on the liquid crystal screen  125 . In this series of processes, the liquid crystal screen  125  performs screen display. 
     The operation performed when the screen display is performed on the liquid crystal screen  125  has been briefly described. 
     Next, a concrete example of the rendering request and an example of rendering performed in response to the rendering request will be described. 
       FIG. 8  is a diagram illustrating a configuration of a rendering request group  300  stored in the rendering request region  121 , and the rendering request group  300  includes rendering requests  301  to  304 . 
     Furthermore,  FIG. 9  includes diagrams illustrating content of the rendering result region  122  rendered in accordance with the rendering request group  200  shown in  FIG. 8 . Note that, since the rendering result region  122  corresponds to a storage space, the content of the rendering result region  122  is shown as a display image displayed in the liquid crystal screen  125  in  FIG. 9  for simplicity of a description. 
     Hereinafter, the description will be made on the basis of  FIGS. 8 and 9  with reference to  FIG. 5 . 
     In  FIG. 8 , the rendering request group  300  includes the rendering requests  301  to  304 . The rendering requests  301 ,  303 , and  304  are used to perform “rendering execution” and the rendering request  302  is used to perform “rendering-range limitation update”. 
     Each of the rendering requests  301  to  304  includes various parameters. Taking the rendering request  301  as an example, the parameters include a command type  301   a , a rendering function type  301   b , an upper-left coordinate  301   c , a lower-right coordinate  301   d , a line thickness  301   e , and a rendering color  301   f . Content of the parameters depends on content of a rendering request. 
     The rendering request  301  is issued to perform rendering such that a square frame ( 301   b ) having an upper-left coordinate (0, 0) ( 301   c ) and a lower-right coordinate (9, 9) ( 301   d ) which are diagonally arranged is rendered with a line thickness of 1 ( 301   e ) and a color of black ( 301   f ). 
     A primary section of a rendering execution process performed based on the rendering request  301  will be mainly described with reference to  FIG. 5 . 
     In  FIG. 5 , coordinates (0, 0) used to render the square frame are calculated (in step S 1303 ), and it is determined whether the coordinates are included in the rendering limitation  116   b  or not (in step S 1304 ). 
     It is assumed here that a rectangular region with the upper-left coordinates (0, 0) and a lower-right coordinates (320, 240) being a diagonal is specified as the rendering limitation  116   b . Since the coordinates (0, 0) are included in the rendering limitation  116   b , the process proceeds to step S 1305  and it is determined whether the coordinates (0, 0) are included in the requested limitation  116   a  (in step S 1305 ). 
     It is assumed here that the rectangular region including the upper-left coordinate (0, 0) and a lower-right coordinate (320, 240) which are diagonally arranged is specified as the request limitation  116   a . Since the coordinate (0, 0) is included in the request limitation  116   a , the process proceeds to step S 1306  where color values of the coordinate (0, 0) is changed (in step S 1306 ), a rendering availability state is changed (in step S 1307 ), and a next rendering coordinate (1, 0) is calculated (in step S 1308 ), and thereafter, the process returns to step S 1302 . 
     Thereafter, the process from step S 1303  to step S 1308  is repeatedly performed on all coordinates included in the square frame. After the process is performed on all the coordinates included in the square frame, that is, the rendering termination condition is satisfied (in step S 1302 ), the process proceeds to step S 1309  where the rendering availability state is checked (in step S 1309 ). Since the rendering availability state is changed in step S 1307 , and therefore, is not the initial state, the determination is negative in step S 1309  and the rendering execution process is terminated (in step S 1313 ). 
       FIG. 9(A)  shows a result of the rendering performed in response to the rendering request  301 . As shown in the Fig., a square frame  401  including the upper-left coordinate (0, 0) and the lower-right coordinate (9, 9) which are diagonally arranged is rendered. Note that, although ruled lines are shown in  FIG. 9  in order to easily recognize the coordinates, the ruled lines are not shown in practice. 
     Furthermore, the rendering request  302  shown in  FIG. 8  corresponds to “rendering range limitation update” in which a rectangular region including an upper-left coordinate (1, 1) and a lower-right coordinate (8, 8) which are diagonally arranged is set as the request limitation  116   a . A detailed process is the same as that described hereinabove. A result of the rendering performed by the rendering processing unit  110  is restricted by the request limitation  116   a , and coordinates which are not included in the request limitation  116   a  are not subjected to the rendering. Note that, at a time when the rendering request  302  is executed, the content of the rendering result region  122  is not changed. 
     Furthermore, the rendering request  303  shown in  FIG. 8  is issued to paint a rectangular region including an upper-left coordinate (0, 0) and a lower-right coordinate (9, 9) which are diagonally arranged with gray. 
     An important section of a rendering execution process performed in response to the rendering request  303  will be mainly described with reference to  FIG. 5 . 
     In  FIG. 5 , the coordinate (0, 0) used to render a solid square is calculated (in step S 1303 ), and it is determined whether this coordinate is included in the rendering limitation  116   b  or not (in step S 1304 ). Since the coordinate (0, 0) is included in the rendering limitation  116   b , the process proceeds to step S 1305  where it is determined whether the coordinate (0, 0) is included in the request limitation  116   a  or not (in step S 1305 ). Since the coordinate (0, 0) is out of the request limitation  116   a  updated by a rendering request  202 , the process proceeds to step S 1308  where a next rendering coordinate (1, 0) is calculated (in step S 1308 ) and the process returns to step S 1302 . That is, the coordinate (0, 0) is not rendered in the rendering result region  122 . 
     Thereafter, the process from step S 1303  to step S 1308  is repeatedly performed on all coordinates included in the solid square. After the process is performed on all the coordinates included in the solid square, that is, the rendering termination condition is satisfied (in step S 1302 ), the process proceeds to step S 1309  where the rendering availability state is checked (in step S 1309 ). Although some coordinates including the coordinate (0, 0), are not to be subjected to the rendering due to the limitation of the request limitation  116   a , the coordinates included in the rectangular region including an upper-left coordinate (1, 1) and a lower-right coordinate (8, 8) which are diagonally arranged are subjected to the rendering. Therefore, the rendering availability state is not the initial state, and accordingly, the determination is negative in step S 1309  and the rendering execution process is terminated (in step S 1313 ). 
       FIG. 9(B)  shows a result of rendering performed in response to the rendering request  303 . In  FIG. 9(B) , a solid square  402  rendered in response to the rendering request  303  is hatched. Although the rendering request  303  specifies the upper-left coordinate (0, 0) and the lower-right coordinate (9, 9), only a rectangular region including an upper-left coordinate (1, 1) and a lower-right coordinate (8, 8) which are arranged at opposing corners is painted due to the limitation of the request limitation  116   a  regarding the rendering request  302  and the square frame  401  is not overwritten. 
     Furthermore, the rendering request  304  shown in  FIG. 8  is issued to perform rendering of a line including a starting point (0, 0) and an ending point (9, 9) which are arranged at opposing ends with a line thickness of 1 and a color of black. 
     A rendering execution process in response to the rendering request  304  is performed in accordance to the process shown in  FIG. 5  similarly to the process described above. 
       FIG. 9(C)  shows a result of the rendering performed in response to the rendering request  304 . As shown in the Fig., although the rendering request  304  specifies rendering of the line including the starting point (0, 0) and the ending point (9, 9) which serve as opposing ends, the limitation of the request limitation  116   a  regarding the rendering request  302  is applied. Therefore, only a line  403  including a starting point (1, 1) and an ending point (8, 8) which serve as opposing ends is rendered, and the coordinates (0, 0) and (9, 9) are not overwritten. 
     Next, examples of another rendering request and another rendering process performed in response to the rendering request will be described in detail. Here, a case where a rendering process is not performed in response to a rendering request will be described as an example. 
       FIG. 10  is a diagram illustrating a configuration of a rendering request group  300 A stored in the rendering request region  121 . Only a rendering request  303 A is different from the rendering request shown in  FIG. 8  described above, and other configurations are the same as those shown in  FIG. 8 . Furthermore,  FIG. 11  includes diagrams illustrating content of the rendering result region  122  rendered in response to the rendering request group  300 A shown in  FIG. 10 . Hereinafter, portions different from those shown in  FIGS. 8 and 9  will be mainly described. 
     Rendering execution process is performed based on the rendering requests  301  and  302  as described above. 
       FIG. 11(A)  shows rendering results obtained after the rendering requests  301  and  302  are executed. As with the case of  FIG. 9(A) , a square frame  401  is rendered. 
     Furthermore, as the request limitation  116   a , a rectangular region with the upper-left coordinates (1, 1) and the lower-right coordinates (8, 8) being the opposing corner is specified. 
     A rendering request  303 A shown in  FIG. 10  is issued to paint with gray a rectangular region including an upper-left coordinate (10, 0) and a lower-right coordinate (20, 10) which are diagonally arranged. 
     An important portion of a rendering execution process performed in response to the rendering request  303 A will be mainly described. 
     In  FIG. 5 , the coordinate (10, 0) is calculated as a coordinate used to render a solid square (in step S 1303 ), and it is determined whether this coordinate is included in the rendering limitation  116   b  of the rendering result region or not (in step S 1304 ). Since the coordinate (10, 0) is included in the rendering limitation  116   b , the process proceeds to step S 1305  where it is determined whether the coordinate (10, 0) is included in the request limitation  116   a  or not (in step S 1305 ). Here, since the coordinate (10, 0) is out of the request limitation  116   a , the process proceeds to step S 1308  where a next rendering coordinate (11, 0) is calculated (in step S 1308 ), and thereafter, the process returns to step S 1302 . 
     Thereafter, the process from step S 1303  to step S 1308  is repeatedly performed on all coordinates included in the solid square. After the process performed on all the coordinates included in the solid square is terminated, that is, the rendering termination condition is satisfied (in step S 1302 ), the process proceeds to step S 1309  where the rendering availability state is checked (in step S 1309 ). 
     Here, all the coordinates included in the rectangular region including the upper-left coordinate (10, 0) and the lower-right coordinate (20, 10) which are diagonally arranged and which are specified by a rendering request  203 A are located out of the request limitation  116   a . In other words, the rectangular region to be subjected to the rendering in response to the rendering request  203 A does not intersect with the region of the request limitation  116   a.    
     Accordingly, rendering is not performed and the rendering availability state remains as the initial state. Therefore, the determination is affirmative in step S 1309 , “out of rendering” is set as the interruption factor in the interruption factor register  108  (in step S 1310 ), an interruption request is issued to the central processing means  101  (in step S 1311 ), and the rendering execution process is interrupted (in step S 1312 ). Note that, since the rendering execution process is interrupted, a rendering process is not executed in response to the rendering request  304  (shown in  FIG. 10 ). 
     A rendering result obtained after the process performed in response to the rendering request  303 A is shown in  FIG. 11(B) . In  FIG. 11(B) , a rectangular region  404  to be the solid square in response to the rendering request  303 A is virtually shown by a dotted line. As shown in  FIG. 11(B) , since the rectangular region  404  is out of the rectangular region specified by the request limitation  116   a , the gray painting is not performed, and as a result, content of the rendering performed on the rendering result region  122  is the same as that shown in  FIG. 11(A) . 
     Note that, although the case where the rendering range of the rendering request  303 A is out of the request limitation  116   a  has been described above, also when a case where the rendering range of the rendering request  303 A is out of the request limitation  116   b , the process in  FIG. 5  can be performed. Furthermore, when the interruption factor is written in step S 1310  of  FIG. 5 , the interruption factor to be written may be determined depending on whether the rendering region is located out of the request limitation  116   a  or out of the rendering limitation  116   b.    
     As described above, the state display device  1  according to Embodiment 1 includes the rendering processing means  104  serving as dedicated hardware which executes the rendering process separately from the central processing means  101  which controls the entire state display device  1 . Accordingly, a processing load applied to the central processing means  101  at the time of the rendering process can be reduced. Furthermore, since the rendering processing means  104  performs the rendering process, the high-speed rendering process is realized. 
     Furthermore, the rendering processing means  104  performs the rendering process independently from the central processing means  101  in a period of time from when the starting command is written to the start/end instruction register  107  to when the rendering termination process is performed in response to the rendering request. Therefore, in the central processing means  101 , processing resources are not occupied by the rendering process performed by the rendering processing means  104 , and accordingly, the processing resources can be sufficiently assigned to processes of controlling a main control application and the like. Consequently, original functions of the state display device  1  and functions of an apparatus including the state display device  1  can be executed at high speed. 
     Furthermore, since the rendering processing means  104  terminates the rendering process in response to the “rendering termination” request serving as the rendering request, the rendering processing means  104  terminates the rendering process independently from the central processing means  101 . On the other hand, the central processing means  101  is not required to monitor the rendering process performed by the rendering processing means  104  and is not required to instruct the rendering processing means  104  to terminate the rendering process, and accordingly, a processing load caused by the monitoring and issuance of the instruction to the rendering processing means  104  is reduced. 
     Furthermore, in the rendering termination process performed in response to the “rendering termination” request, the termination factor is stored in the interruption factor register  108  as the interruption factor. Since an arbitrary interruption factor can be stored, the central processing means  101  recognizes a reason of the interruption of the rendering process of the rendering processing means  104 . For example, when an interruption factor representing that the rendering processing means  104  is merely in a temporary halt state is stored in the interruption factor register  108 , the central processing means  101  recognizes that the rendering processing means  104  has temporarily stopped the process. Moreover, when an interruption factor representing that the entire process is terminated is stored in the interruption factor register  108 , the central processing means  101  recognizes that the entire process is completed. 
     Furthermore, since the rendering request may be stored in the storage means  118  in advance, when the rendering request is repeatedly performed, the process can be efficiently performed. That is, when an FIFO (First In First Out) buffer is used to consecutively issue rendering requests to a graphic processor, for example, all the rendering requests should be stored in the FIFO buffer. Accordingly, rendering requests to be repeatedly executed are stored in the FIFO buffer for the number corresponding to repetitions. However, according to the state display device  1  of Embodiment 1, the rendering requests to be repeatedly performed is merely stored in the rendering request region  121  as a set of a rendering request group. Then, only by writing the starting command to the start/end instruction register  107 , the rendering processing means  104  repeatedly executes the rendering request group stored in the rendering request region  121 . 
     Furthermore, when the rendering of coordinates are not performed in the rendering execution process (in  FIG. 5 ), the interruption factor is written to the interruption factor register  108 , and in addition, the interruption request is issued to the central processing means  101 . Accordingly, the central processing means  101  recognizes an occurrence of an error. Consequently, the central processing means  101  can distinguish whether the display is not performed on purpose or the display is not performed due to an error. When the display is not performed due to an error, the central processing means  101  performs an appropriate process. 
     Furthermore, the request limitation  116   a  and the rendering limitation  116   b  are provided so that the central processing means  101  can recognize that rendering of coordinates is not performed at all by reason of which limitation is out of range. Accordingly, the central processing means  101  can perform an appropriate process as needed. 
     Furthermore, when an image displayed on the screen is moved little by little in accordance with an operation performed by an operator, that is, when animated display is performed, a rendering request for moving a position of the image is repeatedly executed. In this case, in the state display device  1  of Embodiment 1, a plurality of rendering request groups (a rendering execution request and a rendering termination request) to be used until transfer of the position of the image is terminated are stored in the storage means  118  in advance. Then, the central processing means  101  successively issues starting commands with a predetermined interval (0.1 second, for example) so as to cause the rendering processing means  104  to successively perform rendering processes. After termination of the processes performed in accordance with the rendering request groups, the rendering termination factors have been stored in the interruption factor register  108 . By this, even when rendering processes are consecutively performed, that is, when the animated display is performed, for example, the main process performed by the central processing means  101  is hardly interrupted. In general, interruption processes of the central processing means  101  is made to be minimized so that high-speed responses are realized and the main process is not disturbed. Under this circumference, the interruption factor register  108  can independently perform an appropriate rendering process without referring to a state of the main process, and accordingly, this is considerably effective for the central processing means  101  which does not enough power to operate at high speed. 
     Note that, in Embodiment 1, the case where the rendering range limitation storage unit  116  includes the request limitation  116   a  specified by the rendering request and the rendering limitation  116   b  calculated in accordance with the rendering result region  122  has been described as an example. Alternatively, when a displayable range of the liquid crystal screen  125  does not coincide with a size of the rendering result region  122 , the displayable range of the liquid crystal screen  125  may be independently stored as a rendering range in the rendering range limitation storage unit  116 . Furthermore, the rendering availability state is preferably stored in the rendering availability state storage unit  117  for each rendering range stored in the rendering range limitation storage unit  116 . 
     Furthermore, in step S 1307  of  FIG. 5  according to Embodiment 1, only when a rendering coordinate is included in the rendering limitation  116   b  (in step S 1304 ) and included in the request limitation  116   a  (in step S 1305 ), value stored in the rendering availability state storage unit  117  is changed (in step S 1307 ). That is, in Embodiment 1, the first rendering availability variable and the second rendering availability variable according to the present invention are represented by single value. However, a rendering availability state of the rendering limitation  116   b  and a rendering availability state of the request limitation  116   a  may be separately stored, and in this case, more accurate control can be performed. 
     Embodiment 2 
     In Embodiment 2, a case where, when a plurality of rendering request regions are arranged separately from one another in storage means, rendering requests stored in the rendering request regions are consecutively executed will be described as an example. Note that, in Embodiment 2, portions different from those of Embodiment 1 will be mainly described. 
       FIG. 12  is a diagram illustrating configurations of rendering request regions  121   a  and  121   b  according to Embodiment 2. In  FIG. 12 , the rendering request regions  121   a  and  121   b  are arranged separately from each other in storage means  118 . 
     The rendering request regions  121   a  and  121   b  include rendering request groups  501  and  506 , respectively. The rendering request group  501  includes rendering requests  502  to  505 . The rendering requests  502  to  504  are commands for requesting execution of rendering of a square frame and the like. On the other hand, the rendering request region  506  includes rendering requests  507  to  509 . The rendering requests  507  and  508  are commands for requesting execution of rendering, and the rendering request  509  is a command for requesting termination of the rendering. 
     Furthermore, the rendering request  505  is a command for replacing an instruction address stored in an instruction address register  106  by an address where a rendering request to be processed next is stored, and is a characteristic of Embodiment 2. The rendering request  505  has the instruction address which is a destination of the changing as a parameter. When the instruction address of the instruction address register  106  specified the rendering request  505 , rendering processing means  104  performs an address changing process (which will be described hereinafter). 
       FIG. 13  is a flowchart illustrating a rendering request process performed by the rendering processing means  104  according to Embodiment 2 of the present invention. 
       FIG. 13  is substantially the same as  FIG. 4  described above except for step S 1208 . In step S 1208 , when a rendering request corresponds to “address change”, the instruction address of the instruction address register  106  is replaced by an instruction address of a destination of the change. The instruction address of the destination of the change is supplied in response to the rendering request  505  representing “address change” and is where a rendering request to be processed next is stored. 
     Accordingly, when the rendering request process is executed again, the rendering request specified by the instruction address changed in step S 1208  is executed. 
       FIG. 14  is a flowchart illustrating an operation performed in accordance with the rendering request groups  501  and  506  shown in  FIG. 12 . In  FIG. 14 , an operation of central processing means  101  and an operation of the rendering processing means  104  will be described. Note that the rendering request groups  501  and  506  have been written in the rendering request regions  121   a  and  121   b , respectively. 
     (1) Operation of Central Processing Means  101   
     The central processing means  101  writes a starting command to a start/end instruction register  107  (in step S 41 ). Thereafter, the central processing means executes a required control process in accordance with a device control program (in step S 42 ). Subsequently, when the rendering processing means  104  issues an interruption request, the central processing means  101  interrupts the process of step S 42  and performs a predetermined interruption process (in step S 43 ). That is, in a period from when the starting command is written to the start/end instruction register  107  to when the interruption request is issued, the central processing means performs the control process independently from the rendering processing means  104 . 
     (2) Operation of Rendering Processing Means  104   
     Next, the operation of the rendering processing means  104  will be described. 
     When the starting command is written to the start/end instruction register  107 , the rendering processing means  104  performs a rendering request process in accordance with a rendering request included in a rendering request region  121  specified by an instruction address stored in the instruction address register  106  (in step S 51 ). Assuming that the instruction address register  106  stores an instruction address representing the rendering request  502 , a process corresponding to the rendering request  502  is executed. 
     Subsequently, processes corresponding to the rendering requests  503  and  504  are performed (in step S 52  and step S 53 ). 
     Next, an address changing process is performed in response to the rendering request  505  representing “address change” (in step S 54 ). As shown in  FIG. 13 , in the address changing process, an address where the rendering request  507  to be processed next is stored is stored in the instruction address register  106 . Accordingly, in the next rendering request process, the rendering request  507  which is independent from the rendering request group  501  is executed. 
     Subsequently, rendering request processes are performed in response to the rendering requests  507  and  508  (in step S 55  and step S 56 ), and thereafter, a rendering termination process is performed in response to the rendering request  509  representing “rendering termination”. Then, the rendering processing means  104  issues the interruption request to the central processing means  101  in the rendering termination process (in step S 57 ), and terminates the process. 
     As described above, according to Embodiment 2, the rendering request representing “address change” is provided as a rendering request, and the instruction address of the instruction address register  106  is updated in accordance with the request representing “address change”. Accordingly, by separately arranging rendering request groups in a plurality of regions included in the storage means  118  and providing the rendering request representing “address change” for changing an address to a leading address of the rendering request region  506 , the rendering processes corresponding to the rendering requests separately located can be continuously executed. Since a change of an address from the rendering request region  121   a  to the rendering request region  121   b  can be performed independently from the central processing means  101 , a processing load applied to the central processing means  101  is not increased. 
     Furthermore, when a number of rendering requests are required for performing complicated rendering, the rendering requests are arranged in different regions included in the storage means  118  so that a limited region of the storage means  118  is efficiently used. 
     Furthermore, since the rendering requests can be divided into a plurality of units so that the plurality of units are arranged in the storage means  118 , an efficient program configuration for displaying a plurality of screens having common portions and different portions can be attained. That is, rendering requests of the common portions and rendering requests of the different portions are separately stored in the storage means  118 , and when the requests are to be executed, the rendering requests of the different portions are issued followed by the requests of the common portions. Since the rendering requests of the common portions are not required to be stored in the storage means  118  in an intersecting manner, a size of the rendering request region  121  can be reduced. 
     Embodiment 3 
     In Embodiment 3, portions different from those of the state display device according to Embodiment 1 will be mainly described. A configuration of a state display device according to this embodiment itself is similar to that of the state display device according to Embodiment 1. 
     In this embodiment, a single rendering request includes a rendering repeat condition, and an example in which rendering processing means  104  repeatedly performs the same rendering process in accordance with the rendering repeat condition will be described. 
       FIG. 15  is a diagram illustrating an example of contents of data stored in a rendering request region  121  stored in the state display device according to Embodiment 3 of the present invention. 
     As shown in  FIG. 15 , a rendering request  601  is stored in the rendering request region  121  in storage means  118 . 
     The rendering request  601  includes a rendering starting instruction  601   a , a rendering function instruction (image)  601   b , a rendering-range upper-left coordinate  601   c , a rendering-range lower-right coordinate  601   d , a rendering repeat condition  601   e , and a rendering image address  601   f.    
     When an instruction for rendering image data is issued in accordance with the rendering function instruction (image)  601   b , an address of image data  602  to be rendered included in a storage means  118  is stored in the rendering image address  601   f . Furthermore, a repeat condition for repeatedly rendering the same image data is stored in the rendering repeat condition  601   e.    
       FIG. 16  is a diagram illustrating content of the rendered data included in a rendering result region  122  included in the state display device according to Embodiment 3 of the present invention.  FIG. 16  shows the content of the rendering data stored in the rendering result region  122  as a result of execution of the rendering request shown in  FIG. 15 . For sake of a visual description, a screen image  305  is displayed in a liquid crystal screen  125  instead of the rendering data. 
     The rendering processing means  104  repeatedly renders the image data  602  in accordance with the rendering repeat condition  601   e . Here, a case where the image data  602  is repeatedly rendered in a horizontal direction within a rendering range  701  is shown as an example. 
       FIG. 17  is a diagram illustrating a size of the image data  602  and a size of the rendering range  701 . 
     An image height  951  corresponds to a size of the image data  602  in a vertical direction when the image data is rendered in the liquid crystal screen  125 . 
     An image width  952  corresponds to a size of the image data  602  in a horizontal direction when the image data is rendered in the liquid crystal screen  125 . 
     A rendering width  955  corresponds to a size of the rendering range  701  in the horizontal direction when the rendering range is rendered in the liquid crystal screen  125 . 
     A rendering height  956  corresponds to a size of the rendering range  701  in the vertical direction when the rendering range is rendered in the liquid crystal screen  125 . In this example, the rendering height  956  and the image height  951  coincide with each other. 
       FIG. 18  is a diagram illustrating a process of repeatedly writing the image data  602  in the rendering result region  122  performed by rendering processing means  104  included in the state display device according to Embodiment 3 of the present invention in detail. 
     As shown in  FIG. 18 , the image data  602  includes small gray rectangular regions  961  and  981 , and a large gray rectangular region arranged beneath the small gray rectangular regions  961  and  981 . Furthermore, it is assumed that the repetitive process is performed on the individual rectangular regions. 
     Hereinafter, content of the repetitive process will be described in addition to the correspondence relationship with an address included in the storage means  118 . 
     (1) Address Assignation in Storage Means  118   
     In the storage means  118 , addresses which increases in an ascending order are assigned to the rendering result region  122 . The correspondence relationships between the addresses and luminous points of the liquid crystal screen  125  will be described below. 
     (1.1) An uppermost-left luminous point of the liquid crystal screen  125  corresponds to the smallest address in the rendering result region  122 . 
     (1.2) Hereinafter, luminous points toward the right side of the liquid crystal screen  125  correspond to addresses in the rendering result region  122  in the ascending order. 
     (1.3) When a luminance point comes to the rightmost end of the liquid crystal screen  125 , the next address is assigned to a luminance point located at a leftmost end in a row immediately beneath the processed row by one luminance point. 
     (1.4) Thereafter, luminance points of one row from left to right correspond to addresses in the rendering result region  122  in the ascending order. 
     (2) Repeat Range in Horizontal Direction 
     Next, a horizontal rendering range of the rendering range  701  will be described. 
     (2.1) Rendering of Rectangular Region  961   
     The rendering processing means  104  repeatedly writes rendering data used to display the rectangular region  961  into the rendering result region  122 . An address of a writing destination is incremented in an ascending order. By this, in the liquid crystal screen  125 , rendering is repeatedly performed from left to right. Furthermore, the rendering processing means  104  increments the address of the writing destination in the ascending order in course of the repetitive rendering, and interrupts the repetitive rendering when a position of writing of the address exceeds a position corresponding to a right-end portion of the rendering range  701 . This is because, since, among the addresses included in the storage means  118 , an address following the address of the right-end portion of the rendering range  701  is assigned to a left-end portion of the rendering range  701 , wrong repetitive rendering is performed if the repetitive rendering is continued. 
     (2.2) Rendering of Rectangular Region  981   
     The rendering processing means  104  performs repetitive rendering on the rectangular region  981  similarly to the rectangular region  961 . Furthermore, as with the repeat condition of the rectangular region  961 , the rendering processing means  104  interrupts the repetitive rendering when a writing position corresponding to the writing address exceeds the position corresponding to the right-end portion of the rendering range  701 . 
     (2.3) First Item Common to Rectangular Regions  961  and  981   
     The rendering processing means  104  interrupts the repetitive rendering performed for each rectangular region when a writing position corresponding to an address of a writing destination exceeds a position corresponding to the right-end portion of the rendering range  701 . The addresses included in the storage means  118  are not ended at the right end of the rendering range  701  but continued to the left end thereof. Therefore, a determination as to whether the position corresponding to the right-end portion of the rendering range  701  has been exceeded may be determined using a surplus obtained by dividing a value of an address by a total number of luminous points in the horizontal direction, for example. 
     (2.4) Second Item Common to Rectangular Regions  961  and  981   
     Similarly, the rendering processing means  104  interrupts the repetitive rendering when the writing position corresponding to the address of the writing destination exceeds a position corresponding to a right-end portion of the liquid crystal screen  125 . This is because the rendering is not allowed to be performed on regions located out of the right end of the liquid crystal screen  125 . When a difference between an address obtained at a time when the rendering is started and the address of the writing destination at current time exceeds the number of luminous points in the horizontal direction, the repetitive process is preferably interrupted. 
     (3) Repetitive Range in Vertical Direction 
     Next, a rending range in the vertical direction of the rendering range  701  will be described. 
     (3.1) Rendering of Rectangular Region  961   
     After the image data  602  is repeatedly rendered in the horizontal direction in a first row, the rendering processing means  104  calculates a position of the repetitive rendering in a second row. In the example shown in  FIG. 18 , as denoted by an arrow mark  971 , a position in the second row where the rectangular region  961  is to be rendered is obtained. Specifically, an address of a writing destination of the rectangular region  961  is incremented until the address is shifted from the position at the left-end portion of the rendering range  701  in the vertical direction by an amount corresponding to the image height  951 . As a result of the increment of the writing destination address, when the address is larger than an address corresponding to a lower-right end portion of the rendering range  701 , it is determined that the writing position exceeds the rendering range  701 . Accordingly, the rendering processing means  104  interrupts the repetitive rendering. 
     (3.2) Rendering of Rectangular Region  981   
     The rendering processing means  104  repeatedly renders the rectangular region  981  similarly to the case of the rectangular region  961 . That is, after the image data  602  is repeatedly rendered in a first row in the horizontal direction, a repetitive rendering position in a second row is calculated. In the example shown in  FIG. 18 , as denoted by an arrow mark  991 , a position in the second row where the rectangular region  981  is to be rendered is obtained. Furthermore, as with the repeat condition of the rectangular region  961 , the rendering processing means  104  interrupts the repetitive rendering when a writing position corresponding to the writing destination address exceeds the position corresponding to the right-lower end portion of the rendering range  701 . 
     (3.3) Item Common to Rectangular Regions  961  and  981   
     Similarly, the rendering processing means  104  interrupts the repetitive rendering when the writing position corresponding to the writing destination address exceeds a position corresponding to the lower-end portion of the liquid crystal screen  125 . This is because the rendering is not allowed to be performed on regions beyond the lower end of the liquid crystal screen  125 . 
       FIG. 19  is a flowchart illustrating a procedure of the repetitive rendering performed by the rendering processing means  104  included in the state display device according to Embodiment 3 of the present invention. Hereinafter, steps shown in  FIG. 19  will be described. 
     (Step S 1001 ) 
     The rendering processing means  104  starts a rendering process when a starting instruction is written to the start/end instruction register  107 . 
     (Step S 1002 ) 
     The rendering processing means  104  determines whether the repetitive rendering is continued or not in accordance with the rendering repeat condition  601   e  using the criterion described with reference to  FIG. 18 . When the repetitive rendering is to be continued, the process proceeds to step S 1003  whereas when the repetitive rendering is to be terminated, the process proceeds to step S 1006 . 
     (Step S 1003 ) 
     The rendering processing means  104  calculates an address which is included in the storage means  118  and which corresponds to a position in which the rendering is to be performed using the method described with reference to  FIG. 18 . 
     (Step S 1004 ) 
     The rendering processing means  104  determines whether the position corresponding to the address calculated in step S 1003  is included in the rendering range  701  using the criterion described with reference to  FIG. 18 . When included, the process proceeds to step S 1005 , and when not included, the process returns to step S 1002  and the same process is repeated. 
     (Step S 1005 ) 
     The rendering processing means  104  writes rendering data in the address corresponding to the position in which the rendering is to be performed. For example, the rendering processing means  104  writes color value specified by a rendering request in the address. 
     (Step S 1006 ) 
     The rendering processing means  104  terminates the rendering process. 
     Note that, in the description of the procedure of the repetitive rendering described above, it is assumed that the repetitive rendering is performed in the horizontal and vertical directions. However, the same process may be performed when the repetitive rendering is performed in only one of the horizontal and vertical directions. 
     As described above, since the rendering processing means  104  repeatedly renders the image data  602  while incrementing the writing destination address in an ascending order in accordance with the rendering repeat condition  601   e , the rendering processing means  104  operates independently from the central processing means  101  while performing the repetitive rendering. Accordingly, a load applied to the central processing means  101  can be reduced. Furthermore, this is preferable in terms of save of the storage region since the number of rendering requests can be reduced. 
     Furthermore, the image is repeatedly rendered so that a pattern or the like is formed simply by providing small image data in advance. By this, since the number of rendering calculations can be reduced when compared with a case where the pattern is rendered by line rendering, efficiency of the rendering process can be improved. 
     Furthermore, the rendering processing means  104  interrupts the repetitive rendering when the writing destination address included in the storage means  118  exceeds the position corresponding to the right end of the rendering range  701  or the liquid crystal screen  125 , the rendering processing means  104  can appropriately perform the repetitive rendering. 
     Furthermore, the rendering processing means  104  interrupts the repetitive rendering when the writing destination address included in the storage means  118  exceeds the position corresponding to the lower end of the rendering range  701  or the liquid crystal screen  125 , the rendering processing means  104  can appropriately perform the repetitive rendering. 
     Note that it is preferable that, when the rendering processing means  104  increments the writing destination address included in the storage means  118  in the ascending order, while the writing destination address has not reached an address corresponding to the upper-left end portion of the rendering range  701 , the rendering processing means  104  does not perform writing. If the writing is performed before the writing destination address reaches the address corresponding to the upper-left end portion of the rendering range  701 , an image is rendered an upper side or a left side relative to the rendering range  701 . 
     Embodiment 4 
     In Embodiment 4, a portion different from the state display device according to Embodiment 1 will be mainly described. A configuration of a state display device of this embodiment is the same as that of Embodiment 1. 
     In this embodiment, an example of an operation of displaying a GUI component such as a button in a liquid crystal screen  125  included in a liquid crystal display unit  123  will be described. 
       FIG. 20  is a diagram illustrating a button configured by repeatedly rendering image data in a rendering range  1101  in the state display device according to Embodiment 4 of the present invention.  FIG. 20  shows an example of content of rendering data stored in a rendering result region  122 , and shows a screen image  305  displayed in the liquid crystal screen  125  instead of the rendering data for sake of a visual description. 
     As shown in  FIG. 20 , a gradation image which is an image having a color gradually lightened is repeatedly rendered around the button “button” in the rendering range  1101  included in the screen image  305 . In this way, a visual effect is achieved such that the button “button” is surrounded by gradational frame instead of a simple line. 
     Similarly, by repeatedly rendering image data including two colors around the button “button”, a visual effect is achieved such that the button “button” is surrounded by shadow. Furthermore, a visual effect such as shiny highlight can be achieved. 
     Embodiment 5 
     In Embodiment 5, portions different from the state display device of Embodiment 1 will be mainly described. The configuration of a state display device of this embodiment is the same as that described in Embodiment 1. 
     In this embodiment, an example of operations of performing a rendering process from a position on image data by shifting the image data by a surplus obtained by dividing each coordinate value at the upper-left coordinates of the rendering range by the width and the height of the image data will be described. 
       FIG. 21  includes diagrams illustrating content of data stored in a rendering request region  121  included in the state display device according to Embodiment 5 of the present invention. 
     As shown in  FIG. 21(   a ), the rendering request region  121  included in storage means  118  stores a rendering request  801 . 
     The rendering request  801  includes a rendering start instruction  801   a , a rendering function instruction (image surplus)  801   b , a rendering-range upper-left coordinate  801   c , a rendering-range lower-right coordinate  801   d , a rendering repeat condition  801   e , and a rendering image address  801   f.    
     When an instruction for rendering image data using a surplus is issued in accordance with the rendering function instruction (image surplus)  801   b , an address of image data  602  to be rendered which is included in the storage means  118  is stored in the rendering image address  801   f . Furthermore, a repeat condition for performing repetitive rendering while the image data is shifted using the surplus is stored in the rendering repeat condition  801   e.    
       FIG. 21(   b ) shows content of the rendering data stored in a rendering result region  122  in response to the rendering request  801  shown in  FIG. 21(   a ). Here, a screen image  305  is displayed in the liquid crystal screen  125  instead of the rendering data for sake of a visual description. Referring to  FIG. 21 , a procedure of rendering the image data using the surplus will be described in step (1) to step (5) hereinafter. 
     (1) As with the operation of Embodiment 1 shown in  FIG. 2 , rendering processing means  104  obtains a rendering request in accordance with an address stored in an instruction address register  106  and performs a rendering process in response to the rendering request. The rendering processing means  104  obtains the rendering request  801  in accordance with the address stored in the instruction address register  106 .
 
(2) The rendering processing means  104  determines that the image data is to be rendered using a surplus in this rendering process in accordance with the rendering function instruction (image surplus)  801   b.  
 
(3) The rendering processing means  104  calculates a surplus (hereinafter referred to as “Mod(X)”) by dividing a horizontal coordinate (hereinafter referred to as an “X coordinate”) at an upper-left coordinate of a rendering range  610  represented by the rendering-range upper-left coordinate  801   c  by a width of the image data  602 . Here, since the X coordinate at the upper-left coordinate of the rendering range  610  is “0”, the surplus obtained by dividing the coordinate by a value “2” of the width of the image data  602  is represented as follows: Mod(X)=0.
 
(4) The rendering processing means  104  calculates a surplus (hereinafter referred to as “Mod(Y)”) by dividing a vertical coordinate (hereinafter referred to as a “Y coordinate”) at the upper-left coordinate of the rendering range  610  represented by the rendering-range upper-left coordinate  801   c  by a height of the image data  602 . Here, since the Y coordinate at the upper-left coordinate of the rendering range  610  is “0”, the surplus obtained by dividing the coordinate by a value of the height of the image data  602  is represented as follows: Mod(Y)=0.
 
(5) The rendering processing means  104  displays, at the upper left coordinate of the rendering range  610 , pixel data at a position shifted rightward by the surplus Mod(X) and shifted downward by the surplus Mod(Y) from an upper-left pixel data of the image data  602  first, and subsequently, renders data rightward and downward from the upper-left pixel data of the image data  602  onto positions from the upper-left coordinate of the rendering range  610  to the lower-right coordinate of the rendering range  610 .
 
     Note that the surpluses Mod(X) and Mod(Y) of all coordinates included in the rendering range  610  may be calculated, and in each of the coordinates, pixel data obtained by shifting the upper-left pixel data of the image data  602  rightward by the surplus Mod(X) and downward by the surplus Mod(Y) may be displayed. 
     Results of the rendering performed as described above are shown in  FIG. 21(   b ). Here, since the surplus of the X coordinate and the surplus of the Y coordinate are “0”, and a size of the rendering range  610  is equal to a size of the image data  602 , the image data  602  is displayed in the rendering range  610  without change. 
       FIG. 22  is a diagram illustrating other contents of data to be stored in the rendering request region  121  included in the state display device according to Embodiment 5 of the present invention. 
     As shown in  FIG. 22(   a ), a rendering request  802  is stored in the rendering request region  121  in the storage means  118 . 
     The rendering request  802  includes a rendering start instruction  802   a , a rendering function instruction (image surplus)  802   b , a rendering-range upper-left coordinate  802   c , a rendering-range lower-right coordinate  802   d , a rendering repeat condition  802   e , and a rendering image address  802   f.    
     When an instruction for rendering image data using a surplus is issued in accordance with the rendering function instruction (image surplus)  802   b , an address of the image data  602  which is included in the storage means  118  is stored in the rendering image address  802   f . Furthermore, a repeat condition for performing repetitive rendering while the image data is shifted using the surplus is stored in the rendering repeat condition  802   e.    
       FIG. 22(   b ) shows content of the rendering data stored in the rendering result region  122  in response to the rendering request  801  shown in  FIG. 22(   a ). Here, a screen image  305  is displayed in the liquid crystal screen  125  instead of the rendering data for sake of a visual description. Referring to  FIG. 22 , a procedure of rendering the image data using the surplus will be described in step (1) to step (5) hereinafter. 
     (1) As with the operation of Embodiment 1 shown in  FIG. 2 , the rendering processing means  104  obtains a rendering request in accordance with an address stored in an instruction address register  106  and performs a rendering process in response to the rendering request. The rendering processing means  104  obtains the rendering request  802  in accordance with the address stored in the instruction address register  106 .
 
(2) The rendering processing means  104  determines that the image data is to be rendered using a surplus in this rendering process in accordance with the rendering function instruction (image surplus)  802   b.  
 
(3) The rendering processing means  104  calculates a surplus “Mod(X)” by dividing an X coordinate at an upper-left coordinate of a rendering range  710  represented by the rendering-range upper-left coordinate  802   c  by the width of the image data  602 . Here, since the X coordinate at the upper-left coordinate of the rendering range  710  is “1”, the surplus obtained by dividing the coordinate by a value “2” of the width of the image data  602  is represented as follows: Mod(X)=1.
 
(4) The rendering processing means  104  calculates a surplus “Mod(Y)” by dividing a Y coordinate at the upper-left coordinate of the rendering range  710  represented by the rendering-range upper-left coordinate  802   c  by the height of the image data  602 . Here, since the Y coordinate at the upper-left coordinate of the rendering range  710  is “0”, the surplus obtained by dividing the coordinate by a value “4” of the height of the image data  602  is represented as follows: Mod(Y)=0.
 
(5) The rendering processing means  104  displays, at the upper left coordinate of the rendering range  710 , pixel data at a position shifted rightward by the surplus Mod(X) and shifted downward by the surplus Mod(Y) from an upper-left pixel data of the image data  602  first, and subsequently, renders data rightward and downward from the upper-left pixel data of the image data  602  onto positions from the upper-left coordinate of the rendering range  710  to the lower-right coordinate of the rendering range  710 . Here, a pixel data comes to the right end of the image data  602  before coming to the right end of the rendering range  710 , and in this case, rendering is further performed starting from pixel data at the left end of the image data  602 . That is, when coming to the right end of the image data before coming to the right end of the rendering range, the rendering is performed starting from the left end of the image data whereas when coming to a lower end of the image data before coming to a lower end of the rendering range, the rendering is performed starting from an upper end of the image data.
 
     Note that surpluses Mod(X) and Mod(Y) of all coordinates included in the rendering range  710  may be calculated, and in each of the coordinates, pixel data obtained by shifting pixel data at the upper left of the image data  602  rightward by the surplus Mod(X) and downward by the surplus Mod(Y) may be displayed. 
     Results of the rendering by the above operations are shown in  FIG. 22(   b ). Here, since a surplus of the X coordinate is “1”, a surplus of the Y coordinate is “0”, and the size of the rendering range  710  is equal to the size of the image data  602 , the image data  602  is displayed in the rendering range  710  in a mirror-reversed state. 
       FIG. 23  includes diagrams illustrating content of another data stored in the rendering result region  122  included in the state display device according to Embodiment 5 of the present invention. Here, a screen image  305  displayed in the liquid crystal screen  125  is shown instead of the rendering data for sake of a visual description. 
     As shown in  FIG. 23 , rendering requests  901  to  905  are stored in the rendering request region  121 . 
     The rendering request  901  has a data configuration similar to those of the rendering requests  801  and  802  shown in  FIGS. 21 and 22 , respectively. However, in  FIG. 23 , only a rendering-range upper-left coordinate  901   c , a rendering-range lower-right coordinate  901   d , and a rendering image address  901   f  are shown. The rendering requests  902  to  905  are similarly configured. 
     The rendering request  902  includes a rendering-range upper-left coordinate  902   c , a rendering-range lower-right coordinate  902   d , and a rendering image address  902   f.    
     The rendering request  903  includes rendering-range upper-left coordinate  903   c , a rendering-range lower-right coordinate  903   d , and a rendering image address  903   f.    
     The rendering request  904  includes rendering-range upper-left coordinate  904   c , a rendering-range lower-right coordinate  904   d , and a rendering image address  904   f.    
     The rendering request  905  includes rendering-range upper-left coordinate  905   c , a rendering-range lower-right coordinate  905   d , and a rendering image address  905   f.    
     Referring to  FIG. 23 , a procedure of rendering of the image data using a surplus performed in response to a plurality of rendering requests will be described in step (1) to step (5) hereinafter. Note that the rendering process performed in response to a plurality of rendering requests is the same as the operations described with reference to  FIGS. 2 and 14  of Embodiment 1, and therefore, only operations of the rendering process performed in response to each of the rendering request will be described. 
     (1) The rendering processing means  104  calculates a surplus Mod(X) by dividing an X coordinate at an upper-left coordinate of a rendering range  911  represented by the rendering-range upper-left coordinate  901   c  by a width of image data  603  and a surplus Mod(Y) by dividing a Y coordinate at the upper-left coordinate of the rendering range  911  represented by the rendering-range upper-left coordinate  901   c  by a height of the image data  603 . Here, since the X coordinate at the upper-left coordinate of the rendering range  911  is “0” and the Y coordinate is “0”, the surpluses obtained by dividing the coordinate by a value “8” of the width of the image data  603  is represented as follows: Mod(X)=0 and Mod(Y)=0. Then, the rendering processing means  104  displays, at the upper left coordinate of the rendering range  911 , pixel data at a position shifted rightward from pixel data at the upper left of the image data  603  by the surplus Mod(X)=0 and shifted downward from the pixel data at the upper left of the image data  603  by the surplus Mod(Y)=0 first, and subsequently, renders data until coming to a lower-right coordinate of the rendering range  911 .
 
(2) The rendering processing means  104  calculates a surplus Mod(X) by dividing an X coordinate at an upper-left coordinate of a rendering range  912  represented by the rendering-range upper-left coordinate  902   c  by the width of image data  603  and a surplus Mod(Y) by dividing a Y coordinate at the upper-left coordinate of the rendering range  912  represented by the rendering-range upper-left coordinate  902   c  by the height of the image data  603 . Here, since the X coordinate at the upper-left coordinate of the rendering range  912  is “8” and the Y coordinate is “0”, the surpluses obtained by dividing the coordinate by the value “8” of the width of the image data  603  is represented as follows: Mod(X)=0 and Mod(Y)=0. Then, the rendering processing means  104  displays, at the upper left coordinate of the rendering range  912 , pixel data at a position shifted rightward from pixel data at the upper left of the image data  603  by the surplus Mod(X)=0 and shifted downward from the pixel data at the upper left of the image data  603  by the surplus Mod(Y)=0 first, and subsequently, renders information until coming to a lower right coordinate of the rendering range  912 .
 
(3) The rendering processing means  104  calculates a surplus Mod(X) by dividing an X coordinate at an upper-left coordinate of a rendering range  913  represented by the rendering-range upper-left coordinate  903   c  by the width of image data  603  and a surplus Mod(Y) by dividing a Y coordinate at the upper-left coordinate of the rendering range  913  represented by the rendering-range upper-left coordinate  903   c  by the height of the image data  603 . Here, since the X coordinate at the upper-left coordinate of the rendering range  913  is “12” and the Y coordinate is “0”, the surpluses obtained by dividing the coordinate by the value “8” of the width of the image data  603  is represented as follows: Mod(X)=4 and Mod(Y)=0. Then, the rendering processing means  104  displays, at the upper left coordinate of the rendering range  913 , pixel data at a position shifted rightward from pixel data at the upper left of the image data  603  by the surplus Mod(X)=4 and shifted downward from the pixel data at the upper left of the image data  603  by the surplus Mod(Y)=0 first, and subsequently, renders information until coming to a lower right coordinate of the rendering range  913 .
 
(4) The rendering processing means  104  calculates a surplus Mod(X) by obtained dividing an X coordinate at the upper-left coordinate of a rendering range  914  represented by the rendering-range upper-left coordinate  904   c  of the rendering request  904  by the width of image data  603  and a surplus Mod(Y) obtained by dividing a Y coordinate at the upper-left coordinate of the rendering range  914  represented by the rendering-range upper-left coordinate  904   c  by the height of the image data  603 . Here, since the X coordinate of the upper-left coordinate in the rendering range  914  is “16” and the Y coordinate is “4”, the surpluses obtained by dividing the coordinate by the value “8” of the width of the image data  603  is represented as follows: Mod(X)=0 and Mod(Y)=4. Then, the rendering processing means  104  displays, from the upper left coordinates of the rendering range  914 , pixel data at a position shifted rightward from pixel data at the upper left of the image data  603  by the surplus Mod(X)=0 and shifted downward by the surplus Mod(Y)=4, and renders until coming to a lower right coordinates of the rendering range  914 .
 
(5) The rendering processing means  104  calculates a surplus Mod(X) by dividing an X coordinate at an upper-left coordinate of a rendering range  915  represented by the rendering-range upper-left coordinate  905   c  by the width of image data  603  and a surplus Mod(Y) by dividing a Y coordinate at the upper-left coordinate of the rendering range  915  represented by the rendering-range upper-left coordinate  905   c  by the height of the image data  603 . Here, since the X coordinate at the upper-left coordinate of the rendering range  915  is “16” and the Y coordinate is “0”, the surpluses obtained by dividing the coordinate by the value “8” of the width of the image data  603  is represented as follows: Mod(X)=0 and Mod(Y)=4. Then, the rendering processing means  104  displays, at the upper left coordinate of the rendering range  915 , pixel data at a position shifted rightward from pixel data at the upper left of the image data  603  by the surplus Mod(X)=0 and shifted downward from the pixel data at the upper left of the image data  603  by the surplus Mod(Y)=4 first, and subsequently, renders information until coming to a lower right coordinate of the rendering range  915 .
 
     As described above, since the rendering processing means  104  repeatedly renders image data while incrementing writing destination addresses in an ascending order in accordance with a rendering repeat condition, the rendering processing means  104  can operate independently from the central processing means  101  while the repetitive rendering is performed. Accordingly, a load applied to the central processing means  101  can be reduced. Furthermore, the number of rendering requests can be reduced which is preferable in terms of save of a storage region. 
     Furthermore, by performing the rendering process starting from an upper portion of image data obtained by shifting image data by surpluses obtained by dividing coordinate values at an upper-left coordinate of a rendering range by a width and a height of the image data, portions of the image data can be extracted and displayed and various rendering processes can be performed. Also in this case, when compared with a case where a line rendering process is performed, the number of rendering calculations can be reduced, and accordingly, efficiency of the rendering process can be improved. 
     Embodiment 6 
       FIG. 24  is a block diagram illustrating a function of a state display device according to Embodiment 6. 
     The state display device of Embodiment 6 has a configuration the same as that described in Embodiment 1, and additionally includes a line rendering function register  112   b , a square frame rendering function register  113   b , a solid square rendering function register  114   b , and an image rendering function register  115   b . These registers are collectively referred to as “function registers”. 
     Furthermore, storage means  118  does not include a rendering request region  121 . 
     Other configurations are the same as those of Embodiment 1 described above, and only main portions are shown in  FIG. 24 . 
     In Embodiment 1 described above, the central processing means  101  individually writes rendering requests to the rendering request region  121 . 
     However, in Embodiment 6, central processing means  101  writes rendering requests regarding various rendering functions to the line rendering function register  112   b , the square frame rendering function register  113   b , the solid square rendering function register  114   b , and the image rendering function register  115   b.    
     When a rendering request corresponding to one of the function registers is written, a corresponding one of the rendering functions performs rendering in accordance with the rendering request. 
     According to this method, the rendering request is not required to be issued through the storage means  118 , and accordingly, an I/O process load regarding the rendering process can be reduced. 
     The state display devices according to Embodiment 1 to Embodiment 6 are applicable to a display device which displays a state of an air conditioner, and in addition, are applicable to display devices of various electric devices which display a power-activation state, a power shut-down method, and a device state by an image, a diagram, text, or the like. 
     REFERENCE SIGNS LIST 
       1  state display device,  100  controller,  101  central processing means,  102  main register,  103  command address register,  104  rendering processing means,  105  rendering register,  106  instruction address register,  107  start/end instruction register,  108  interruption factor register,  109  rendering address register,  110  rendering processing unit,  111  interpreter,  112  line rendering circuit,  113  square frame rendering circuit,  114  solid square rendering circuit,  115  image rendering circuit,  116  rendering range limitation storage unit,  116   a  request limitation,  116   b  rendering limitation,  117  rendering availability state storage unit,  118  storage means,  119  display program region,  120  device control program region,  121  rendering request region,  121   a  rendering request region,  121   b  rendering request region,  122  rendering result region,  123  liquid crystal display unit,  124  display address register,  125  liquid crystal screen,  126  liquid crystal controller,  131  to  135  arrow mark,  200  rendering request group,  201  to  206  rendering request,  203 A rendering request,  300  rendering request group,  300 A rendering request group,  301  to  304  rendering request,  301   a  instruction type,  301   b  rendering function type,  301   c  upper-left coordinate,  301   d  lower-right coordinate,  301   e  line thickness,  301   f  rendering color,  303 A rendering request,  305  screen image,  401  square frame,  402  solid square,  403  line,  404  rectangular region,  501  and  506  rendering request group,  502  to  505  rendering request,  507  to  509  rendering request,  601  rendering request,  601   a  rendering starting instruction,  601   c  rendering range upper-left coordinate,  601   d  rendering range lower-right coordinate,  601   e  rendering repeat condition,  601   f  rendering image address,  602  image data,  603  image data,  610  rendering range,  701  rendering range,  710  rendering range,  801  rendering request,  801   a  rendering start instruction,  801   c  rendering-range upper-left coordinate,  801   d  rendering-range lower-right coordinate,  801   e  rendering repeat condition,  801   f  rendering image address,  802  rendering request,  802   a  rendering start instruction,  802   c  rendering-range upper-left coordinate,  802   d  rendering-range lower-right coordinate,  802   e  rendering repeat condition,  802   f  rendering image address,  901  rendering request,  901   c  rendering-range upper-left coordinate,  901   d  rendering-range lower-right coordinate,  901   f  rendering image address,  902  rendering request,  902   c  rendering-range upper-left coordinate,  902   d  rendering-range lower-right coordinate,  902   f  rendering image address,  903  rendering request,  903   c  rendering-range upper-left coordinate,  903   d  rendering-range lower-right coordinate,  903   f  rendering image address,  904  rendering request,  904   c  rendering-range upper-left coordinate,  904   d  rendering-range lower-right coordinate,  904   f  rendering image address,  905  rendering request,  905   c  rendering-range upper-left coordinate,  905   d  rendering-range lower-right coordinate,  905   f  rendering image address,  911  rendering range,  912  rendering range,  913  rendering range,  914  rendering range,  915  rendering range,  951  image height,  952  image width,  955  rendering width,  956  rendering height,  961  rectangular region,  971  arrow mark,  981  rectangular region,  991  arrow mark,  1101  rendering range,  112   b  line rendering function register,  113   b  square frame rendering function register,  114   b  solid square rendering function register,  115   b  image rendering function register