Patent Publication Number: US-6213015-B1

Title: Printer

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a stencil printer or similar printer. 
     Various kinds of papers have customarily been used with a stencil printer or similar printer. Thin papers, for example, include rough printing papers and fine 45 kg papers. Papers of standard thickness (sometimes referred to as standard papers hereinafter) include copy papers, mediumquality papers, fine quality 55 kg papers, recycled papers, and fine papers for stencil printers. Further, thick papers include drawing papers, postcards, envelopes, fine 135 kg papers, and fine 160 kg papers. 
     To guarantee the paper feeding and discharging ability of the printer, i.e., to reduce troubles relating to paper transport as far as possible, it is necessary to variably set optimal transport conditions at the paper feed section, paper discharge section and other various sections of the printer in accordance with the kind of papers including thickness and size. This is because particular optimal transport conditions exist for each kind of papers. Necessary transport conditions to be set include a paper feed pressure, a paper separation pressure, a jump board angle and a side fence position relating to paper discharge, and a tray angle relating to paper feed. The troubles relating to paper transport are typified by the simultaneous feed of two or more papers (sometimes referred to as overlap feed hereinafter), the failure of paper feed (sometimes referred to as feed failure hereinafter), and jams occurring at the paper feed section and paper discharge section. 
     It is a common practice for the operator, user or serviceman (operator hereinafter) to determine the kind of papers by confirming the thickness and size of papers by eye, and manually switch a pick-up roller pressure, a separation pad pressure, a jump board angle and so forth in such a manner as to set up optimal transport conditions for the papers. 
     In practice, however, it is extremely difficult for an ordinary or untrained operator to determine or set optimal transport conditions paper by paper. For this reason, the manual switching function available with the printer has been rarely used, resulting in the troubles relating to paper transport. 
     Moreover, when any one of the troubles occurs, the operator is often simply perplexed and cannot see or execute an optimal troubleshooting measure. Although an operation manual attached to the printer describes measures for dealing with various kinds of troubles specifically, it is not readable for ordinary operators and is, if readable, troublesome and time-consuming to read. 
     Technologies relating to the present invention are disclosed in, e.g., Japanese Patent Publication No. 5-32296, Japanese Patent Laid-Open Publication Nos. 9-30714, 9-235033 (corresponding to U. S. Ser. No. 08/719,960, filed Sep. 24, 1996) and 10-139191 (corresponding to U.S. Ser. No. 08/925,648, filed Sep. 9, 1997), Japanese Utility Model Publication Nos. 4-23862 and 5-18342, and Japanese Patent Laid-Open Publication Nos. 9-20436, 8-259099, 9-26678, and 2-144335. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide a printer capable of automatically determining, only if the operator, trained or not, selects and inputs the kind of papers while watching an LCD (Liquid Crystal Display) provided on an operation panel without any manual switching operation, optimal transport conditions matching with the kind of papers and setting up the optical conditions, thereby obviating transport troubles. 
     It is another object of the present invention to provide a printer capable of automatically varying, only if the operator inputs the kind and degree of a transport trouble while watching an LCD provided on an operation panel, existing transport conditions, thereby setting up optimal conditions for obviating the trouble and making a troubleshooting operation extremely simple. 
     It is a further object of the present invention to provide a printer capable of storing optimal conditions selected and allowing them to be called every time papers of the same kind are used, thereby obviating the repetition of troublesome setting. 
     A printer for printing an image on a paper paid out by a pick-up roller and separated from the other papers by a separating device of the present invention includes a kind-of-paper setting device for allowing the operator of the printer to select and input the kind of papers to be used. A controller automatically selects, among transport conditions stored beforehand in correspondence to the kinds of papers, optimal transport conditions matching with the kind of papers input by the operator in response to a signal received from the kind-of-paper setting device. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description taken with the accompanying drawings in which: 
     FIG. 1 is a front view showing a printer embodying the present invention; 
     FIG. 2 is a partly taken away perspective view showing a paper size sensing mechanism included in the illustrative embodiment together with members associated with a tray; 
     FIG. 3 is a block diagram schematically showing a control system included in the illustrative embodiment; 
     FIG. 4 is a fragmentary plan view showing an operation panel included in the illustrative embodiment; 
     FIGS. 5 and 6 are fragmentary plan views each showing a particular picture to appear on an LCD included in the operation panel together with keys associated with the LCD; 
     FIGS. 7 and 8 are fragmentary plan views each showing a particular picture representative of a first modification of the illustrative embodiment together with the keys associated with the LCD; 
     FIG. 9 is a fragmentary plan view showing a specific picture representative of a second modification of the illustrative embodiment together with the keys associated with the LCD; and 
     FIG. 10 is a fragmentary front view showing a tray angle adjusting mechanism representative of a third modification of the illustrative embodiment. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A preferred embodiment of the printer in accordance with the present invention and modifications thereof will be described hereinafter. In the embodiment and modifications thereof, structural elements identical in configuration and/or function are designated by like reference numerals and will not be repetitively described in order to avoid redundancy. As for structural elements provided in pairs, only one of them will be described so far as circumstances permit. Further, some structural elements which should be shown in the drawings, but do not need specific description, are not be shown for the simplicity of illustration. 
     Referring to FIG. 1 of the drawings, a printer embodying the present invention is shown and implemented as a stencil printer by way of example. As shown, the stencil printer includes a print drum  1 . A damper  2  is mounted on the outer periphery of the ink drum  1  for clamping the leading edge of a stencil having been perforated, or cut, (master  3  hereinafter). While the print drum  1  is rotated in a direction indicated by an arrow, the master  3  is sequentially wrapped around the drum  1 . 
     A tray  4  loaded with a stack of papers  6  is positioned at the right-hand side of the print drum  1 , as viewed in FIG.  1 . As shown in FIG. 2 specifically, the tray  4  includes a right and a left side fence  5  movable toward and away from each other in the widthwise direction  66  of the papers  6  perpendicular to a paper feed direction  65 . The side fences  5  are interlocked to each other for positioning the opposite side edges of the papers  6  in accordance with the size of the papers  6 , as will be described in detail later. 
     A mechanism for sensing the size of the papers  6  will be described with reference to FIG.  2 . Briefly, the mechanism senses the size of the papers  6  in interlocked relation to the movement of the side fences  5 . As shown, a pinion  73  is rotatably mounted on a stationary member positioned below the tray  4 . A rack  72  is formed in one bottom edge portion of the side fence  5  positioned at the left in FIG.  2 . The rack  72  is held in mesh with the pinion  73 . A rack  71  is formed in one bottom edge portion of the other or right side fence  5  and faces the rack  72 . The rack  71  is also held in mesh with the pinion  73 . A shield portion  71   a  protrudes downward from the other bottom edge portion of the right side fence  5  opposite to the rack  71  and has a plurality of notches formed at a suitable distance. Two size sensors  7   a  and  7   b  are mounted on the above stationary member at a suitable distance from each other such that the shield portion  71   a  selectively meets either one of the size sensors  7   a  and  7   b . In addition, a size sensor  8  is mounted on the stationary member and spaced from the size sensors  7   a  and  7   b  by a suitable distance in the paper feed direction  65 . 
     The size sensors  7   a  and  7   b  are implemented by transmission type photosensors each having a light emitting portion and a light receiving portion. The size of the papers  6  in the widthwise direction  66  is determined on the basis of the output of the size sensor  7   a  or  7   b  aligning with the shield portion  71   a . The size sensor  8  is a reflection type photosensor having a light emitting portion and a light receiving portion and senses the size of the papers  6  in the paper feed direction  65 . The size sensors  7   a ,  7   b  and  8  constitute a size sensor group  70 . A CPU (Central Processing Unit), which will be described later, determines the size of the papers  6  on the basis of the combination of the outputs of the size sensor group  70 . 
     For detals of the above paper size sensing system, reference may be made to Japanese Patent Laid-Open Publication No. 9-30714 mentioned earlier. Of course, such a paper size sensing system may be replaced any other suitable sensing system if the advantages of the interlocked side fence scheme are not necessary. 
     As shown in FIGS. 1 and 2, a paper sensor  100  for determining whether or not the papers  6  are present is also mounted on the stationary member of the tray  4  and implemented by a reflection type photosensor. It is to be noted that in FIG. 1 the side fences  5  are shown at a position slightly shifted to the upstream side in the paper feed direction  65  relative to the tray  4  for the clarity of illustration. 
     Guide means, not shown, supports the tray  4  such that the tray  4  is movable up and down therealong. As shown, in FIG. 1, a tray motor  9  drives the tray  4  up and down via a pinion gear  11  and a rack  10 . The pinion gear  11  is affixed to the output shaft of the tray motor  9  while the rack  10  is affixed to the tray  4  and held in mesh with the pinion gear  11 . The tray motor  9  may be implemented by a stepping motor by way of example. As shown in FIG. 1, a pick-up roller or feeding means  12  is positioned at the front side of the tray  4  for sequentially feeding the papers  6  stacked on the tray  4  one by one, the top paper  6  being first. A separator roller  13  and a separator pad  14  constituting separating means in combination are also positioned at the front side of the tray  4  in order to separate the paper  6  picked up by the pick-up roller  12  from the underlying papers  6  while conveying it. The separator roller  13  is mounted on a shaft  15  journalled to a frame  60  included in the printer body. A paper feed motor  16  is located in the vicinity of the shaft  15  for driving the separator roller  13  and constituted by a stepping motor. Specifically, the paper feed motor  16  drives the separator roller  13  via a timing belt  17  and the shaft  15 . The timing belt  17  is passed over a drive pulley mounted on the output shaft of the motor  16  and a double driven pulley mounted on the shaft  15 . 
     If desired, the pick-up roller  12  playing the role of feeding means may be replaced with, e.g., a separator/pick-up roller taught in Japanese Patent Publication No. 5-32296 mentioned earlier or a paper feed roller  104  shown in FIG. 6 of Japanese Patent Laid-Open Publication No. 9-235033 also mentioned earlier. Also, the separator roller  13  and separator pad  14  playing the role of separating means may be replaced with, e.g., a pair of rollers pressed against each other, the separator/pick-up roller and a pad taught in the above Publication No. 5-32296, or the paper feed roller  104  and a pad  106  shown in FIG. 6 of the above Laid-Open Publication No. 9-235033. 
     An arm  18  is rotatable about the shaft  15 . The pick-up roller  12  is rotatably mounted on the free end of the arm  18  via a shaft  19 . The pick-up roller  12  is therefore movable up and down about the shaft  15  integrally with the arm  18 . A timing belt  20  is passed over a double driven pulley mounted on the shaft  15  and a pulley mounted on a shaft on which the pick-up roller  12  is also mounted. The paper feed motor  16  causes the pick-up roller  12  to rotate at the same time as the separator roller  13 . 
     An upper limit sensor  21  is mounted on the frame  60  above the tray  4  for sensing the top of the paper stack  6  brought to its upper limit position. Specifically, the upper limit sensor  21  includes a feeler  21   a  and senses the upper limit position of the paper stack  6  when the upper edge of the arm  18  contacts the feeler  21   a . A lower limit sensor  44  is positioned below the tray  4 . 
     A mechanism for controlling the force of the pick-up roller  12  pressing the top of the paper stack  6 , i.e., a feed pressure is positioned above the separator roller  13 . This mechanism includes a spring or feed pressure source  22  anchored to the arm  18  at one end and to a slider  23  at the other end. The slider  23  includes a rack  23   a  and is guided by guide means, not shown, in the up-and-down direction. A variable feed pressure motor or variable feed pressure drive source  25  causes the slider  23  to move up and down via a pinion gear  24  mounted on its output shaft and meshing with the rack  23   a . A feed displacement sensor  101  (see FIG. 3) is used to determine the displacement or position of the slider  23 . The motor  25  is implemented by a stepping motor. 
     In the above construction, the spring  22  biases the arm  18  and thereby causes a moment of rotation to act on the pick-up roller  12 . As a result, a feed pressure (sometimes referred to as a pick-up roller pressure hereinafter) acts on the top of the paper stack  6 . When the motor  25  drives the slider  23  upward, as viewed in FIG. 1, the biasing force of the spring  22  (tensile force) and therefore the feed pressure increases. With the motor  25 , therefore, it is possible to vary the feed pressure stepwise. 
     Japanese Patent Laid-Open Publication No. 9-235033, for example, teaches a position sensing board  52  included in a feed pressure adjusting mechanism. The feed displacement sensor  101 , FIG. 3, may sense the displacement of the slider  23  with the same configuration as the above positionsensing board 52 . Alternatively, the feed displacement sensor  101  may include a photoencoder mounted on the motor  25 , a shield plate mounted on the slider  23  for sensing the home position of the slider  23 , and a transmission type  6  photosensor mounted on the frame  60  and selectively engageable with the shield plate. 
     The separator pad  14  is pressed against the bottom of the separator roller  13  for surely separating the top paper  6  from the underlying papers  6 . A mechanism for controlling the force of the pad  14  pressing the paper  6  against the separator roller  13 , i.e., a separation pressure includes a compression spring or separation pressure source  26  anchored to the pad  14  at one end and to a slider  27  at the other end. The slider  27  is guided by guide means, not shown, in the up-and-down direction and includes a rack  27 a. A variable separation pressure motor or variable separation pressure source  29  has a pinion gear  28  mounted on its output shaft and meshing with the rack  27   a . The motor  29  causes the slider  27  to move up and down to thereby vary the separation pressure. A separation displacement sensor  102  (see FIG. 3) senses the displacement or position of the slider  27 . 
     The motor  29  is implemented by a stepping motor. The above Laid-Open Publication No. 9-235033, for example, teaches a position sensing board  80  included in a separation pressure adjusting mechanism  34 . The separation displacement sensor  102 , FIG. 3, may sense the displacement of the slider  27  with the same configuration as the above position sensing board  80 . Alternatively, the sensor  102  may include a photoencoder mounted on the motor  29 , a shield plate mounted on the slider  27  for sensing the home position of the slider  27 , and a transmission type photosensor mounted on the frame  60  and selectively engageable with the shield plate. 
     The compression spring  26  presses the separator pad  14  against the separator roller  13  to thereby generate a separation pressure (sometimes referred to as a pad pressure hereinafter). When the motor  29  causes the slider  27  to move upward, as viewed in FIG. 1, the compression spring  26  is compressed to increase its compression load, i.e., the separation pressure. With the motor  29 , therefore, it is possible to adjust the separation pressure stepwise. 
     Laid-Open Publication No. 9-235033 additionally shows a feed pressure adjusting mechanism  22  and a separation pressure adjusting mechanism  34  in FIGS. 2 and 3 and a feed pressure adjusting mechanism  110  and a separation pressure adjusting mechanism  108  in FIGS. 6 and 7. 
     A press roller or pressing means  30  is positioned below the print drum  1  for pressing the paper, labeled  6   a , against the drum  1  at the time of image formation. A pair of registration rollers  31  and  32  are positioned upstream of the press roller  30  in the paper feed direction  65  and feeds the paper  6   a  toward the print drum  1  and press roller  30  facing each other. The registration rollers  31  and  32  each is rotated in a particular direction indicated by an arrow. The rollers  31  and  32  cooperate to drive the leading edge of the paper  6   a  at a preselected timing based on the rotation of the print drum  1 . A lead edge sensor  33  implemented by a reflection type photosensor is positioned upstream of and in the vicinity of the registration rollers  31  and  32  for sensing the leading edge of the paper  6   a.    
     An air blower  34  separates the paper  6   b  carrying an image thereon from the print drum  1 . A belt conveyor  35  is passed over rollers, as i llustrated. A fan  36  sucking the paper  6   b  onto the belt  35  cooperates with the belt  35  to discharge the paper  6   b  toward a tray  37 . An end fence  38  and a pair of side fences  39  are positioned on the top of the tray  37 . The end fence  38  stops the paper  6   a  in order to position the leading edge and trailing edge of the paper  6   a . The side fences  39  guide and position the opposite side edges of the paper  6   b.    
     A right and a left jump board  40  cause the paper, labeled  6   b , to bend substantially in the form of a letter U before the paper  6   b  is driven out to the tray  37 . The bend provides the paper  6   b  with an adequate degree of stiffness and thereby obviates a paper jam and promotes neat positioning on the tray  37 . A rack-like slider  41  is anchored at one end to a part of each jump board  40  and guided in the up-and-down direction by guide means not shown. A jump board motor  43  is mounted on the frame  60  in the vicinity of the slider  41  and has a pinion gear  42  mounted on its output shaft and meshing with the rack  41   a . The motor  43  causes the slider  41  to move in substantially the up-and-down direction. A jump board angle sensor  103  (see FIG. 3) is mounted on the lower end of the slider  41  for sensing the displacement or position of the slider  41 . The motor  43  is implemented by a stepping motor. The jump board angle sensor  103  operates with the same configuration as the displacement sensor  101  or  102 . 
     In the above construction, the motor  43  allows the angle of the jump board  40  to vary stepwise. It is therefore possible to adjust the degree of U-shaped deformation of the paper  6   b , i.e., the degree of stiffness of the paper  6   b.    
     A scanner or document reading device, not shown, is mounted in the upper portion of the frame  60 , FIG.  1 . FIG. 4 shows an operation panel or operation panel portion positioned above the scanner. As shown, a perforation start key  49 , a print start key  50 , an initial set key  51 , four cursor keys  53 , numeral keys  54  and so forth are arranged on the operation panel  46 . Also arranged on the operation panel  46  is an LCD or display means  47 . It is to be noted that the operation panel portion refers not only to the operation panel itself, but also to an easy-to-see position around the operation panel and not obstructing the operator&#39;s access. For example, the operation panel portion includes an LCD located in the vicinity of the operation panel in a standing position. 
     In the condition shown in FIG. 4, the LCD  47  displays an initial picture to appear when a power switch, not shown, provided on the printer is turned on. Four elongate frames appear at the bottom of the LCD  47  and respectively assigned to the kind of documents, magnification change, the kind of papers, and position adjustment. Arranged below the four frames are four elongate keys, i.e., a kind-of-document key, a magnification change key, a kind-of-paper key  52  and a position adjust key, as named from the left to the right in FIG.  4 . The kind-of-document key is used to input the type of characters of documents based on the kind of documents. The magnification change key is used for enlargement or reduction in accordance with the document size. The kind-of-paper key  52  is used to input the kind of the papers  6  including the thickness and size of the papers  6 . The position adjust key is used to adjust the position of an image on the paper  6  in the right-and-left and front-and-rear directions. The keys other than the kind-of-paper key  52  are not relevant to the illustrative embodiment and are not labeled for simplicity. When the kind-of-paper key  52  is pressed once, the above keys including the key  52  respectively turn out a left arrow key  48   a , a right arrow key  48   b , a condition change key  48   c  and a set key  48   d , as indicated by brackets in FIG.  4 . This will be described specifically later with reference to FIGS. 5-9. 
     The perforation start key  49  is used to set a sequence of steps beginning with the reading of a document and ending with the feed of a master or trial printing and to input such a sequence. The numeral keys  54  are used to set and input, e.g., a desired number of printings. The print start key  50  is used to start an operation for outputting the desired number of printings input on the numeral keys  54 . The LCD  47  displays information set or sensed in a sequence beginning with the reading of a document and ending with printing and trouble information, as needed. 
     The kind-of-paper key  52  plays the role of kind-of-paper setting means for allowing the operator to select and input the kind of the papers  6  including the thickness and size of the papers  6 . The left arrow key  48   a  constitutes a part of the kind-of-paper setting means and effects a leftward shift for selecting job information appearing on the LCD  47 . The right arrow key  48   b  is identical in function with the left arrow key  48   a  except that it effects a rightward shift. The cursor keys  53  arranged in a cruciform configuration also constitute a part of the kind-of-paper setting means and has four shift keys  53   c ,  53   a ,  53   b  and  53   d  assigned to a leftward shift, a rightward shift, an upward shift, and a downward shift, respectively. 
     The condition change key  48   c  plays the role of condition changing and setting means for allowing the operator to select and input, when a trouble relating to paper transport occurs, the pattern and degree of the trouble. The set key  48   d  bifunctions as the kind-of-paper setting means and condition changing and setting means. The set key  48   d  fixes the job information selected on any one of the keys  48   a ,  48   b  and  53 . It is to be noted that the keys  48   a ,  48   b  and  53  each shifts a job information message corresponding to the kind of the papers  6  selected or the pattern and degree of the trouble while highlighting the message, urging the operator to select the message. In this sense, the keys  48   a ,  48   b  and  53  play the role of the condition changing and setting means also. The LCD  47  is driven by an LCD driver, not shown, and control led by a controller  45  via the LCD driver, as will be described specifically later. As shown in FIG. 4, the LCD  47  displays at its top characters showing the outline of operation to be performed by the operator (content of a job). The LCD  47  displays at its intermediate portion characters showing the kind of papers and contents set by the operator which will be described later. Further, the LCD  47  displays at its lower portion characters showing more specific kinds of papers and displays at its bottom the kind of documents, magnification change, the kind of papers, and position adjustment stated earlier. When the kind-of-paper key  52  is pressed, a picture showing an operation to be performed when any one of the keys  48   a ,  48   b ,  53 ,  52 ,  48   c ,  48   d  and  51  is pressed appears on the LCD  47  in the form of characters or an arrow, as will be described specifically later with reference to FIG.  5 . 
     The printer is control led by the controller or control means  45  shown in FIG.  3 . The control ler  45  includes a microcomputer made up of an I/O (Input/Output) port, a ROM (Read Only memory), a RAM (Random Access Memory), a PROM (Programmable ROM) and a timer in addition to the previously mentioned CPU, although not shown specifically. Such constituents of the microcomputer are interconnected by a signal bus. The ROM stores an optimal transport condition pattern table determined beforehand by, e.g., experiments and an operation program assigned to the printer. The RAM a lows data to be written thereto, as needed. 
     As shown in FIG. 3, the control ler  45  adequately controls the LCD  47 , tray motor  9 , feed pressure motor  25 , separation pressure motor  29 , jump board angle motor  43 , air blower  34  and feed motor  16  in response to the outputs of the upper limit sensor  21 , keys arranged on the operation panel  46 , size sensor group  70 , lead edge sensor  33 , paper sensor  100 , feed displacement sensor  101 , separation displacement sensor  102 , and jump board angle sensor  103 . It is to be noted that blocks indicated by phantom lines in FIG. 3 are not used in the illustrative embodiment, but will be used in a third modification of the illustrative embodiment to be described later. 
     Specifically, the controller  45  automatically selects and sets, in response to the outputs of the kind-of-paper setting means, one of various transport conditions matching with the kind of the papers  6 . The transport conditions are stored in the ROM in correspondence to the kinds of papers beforehand. When a trouble relating to paper transport occurs, the controller  45  automatically selects and sets, in response to the outputs of the condition changing and setting means, corrected transport conditions stored in the ROM and matching with the kind of the papers  6 . 
     The illustrative embodiment makes it needless for the operator to select the paper transport conditions of various sections in accordance with the kind of papers by hand. That is, only if the operator selects and inputs the kind of the papers  6  while watching the LCD  47 , the controller  45  automatically determines and sets optimal transport conditions matching with the papers  6  and thereby obviates transport troubles. Hereinafter will be described the contents to appear on the LCD  47  and the operation of the five keys  52 ,  48   a ,  48   b ,  48   c  and  48   d.    
     First, when the operator turns on the power switch of the printer, the LCD  47  displays the initial picture shown in FIG.  4 . In the initial picture, a job to be performed by the operator appears at the top. In FIG. 4, a specific message “Ready to make a master and print.” appears to show the operator that the printer is ready to perform the sequence beginning with master making and ending with printing. 
     Assume that the operator watching the initial picture on the LCD  47  presses the kind-of-paper key  52 . Then, a picture shown in FIG. 5 appears on the LCD  47  in place of the initial picture. As shown, four kinds of papers, i.e., “Standard Paper”, “Thin Paper”, “Thick Paper” and “Envelope” and “User 1” and “User 2” are included in the picture. “User 1” and “User 2” each allows the user to select a special kind of papers, as will be described specifically later. The illustrative embodiment allows the user to select transport conditions delicately in accordance with the kind of the papers  6 . This is why the above four different kinds of papers are displayed and selected by any one of the keys  48   a ,  48   b ,  53  and  48   d . If such delicate selection is not necessary, at least “Standard Paper” and “Thick Paper” suffice, as determined by a series of experiments. 
     The operator may not be fully informed of the contents of “Standard Paper”. In light of this, when the kind of the papers  6  is set via the kind-of-paper setting means, the illustrative embodiment displays together with “Standard Paper” more specific contents of the kind of the paper  6 . This allows the operator to easily see the kind of the papers  6  and select it immediately. 
     Usually, “Standard Paper” is selected and highlighted in black. The operator presses any one of the left arrow key  48   a , right arrow key  48   b , shift keys  53   c  and  53   a  in order to shift the highlighted portion and then presses the set key  48   d . In the specific condition shown in FIG. 5, “Standard Paper” is selected as the kind of the papers  6 , and “Ex. copy paper, medium quality paper, fine paper, recycled paper” is displayed below “Standard Paper” as more specific kinds. Likewise, when “Thin Paper” is selected, “Ex. rough printing paper” is displayed. For “Thick Paper”, “Ex. drawing paper, postcard” is displayed. For “Envelope”, “Ex. long, square and other regular envelopes” is displayed. 
     The operator having selected the kind of the papers  6  shifts the highlighted portion to the set key  48   d  on any one of the keys  48   a ,  48   b ,  53   c  and  53   a  in order to input the kind of the papers  6 . In response, the controller  45  automatically selects optimal transport conditions for the kind of the papers  6  input, i.e., a pick-up roller pressure, a pad pressure and a jump board angle out of a transport condition pattern table listed in Table 1 below. 
     
       
         
           
               
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Pick-Up Roller Pressure 
                 Pad Pressure 
                 Jump Board Angle 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                 Standard 
                 1 
                 4 
                 Medium to large 
               
               
                 Thin 
                 1 
                 2 
                 large 
               
               
                 Thick 
                 3 
                 2 
                 small 
               
               
                 Envelope 
                 2 
                 1 
                 small 
               
               
                   
               
            
           
         
       
     
     Then, the control ler  45  controls the feed pressure motor  25 , separation pressure motor  29  and jump board motor  43  such that the above pick-up roller pressure, pad pressure and jump board angle selected are set up. In this manner, transport conditions adequate for the kind of the papers  6  input are automatically set up. 
     Table 2 shown below is supplementary to the contents of Table 1 and roughly shows a relation between the pick-up roller pressure, pad pressure, feed failure, and overlap feed. 
     
       
         
           
               
               
             
               
                   
                 TABLE 2 
               
               
                   
                   
               
             
            
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
                   
               
            
           
           
               
               
            
               
                 Pick-Up Roller Pressure 
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
               
               
                 Pad Pressure 
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
               
            
           
         
       
     
     As shown in Table 2, the pick-up roller pressure causes paper feed to fail if excessively low or causes two or more papers to be fed at the same time if excessively high. In light of this, for thin papers or standard papers, a pick-up roller pressure lying in a low to medium range is selected as far as possible, as shown in Table 1 (corresponding to numerical value “1”; the pressure decreases with a decrease in the numerical value). For thick papers needing a great conveying force, a pick-up roller pressure lying in a high range (corresponding to numerical value “3”; the pressure increases with an increase in the numerical value) is selected. For envelopes, a pick-up roller pressure between the above two ranges (corresponding to numerical value “2”) should preferably be selected, as experimentally proved. 
     As shown in Table 2, the pad pressure causes paper feed to fail if excessively high or causes two or more papers to be fed at the same time if excessively low. In light of this, for standard papers, a pad pressure lying in a medium to high range is selected in order to obviate over lap feed, as shown in Table 1 (corresponding to numerical value “4”; the pressure increases with an increase in the numerical value). However, for thin papers, a pad pressure lying in a low to medium range (corresponding to numerical value “2”; the pressure decreases with a decrease in the numerical value) is selected because higher pressures would cause the papers to crease. For thick papers, too, the pad pressure Lying in the low to medium range (corresponding to numerical value “2”) is selected because higher pressures would cause the papers to peel off. For envelopes, a pad pressure lying in a low range (corresponding to numerical value “1” should preferably be selected, as experimentally determined. 
     As for the jump board angle, a medium to large range should be selected for standard papers in order to provide the papers with a sufficient degree of stiffness. This is also true with thin papers. For thick papers and envelopes, stiffening is not necessary and cannot be effected because such papers are originally stiff. Therefore, a small jump board angle must be selected for thick papers. 
     The transport condition pattern table of Table 1 is determined beforehand on the basis of, e.g., the results of experiments and stored in the ROM of the controller  45 . 
     In the illustrative embodiment, the transport condition pattern table lists only pick-up roller pressures, pad pressures and jump board angles in relation to the kinds of the papers  6 . For more delicate control, the table may additionally list, paying attention to the slip of the separator roller  13 , the amount of rotation of the separator roller  13  or list, paying attention to the rolling of papers, the velocity of air to issue from the air blower  34 . 
     A specific procedure for the operator to select and input the kind of the papers  6  and a paper feed and printing operation will be described hereinafter. First, when the operator turns on the power switch of the printer, the initial picture shown in FIG. 4 appears on the LCD  47 . The initial picture shows the previously mentioned message “Ready to make a master and print.” at its top, showing a job to be performed by the operator. 
     The operator watching the initial picture presses the kind-of-paper key  52 . Then, the picture shown in FIG. 5 appears on the LCD  47  in place of the initial picture. This picture shows a message “Please select the kind of papers.” at its top. Usually, “Standard Paper” is highlighted in the picture of FIG.  5 . When the operator desires to use drawing papers (thick papers) by way of example, the operator shifts the highlighted portion to the position of “Thick Paper” on the right arrow key  48   b  (arrow →) or the shift key  53   a  and then inputs it on the set key  48   d . As a result, “Ex. drawing paper, postcard” appears in the lower portion of the LCD  47 , allowing the operator to easily see that drawing papers belong to a group of thick papers. The operator can therefore immediately select and input “Thick Paper” without any doubt. 
     When the operator selects “Thick Paper” in the picture shown in FIG. 5, the controller  45  automatically selects the optical conditions for the thick papers  6 , i.e., a pick-up roller pressure “3”, a pad pressure “2” and a jump board angle “small” out of the transport condition pattern table of Table 1. Then, the controller  45  controls the motors  25 ,  29  and  43  such that the above particular numerical values are set up. 
     The operator having input the kind of the papers  6  presses the perforation start key  49 . In response, the conventional operation of the scanner for reading a document and the conventional automatic master making operation proceed in parallel. As a result, a master is wrapped around the print drum  1 . When the tray  4  is positioned at its lower limit position, as determined by the lower limit sensor  44 , the operator having input the kind of the papers  6  stacks the papers or drawing papers  6  on the tray  4  and then presses the print start key  50 . In response, the controller  45  causes the tray motor  9  to lift the tray  4 . 
     When the top of the paper stack  6  contacts the pick-up roller  12  and pushes it upward, the arm  18  also rises and presses the feeler  21   a  of the upper limit sensor  21 . As a result, the upper limit sensor  21  is turned on and sends an ON signal to the controller  45 . In response, the control ler  45  deenergizes the tray motor  9  and thereby stops the tray  4  at a preselected level for paper feed (paper feed position hereinafter). This is followed by a print mode operation. If the operator&#39;s recognition as to “Thick Paper” is objectively correct, then printing will occur under the adequate transport conditions from the beginning. 
     Subsequently, the print drum  1  is caused to rotate while the pick-up roller  12  is rotated by the feed motor  16 . The pick-up roller  12  pays out the top paper  6  in the paper feed direction  65 . The separator roller  13  and pad  14  cooperate to separate the top paper  6  from the underlying papers. Because the optimal transport conditions have already been set up, the papers  6  are surely fed one by one without jamming the transport path due to, e.g., feed failure. 
     When several papers  6  are fed out from the top of the paper stack on the tray  4 , the pick-up roller  12  and therefore the arm  18  is lowered. On sensing the arm  18 , the upper limit sensor  21  turns off and sends an OFF signal to the control ler  45 . In response, the controller  45  again energizes the tray motor  9 . As a result, the tray  4  is again raised until the upper limit sensor  21  turns on. In this manner, the tray motor  9  is selectively energized or deenergized in order to raise the tray  4  intermittently to the paper feed position. 
     The paper  6  fed out by the separator roller  13  abuts against the nip between the registration rollers  31  and  32  and is caused to suitably bend thereby. The registration rollers  31  and  32  start rotating in synchronism with the rotation of the ink drum  1 , feeding the paper  6  at a preselected timing. An image is printed on the paper  6  at the nip between the print drum I and the press roller  30 . Thereafter, the paper  6  with the image, i.e., a printing is driven out to the tray  37 . Because the optimal jump board angle has already been set up, the printing  6  is neatly positioned on the tray  37  with adequate stiffness (except when the paper is thick). The above procedure is repeated with the successive papers  6 . That is, a single paper  6  is fed and printed for one rotation of the print drum  1  without any jam or similar transport trouble and then driven out of the printer without any jam or similar transport trouble. 
     Even though the papers  6  are sequentially transported under the optimal transport conditions, a transport trouble may occur depending on the brand or the kind of the papers  6 , environmental conditions including temperature and humidity, and the degree of curl. In such a case, the operator may restore the picture shown in FIG. 5 in order to correct the transport conditions. When the operator watching the picture of FIG. 5 presses the condition change key  48   c , a picture shown in FIG. 6 appears on the LCD  47  in place of the picture of FIG.  5 . 
     In FIG. 6, a message “Please select a change of paper feed conditions.” is shown at the top of the picture. When overlap feed, for example, frequency occurs, the operator may press the right arrow key  48   b  (arrow →) five times (or press the shift key  53   d  once and then the shift key  53   a  twice) so as to shift the highlighted portion from “standard” to “Overlap feed: frequent), and then press the set key  48   d . As a result, the transport conditions (paper feed conditions) are corrected, as listed in Table 3 shown below. Table 3 will be referred to as a corrected transport condition pattern table. 
     
       
         
           
               
               
               
               
               
             
               
                   
                 TABLE 3 
               
               
                   
                   
               
               
                   
                 Rather 
                   
                   
                 Frequent 
               
               
                   
                 Frequent 
                 Frequent Feed 
                 Rather 
                 Overlap 
               
               
                   
                 Feed Failure 
                 Failure 
                 Frequent 
                 Feed 
               
               
                   
                 Pick-Up Roller 
                 Pick-Up Roller 
                 Overlap Feed 
                 Pad 
               
               
                   
                 Pressure 
                 Pressure 
                 Pad Pressure 
                 Pressure 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 Standard 
                 3 
                 5 
                 5 
                 6 
               
               
                 Thin 
                 3 
                 5 
                 3 
                 4 
               
               
                 Thick 
                 5 
                 6 
                 3 
                 4 
               
               
                 Envelope 
                 3 
                 5 
                 2 
                 3 
               
               
                   
               
            
           
         
       
     
     The above corrected transport condition pattern table is stored in the ROM beforehand for the reasons according to the reasons stated in relation to Tables 1 and 2 and on the basis of experimental results. 
     When the operator selects the change of paper feed conditions, the control ler  45  automatically selects optimal transport conditions, i.e., pick-up roller pressure, pad pressure and jump board angle listed in the above pattern table and matching with the kind of the papers  6 . Then, the controller  45  controls the variable feed pressure motor  25 , variable separation pressure motor  29  and jump board motor  43  such that the above corrected transport conditions are set up. The operator therefore should only select and input information matching with the pattern and degree of the transport trouble on any one of the keys  48   c ,  48   a ,  48   b  and  48   d . In response, the controller  45  automatically varies the existing transport conditions in order to avoid the transport trouble. 
     When the power switch is turned off, the corrected transport conditions are automatically replaced with the “standard” conditions. If desired, the corrected transport conditions may be temporarily stored by a preselected operation. 
     A first modification of the illustrative embodiment is as follows. This modification copes with special papers  6  particular to the user of the printer and unable to be adequately transported when any one of the standard papers, thin papers, thick papers and envelopes discussed above is selected. For this purpose, the modification allows the operator to select “User 1” or “User 2” mentioned previously for inputting optical transport conditions particular to the user. The ROM or the PROM stores many transport condition patterns beforehand in addition to the transport condition pattern table and corrected transport condition pattern table corresponding to the four different kinds of papers  6 . Any one of such additional tables is selected in accordance with transport conditions and allocated to “User 1” or “User 2” and can be called any time. The allocation of the additional table is performed in an initial set mode. The controller  45  includes the following additional control functions for executing the initial set mode. 
     When the operator presses the initial set key  51  on the operation panel  46 , a picture shown in FIG. 7 appears on the LCD  47 . As shown in FIG. 7, “User 1” is initially highlighted. When the operator watching the picture of FIG. 7 presses the set key  48   d , the LCD  47  shows a picture shown in FIG.  8 . As shown in FIG. 8, “Standard Paper: feed failure tendency” is highlighted. When the operator  48   d  watching the picture of FIG. 8 presses the set key  48   d , “Standard Paper: feed failure tendency” is allocated to “User 1”. In the picture of FIG. 8, examples of the papers  6  belonging to the highlighted kind are shown at the third row in a readable manner. This allows anyone to easily see the kind of papers  6  referred to by “Standard Paper: feed failure tendency”. As for “Thick Paper: feed failure tendency”, there may be displayed “Drawing paper and other thick papers apt to fail”. As for “medium thickness paper”, there may be displayed “Paper between standard paper and thick paper”. 
     In FIG. 8, “special paper” refers to papers set independently of the other papers, e.g., rare papers needing particular transport conditions and needing a serviceman. 
     Table  4  shown below is representative of a transport condition pattern table listing specific transport conditions to be allocated to “User 1” or “User 2”. 
     
       
         
           
               
               
               
               
             
               
                   
                 TABLE 4 
               
               
                   
                   
               
               
                   
                 Pick-Up Roller 
                   
                   
               
               
                   
                 Pressure 
                 Pad Pressure 
                 Jump Board Angle 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                 Standard: Feed 
                 3 
                 4 
                 large to medium 
               
               
                 Failure Tendency 
               
               
                 Standard: Overlap 
                 1 
                 5 
                 large to medium 
               
               
                 Feed Tendency 
               
               
                 Thick: Feed Failure 
                 5 
                 2 
                 small 
               
               
                 Tendency 
               
               
                 Thick: Overlap Feed 
                 3 
                 4 
                 small 
               
               
                 Tendency 
               
               
                 Medium Thick 
                 3 
                 3 
                 medium 
               
               
                 Special 
                 blank 
                 blank 
                 blank 
               
               
                 Thin 
                 1 
                 1 
                 large 
               
               
                   
               
            
           
         
       
     
     The data listed in Table  4  are stored in the ROM or the PROM beforehand for the same reasons as stated in relation to Tables 1 and 2 and on the basis of experimental results. 
     A conventional construction using a plurality of paper sensors may be used to detect transport troubles including over lap feed, feed jam and discharge jam, although not shown or described specifically. 
     If desired, an arrangement may be made such that when the paper sensor  100  determines that papers are absent or when the lower limit sensor  44  senses the lower limit position, the LCD  47  displays the kind of the current papers  6  and a message inquiring the operator whether or not to clear the current setting. 
     A second modification of the illustrative embodiment will be described hereinafter. As for the kind of the papers  6 , the illustrative embodiment has concentrated on the thickness of the papers  6 . The second modification differs from the illustrative embodiment mainly in that it pays attention to the size of the papers  6  in selecting optical transport conditions. 
     Specifically, when the operator watching the initial picture shown in FIG. 4 presses the kind-of-paper key  52 , a picture shown in FIG. 9 appears on the display  47 . In FIG. 9, a message “Please select a paper size. ” is shown at the top of the picture. “A3, B4”, “A4, B5” and “Postcard” are shown at the second row of the same picture as paper sizes. In this modification, any one of the above three different groups of paper sizes is automatically selected, as follows. 
     In the second modification, the paper size sensing mechanism including the size sensor group  70 , FIGS. 2 and 3, automatically determines the size of papers. When the papers  6  stacked on the tray  4  are of size A3 or B4 by way of example, “A3, B4” is highlighted in the picture of FIG. 9, informing the operator of the automatic selection of the paper size. The operator therefore should only press the set key  48   d  after confirming the highlighted paper size. In response, the controller  45  automatically selects optimal transport conditions matching with the above paper size, i.e., a pick-up roller pressure, a pad pressure and a jump board angle out of a transport condition pattern table based on experimental results and stored in the ROM beforehand. Table 5 shown below is the transport condition pattern table. 
     
       
         
           
               
               
               
               
             
               
                 TABLE 5 
               
               
                   
               
               
                   
                 Pick-Up Roller 
                   
                   
               
               
                 Paper Size 
                 Pressure 
                 Pad Pressure 
                 Jump Board Angle 
               
               
                   
               
             
            
               
                 A3, B4 
                 3 
                 3 
                 medium 
               
               
                 A4, B5 
                 1 
                 2 
                 large 
               
               
                 Postcard 
                 2 
                 1 
                 small 
               
               
                   
               
            
           
         
       
     
     The controller  45  controls the feed pressure motor  25 , separation pressure motor  29  and jump board motor  43  such that the optimal pick-up roller pressure, pad pressure and jump board angle matching with the paper size selected are set up. To supplement the contents of Table 5, for the papers  6  of relatively large size A3 or B4 needing a great conveying force, a high pick-up roller pressure is selected (corresponding to numerical value “3”). For the papers  6  of relatively small size A4 or B5 not needing a great conveying force, a low pick-up roller pressure is selected (corresponding to numerical value “1”). For postcards, a pick-up roller pressure substantially between the above high and low pick-up roller pressures should preferably be selected (corresponding to numerical size “2”), as experimentally proved. 
     A high pad pressure (corresponding to numerical value “3”) is selected for the papers  6  of relatively large size A3 or B4 in order to avoid overlap feed. However, amedium pad pressure (corresponding to numerical value “2”) is selected for the papers  6  of relatively small size A4 or B5. Likewise, a low pad pressure (corresponding to numerical value “1”) is selected for postcards, as determined on the basis of the results of experiments. 
     A large jump board angle is selected for the papers  6  of relatively small size A4 or B5 in order to provide them with a sufficient degree of stiffness. This is also true with the papers  6  of relatively large size A3 or B4. However, for postcards, a relatively small jump board angle is selected because postcards are originally stiff and because they cannot be stiffened. 
     The above automatic paper size selection using the size sensor group  70 , FIGS. 2 and 3, may be replaced with manual paper size selection, if desired. Specifically, assume that the operator stacks the papers  6  of size A4 or B5 on the tray  4 . In the picture shown in FIG. 9, “A3, B4” is initially highlighted, as stated earlier. The operator may shift the highlighted portion to “A4, B5” on either one of the keys  48   a ,  48   b ,  53   c  and  53   a  and then press the set key  48   d.    
     Of course, the contents of Table 3 or 4 are also applicable to the second modification. In the second modification, Table 5 lists only the pick-up roller pressures, pad pressures and jump board angles as transport conditions in relation to the sizes of the papers  6  to be selected. For more delicate control, the table may additionally list, paying attention to the slip of the separator roller  13 , the amount of rotation of the separator roller  13  or list, paying attention to the rolling of papers, the velocity of air to issue from the air blower  34 . Further, the thickness and size of the papers  6  may, of course, be combined for even more delicate control. 
     A third modification of the illustrative embodiment is as follows. The third modification differs from the illustrative embodiment mainly in that it adopts a tray angle as a transport condition in addition to the pick-up roller pressure, pad pressure, and jump board angle in order to implement more delicate control over the transport conditions. 
     FIG. 10 shows a tray angle adjusting mechanism  99 . As shown, the mechanism  99  has two tray parts  91  and  92  in place of the tray  4  shown in FIG.  1 . The tray part  91  is elevatable while the tray part  92  is tiltable relative to the tray part  91 . Tilting means  99 A causes the tray part  92  to angularly move relative to the tray part  91 . 
     The rack  10 , FIG. 1, is affixed to the tray part  91 . The tray part  91  is moved up and down by the tray motor  9 , FIG. 1, via the pinion gear  11 , FIG.  1 . The tray part  92  is tiltably connected to the side wall of the tray part  91  at the upstream side in the paper feed direction  65  by a pin  93 . 
     The tilting means  99 A includes a sector gear  98  formed integrally with the downstream end of the tray part  92  in the paper feed direction  65 . A tilt motor  94  is mounted on one side wall of the tray part  91  via a stationary member not shown. A worm gear  95  is mounted on the output shaft of the tilt motor  94 . A worm wheel  96  is rotatably mounted on one side wall of the tray part  91  via a shaft and held in mesh with the worm gear  95 . A small diameter gear  97  is mounted on the same shaft as the worm wheel  96  and held in mesh with the sector gear  98 . A tray angle sensor  104  (represented by a phantom block in FIG. 3) senses the angle θ of the tray part  92 . 
     The tilt motor  94  is implemented by a stepping motor and also represented by a phantom block in FIG.  3 . The tray angle sensor  104  may be implemented by a photoencoder mounted on the motor  94 , a shield plate mounted on one side wall of the tray part  92  for sensing the home position of the tray part  92 , and a transmission type photosensor mounted on one side wall of the tray part  91  and selectively engageable with the shield plate. The tray part  92  is determined to be in its home position when the stacking surface of the tray part  91  and that of the tray part  92  are substantially flush with each other. 
     In the above construction, the tilt motor  94  is driven to tilt the tray part  92  by the angle θ which is variable in a stepwise or stepless fashion, as desired. 
     In the third modification, when the operator selects and inputs the kind of the papers  6 , the controller  45  automatically selects an optimal transport condition matching with the kind of the papers  6 ,i.e., the angle θ of the tray part  92  out of a transport condition pattern table represented by Table 6 shown below. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 6 
               
               
                   
                   
               
               
                   
                 Kind of Paper 
                 Angle θ 
               
               
                   
                   
               
             
            
               
                   
                 Standard 
                  3° 
               
               
                   
                 Thick &amp; Postcard 
                 10° 
               
               
                   
                 Envelope 
                 15° 
               
               
                   
                   
               
            
           
         
       
     
     The controller  45  controls the tilt motor  94  such that the above angle θ matching with the kind of the papers  6  is set up. The angle θ added to the pick-up roller pressure, pad pressure and jump board angle implements more delicate control over the transport conditions in accordance with the kind of the papers  6 . 
     To supplement the contents of Table 6, a relatively small angle θ of 3° suffices for standard papers, as indicated by the results of experiments. For thick papers and postcards, a relatively great angle θ of 10° is selected to cope with the thickness. Envelopes are stacked on the tray parts  91  and  92  with their thickest portions overlapping each other directed to the downstream side in the paper feed direction  65 . Therefore, for the envelopes, an angle θ of 15° even greater than the angle θ assigned to the thick papers should preferably be selected in order to prevent the pick-up roller  12  from failing to feed them, as experimentally determined. 
     The contents of Table 6 are based on data derived from experiments and stored the in ROM beforehand. 
     Table 7 shown below roughly indicates a relation between the angle θ, feed failure, and overlap feed. 
     
       
         
           
               
               
             
               
                 TABLE 7 
               
               
                   
               
             
            
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
               
               
                 Angle θ 
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
               
            
           
         
       
     
     As shown in Table 7, increasing the angle θ is equivalent to increasing the pick-up roller pressure and therefore results in frequent overlap feed. It follows that if overlap feed frequently occurs at, e.g., the angle θ of 3° assigned to standard papers, then the angle θ should only be reduced. 
     Of course, the third modification may be combined with one or both of the first and second modifications. For more delicate control, thickness and size representative of the kind of the papers  6  may be combined. 
     At least an optimal pick-up roller pressure and an optimal pad pressure matching with the kind of the papers  6  are selected in order to obviate feed failure and overlap feed, as shown and described. Alternatively, only one of the pick-up roller pressure and pad pressure may be adjusted on the basis of the relation shown in Table 2. A fourth and a fifth modification of the illustrative embodiment to be described hereinafter uses such an alternative control scheme. 
     The fourth modification controls only the pick-up roller pressure included in the three different transport conditions of the illustrative embodiment. For this purpose, the fourth modification uses the pick-up roller pressure adjusting mechanism of the illustrative embodiment. The controller  45  selects an optimal pick-up roller pressure matching with the kind of the papers  6  selected and controls the feed pressure motor  25  in such a manner as to set up the optimal pressure. Table 8 shown below lists specific pick-up roller pressures. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 8 
               
               
                   
                   
               
               
                   
                 Pick-Up Roller 
                   
               
               
                   
                 Pressure 
                 Pad Pressure 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                   
                 Standard 
                 1 
                 3 
               
               
                   
                 Thin 
                 2 
               
               
                   
                 Thick 
                 4 
               
               
                   
                 Envelope 
                 3 
               
               
                   
                   
               
            
           
         
       
     
     To supplement the contents of Table 8, when the pick-up roller pressure is varied alone, a pad pressure of about “3” is set up. This, however, would make the pad pressure excessive for thin papers, thick papers and envelopes. In the fourth modification, slightly high pick-up roller pressures corresponding to numerical values “2”, “4” and “3” are respectively assigned to thin papers, thick papers and envelopes in order to avoid feed failure. 
     In this modification, when feed failure which is a specific transport trouble occurs, the condition changing and setting means sends a signal representative of the pattern and degree of the trouble to the controller  45 . In response, the controller  45  automatically selects a corrected transport condition, i.e., a corrected pick-up roller pressure matching with the kind of the papers  6  and controls the feed pressure motor  25  in such a manner as to set up the above pressure. 
     This modification may include, based on the basic concept of Table 2 and a concept according to Table 3 and Table 4 of the first modification, a corrected transport condition pattern table relating to feed failure which is one of the patterns of the above trouble. Then, the degree of the pattern of the trouble can be set by selecting feed failure listed in the above table. Alternatively, the modification may include a corrected transport condition pattern table relating overlap feed which is another pattern of the trouble. In this case, the degree of the pattern of the trouble can be set by selecting overlap feed listed in the table. 
     The fifth modification controls only the pad pressure. For this purpose, the fifth modification uses the separation pressure adjusting mechanism of the illustrative embodiment. The controller  45  selects an optimal pad pressure matching with the kind of the papers  6  selected and controls the separation pressure motor  29  in such a manner as to set up the optimal pressure. Table 9 shown below lists specific pad pressures. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 9 
               
               
                   
                   
               
               
                   
                   
                 Pick-Up Roller 
               
               
                   
                 Pad Pressure 
                 Pressure 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                   
                 Standard 
                 4 
                 2 
               
               
                   
                 Thin 
                 2 
               
               
                   
                 Thick 
                 1 
               
               
                   
                 Envelope 
                 1 
               
               
                   
                   
               
            
           
         
       
     
     To supplement the contents of Table 9, when the pad pressure is varied alone, a pick-up roller pressure of about “2” is set up. This, however, would make the pick-up roller pressure short for thick papers and envelopes. In the fifth modification, a slightly low pad pressure corresponding to numerical value “1” is assigned to thick papers and envelopes in order to avoid feed failure. 
     In the fifth modification, when overlap fed which is another specific transport trouble occurs, the condition changing and setting means sends a signal representative of the pattern and degree of the trouble to the controller  45 . In response, the controller  45  automatically selects a corrected transport condition, i.e., a corrected pad pressure matching with the kind of the papers  6  and controls the separation pressure motor  29  in such a manner as to set up the above pressure. 
     This modification may include, based on the basic concept of Table 2 and a concept according to Table 3 and Table 4 of the first modification, a corrected transport condition pattern table relating to overlap feed which is one of the patterns of the above trouble. Then, the degree of the pattern of the trouble can be set by selecting overlap feed listed in the above table. Alternatively, the modification may include a corrected transport condition pattern table relating to feed failure which is another pattern of the trouble. In this case, the degree of the pattern of the trouble can be set by selecting feed failure listed in the table. 
     The present invention is not limited to the illustrative embodiment or the first to fifth modifications thereof. For example, in a printer including a suitable combination of a feed pressure adjusting mechanism, a separation pressure adjusting mechanism, a jump board angle adjusting mechanism, and a tray angle adjusting mechanism, an arrangement may be made such that control means automatically selects, in response to the output of kind-of-paper setting means or condition changing and setting means, optimal transport conditions relating to the above mechanisms and controls variable drive sources respectively included in the mechanisms. 
     In summary, it will be seen that the present invention provides a printer having various unprecedented advantages, as enumerated below. 
     (1) Only if the operator selects and inputs the kind of papers to be used, control means automatically selects optimal transport conditions and sets them without resorting to operator&#39;s manual switching operation. This successfully obviates overlap feed, feed failure jam and other troubles relating to paper transport at at least a paper feed section. 
     (2) Even an untrained person can immediately input the kind of papers without any doubt while watching information appearing on an LCD provided on an operation panel. 
     (3) The operator should only select and input the kind and frequency of a trouble while watching the LCD of the operation panel. The control means automatically varies the transport conditions set beforehand and sets up optimal corrected transport conditions for obviating the trouble. This realizes an extremely simple measure for dealing with transport troubles. 
     (4) At least standard papers and thick papers can be selected and input as the kinds of papers. Such papers can therefore be used more effectively than papers conventionally used with printers. 
     (5) Optimal transport conditions selected can be stored in the control means and can therefore be called every time papers of the same kind are used. This makes it needless for the operator to set transport conditions each time. 
     Various modifications will become possible for those skilled in the art after receiving the teachings of the present disclosure without departing from the scope thereof.