Abstract:
An electronic preview guide (EPG) display apparatus for use in a broadcast receiver, for selectively presenting viewers a broadcast schedule. The broadcast schedule is presented in a grid pattern with one or more rows each showing a TV channel number or a TV station name and an array of slots containing preview guide messages of its broadcast schedule extending in the direction of time axis, using a preview guide data broadcast by each broadcast station and a present time. The apparatus includes a display controller for making an EPG slot at the present time or a viewer-designated time wider than other slots within the EPG screen.

Description:
FIELD OF THE INVENTION 
     The present invention generally relates to an electronic preview guide display system for use in digital broadcast receivers, for providing viewers broadcast program information. 
     BACKGROUND OF THE INVENTION 
     Recent development of the digital technologies in the broadcast industry has permitted digital satellite broadcast to come into service in many countries. One feature of the digital broadcast is directed to increasing broadcast channels, i.e., multi-channel broadcasting. According to the capability of multi-channel broadcasting, more and more the specific channels, for instance channels serving movie film programs or news for all day, are increasing. Thus it becomes convenient for viewers to enjoy a wide variety of programs. 
     However, the increase of channels makes it harder for viewers to easily find out about what programs are showing or will be showed in the plurality of channels. 
     Digital satellite broadcasts in Japan and the United States, or CATVs serving multi-channels in analog systems though, in the United States, have an accompanying preview channel for an EPG (Electric Preview Guide) data service to give viewers information regarding broadcast programs. 
     The EPG data is displayed in a grid pattern or a two-dimensional matrix with an axis listing channel numbers of TV station names (hereinafter referred to as a channel-list axis) and a time-axis listing program titles to be broadcast. However, the time-axis of the EPG screen is limited to the information of programs two hours ahead from the present time. The viewer cannot tell what programs will be broadcast thereafter. Further, along with the capability of the multi-channel broadcast of the program information, the number of TV channels to be listed should be increased. However due to the limitation of the display size, the number of the capable channels available on one screen would be in a range of 6 to 8. So that, a viewer has to many times operate scroll to search over or reach a program information of his/her interest. 
     As described above, the conventional electronic preview guide display system had a problem that it only shows program information within two or three hours in the direction of the time-axis, and about six to eight channels in the direction of the channel-list axis, so that it imposed a considerable inconvenience on viewers. 
     SUMMARY OF THE INVENTION 
     In consideration of the above problem, the present invention has been made, and an object of the present invention is to provide an electronic preview guide display system capable of increasing an amount of information given in at least one of the directions of the time-axis direction and the channel-list axis of an EPG screen, while in a pattern easily readable for viewers. 
     In order to achieve the above object, an electronic preview guide display apparatus for use in a broadcast receiver, selectively presents viewers its broadcast schedule, in a grid pattern with one or more rows each showing a TV channel number or a TV station name and an array of slots containing preview guide messages of its broadcast schedule extending in the direction of time axis, by using a preview guide data broadcast by each broadcast station and a present time. The apparatus is provided with a display controller for making EPG slot at the present time or a viewer-designated time wider than other slots within the EPG screen. 
     Accordingly, viewers can easily view information of programs at a time, of a TV channel number or a broadcast station that they wish. In addition, the electronic preview display apparatus can display information of programs by compressing the size of other slots. 
     In the case, by using the non-linear logarithm characteristics in the change of the time-axis, or the change of the line width in the direction of the channel-list axis, viewers can view the display in a natural visual form. So that, viewers can perform a channel selection in agreeable to the occasion. 
     Additional objects and advantages of the present invention will be apparent to persons skilled in the art from a study of the following description and the accompanying drawings, which are hereby incorporated in and constitute a part of this specification. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A more complete appreciation of the present invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein: 
     FIG. 1 is a slot diagram showing a construction of the TV receiver to which the present invention is applied; 
     FIG. 2 is a slot diagram showing the construction of the TV receiver having a double-window display function to which the present invention is applied; 
     FIG. 3 a  is a diagram showing a EPG screen according to a first embodiment; 
     FIG. 3 b  is a diagram showing three patterns of non-linear change characteristics applicable to the EPG screen of FIG. 3 a;    
     FIG. 4 is a flowchart showing the steps of the EPG screen processing according to the first embodiment; 
     FIG. 5 is a diagram showing another example of the EPG screen applied to a double-window display according to the first embodiment; 
     FIG. 6 a  is a diagram showing the EPG screen according to a second embodiment; 
     FIG. 6 b  is a diagram showing three patterns of non-linear change characteristics applicable to the EPG screen of FIG. 6 a;    
     FIG. 7 is a flowchart showing the steps of the EPG screen processing according to the second embodiment; 
     FIG. 8 is a diagram showing another example of the EPG screen presented by a semi-transparent display technique according to the second embodiment; 
     FIG. 9 a  is a diagram showing the EPG screen according to a third embodiment; 
     FIG. 9 b  is a diagram showing the relation between the non-linear logarithmic curve and the size of the EPG slots applied to the EPG screen of FIG. 9 a;    
     FIG. 10 is a flowchart showing the steps of the EPG screen processing according to the third embodiment; 
     FIG. 11 is a diagram showing another example of the EPG screen applied to a double-window display according to the third embodiment; 
     FIG. 12 a  is a diagram showing the EPG screen according to a fourth embodiment; 
     FIG. 12 b  is a diagram showing the relation between the non-linear logarithmic curve and the size of the EPG slots applied to the EPG screen of FIG. 12 a;    
     FIG. 13 is a flowchart showing the steps of the EPG screen processing according to the fourth embodiment; 
     FIG. 14 is a diagram showing another example of the EPG screen presented by a semi-transparent display technique according to the fourth embodiment; 
     FIG. 15 a  is a diagram showing the EPG screen according to a fifth embodiment; 
     FIG. 15 b  is a diagram showing three patterns of non-linear change characteristics applicable to the EPG screen of FIG. 15 a.    
     FIG. 16 is a flowchart showing the steps of the EPG screen processing according to the fifth embodiment; 
     FIG. 17 is a diagram showing another example of the EPG screen applied to a double-window display according to the fifth embodiment; 
     FIG. 18 is a diagram showing the EPG screen of a sixth embodiment and the 1/f-fluctuation characteristic; 
     FIG. 19 is a flowchart showing the steps of the EPG screen processing of the sixth embodiment; 
     FIG. 20 is a diagram showing another example of the EPG screen presented by a semi-transparent display technique according to the sixth embodiment; 
     FIG. 21 a  is a diagram showing the EPG screen according to a seventh embodiment; 
     FIG. 21 b  is a diagram showing the relation between the non-linear logarithmic curve and the size of the EPG slots applied to the EPC screen of FIG. 12 a;    
     FIG. 22 is a flowchart showing the steps of the EPG screen processing according to the seventh embodiment; 
     FIG. 23 is a diagram showing another example of the EPG screen applied to a double-window display according to the seventh embodiment; 
     FIG. 24 a  is a diagram showing the EPG screen according to the eighth embodiment; 
     FIG. 24 b  is a diagram showing the relation between the non-linear logarithmic curve and the size of the EPG slots applied to the EPG screen of FIG. 24 a;    
     FIG. 25 is a flowchart showing the steps of the EPG screen processing according to an eighth embodiment; 
     FIG. 26 is a diagram showing another example of the EPG screen applied to a double-window display according to the eighth embodiment; and 
     FIG. 27 is a diagram showing the EPG screen of its time-axis and channel-list axis processed complexly in the non-linear change pattern. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention will be described in detail with reference to the FIGS. 1 through 27. 
     FIG. 1 shows a general TV receiver having a EPG screen system, according to a first embodiment of the present invention. In FIG. 1, a TV signal received by an antenna  11  is input to a tuner  12 . The tuner  12  selects a channel that the viewer wishes to see. Here the channel selection is carried out through operations on a remote controller by the viewer. An output signal from the tuner  12  is applied to a demultiplexer (DMUX)  13 . The demultiplexer  13  demultiplexes the signal into a video stream, an audio stream, and a data stream. The video data is applied to a video decoder  14 , while the audio data is applied to an audio decoder  15 . The decoded video signal is processed in an image processor  16 , and then applied to a back-end processor  17 . An output from the back-end processor  17  is supplied to a display  18  and displayed thereon. An output from the audio decoder  15  is converted to an analog signal using a digital/analog converter (D/A)  19 , and then supplied to a speaker  20 . 
     In the case of displaying the EPG screen, the tuner  12  is connected to a tuner controller  21 . The tuner controller  21  controls the tuner  12  to select channels in a round-robin fashion at prescribed periods. The tuner  12  takes a TV signal of each channel under the control of the tuner controller  21  and then supplies the TV signal to the demultiplexer  13 . The demultiplexer  13  demultiplexes the TV signal to a video stream and a data stream. The video stream is then forwarded to a video decater  14 , while the data stream is forwarded to a CPU  22 . 
     When the video data is processed in an MPEG format, the video decoder  14  decodes only I-frames for presenting an opening stage rough. The I-frame video data are then supplied to an image processor  16 . The image processor  16  processes the input video data so as to present a predetermined size of EPG screen. A back-end processor  17  receives the output of the image processor  16  and then displays the video data on a display  18 . 
     When a viewer instructs the receiver to display the EPG screen through a remote controller  23 , an infrared light receiver  24  coupled to the remote controller  23  transfers the instruction signal to a CPU  22 . Then the CPU  22  extracts EPG data from the data stream and stores them in a main memory  25 . The EPG data are then supplied to a video decoder  14  for developing the EPG screen on the display  18 . In receipt of the EPG data, the video decoder  14  changes from a normal program display mode to the EPG screen display mode, and then displays the EPG screen on the display  18  through the image processor  16  and the back-end processor  17 . 
     FIG. 2 shows a slot diagram of a TV receiver having a double-window function and an EPG screen system according to the present invention. Here, in FIG. 2, same elements as those shown in FIG. 1 are assigned with the same reference numerals or symbols, and only the different parts will be explained hereinafter. 
     In FIG. 2, a TV signal received by an antenna  11  is also input to a tuner  26 . The tuner  26  performs a back-end processing in place of the tuner  12 . The tuner  26  is coupled to a tuner controller  21  for an EPG operation. The tuner controller  21  controls the tuner  26  to select several channels in each specific period. The tuner  26 , according to the control, takes the TV signals of each channel and inputs it to the demultiplexer (DMUX)  27 . The demultiplexer  27  demultiplexes its input signal into a video stream and a data stream. The video stream is forwarded to a video decoder  28 , while the data stream is forwarded to a CPU  22 . 
     The video decoder  28  decodes only I-frame contained in an MPEG data to display a preview screen of the EPG data. The decoded image data are supplied to an image processor  29 . The image processor  29  stores the input image data into its internal memory, after compressing the image data in relation to its horizontal and vertical scales. 
     When a viewer instructs an EPG screen operation for the receiving through a remote controller  23 , the instruction is passed to the CPU  22  via an infrared light receiver  24 . The CPU  22  issues a command for instructing the back-end processor  17  to divide the screen, and at the same time issues a command for instructing the image processor  29  to compress the horizontal size of the image size into a half. In receipt of the commands, the back-end processor  17  divides the screen into two sub-screens, assigning the left sub-screen to display usual programs, and the right sub-screen to display an EPG screen. At the same time, the image processor  16  compresses the horizontal size of the image data output from the decoder  14  into a half. 
     Then, the CPU  22  extracts the EPG data from the data stream and stores them in a main memory  25 . The EPG data are then developed to an EPG screened data and pass the screen data to the video decoder  28 . In receipt of the screen data, the video decoder  28  changes the operation of the receiver from the usual program display mode formerly displayed to the EPG screen mode. Then the EPG screen is displayed in the right half of the display  18  through the image processor  16  and the back-end processor  17 . 
     Referring now to FIGS. 3 to  5 , the manner to display the EPG screen according to the first embodiment of the present invention will be explained in relation to the above construction. 
     According to the present inventions, it is characterized by that the EPG screen is presented by using a non-linear logarithm change characteristics. So, in this invention the EPG screen has slots changed their size in the direction of the time-axis is accordance with the non-linear logarithm characteristics. 
     FIG. 3 a  shows an example of the EPG screen for one TV station which serves two channels. In the EPG screen two lines of channel information are aligned in the vertical direction. Each line has a plurality of EPG slots in the order of time running in the horizontal direction (time axis direction). The example of the EPG screen is characterized by that size of the EPG slots change gradually in a non-linear manner in the direction of the time axis. FIG. 3 b  shows three patterns of curves A; 1/Log m (NXT), B; 1/(NXT), and C; 1/exp (NXT), as the examples of the non-linear change characteristic. In FIG. 3 a  the EPG screen is presented based on the curve A. Here, it is a matter of course that the EPG screen can be presented based on either one of the other curves B or C. 
     In FIG. 3A, a hair-line cursor is displayed on the EPG screen. By designating the right of the left in relation to the cursor, a viewer can scroll the EPG screen to the designated direction. While increasing the distance from the hair-line cursor in the time axis direction, the size of the slots decreases in accordance with the curve A, as shown in FIG. 3 b.  Accordingly, a large amount of EPG slots can be packed in the limited space of the EPG screen, in comparison to conventional EPG screens having a linear scale of time axis. In this case, since the time axis had the non-linear logarithmic change, the EPC screen is presented in a natural visual form for viewers, so that they can perform a channel selection. 
     Here there arises a problem that the amount of characters available in each EPG slot decreases as the slot size becomes smaller. To solve the problem, as the EPG slots become smaller, sub-titles are eliminated from the reduced-size slots. As the slots further reduced in-size, main titles, for instance, are recapped. 
     FIG. 4 shows the flow of operation steps for displaying the non-linear patterned EPG screen. In FIG. 4, the EPG data from the TV station and the present time data are updated and stored in the step S 1 . When the viewer selects the EPG screen (step S 2 ), a menu screen listing display patterns is presented (step S 3 ). The viewer then selects his/her favorite display pattern (step S 4 ). A non-linear processing routine corresponding to the selected display pattern is prepared, and a time defining a fiducial (or the present time, at the beginning) is read out from the main memory  25  (step S 5 ). A shown in FIG. 3 a,  the fiducial time is pointed by a hair-line cursor (step S 6 ). Here the initial value of the fiducial time is set to the present time. 
     On the other hand, a start time Ts of each program is extracted from the EPG data (step S 7 ). In relation to the start time Ts, the time different TD from the start time Ts to the present time T 1  is obtained by the following equation 1. 
     
       
           Td=Ts−T   1    (1)  
       
     
     Next, the size of the EPG slot DS is sought (step S 8 ). This seek operation can be carried out to present the EPG screen on either the right or the left screen not but on a whole screen as shown in FIG. 3 a,  for example in a TV receiver with a high performance function like the double-window system as shown in FIG.  2 . FIG. 5 shows an example of such a double-window display. Here, in FIG. 6, slots A and E are allotted for channel numbers (or TV station names). 
     When a viewer selects the non-linear logarithmic change characteristics for the EPG screen after the time difference Td and the size of the EPG slot DS have been determined, the size of a given EPG slot is determined by the following equations (step S 9 ). Here, the base m of the logarithmic function Log is set to 10, while its coefficient N is also set to 10. 
     
       
           Px=DS/Max  (Pixel Number)×(1/Log 10 ( N×Td ))   (2)  
       
     
     Herein “Pixel Number” represents the number of effective display pixels in a line. For instance, in the case that the EPG screen is displayed on a whole screen, the slot position for a program starting after one hour is determined as follows. 
     
       
           Px= 1×(1Log 10 10×1)=1  
       
     
     Further the slot position for a program starting after two hours is determined as follows. 
     
       
           Px= 1×(1/Log 10 10×2)=0.77  
       
     
     Next, the actual size of the EPG slot in the time-axis direction is determined based on the basic size Psz (step S 10 ). For instance, for the case of 200 Pixel, the size Pu of the EPG slot in the time-axis direction for a program starting after two hours is given by the following equation 3. 
     
       
           Pu=Px×Psz= 0.77×200=154   (3)  
       
     
     Next, based on the size of the EPG slot determined by the equation 3, it is checked how many characters can be placed in the slot. Then based on the result available characters are displayed in the EPG slot. Referring back to FIG. 4, the flow of the above-described operation will be described. 
     Further, a character string such as a program title is extracted from the EPG data (step S 11 ). A number of characters Pc in the program title is then counted (step S 12 ). Further, a number of characters Pg in additional information such as a sub-title counted (step S 13 ). At this time, for the number of characters Pc obtained in the step S 12 , the number of displayable characters is checked from the size Pu determined by the equation 3. 
     First in this operation, in the case that the character size is fixed, the pixel size Cs of the character in the X direction (i.e., the time-axis direction of the EPG screen) is checked (step S 14 ). When a gap (blank Gp is required between characters, the size Cp of each character including the gap Gp in the X direction will be determined by the following equation 4 (step S 14 ). 
     
       
           Cp=Cs+Gp    (4)  
       
     
     Then the number of displayable characters CC is determined by dividing the slot size Pu determined by the equation 3 by the character size Cp determined by the equation 4, as shown by the following equation 5 (step S 15 ) 
     
       
           CC=Pu/Cp    (5)  
       
     
     Then a character string available in the EPG slot is decided steps S 19 , S 20 , and S 21 ) by comparing the number of characters Pc (or Pc+Pg) obtained in the step S 12  with the number of displayable characters CC calculated by the equations 5 (steps S 16 , S 17 , and S 18 ). 
     If “CC&gt;=(Pc+Pg)” is positive (step S 16 ), then a whole character string display will be carried out (step S 19 ). 
     If “CC&lt;(Pc+Pg)&amp;&amp;CC&gt;=PC” is positive (step  17 ), only a program title display will be carried out (step S 20 ). 
     If “CC&lt;PC” is positive (step S 18 ), no character display will be carried out (step S 21 ). 
     Then, it is determined whether the character display processing has been carried out for EPG slots. If there remains any EPG slot unfinished the character presentation, the operation repeats the routine on and after the step S 7 (step S 22 ). 
     As is evident from the flow of steps as described above, the present embodiment can provide an EPG screen presenting a lot of program information for a long time due to that the size of the EPG slots varies in the time-axis direction. Especially, since the size of the EPG slots varies with the non-linear logarithmic function, viewers can view the screen in agreeable to the occasion. 
     Now a second embodiment of the present invention will be explained hereinafter. This second embodiment is different from the first embodiment by that the size of the characters are variable. 
     FIGS. 6 a  and  6   b  show an example in which the size of the EPG slots is compressed in a non-linear manner in the time-axis direction, and that the character size varies in accordance with the size of the EPG slot. FIG. 6 a  shows the EPG screen according to this second embodiment and FIG. 6 b  shows three patterns of non-linear change characteristics. FIG. 7 shows the flow of operation steps for displaying the non-linear patterned EPG screen according to the second embodiment. 
     In FIG. 7, the EPG data from the TV station and the present time data are updated, and stored in the step S 31 . When the viewer selects the EPG screen (step S 32 ), a menu screen listing display patterns is presented (step S 33 ). The viewer then selects his/her favorite display pattern (step S 34 ). A non-linear processing routine corresponding to the selected display pattern is prepared, and a time defining a fiducial (or present time, at the beginning) is read out from the main memory  25  (step S 35 ). As shown in FIG. 6 a,  the fiducial time is indicated by a hair-line cursor (step S 36 ). Here the initial value of the fiducial time is set to the present time. 
     A start time Ts of each progrma is extracted from the EPG data (step S 37 ). In relation to the start time Ts, the time difference Td from the start time Ts to the present time T 1  is obtained by the following equation 1. 
     
       
           Td=Ts−T   1    (6)  
       
     
     Next, the size of the EPG slot DS is sought (step S 38 ). This seek operation can be carried out to present the EPG screen on either the right on the left screen, for example, in the TV receiver with the double-window display system. FIG. 8 shows an example of that the EPG screen is superimposed on the normal program display screen by using a semi-transparent display. 
     When a viewer selects the non-linear logarithmic change characteristics, i.e., the curve A of FIG. 6 b,  for the EPG slot after the time difference Td and the EPG slot size DS have been determined, the size Px of a given EPG slot is determined by the following equations (step S 39 ). Here the beam m of the logarithmic function Log is set to 10, while its coefficient N is also set to 10. 
     
       
           Ps=DS/Max (Pixel Number)×(1/Log 10 ( N×Td ))   (7)  
       
     
     Herein “Pixel Number” represents the number of effective display pixels in a line. 
     For instance, in the case that the EPG screen is displayed on a whole screen, the slot position for a program starting after one hour is determined as follows. 
     
       
           Px= 1×(1/Log 10 33 1)=1  
       
     
     Further the slot position for a program starting after three hours is determined as follows. 
     
       
           Px= 1×(1/Log 10 10×3)=0.68  
       
     
     Next, the actual size of the program display in the time-axis direction is calculated by using the basic size Psz (step S 40 ). For instance, for the case of 200 Pixel, the size Pu of the EPG slot in the time-axis direction for a program starting after two hours is given by the following equation 8. 
     
       
           Pu=Px=Psz= 0.77×200=154   (8)  
       
     
     Next, based on the size of the EPG slot determined by the equation 8, it is checked how many characters are required to be placed in the slot. Then the size of the characters are changed in accordance with the result of the check and then the characters with the size as changed are displayed in the EPG slot. Referring back to FIG. 7, the flow of the above-described operation will be described. 
     First, a character string such as a program title in the EPG data is read out (step S 41 ). A number of characters Pc in the program title is then counted (step S 42 ). Further, a number of characters Pg in additional information such as a sub-title is counted (step S 43 ). Then, the total number of the characters to be displayed is calculated (step S 44 ). then the sizes of the characters are determined from the total number of characters and the size of the EPG slot determined by the equation 8. 
     In this determination, first the number of character is selected from the large ranking the number of characters Pc in the program title and the number of characters Pg in the sub title. The size of the EPG slot Pu is divided by the selected one of the number of characters by the following equation 9 (step S 45 ). 
     
       
           Fsz=Pu/Max ( Pc|Pc+Pg )   (9)  
       
     
     The result Fsz of the equation 9 is compared with a threshold value Fmin of the minimum character size stored in the main memory  25  (step S 46 ). When the Fsz is greater than the Fmin, characters with the font-size nearest to the Fsz are used for the EPG (step S 47 ). If the Fsz is smaller than the Fmin, first the number of characters Pc in the program title and the number of characters Pg in the sub-title are compared with each other. If the Pc is smaller than the Pg, the value Fsz is again calculated by the following equation 10 (steps S 48 , and S 49 ). 
     
       
           Fsz=Pu/Pc    (10)  
       
     
     Here, the reason that the number of characters Pc in the program title is used for the determination of the Fsz is because the program title is more important for viewers than the additional program information such as the sub-title. Here, again the value Fsz and the Fmin are compared with each other (step S 46 ). If the value Fsz is greater than the Fmin, characters with the font-size nearest to the Fsz are used for the EPG slot (step S 47 ). 
     If the value Fsz is smaller than the Fmin in the step S 46 , the display of character string in the EPG slots is given up and the slots are left in a blank (step S 50 ). 
     Then, it is determined whether the character display processing has been carried out for EPG slots. If there remain any EPG slot unfinished the character presentation, the operation repeats the routine on and after the step S 37  (step (S 51 ). 
     As is evident from the flow of steps as described above, the present embodiment can suppress the reduction of the characters to be displayed in the EPG slots when the size of the slots had been reduced, since although the EPG slots are compressed in only the time-axis direction by the non-linear processing, the size that the characters are reduced is tied to the size of the EPG slots. Accordingly, it can provide viewers a large amount of program information. 
     Now a third embodiment of the present invention will be explained hereinafter. Here, a process for shifting the start position on the EPG screen according to the non-linear processing will be explained. 
     FIGS. 9 a  and  9   b  show an example that the start position of the EPG slots on the EPG screen is compressed in a non-linear manner in the time-axis direction, and that the number of characters available in the EPG slot is variable. Wherein FIG. 9 a  shows the EPG screen according to this third embodiment and FIG. 9 b  shows the relation between the non-linear logarithmic curve and the size of the EPG slots. FIG. 10 shows the flow of operation steps for displaying the non-linear patterned EPG screen according to the third embodiment. FIG. 11 shows an example of such a double-window display to which the operation FIG. 10 is adapted. 
     In FIG. 10, the EPG data from the TV station and the present time data are updated and stored in the step S 61 . When the viewer selects the EPG screen (step S 62 ), a menu screen listing display patterns is presented (step S 63 ). The viewer then selects his/her favorite display pattern (step S 64 ). A non-linear processing routine corresponding to the selected display pattern is prepared, and a time defining a fiducial (or the present time, at the beginning) T 0  is read out from the main memory  25  (step S 65 ). As shown in FIG. 9 a,  the fiducial time is indicated by a hair-line cursor (step S 66 ). Here the initial value of the fiducial time is set to the present time. 
     A start time Ts of each program is extracted from the EPG data (step S 67 ). The start time Ts is then used in the non-linear processing routine (step S 68 ). In the non-linear processing routine, a logarithmic function Log m  it is read out from a memory (the base m of the logarithmic function Log is set to any number, while its coefficient N is also set to any number) (step  69 ). Then a start position St of each of the EPG slot is determined by the following equation 11 (step S 70 ). The operation of the steps S 67  through S 70  is repeated until the start positions St of all EPG slots have been determined (step S 71 ). 
     
       
           St=Lot   m   N ( Ts−T   0 )   (11)  
       
     
     The relation of the start position St determined by the equation 11 and the time has a logarithmic function Log, as shown in FIG. 9 b.    
     Next, based on the start position of the EPG slot determined by the equation 11, the size of the EPG slot is determined and also it is checked how many characters can be picked in the slot. Then, based on the result, necessary characters are displayed in the EPG slot. Referring back to FIG. 10, the flow of the above-described operation will be described. 
     First, the size of the EPG slot Pu is determined from the difference between the start position St 0  of the EPG slot and the start position St 1  of the following EPG slot (step S 72 ). 
     
       
           Pu=St   1 − St   0    (12)  
       
     
     Further, a character string such as a program title is extracted from the EPG data (step S 73 ). A number of characters Pc in the program title is then counted (step S 74 ). Further, a number of characters Pg in additional information such as a sub-title is counted (step S 75 ). First, for the number of characters obtained in the step S 73 , the number of displayable characters is checked from the size determined by the equation 12. First in this operation, in the case that the character size is fixed, the pixel size Cs of the character in the X direction (i.e., the time-axis direction on the EPG screen) is checked (step S 76 ). When a gap (blank) Gp is required between characters, the size Cp of each character including the gap Gp in the X direction will be determined by the following equation 13 (step S 77 ). 
     
       
           Cp=Cs+Gp   (13) 
       
     
     Then the number of displayable characters CC is determined by dividing the slot size Pu determined by the equation 12 by the character size Cp determined by the equation 13, as shown by the following equation 14 (step S 78 ). 
     
       
           CC=Pu/Cp   (14) 
       
     
     Then a character string available in the EPG slot is decided (steps S 79 , S 81 , and S 82 ) by comparing the number of characters Pc (or Pc+Pg) obtained in the step S 77  with the number of displayable characters CC calculated by the equation 14 (steps S 80 , S 82 , and S 84 ). 
     If “CC&gt;=(Pc+Pg)” is positive (step S 79 ), then a whole character string display will be carried out (step S 80 ). 
     If “CC&lt;(Pc+Pg) &amp;&amp; CC&gt;=PC” is positive (step S 81 ), only a program title display will be carried out (step S 82 ). 
     If “CC&lt;PC” is positive (step S 83 ), no character display will be carried out (step S 84 ). 
     Then, it is determined whether the character display processing has been carried out for EPG slots. If there remains any EPG slot unfinished the character presentation, the operation repeats the routine on and after the step S 67  (step S 85 ). 
     As it is obvious from the processing flow described above, according to the present embodiment, since the start position of the EPG slot is compressed in the time-axis direction by the non-linear processing, and the number of characters available in the EPG slot is made variable, it can provide viewers an EPG screen with the easily readable pattern. 
     Next, the fourth embodiment according to the present invention will be explained hereinafter. Here, the case that the start point of the EPG slot is changed by the non-linear processing and the size of the characters can be varied in accordance with the size of the EPG slot will be explained. 
     FIGS. 12 a  and  12   b  show an example that the start position of the EPG slots on the EPG screen is compressed in a non-linear manner in the time-axis direction, and that the size of characters is variable. Wherein FIG. 12 a  shows the EPG screen according to this fourth embodiment and FIG. 12 b  shows the relation between the non-linear logarithmic curve and the size of the EPG slots. FIG. 13 shows the flow of operation steps for displaying the non-linear patterned EPG screen according to the fourth embodiment. FIG. 14 shows an example in which the EPG screen is superimposed on the normal program display screen on a wide-aspect display by using a semi-transparent display. 
     In FIG. 13, the EPG data from the TV station and the present time data are updated and stored in the step S 91 . When the viewer selects the EPG screen (step S 92 ), a menu screen listing display patterns is presented (step S 93 ). The viewer then selects his/her favorite display pattern (step S 94 ). A non-linear processing routine corresponding to the selected display pattern is prepared, and a time defining a fiducial (or the present time, at the beginning) T 0  is read out from the main memory  25  (step S 95 ). As shown in FIG. 12 a , the fiducial time is indicated by a hair-line cursor (step S 96 ). Here the initial value of the fiducial time is set to the present time. 
     A start time Ts of each program is extracted from the EPG data (step S 97 ). The start time Ts is then used in the non-linear processing routine (step S 98 ). In the non-linear processing routine, a logarithmic function Log m  T is read out from a memory (the base m of the logarithmic function Log is set to any number, while its coefficient N is also set to any number) (step S 99 ). A start position St of each of the EPG slot is determined by the following equation 15 (step S 100 ). The operation of the steps S 97  through S 100  is repeated until the start positions St of all EPG slots have been determined (step S 101 ). 
     
       
           St =Log m    N ( Ts−T   0 )  (15) 
       
     
     The relation of the start position St determined by the equation 15 and the time has a logarithmic function Log, as shown in FIG. 12 b.    
     Next, based on the start position of the EPG slot determined by the equation 15, the total number of the characters to be displayed and the size of characters to be included in the EPG slot are determined. Then based on the result, available characters are displayed in the EPG slot. Referring back to FIG. 13, the flow of the above-described operation will be described. 
     First, the size of the EPG slot Pu is determined from the difference between the start position St 0  of the EPG slot and the start position St 1  of the following EPG slot (step S 102 ). 
     
       
           Pu=St   1 − St   0   (16) 
       
     
     Then, a character string such as a program title is extracted from the EPG data (step S 103 ). A number of characters Pc in the program title is then counted (step S 104 ). Further, a number of characters Pg in additional information such as a sub-title is counted (step S 105 ). Then, the total number of the characters to be displayed is calculated (step S 106 ). Then the sizes of the characters are determined from the total number of the characters and the size of the EPG slot determined by the equation 16. 
     In this determination, first the number of characters is selected from the larger ranking the number of characters Pc in the program title and the number of characters Pg in the sub-title. The size of the EPG slot Pu is divided by the selected one of the number of characters by the following equation 17 (step S 107 ). 
     
       
           Fsz=Pu/ Max( Pc|Pc+Pg )  (17) 
       
     
     The result Fsz of the equation 17 is compared with a threshold value Fmin of the minimum character size stored in the main memory  25  (step S 108 ). When the Fsz is greater then the Fmin, characters with the font-size nearest to the Fsz are used for the EPG (step S 109 ). If the Fsz is smaller than the Fmin, first the number of characters Pc in the program title and the number of characters Pg in the sub-title are compared with each other. If the Pc is smaller than the Pg, the value Fsz is again calculated by the following equation 18 (steps S 110 , S 111 ). 
     
       
           Fsz=Pu/Pc   (18) 
       
     
     Here, the reason that the number of characters Pc in the program title is used for the determination of the Fsz is because of that the program title is more important for viewers than the additional program information such as the sub-title. Here, again the value Fsz and the Fmin are compared with each other (step S 112 ). If the value Fsz is greater than the Fmin, characters with the font-size nearest to the Fsz are used for the EPG slot (step S 113 ). 
     If the value Fsz is yet smaller than the Fmin in the step S 112 , the display of character string in the EPG slots is given up and the slots are left in a blank (step S 114 ). 
     Then, it is determined whether the character display processing has been carried out for EPG slots. If there remains any EPG slot unfinished the character presentation, the operation repeats the routine on and after the step S 97  (step S 115 ). 
     As is evident from the flow of steps as described above, the present embodiment can provide a lot of program information when the size of the slots had been reduced, since although the start positions of the EPG slots are compressed in only the time-axis direction by the non-linear processing the size of the characters is made variable for inserting an entire character string into the EPG slots. 
     Now a fifth embodiment of the present invention for processing the line of the EPG slots in the direction of the channel-list axis will be explained hereinafter. Here the fifth embodiment has a configuration similar to the first embodiment, but different by that the size of the characters are variable. 
     FIGS. 15 a  and  15   b  show an example in which the size of the EPG slots is compressed in a non-linear manner in the channel-lists axis direction, and that the number of characters varies in accordance with the vertical size of the EPG slot. Wherein FIG. 15 a  shows the EPG screen according to this fifth embodiment and FIG. 15 b  shows three patterns of non-linear change characteristics. FIG. 16 shows the steps of the non-linear processing. FIG. 16 shows the flows of operation steps for displaying the non-linear patterned EPG screen according to the fifth embodiment. FIG. 17 shows the case applying the same processing shown in FIG. 16 to the double-window display. FIG. 17 shows an example of such a double-window display to which the operation of FIG. 16 is adapted. 
     In FIG. 16, the EPG data from the TV station and the present time data are updated and stored in the step S 121 . When the viewer selects the EPG screen (step S 122 ), a menu screen listing display patterns is presented (step S 123 ). The viewer then selects his/her favorite display pattern (step S 124 ). A non-linear processing routine corresponding to the selected display pattern is prepared. Further at a beginning of the operation, a channel slot corresponding to the channel that is currently received by the viewer is defined (step S 125 ). Then the channel slot of the channel number or the TV station name is highlighted as shown in FIG. 15 a  or  17  (step S 126 ). 
     On the other hand, a channel number data of an available channel is extracted from the EPG data (step S 127 ). In relation to the channel number Cn, an absolute value of the difference Cd from the channel number Cn to the channel number Cp of currently received program by the following equation 19. 
     
       
           Cd=abs ( Cp−Cn )  (19) 
       
     
     Next, the size of the EPG slot DS is sought (step S 128 ). This seek operation can be carried out to present the EPG screen on either the right or the left screen not but on a whole screen as shown in FIG. 15 a , for example in a TV receiver with a high-performance function like the double-window system. FIG. 17 shows an example of the EPG screen presented on such a double-window display. 
     When a viewer selects the non-linear logarithmic change characteristics for the EPG slot after the absolute channel number difference Cd and the size of the EPG slot DS have been determined, the size of a given EPG slot is determined by the following equations (step S 129 ). Here the base m of the logarithmic function Log is set to 10, while its coefficient N is also set to 10. 
     
       
           Ps=DS /Max (Pixel Number)×(1/Log 10  ( N×Cd ))  (20) 
       
     
     Herein “Pixel Number” represents the number of effective display pixels in a line. For instance, in the case that the EPG screen is displayed on a whole screen, the position of the next EPG slot is determined as follows. 
     
       
           Px= 1×(1/Log 10  10×1)=1 
       
     
     Further the position of the next EPG slot but one to the EPG slot is determined as follows. 
     
       
           Px= 1×(1/Log 10  10×2)=0.77 
       
     
     Next, the actual size of the EPG slot in the time-axis direction is determined based on the basic size Psz (step S 130 ). For instance, for the case of 200 Pixel, the size Pu of the next EPG slot but one to the EPG slot in the time-axis direction is given by the following equation 21. 
     
       
           Pu=Px×Psz= 0.77×200=154  (21) 
       
     
     Next, based on the size of the EPG slot determined by the equation 21, it is checked how many characters can be placed in the slot. Then based on the result available characters are displayed in the EPG slot. The processing will be explained hereinafter. Referring back to FIG. 16, the flow of the above-described operation will be described. 
     Further, a character string such as a program title is extracted from the EPG data (step S 131 ). A number of characters Pc in the program title is then counted (step S 132 ). Further, a number of characters Pg in additional information such as a sub-title is counted (step S 133 ). For the number of characters Pc obtained in the step S 132 , the number of displayable characters is checked from the size Pu determined by the equation 3. 
     First in this operation, in the case that the character size is fixed, the pixel size Cs of the character in the X direction (i.e., the time-axis direction on the EPG screen) is checked (step S 134 ). When a gap (blank) Gp is required between characters, the size Cp of each character including the gap Gp in the X direction will be determined by the following equation 4 (step S 134 ). 
     
       
           Cp=Cs+Gp   (22) 
       
     
     Then the number of displayable characters CC is determined by dividing the slot size Pu determined by the equation 21 by the character size Cp determined by the equation 22, as shown by the following equation 23 (step S 135 ) 
     
       
           CC=Pu/Cp   (23) 
       
     
     Then a character string available in the EPG slot is decided (steps S 137 , S 139 , and S 141 ) by comparing the number of characters Pc (or Pc+Pg) obtained in the step S 132  with the number of displayable characters CC calculated by the equation 23 (steps S 136 , S 137 , and S 138 ). 
     If “CC&gt;=(Pc+Pg)” is positive (step S 136 ), then a whole character string display will be carried out (step S 139 ). 
     If “CC&lt;(Pc+Pg) &amp;&amp; CC&gt;=PC” is positive (step S 138 ), only a program title display will be carried out (step S 139 ). 
     If “CC&lt;PC” is positive (step S 140 ), no character display will be carried out (step S 141 ). 
     Then, it is determined whether the character display processing has been carried out for EPG slots. If there remains any EPG slot unfinished the character presentation, the operation repeats the routine on and after the step S 127  (step S 142 ). 
     As is evident from the flow of steps as described above, the present embodiment can provide a lot of program information due to the size of the EPG slots varies in the channel-list axis direction. 
     Now a sixth embodiment of the present invention will be explained hereinafter. This sixth embodiment is different from the fifth embodiment by that the size of the characters are variable. 
     FIGS. 18 a  and  18   b  show an example that the size of the EPG slots is compressed in a non-linear manner in the time-axis direction, and that the character size varies in accordance with the size of the EPG slot. Wherein FIG. 18 a  shows the EPG screen according to this sixth embodiment and FIG. 18 b  shows three patterns of non-linear change characteristics. FIG. 19 shows the flow of operation steps for displaying the non-linear patterned EPG screen according to the sixth embodiment. FIG. 20 shows an example in which the EPG screen is superimposed on the normal program display screen on a wide-aspect display by using a semi-transparent display. 
     In FIG. 19, the EPG data from the TV station and the present time data are updated and stored in the step S 151 . When the viewer selects the EPG screen (step S 152 ), a menu screen listing display patterns is presented (step S 153 ). The viewer then selects his/her favorite display pattern (step S 154 ). To the selected display pattern, it reads out the non-linear processing routine. Further at a beginning of the operation, a channel slot corresponding to the channel that is currently received by the viewer is defined (step S 155 ). Then the channel slot of the channel number or the TV station name is highlighted as shown in FIG. 18 a  (step S 156 ). 
     On the other hand, a channel number dat of an available channel is extracted from the EPG data (step S 157 ). In relation to the channel number Cn, an absolute value of the difference Cd from the channel number Cn to the channel number Cp of currently received program by the following equation 24. 
     
       
           Cd=abs ( Cp−Cn )  (24) 
       
     
     Next the size of the EPG slot DS is sought (step S 158 ). This seek operation can be carried out to present the EPG screen on either the right or the left screen, for example in a TV receiver with a high-performance function like the double-window system. FIG. 20 shows an example in which the EPG screen is superimposed on the normal program display screen by using a semi-transparent display. 
     When a viewer selects the non-linear logarithmic change characteristics for the EPG screen after the time difference Td and the EPG slot size DS have been determined, the size Px of a given EPG slot is determined by the following equations (step S 159 ). Here the base m of the logarithmic function Log is set to 10, while its coefficient N is also set to 10. 
     
       
           Ps=DS /Max(Pixel Number)×(1/Log 10  ( N×Cd ))  (25) 
       
     
     Herein “Pixel Number” represents the number of effective display pixels in a line. For instance, in the case that the EPG screen is presented on a whole screen, the position of the next channel slot will be given as follows. 
     
       
           Px= 1×(1/Log 10  10)=1 
       
     
     Further that of a next EPG slot but three to the EPG slot will be given as follows. 
     
       
           Px= 1×(1/Log 10  30)=0.68 
       
     
     Further the position of the next channel slot but two to the channel slot is determined as follows. 
     
       
           Px= 1×(1/Log 10  20)=0.77 
       
     
     Next, the actual size of the EPG slot in the time-axis direction is determined based on the basic size Psz (step S 160 ). For instance, for the case of 200 Pixel, the size Pu of the next EPG slot but one to the EPG slot in the time-axis direction is given by the following equation 21. 
     
       
           Pu=Px×Psz= 0.68×200=135  (26) 
       
     
     Next, based on the size of the EPG slot determined by the equation 26, it is checked how many characters are required to be placed in the slot. Then the size of the characters are changed in accordance with the result of the check and then the characters with the size as changed are displayed in the EPG slot. Referring back to FIG. 16, the flow of the above-described operation will be described. 
     First, a character string such as a program title in the EPG data is read out (step S 161 ). A number of characters Pc in the program title is then counted (step S 162 ). Further, a number of characters Pg in additional information such as a sub-title is counted (step S 163 ). Then, the total number of the characters to be displayed is calculated (step S 164 ). Then the sizes of the characters are determined from the total number of the characters and the size of the EPG slot determined by the equation 8. 
     In this determination, first the number of characters is selected from the larger ranking the number of characters Pc in the program title and the number of characters Pg in the sub-title. The size of the EPG slot Pu is divided by the selected one of the number of characters by the following equation 27 (step S 165 ). 
     
       
           Fsz=Pu /Max( Pc|Pc+Pg )  (27) 
       
     
     The result Fsz of the equation 27 is compared with a threshold value Fmin of the minimum character size stored in the main memory  25  (step S 166 ). When the Fsz is greater then the Fmin, characters with the font-size nearest to the Fsz are used for the EPG (step S 167 ). If the Fsz is smaller than the Fmin, first the number of characters Pc in the program title and the number of characters Pg in the sub-title are compared with each other. If the Pc is smaller than the Pg, the value Fsz is again calculated by the following equation 28 (steps S 168 , S 169 ). 
     
       
           Fsz=Pu/Pc   (28) 
       
     
     Here, the reason that the number of characters Pc in the program title is used for the determination of the Fsz is because of that the program title is more important for viewers than the additional program information such as the sub-title. Here, again the value Fsz and the Fmin are compared with each other (step S 166 ). If the value Fsz is greater than the Fmin, characters with the font-size nearest to the Fsz are used for the EPG slot (step S 167 ). 
     If the value Fsz is yet smaller than the Fmin in the step S 166 , the display of character string in the EPG slots is given up and the slots are left in a blank (step S 170 ). 
     Then, it is determined whether the character display processing has been carried out for EPG slots. If there remains any EPG slot unfinished the character presentation, the operation repeats the routine on and after the step S 155  (step S 171 ). 
     As is evident from the flow of steps as described above, the present embodiment can present a lot of program information in the EPG slots when the size of the slots had been reduced, since although the EPG slots are companded in only the time-axis direction by the non-linear processing the size of the characters is reduced in tied to the size of the EPG slots. 
     Now a seventh embodiment of the present invention will be explained hereinafter. Here, a process for shifting the start position on the EPG screen according to the non-linear processing will be explained. 
     FIGS. 21 a  and  21   b  an example that the start position of the EPG slots on the EPG screen is compressed in a non-linear manner in the channel-list axis direction, and that the number of characters available in the EPG slot is variable. FIG. 21 a  shows the EPG screen according to this seventh embodiment and FIG. 21 b  shows the relation between the non-linear logarithmic curve and the size of the EPG slots. FIG. 22 shows the flow of operation steps for displaying the non-linear patterned EPG screen according to the seventh embodiment. FIG. 23 shows an example of such a double-window display to which the operation of FIG. 22 is adapted. 
     In FIG. 22, the EPG data from the TV station and the present time data are updated and stored in the step S 181 . When the viewer selects the EPG screen (step S 182 ), a menu screen listing display patterns is presented (step S 183 ). The viewer then selects his/her favorite display pattern (step S 184 ). A non-linear processing routine corresponding to the selected display pattern is prepared. Further at a beginning of the operation, a channel slot corresponding to the channel that is currently received by the viewer is defined (step S 185 ). Then the channel slot of the channel number or the TV station name is highlighted as shown in FIG. 21 a  (step S 186 ). 
     On the other hand, a channel number data of an available channel is extracted from the EPG data (step S 187 ). The channel number data is then used in the non-linear processing routine (step S 188 ). In the non-linear processing routine, a logarithmic function Log m  Cd is read out from a memory (the base m of the logarithmic function Log is set to any number, while its coefficient N is also set to any number) (step S 189 ). Then a start position St of each of the EPG slot is determined by the following equation 29 (step S 190 ). The operation of the steps S 187  through S 190  is repeated until the start positions St of all EPG slots have been determined (step S 71 ). 
     
       
           St =Log m    N ( abs ( Cp−Cn ))  (29) 
       
     
     The relation of the start position St determined by the equation 29 and the time has a logarithmic function Log, as shown in FIG. 21 b.    
     Next, based on the start position of the EPG slot determined by the equation 29, the size of the EPG slot is determined. Further, it is checked how many characters can be placed in the slot. Then, based on the result, necessary characters are displayed in the EPG slot. Referring back to FIG. 22, the flow of the above-described operation will be described. 
     First, the size of the EPG slot Pu is determined from the difference between the start position St 0  of the EPG slot and the start position St 1  of the following EPG slot (step S 192 ). 
     
       
           Pu=St   1 − St   0   (30) 
       
     
     Further, a character string such as a program title is extracted from the EPG data (step S 193 ). A number of characters Pc in the program title is then counted (step S 194 ). Further, a number of characters Pg in additional information such as a sub-title is counted (step S 195 ). First, for the number of characters obtained in the step S 193 , the number of displayable characters is checked from the size determined by the equation 30. 
     First in this operation, in the case that the character size is fixed, the pixel size Cs of the character in the X direction (i.e., the time-axis direction on the EPG screen) is checked (step S 196 ). When a gap (blank) Gp is required between characters, the size Cp of each character including the gap Gp in the X direction will be determined by the following equation 31 (step S 197 ). 
     
       
           Cp=Cs+Gp   (31) 
       
     
     Then the number of displayable characters CC is determined by dividing the slot size Pu determined by the equation 30 by the character size Cp determined by the equation 31, as shown by the following equation 32 (step S 198 ). 
     
       
           CC=Pu/Cp   (32) 
       
     
     Then a character string available in the EPG slot is decided (steps S 199 , S 201 , and S 202 ) by comparing the number of characters Pc (or Pc+Pg) obtained in the step S 77  with the number of displayable characters CC calculated by the equation 32 (steps S 200 , S 202 , and S 204 ). 
     If “CC&gt;=(Pc+Pg)” is positive (step S 199 ), then a whole character string display will be carried out (step S 200 ). 
     If “CC&lt;(Pc+Pg) &amp;&amp; CC&gt;=PC” is positive (step S 201 ), only a program title display will be carried out (step S 202 ). 
     If “CC&lt;PC” is positive (step S 203 ), no character display will be carried out (step S 204 ). 
     Then, it is determined whether the character display processing has been carried out for EPG slots. If there remains any EPG slot unfinished the character presentation, the operation repeats the routine on and after the step S 187  (step S 205 ). 
     As is evident from the flow of steps as described above, according to the present embodiment, since the start position of the EPG screen is companded in the channel-list axis direction by the non-linear processing, and the number of characters available in the EPG slot is made variable, it can provide viewers an EPG screen with the easily readable pattern in accordance with the size of the EPG slots. 
     Next the eighth embodiment of the present invention will be explained hereinafter. Here, in this eighth embodiment the start position on the EPG screen according to the non-linear processing is shifted, and the character size varies in accordance with the size of the EPG slot. 
     FIGS. 24 a  and  24   b  an example that the start position of the EPG slots on the EPG screen is compressed in a non-linear manner in the channel-list axis direction, and that the number of characters available in the EPG slot is variable. FIG. 24 a  shows the EPG screen according to this eighth embodiment and FIG. 24 b  shows the relation between the non-linear logarithmic curve and the size of the EPG slots. FIG. 25 shows the flow of operation steps for displaying the non-linear patterned EPG screen according to the eighth embodiment. FIG. 26 shows an example of such a double-window display to which the operation of FIG. 25 is adapted. 
     In FIG. 25, the EPG data from the TV station and the present time data are updated and stored in the step S 211 . When the viewer selects the EPG screen (step S 212 ), a menu screen listing display patterns is presented (step S 213 ). The viewer then selects his/her favorite display pattern (step S 214 ). A non-linear processing routine corresponding to the selected display pattern is prepared. Further at a beginning of the operation, a channel slot corresponding to the channel that is currently received by the viewer is defined (step S 215 ). Then the channel slot of the channel number or the TV station name is highlighted as shown in FIG. 24 a  (step S 216 ). 
     On the other hand, a channel number data of an available channel is extracted from the EPG data (step S 217 ). The channel number data is then used in the non-linear processing routine (step S 218 ). In the non-linear processing routine, a logarithmic function Log m  Cd is read out from a memory (the base m of the logarithmic function Log is set to any number, while its coefficient N is also set to any number) (step S 219 ). Then a start position St of each of the EPG slot is determined by the following equation 33 (step S 220 ). The operation of the steps S 217  through S 220  is repeated until the start positions St of all EPG slots have been determined (step S 221 ). 
     
       
           St =Log m    N ( abs ( Cp−Cn ))  (33) 
       
     
     The relation of the start position St determined by the equation 33 and the time has a logarithmic function Log, as shown in FIG. 24 b.    
     Next, based on the start position of the EPG slot determined by the equation 33, the size of the EPG slot is determined. 
     Further, from the total number of the characters to be displayed, the size of characters to be included in the EPG slot is determined. Then based on the result available characters are displayed in the EPG slot. Referring back to FIG. 25, the flow of the above-described operation will be described. 
     First, the size of the EPG slot Pu is determined from the difference between the start position St 0  of the EPG slot and the start position St 1  of the following EPG slot (step S 222 ). 
     
       
           Pu=St   1 − St   0   (34) 
       
     
     Then, a character string such as a program title is extracted from the EPG data (step S 223 ). A number of characters Pc in the program title is then counted (step S 224 ). Further, a number of characters Pg in additional information such as a sub-title is counted (step S 225 ). Then, the total number of the characters to be displayed is calculated (step S 226 ). Then the sizes of the characters are determined from the total number of the characters and the size of the EPG slot determined by the equation 34. 
     In this determination, first the number of characters is selected from the larger ranking the number of characters Pc in the program title and the number of characters Pg in the sub-title. The size of the EPG slot Pu is divided by the selected one of the number of characters by the following equation 35 (step S 227 ). 
     
       
           Fsz=Pu /Max( Pc|Pc+Pg )  (35) 
       
     
     The result Fsz of the equation 17 is compared with a threshold value Fmin of the minimum character size stored in the main memory  25  (step S 228 ). When the Fsz is greater then the Fmin, characters with the font-size nearest to the Fsz are used for the EPG (step S 229 ). If the Fsz is smaller than the Fmin, first the number of characters Pc in the program title and the number of characters Pg in the sub-title are compared with each other (step S 230 ). If the Pc is smaller than the Pg, the value Fsz is again calculated by the following equation 35 (step S 231 ). 
     
       
           Fsz=Pu/Pc   (36) 
       
     
     Here, the reason that the number of characters Pc in the program title is used for the determination of the Fsz is because the program title is more important for viewers than the additional program information such as the sub-title. Here, again the value Fsz and the Fmin are compared with each other (step S 232 ). If the value Fsz is greater than than the Fmin, characters with the font-size nearest to the Fsz are used for the EPG slot (step S 233 ). 
     If the value Fsz is yet smaller than the Fmin in the step S 232 , the display of character string in the EPG slots is given up and the slots are left in a blank (step S 234 ). 
     Then, it is determined whether the character display processing has been carried out for EPG slots. If there remains any EPG slot unfinished the character presentation, the operation repeats the routine on and after the step S 215  (step S 235 ). 
     As is evident from the flow of steps as described above, according to the present embodiment, since the start position of the EPG screen is compressed in the channel-list axis direction by the non-linear processing, and the character size is made variable, it can provide viewers an EPG screen with the easily readable pattern in accordance with the size of the EPG slots. 
     The present invention is not limited to the above-described embodiments. For example, in the EPG screen both of its time-axis and channel-list axis be processed in the non-linear change pattern, as shown in FIG.  27 . Further, for instance, in the case that the character size is made variable, the main-title and the additional information such as the sub-title can have different font size with each other. 
     As is evident from the above explanations, according to the embodiments of the present invention, in displaying EPG information of the multi-channel broadcast it is possible to provide the EPG screen with program information of not only programs starting within two or three hours from present time, but also programs starting at time apart more than a half of a day from the present time. Further, it can provide viewers an easily readable EPG screen. 
     As described above the present invention provides an extremely preferable electronic preview guide display system capable of increasing an amount of information given in at least one of the directions of the time-axis direction and the channel-list axis of an EPG screen, while in a pattern easily readable for viewers. 
     While there have been illustrated and described what are at present considered to be preferred embodiments of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made, and equivalents may be substituted for elements thereof without departing from the true scope of the present invention. In addition, many modifications may be made to adapt a particular situation or material to the teaching of the present invention without departing from the central scope thereof. Therefor, it is intended that the present invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out the present invention, but that the present invention includes all embodiments falling within the scope of the appended claims. 
     The foregoing description and the drawings are regarded by the application as including a variety of individually inventive concepts, some of which may lie partially or wholly outside the scope of some or all of the following claims. The fact that the applicant has chosen at the time of filing of the present application to restrict the claimed scope of protection in accordance with the following claims is not to be taken as a disclaimer or alternative inventive concepts that are included in the contents of the application and could be defined by claims differing in scope from the following claims, which different claims may be adopted subsequently during prosecution, for example, for the purposes of a divisional application.