Patent Publication Number: US-6985166-B2

Title: Color printer with an optical encoding disk for economizing the length of a ribbon

Description:
BACKGROUND OF INVENTION 
   1. Field of the Invention 
   The present invention relates to a color printer and more particularly, to a color printer for driving a ribbon according to the count of an optical encoding disk so as to economize the length of the ribbon. 
   2. Description of the Prior Art 
   Please refer to  FIG. 1 ,  FIG. 1  is a perspective view of a ribbon apparatus of a conventional color printer  10 . As shown in  FIG. 1 , the ribbon apparatus of the color printer  10  includes a ribbon  12 , two light sources  14 ,  16 , and two sensors  18 ,  20 . The ribbon  12  includes a plurality of sequentially arranged dye regions  22 . Each dye region  22  includes four dye areas  24 ,  26 ,  28 ,  30  for placing yellow dye, magenta dye, cyan dye, and overcoating dye. An opaque dividing section  32  is located between an overcoating dye area  30  and a yellow dye area  24 . An opaque dividing section  34  and a transparent dividing section  36  are installed between the yellow dye area  24  and a magenta dye area  26 . An opaque dividing section  34  and a transparent dividing section  36  are installed between the magenta dye area  26  and a cyan dye area  28 . An opaque dividing section  34  and a transparent dividing section  36  are installed between the cyan dye area  28  and the overcoating dye area  30 . 
   The light sources  14 ,  16  are located on one side of the ribbon  12  for producing light beams  38 ,  40  of two predetermined colors. The sensors  18 ,  20 , corresponding to the light sources  14 ,  16 , are located on the opposite side of the ribbon  12 . The sensors  18 ,  20  are used to detect light beams  38 ,  40  penetrating through the ribbon  12  and produce corresponding signals to determine the position of the ribbon  12 . The detection of an opaque dividing section  32  signals the beginning position of a new dye region  22  of the ribbon  12 , and also corresponds to the beginning position of a yellow dye area  24 . The detection of an opaque dividing section  34  and a transparent dividing section  36  by the sensors  18 ,  20  corresponds to the beginning position of the magenta dye area  26 , cyan dye area  28 , or overcoating dye area  30 . The reservation of opaque dividing sections  34  and transparent dividing sections  36  for detection of the position of the ribbon  12  is a disadvantage of the prior art color printer  10  because it decreases the effective utilization of the ribbon  12 , resulting in higher production costs of the ribbon  12 . 
   SUMMARY OF INVENTION 
   It is therefore a primary objective of the claimed invention to provide a color printer for economizing an ribbon for solving the above-mentioned problem. 
   According to the claimed invention, a color printer for economizing an ribbon is proposed. The color printer includes a ribbon including a plurality of dye regions, and each dye region includes a plurality of dye areas for carrying dye of different colors. The color printer further includes a print head for transferring dye on the ribbon onto a subject, a ribbon-moving device for moving the ribbon so that the print head can transfer the dye on each of the dye areas of one dye region onto the subject to form a color picture, an optical sensing module installed on the side of the ribbon including an optical encoding disk driven by the ribbon-moving device for generating a count when the ribbon-moving device moves the ribbon, and a control module for controlling the ribbon-moving device to move the next dye region of the ribbon to the print head after finishing printing one dye region of the ribbon according to the count of the optical encoding disk. 
   These and other objectives of the claimed invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment, which is illustrated in the various figures and drawings. 

   
     BRIEF DESCRIPTION OF DRAWINGS 
       FIG. 1  is a perspective view of a ribbon apparatus of a conventional color printer. 
       FIG. 2  is a functional block diagram of a color printer according to the present invention. 
       FIG. 3  is a perspective view of the color printer according to the present invention. 
       FIG. 4  is a diagram of a ribbon of the color printer according to the present invention. 
       FIG. 5  is a diagram illustrating the print regions of the ribbon. 
       FIG. 6  is a flowchart illustrating actions that the color printer performs when printing an image on a piece of photo paper. 
       FIG. 7  is lateral view of the color printer according to the present invention. 
   

   DETAILED DESCRIPTION 
   Please refer  FIG. 2 .  FIG. 2  is a functional block diagram of a color printer  50  according to the present invention. The color printer  50  can be a photo printer using a thermal print transfer method. The color printer  50  includes a ribbon  52 , a print head  54  for transferring dye on the ribbon  52  onto a subject, a ribbon-moving device  56  for moving the ribbon  12  so that the print head  54  can transfer the dye of the ribbon  52  onto the subject to form a color picture, an optical sensing module  58 , and a control module  60  for controlling the ribbon-moving device  56  to move the ribbon  52  according to the detection of the optical sensing module  58 . 
   Please refer to  FIG. 3 .  FIG. 3  is a perspective view of the color printer  50  according to the present invention. The optical sensing module  58  includes an optical encoding disk  62  driven by the ribbon-moving device  56  for rotating and generating a count when the ribbon-moving device  56  moves the ribbon  52 , a first light source  64  for emitting light to the ribbon  52 , a light sensor  66  for sensing the light which is emitted from the first light source  64  and penetrates the ribbon  52 , a second light source  68  for emitting light to the optical encoding disk  62 , and a light detector  70  for receiving the light emitted from the second light source  68  and passing through the optical encoding disk  62  so as to obtain the count of the optical encoding disk  62 . The first light source  64  and the second light source  68  can be light emitting diodes (LEDs). The ribbon-moving device  56  includes a driving roller  72  and a feeding roller  74 . The driving roller  72  moves the ribbon  52  in a predetermined direction, the ribbon  52  wound around the feeding roller  74  decreasing and the ribbon  52  wound around the driving roller  72  increasing. The driving roller  72  holds the printed part of the ribbon  52 , and the feeding roller  74  holds the unprinted part of the ribbon  52 . The ribbon-moving device  56  winds the ribbon  52  at a constant linear speed or at a constant angular speed. 
   Please refer to  FIG. 4 .  FIG. 4  is a diagram of the ribbon  52  of the color printer  50  according to the present invention. The ribbon  52  includes a plurality of sequentially arranged dye regions  78 . Each of the dye regions  78  includes four dye areas  82 ,  84 ,  86 ,  88  for carrying dye of different colors, and each of the dye areas  82 ,  84 ,  86 ,  88  has a substantially equal length L. The dye areas  82 ,  84 ,  86 ,  88  are used for separately placing yellow dye, magenta dye, cyan dye, and overcoating dye. Dividing sections  80  are positioned at the front end of each of the dye regions  78  respectively. Each of the dividing sections  80  has a substantially equal length L″, which is shorter than the length L. The dividing sections  80  are opaque. When the first light source  64  emits a light beam  76  to the ribbon  52 , the light sensor  66  can generate a sensing signal to the control module  60  by detecting the light beam  76  which is emitted from the first light source  64  and penetrates the ribbon  52 . And when the light sensor  66  detects the dividing section  80 , it can signal the control module  60  for the beginning position of the new dye region  78  of the ribbon  52 , corresponding to the beginning position of the yellow dye area  82 . 
   Please refer to  FIG. 5 .  FIG. 5  is a diagram illustrating the print regions of the ribbon  52 . The dye areas  82 ,  84 ,  86 ,  88  of each dye region  78  of the ribbon  52  are used for separately placing yellow dye, magenta dye, cyan dye, and overcoating dye for being printed onto a piece of photo paper. The printing range of the dye areas  82 ,  84 ,  86 ,  88  are on the inside of the dotted region. The length of the printing range is substantially equal to Lp, and the distance between the adjacent printing ranges is substantially equal to L″ for ensuring that the next beginning print point of the print head  54  is located inside the next printing range. So the length L of the dye area will not be equal to the length Lp of the printing range. Furthermore, the distance between the dividing section  80  positioned in front of the yellow dye area  82  and the beginning print point of the yellow dye area  82  is substantially equal to L — f 1 . 
   Please refer to  FIG. 6 .  FIG. 6  is a flowchart illustrating actions that the color printer  50  performs when printing an image on a piece of photo paper. The method includes: 
   Step  100 : Start the first light source  64  and the light sensor  66  for detecting the dividing section  80  in front of the yellow dye area  82 , and wind the ribbon  52  at a constant linear speed with the ribbon-moving device  56 ; 
   Step  102 : Please refer to  FIG. 7 .  FIG. 7  is a lateral view of the color printer  50  according to the present invention. The distance between the first light source  64  and the print head  54  and the distance between the light sensor  66  and the print head  54  are both substantially equal to length L — f 1 . So when the light sensor  66  detects the dividing section  80  in front of the yellow dye area  82 , the print head  54  is positioned at the beginning print point of the yellow dye area  82 . Simultaneously the light sensor  66  generates a sensing signal to the control module  60  so that the control module  60  can control the print head  54  for transferring dye on the yellow dye area  82  onto the piece of photo paper; 
   Step  104 : Start the second light source  68  and the light detector  70 . When the ribbon-moving device  56  moves the ribbon  52  the length of the printing range of the yellow dye area  82  Lp, the light detector  70  can detect the count N of the optical encoding disk  62  synchronously. Simultaneously the print head  54  finishes printing the yellow dye area  82  and the print head  54  stops printing; 
   Step  106 : The ribbon-moving device  56  moves the ribbon  52  until the light detector  70  detects the count N of the optical encoding disk  62 , wherein N″ can be obtained by the relation (Lp/N)=(L″/N″). At the same time, the light detector  70  generates a sensing signal to the control module  60  for controlling the ribbon-moving device  56  to stop winding the ribbon  52 . Thus, the print head  54  can locate on the beginning print point of the next magenta dye area  84 ; 
   Step  108 : Start the print head  54  to print the magenta dye area  84 , and then repeat Step  104  and Step  106  until the print head  54  finishes printing the magenta dye area  84 , the cyan dye area  86 , and the overcoating dye area  88 . The color printer  50  finishes printing the piece of photo paper; and 
   Step  110 : If it is necessary to print to another photo paper, repeat Step  100  to Step  108 . Otherwise the printing work is complete. 
   As mentioned above, the color print  50  can utilize the relation of the length Lp, the count N of the optical encoding disk  62 , and the length L″ to get the necessary count N″ corresponding to the length L″ that the ribbon-moving device  52  has to move the ribbon  52 . That is, when the optical encoding disk  62  rotates by the count N″, the ribbon  52  moves in the distance L″. So the print head  54  can be accurately located at the beginning print point of the next dye area. The necessary count N″ of the optical encoding disk  62  can be calculated after the print head  54  finishes printing one dye area and the count N is obtained. In addition, the count N corresponding to each dye area can be obtained by experiment before the color print  50  leaves the factory, so the necessary count N″ corresponding to each dye area can be calculated and stored in the control module  60  of the color printer  50  in advance. Thus, the next count N″ of the optical encoding disk  62  can be looked up from a stored table in the control module  60  after the print head  54  finishes printing one dye area and the count N is obtained. Furthermore, the control module  60  can recognize the present position of the dye region of the ribbon  52  according to the count of the optical encoding disk  62  for providing information about the used position of the ribbon  52 . In addition, since one piece of photo paper is printed to by one dye region, a user can recognize how many dye regions have been printed onto pieces of photo paper and how many dye regions can be printed onto pieces of photo paper in the future. 
   Compared to the prior art color printer, the color printer of the present invention needs only a dividing section in front of the first dye area of a dye region to detect the beginning print point of the ribbon. The beginning print points of the other three dye areas are determined by counts of optical encoding disk instead of reserving additional dividing sections in front of three dye areas and the length L — f 1 . This increases the effective utilization of the ribbon. Besides, the present invention provides users with information about the used position of the ribbon and how many pieces of photo paper can be printed to in the future. 
   Those skilled in the art will readily observe that numerous modifications and alterations of the device may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.