JP6305586B2 - Printing device - Google Patents

Description

  The present invention relates to a printing apparatus, and more particularly to a printing apparatus that performs printing processing on a recording medium with a thermal head via an ink ribbon.

  2. Description of the Related Art Conventionally, printing apparatuses that form images such as face photographs and character information on a printing medium such as a plastic card are widely known. In this type of printing apparatus, a direct printing method in which an image is directly formed on a recording medium with a thermal head via an ink ribbon, or an image (mirror image) is formed on a transfer film with a thermal head via an ink ribbon, and then An indirect printing method is used in which an image formed on a transfer film is transferred to a recording medium.

  In general, when printing is performed using a thermal head, the thermal head is used to reduce the capacity of the power supply voltage, to ensure the stability of the power supply voltage (to prevent voltage drop), and to reduce the size of the thermal head. A time difference is provided in the energization start timing so that energization for each strobe applied (input) is not simultaneous. Each heating element of the thermal head is composed of a resistor, and the current (energy amount) flowing through each heating element is I (current) = V (voltage) / R (resistance). In addition, a voltage drop occurs in the power supply voltage due to a large current when the thermal head is energized.

  For example, in Patent Document 1, a heating period and a non-heating period are provided, and divided into a start period and an end period in a printing cycle, and a chopping energization period near the end period between heating periods near the start period. A technique has been disclosed in which withstanding the temperature, the withstand voltage or the withstand electric capacity is reduced and the printing speed is improved.

  That is, in the technique of Patent Document 1, as shown in FIG. 21, the first strobe signal STB1 is changed from the OFF state to the ON state at time t1, and the first strobe signal is turned on at time t2, as shown in FIG. The STB1 is turned off, the second strobe signal STB2 is turned from the off state to the on state, the second strobe signal STB2 is turned off at time t3, and the same energization control is performed for the print processing for the second and subsequent print lines. And by not simultaneously energizing the heating elements by the first strobe signal STB1 and the second strobe signal STB2, the amount of energy is suppressed and the electric resistance is reduced.

Japanese Patent Application No. 2010-84499 (see FIG. 8)

  On the other hand, in recent years, this type of printing apparatus is particularly required to increase the printing speed. As a countermeasure, it is effective to reduce the time difference between energization start timings. For example, as shown in FIG. 22, for the printing process of the first print line, the first strobe signal STB1 is changed from the off state to the on state at time t1, and the second strobe signal STB2 is changed from the off state to the on state at time t2. At time t3, the first strobe signal STB1 is turned off, and at time t4, the second strobe signal STB2 is turned off (from time t2 to time t3, the first strobe signal STB1 and the second strobe signal STB2 are applied to the heating elements. It is conceivable that the same energization control is performed for the printing processing for the second and subsequent printing lines.

  However, when the energization control shown in FIG. 22 is performed, the printing speed can be increased, but there is a problem that density unevenness occurs. That is, a voltage drop of the thermal head applied voltage Vhead (power supply voltage) occurs when the first strobe signal STB1 is turned on at time t1, and after the thermal head applied voltage Vhead due to this voltage drop (at time t2) When the strobe signal STB2 is turned on, a further voltage drop of the thermal head applied voltage Vhead is caused, so that a difference occurs in the current (energy amount). As a result, during the printing of one print line, the first strobe signal STB1 has a larger energy loss than the second strobe signal STB2.

  FIG. 20A shows one printing line to four printings by eight (R1 to R8) heating elements among the heating elements arranged in the main scanning direction when the energization control shown in FIG. 22 is performed. The printing state up to the line is schematically shown. Image formation by the heating elements (R2, R4, R6, R8) driven by the second strobe signal STB2 becomes darker than image formation by the heating elements (R1, R3, R5, R7) driven by the first strobe signal STB1. Density unevenness occurs.

  An object of the present invention is to provide a printing apparatus capable of speeding up printing and reducing density unevenness in view of the above-described case.

In order to solve the above-described problem, the present invention provides a thermal head having a plurality of heating elements arranged in a main scanning direction in a printing apparatus that performs printing processing on a recording medium with an ink ribbon via a thermal head; Energization control means for switching energization timings of the plurality of heating elements, wherein the energization control means includes a first strobe signal for switching on / off of energization of a part of the plurality of heating elements, and the plurality of heating elements. The second strobe signal for switching on / off of the other part of the energization is partially overlapped with the energization time for energizing part of the plurality of heating elements and the other part. And an energization start timing for switching energization to a part of the plurality of heating elements to an ON state and an energization start for switching energization to other parts of the plurality of heating elements to an ON state. And timing is controlled to temporally different, the said second strobe signal is turned on the first strobe signal after the on-state, the first strobe signal after the second strobe signal in an on state Is turned off, the second strobe signal is turned off, the second strobe signal is turned on, the first strobe signal is turned on, and the first strobe signal is turned on. The energization timing is switched for a part of the plurality of heating elements and the other part so that the two strobe signals are turned off and the first strobe signal is turned off .

In the present invention, the energization control means, and the application end timing of switching the conduction of the power supply to part of the plurality of heating elements to another part of the power distribution end timing and a plurality of heating elements switching off state to the OFF state temporally may be controlled a first strobe signal and second strobe signal so different.

Et al is, the plurality of heating elements are composed of a main scanning direction a plurality of which are divided into blocks, the heating elements of the odd-numbered blocks are energized controlled by the energization control means at the same timing as the first strobe signal, the even The heating elements of the second block may be energized and controlled by energization control means at the same timing as the second strobe signal.

  Further, the first strobe signal and the second strobe signal have a plurality of energization pulses for turning on energization of a part of the plurality of heating elements and the other part of the printing process of one printing line. You may do it.

  The first strobe signal and the second strobe signal have a plurality of energization pulses for turning on energization of a part of the plurality of heating elements and the other part of the printing process for one print line. Then, the energization control means may control so that the strobe signal to which the energization pulse that is first turned on among the first strobe signal and the second strobe signal belongs is different for each print line.

According to the present invention, the energization control means causes the first and second strobe signals to partially overlap the energization times of a part of the plurality of heating elements and the other part, and a plurality of The energization start timing for switching energization to a part of the heating elements to the on state and the energization start timing for switching energization to other parts of the plurality of heating elements to the on state are controlled so as to be temporally different. The printing speed can be increased , the second strobe signal is turned on after the first strobe signal is turned on, and the first strobe signal is turned off after the second strobe signal is turned on. 2 strobe signals are turned off, then the second strobe signal is turned on, the first strobe signal is turned on, and the first strobe signal is turned on. Since the energization timing is switched for a part of the plurality of heating elements and the other part so that the strobe signal is turned off and the first strobe signal is turned off, the shades are mixed evenly. When viewed, it is possible to obtain an effect that there appears to be no density unevenness .

1 is an external view of a printing system including a printing apparatus according to a first embodiment to which the present invention is applicable. It is a block diagram of the printing apparatus of 1st Embodiment. It is explanatory drawing of the control state by the cam in the stand-by position where the pinch roller and the film transport roller are separated and the platen roller and the thermal head are separated. It is explanatory drawing of the control state by the cam in the printing position which the pinch roller and the film conveyance roller contact | abut, and the platen roller and the thermal head are contact | abutting. It is explanatory drawing of the control state by the cam in the conveyance position which the pinch roller and the film conveyance roller contact | abut, and the platen roller and the thermal head are contact | abutting. FIG. 6 is an operation explanatory diagram illustrating a state of a standby position of the printing apparatus. FIG. 6 is an operation explanatory diagram illustrating a state of a conveyance position of the printing apparatus. It is operation | movement explanatory drawing explaining the state of the printing position of a printing apparatus. It is an external view which shows the structure of the 1st unit integrated so that a film conveyance roller, a platen roller, and its peripheral part may be integrated in a printing apparatus. It is an external view which shows the structure of the 2nd unit integrated so that a pinch roller and its peripheral part may be integrated in a printing apparatus. It is an external view of the 3rd unit integrated to incorporate a thermal head in a printing apparatus. FIG. 2 is a block diagram illustrating a schematic configuration of a control unit of the printing apparatus according to the first embodiment. It is a block circuit diagram which shows the thermal head energization control circuit of 1st Embodiment. It is a block circuit diagram which simplified the thermal head energization control circuit of a 1st embodiment typically. First embodiment showing the relationship among the first strobe signal, the second strobe signal, the thermal head applied voltage, the thermal head ground voltage, the supply energy to the heating element by the first strobe signal, and the supply energy to the heating element by the second strobe signal. It is a timing chart of a form. 3 is a flowchart of a print processing routine executed by a CPU of a control unit of the printing apparatus according to the first embodiment. Second embodiment showing the relationship among the first strobe signal, the second strobe signal, the thermal head applied voltage, the thermal head ground voltage, the supply energy to the heating element by the first strobe signal, and the supply energy to the heating element by the second strobe signal. It is a timing chart of a form. The third embodiment showing the relationship among the first strobe signal, the second strobe signal, the thermal head applied voltage, the thermal head ground voltage, the supply energy to the heating element by the first strobe signal, and the supply energy to the heating element by the second strobe signal. It is a timing chart of a form. 10 is a flowchart of a print processing routine executed by a CPU of a control unit of a printing apparatus according to a third embodiment. FIG. 22 schematically shows a printing state from one printing line to four printing lines by eight heating elements among the heating elements arranged in the main scanning direction, and FIG. , (B) corresponds to the energization control shown in FIG. 15, and (C) corresponds to the energization control shown in FIG. The prior art shows the relationship between the first strobe signal, the second strobe signal, the thermal head applied voltage, the thermal head ground voltage, the supply energy to the heating element by the first strobe signal, and the supply energy to the heating element by the second strobe signal. It is a timing chart. FIG. 6 is a timing chart showing the relationship between the first strobe signal, the second strobe signal, the thermal head applied voltage, the thermal head ground voltage, the energy supplied to the heating element by the first strobe signal, and the energy supplied to the heating element by the second strobe signal. is there. Reference timing chart showing the relationship among the first strobe signal, the second strobe signal, the thermal head applied voltage, the thermal head ground voltage, the supply energy to the heating element by the first strobe signal, and the supply energy to the heating element by the second strobe signal It is. It is a reference block circuit diagram showing a thermal head energization control circuit. FIG. 23 schematically shows a printing state from one printing line to four printing lines by eight heating elements among the heating elements arranged in the main scanning direction, and corresponds to the energization control shown in FIG.

(First embodiment)
A first embodiment in which the present invention is applied to a printing apparatus that prints and records characters and images on a card (recording medium) and magnetically or electrically records information on the card will be described below.

<System configuration>
As shown in FIGS. 1 and 12, the printing apparatus 1 of the present embodiment constitutes a part of a printing system 200. In other words, the printing system 200 is roughly configured by a host device 100 (for example, a host computer such as a personal computer) and the printing device 1.

  The printing apparatus 1 is connected to the upper apparatus 100 via an interface (not shown), and print data, magnetic or electrical recording data, etc. are transmitted from the upper apparatus 100 to the printing apparatus 1 to perform a recording operation or the like. Can be instructed. Note that the printing apparatus 1 includes an operation panel unit (operation display unit) 5 (see FIG. 12), and in addition to a recording operation instruction from the host apparatus 100, a recording operation instruction from the operation panel unit 5 is also possible.

  The host device 100 generally includes an image input device 110 such as a digital camera or a scanner, an input device 102 such as a keyboard or a mouse for inputting commands and data to the host device 100, data generated by the host device 100, and the like. A monitor 101 such as a liquid crystal display for displaying is connected.

<Printing device>
As illustrated in FIG. 2, the printing apparatus 1 includes a housing 2, and the housing 2 includes an information recording unit A, an image forming unit B, a medium storage unit C, and a storage unit D.

  The information recording unit A includes a magnetic recording unit 24, a non-contact type IC recording unit 23, and a contact type IC recording unit 27.

  The medium accommodating portion C accommodates a plurality of cards arranged in a standing posture, and a separation opening 7 is provided at the tip thereof so that the pickup roller 19 feeds out the cards from the front row. It has become.

  The fed card is first sent to the reversing unit F by the carry-in roller 22. The reversing unit F includes a rotating frame 80 supported by the housing 2 so as to be pivotable and two pairs of rollers 20 and 21 supported by the frame. The roller pairs 20 and 21 are axially supported by the rotary frame 80 so as to be rotatable.

  A magnetic recording unit 24, a non-contact type IC recording unit 23, and a contact type IC recording unit 27 are disposed on the outer periphery around which the reversing unit F turns. The pair of rollers 20 and 21 forms a medium carry-in path 65 for carrying in either of the information recording units 23, 24, and 27, and the card is magnetically or electrically connected to the card in these recording units. Data is written.

  The image forming unit B forms an image such as a face photograph or character data on the front and back surfaces of the card, and a medium transport path P1 for transporting the card is provided on the extension of the medium transport path 65. In addition, transport rollers 29 and 30 for transporting the cards are arranged in the medium transport path P1, and are connected to a transport motor (not shown).

  The image forming unit B includes a film-like medium conveyance device. First, a primary transfer unit that prints an image with a thermal head 40 on a transfer film 46 conveyed by the conveyance device, and then a heat roller 33. And a secondary transfer portion that prints an image printed on the transfer film 46 on the surface of the card in the medium transport path P1.

  On the downstream side of the image forming unit B, a medium transport path P2 for transporting the printed card to the storage stacker 60 is provided. Conveying rollers 37 and 38 for conveying cards are arranged in the medium conveying path P2, and are connected to a conveying motor (not shown).

  A decurling mechanism 36 is disposed between the conveying roller 37 and the conveying roller 38, and the curl generated by the thermal transfer by the heat roller 33 is corrected by pressing the central portion of the card held between the conveying rollers 37 and 38. For this reason, the decurling mechanism 36 is configured to be movable in the vertical direction shown in FIG. 2 by a lifting mechanism such as a cam (not shown).

  The accommodating portion D is configured to accommodate the card sent from the image forming portion B in the accommodating stacker 60. The storage stacker 60 is configured to move downward in FIG.

  The image forming unit B in the overall configuration of the printing apparatus 1 will be described in more detail.

  The transfer film 46 is wound around a take-up roll 47 and a feed roll 48 of a transfer film cassette that is rotated by driving of the motor Mr2. The film transport roller 49 is a main driving roller that transports the transfer film 46, and the transport amount and transport stop position of the transfer film 46 are determined by controlling the driving of the roller 49. Although the motor Mr2 is also driven when the film transport roller 49 is driven, it is for winding the transfer film 46 fed out by the take-up roll 47, and is not intended to drive the transfer film 46 as a main transporter. .

  A pinch roller 32 a and a pinch roller 32 b are disposed on the peripheral surface of the film transport roller 49. Although not shown in FIG. 2, the pinch rollers 32 a and 32 b are configured to be movable so as to advance and retreat with respect to the film conveyance roller 49, and the state shown in the drawing advances to the film conveyance roller 49 and comes into pressure contact therewith. Thus, the transfer film 46 is wound around the film transport roller 49. As a result, the transfer film 46 is accurately transported at a distance corresponding to the number of rotations of the film transport roller 49.

  The ink ribbon 41 is accommodated in a cassette 42, and a feed roll 43 and a take-up roll 44 are accommodated in the cassette 42. The take-up roll 44 is driven by a motor Mr1.

  The platen roller 45 and the thermal head 40 constitute a primary transfer portion, and the thermal head 40 is disposed at a position facing the platen roller 45. The thermal head 40 is heated and controlled in accordance with image data by a head control IC (see FIG. 13), and prints an image on the transfer film 46 using a sublimation ink ribbon 41. The thermal head 40 of this embodiment has 1344 heating elements arranged in the main scanning direction, details of which will be described later (see <Thermal Head Energization Control Circuit>). The cooling fan 39 is for cooling the thermal head 40.

  The ink ribbon 41 that has finished printing on the transfer film 46 is peeled off from the transfer film 46 by the peeling roller 25 and the peeling member 28. The peeling member 28 is fixed to the cassette 42, and the peeling roller 25 moves to the peeling member 28 at the time of printing, and the transfer film 46 and the ink ribbon 41 are sandwiched between them to perform peeling. The peeled ink ribbon 41 is taken up by a take-up roll 44 driven by a motor Mr1, and the transfer film 46 is conveyed by a film conveying roller 49 to a secondary transfer portion including the platen roller 31 and the heat roller 33. The

  In the secondary transfer portion, the transfer film 46 is sandwiched between the heat roller 33 and the platen roller 31 together with the card, and the image on the transfer film 46 is transferred to the card surface. The heat roller 33 is attached to an elevating mechanism (not shown) so as to be pressed against and separated from the platen roller 31 via the transfer film 46.

  The configuration of the primary transfer portion will be described in more detail along with its operation. As shown in FIGS. 3 to 5, the pinch rollers 32 a and 32 b are respectively supported by the upper end and the lower end of the pinch roller support member 57, and the pinch roller support member 57 is attached to a support shaft 58 that passes through the central portion thereof. It is supported rotatably. As shown in FIG. 10, both ends of the support shaft 58 are bridged over elongated holes 76 and 77 provided in the pinch roller support member 57, and are fixed by a fixing portion 78 of the bracket 50 at an intermediate portion. Further, the long holes 76 and 77 have a space in the horizontal direction and the vertical direction with respect to the support shaft 58. Therefore, the pinch rollers 32a and 32b can be adjusted with respect to a film transport roller 49 described later.

  Then, the spring member 51 (51a, 51b) is mounted on the support shaft 58, and the ends of the pinch roller support member 57 on the side where the pinch rollers 32a, 32b are mounted are in contact with the spring member 51 and the springs. It is urged toward the film transport roller 49 by force.

  The bracket 50 is in contact with the cam operating surface of the cam 53 at the cam receiver 81, and rotates the cam 53 in the direction of the arrow with the cam shaft 82 driven by the drive motor 54 (see FIG. 10) as a fulcrum. Accordingly, the film conveying roller 49 is configured to move in the left-right direction in the figure. Therefore, when the bracket 50 advances toward the film transport roller 49 (FIGS. 4 and 5), the pinch rollers 32a and 32b press against the film transport roller 49 with the transfer film 46 sandwiched against the spring member 51, The transfer film 46 is wound around the film transport roller 49.

  At this time, the pinch roller 32b located far from the shaft 95, which is the pivot point of the bracket 50, first presses the film transport roller 49, and then the pinch roller 32a presses. As described above, by arranging the shaft 95 that is the rotation fulcrum above the film transport roller 49, the pinch roller support member 57 contacts the film transport roller 49 while rotating, not in parallel. There is an advantage that the space in the width direction is less than that of the movement.

  Further, the pressure contact force when the pinch rollers 32 a and 32 b are in pressure contact with the film transport roller 49 is made uniform with respect to the width direction of the transfer film 46 by the spring member 51. At that time, since the elongated holes 76 and 77 are provided on both sides of the pinch roller support member 57 and the support shaft 58 is fixed by the fixing portion 78, the pinch roller support member can be adjusted in three directions, and the film The transfer film 46 is conveyed in a correct posture without causing skew by the rotation of the conveying roller 49. The adjustment in the three directions here means (i) the pinch roller 32a with respect to the axis of the film conveying roller 49 in order to make the axial contact force of the pinch rollers 32a, 32b uniform with respect to the film conveying roller 49. In order to adjust the parallelism of the horizontal axis of the shaft 32b, and (ii) the pressure contact force of the pinch roller 32a to the film transport roller 49 and the pressure contact force of the pinch roller 32b to the film transport roller 49 Adjusting the moving distance between the pinch roller 32a and the pinch roller 32b with respect to the transport roller 49, and (iii) the axis of the film transport roller 49 so that the axes of the pinch rollers 32a and 32b are perpendicular to the film traveling direction. The parallelism in the vertical direction of the axes of the pinch rollers 32a and 32b is adjusted.

  The bracket 50 is provided with a tension receiving member 52 that comes into contact with a portion of the transfer film 46 that is not wound around the film transport roller 49 when the bracket 50 advances toward the film transport roller 49.

  In the tension receiving member 52, the pinch rollers 32a and 32b resist the biasing force of the spring member 51 by the tension of the transfer film 46 generated when the pinch rollers 32a and 32b press the transfer film 46 against the film transport roller 49, respectively. Are provided to prevent the film from being retracted from the film conveying roller 49. Therefore, the tension receiving member 52 is attached to the tip of the end portion on the rotating side of the bracket 50 so as to come into contact with the transfer film 46 at a position left of the pinch rollers 32a and 32b in the drawing. FIG. 2 shows a state in which the tension receiving member 52 is in contact with the transfer film 46.

  Thereby, the tension generated from the elasticity of the transfer film 46 can be directly received by the cam 53 through the tension receiving member 52. Therefore, this tension prevents the pinch rollers 32a and 32b from retracting from the film transport roller 49 and weakening the pressure contact force of the pinch rollers 32a and 23b, so that the transfer film 46 is tightly wound around the film transport roller 49. The state is maintained and accurate conveyance can be performed.

  As shown in FIG. 9, the platen roller 45 disposed along the horizontal width direction of the transfer film 46 is supported by a pair of platen support members 72 that can rotate about a shaft 71. The pair of platen support members 72 support both ends of the platen roller 45. Each of the platen support members 72 is connected to an end portion of a bracket 50 </ b> A having the shaft 71 as a common rotation shaft via a spring member 99.

  The bracket 50 </ b> A includes a substrate 87 and a cam receiving support portion 85 formed by bending the substrate 87 in the direction of the platen support member 72. The cam receiving support portion 85 holds the cam receiver 84. A cam 53A that rotates with a cam shaft 83 driven by the drive motor 54 as a fulcrum is disposed between the substrate 87 and the cam receiver support 85, and the cam operating surface and the cam receiver 84 come into contact with each other. It is configured as follows. Accordingly, when the bracket 50 </ b> A advances toward the thermal head 40 by the rotation of the cam 53 </ b> A, the platen support member 72 also moves and the platen roller 45 comes into pressure contact with the thermal head 40.

  Thus, by arranging the spring member 99 and the cam 53A vertically between the bracket 50A and the platen support member 72, the platen moving unit can be accommodated within the interval between the bracket 50A and the platen support member 72. . Further, the width direction can be accommodated within the width of the platen roller 45, and space saving can be achieved.

  Further, since the cam receiving and supporting portion 85 is fitted into the perforated portions 72a and 72b (see FIG. 9) formed in the platen supporting member 72, the cam receiving and supporting portion 85 protrudes in the direction of the platen supporting member 72. Even if it forms, the space | interval of bracket 50A and the platen support member 72 does not spread, and space saving can be achieved also in the surface.

  When the platen roller 45 is in pressure contact with the thermal head 40, the spring members 99 connected to the respective platen support members 72 act so that the pressure contact force in the width direction of the transfer film 46 becomes uniform. Therefore, skew is prevented when the transfer film 46 is transported by the film transport roller 49, and the thermal transfer by the thermal head 40 can be performed accurately without the print area of the transfer film 46 being shifted in the width direction.

  The substrate 87 of the bracket 50A is provided with a pair of peeling roller support members 88 that support both ends of the peeling roller 25 via spring members 97. The peeling roller 25 is provided by the rotation of the cam 53A by the bracket 50A. When advancing to the thermal head 40, the transfer film 46 and the ink ribbon 41, which are in contact with the peeling member 28 and are sandwiched between them, are peeled off. Similarly to the platen support member 72, the peeling roller support members 88 are also provided at both ends of the peeling roller 25, respectively, so that the pressure contact force in the width direction with respect to the peeling member 28 is uniform.

  A tension receiving member 52A is provided at the end of the bracket 50A opposite to the end on the shaft support 59 side. The tension receiving member 52A is provided so as to absorb the tension of the transfer film 46 that is generated when the platen roller 45 and the peeling roller 25 are pressed against the thermal head 40 and the peeling member 28, respectively. The spring member 99 and the spring member 97 are provided to make the pressure contact force in the width direction of the transfer film 46 uniform, but conversely, the spring members 99 and 97 lose the tension of the transfer film 46 and apply to the transfer film 46. The tension receiving member 52A receives the tension from the transfer film 46 so that the pressure contact force is not weakened. Since the tension receiving member 52A is also fixed to the bracket 50A similarly to the tension receiving member 52 described above, the tension of the transfer film 46 is received by the cam 53A via the bracket 50A. You wo n’t lose. As a result, the pressure contact force between the thermal head 40 and the platen roller 45 and the pressure contact force between the peeling member 28 and the peeling roller 25 are maintained, so that favorable printing and peeling can be performed. Further, when the film transport roller 49 is driven, there is no error in the transport amount of the transfer film 46, and the length of the printing area is accurately transported to the thermal head 40 and can be printed with high accuracy.

  The cam 53 and the cam 53A are driven by the same drive motor 54 with a belt 98 (see FIG. 3) stretched between them.

  When the image forming unit B is in the standby position shown in FIG. 6, the cam 53 and the cam 53A are in the state shown in FIG. 3, and the pinch rollers 32a and 32b are not in pressure contact with the film transport roller 49. The platen roller 45 is not in pressure contact with the thermal head 40.

  Then, when the cam 53 and the cam 53A rotate in conjunction with each other and the state shown in FIG. 4 is reached, the image forming unit B shifts to the printing position shown in FIG. At that time, first, the pinch rollers 32 a and 32 b wind the transfer film 46 around the film transport roller 49, and the tension receiving member 52 contacts the transfer film 46. Thereafter, the platen roller 45 comes into pressure contact with the thermal head 40. In this printing position, the platen roller 45 moves toward the thermal head 40 to sandwich and press the transfer film 46 and the ink ribbon 41, and the peeling roller 25 is in contact with the peeling member 28.

  In this state, when the transfer of the transfer film 46 is started by the rotation of the film transport roller 49, the ink ribbon 41 is simultaneously wound around the winding roll 44 by the operation of the motor Mr1 and transported in the same direction. During this conveyance, the positioning mark provided on the transfer film 46 moves by a predetermined amount through the sensor Se, and when the transfer film 46 reaches the print start position, the thermal head 40 is placed in a predetermined area of the transfer film 46. Is printed. In particular, since the tension of the transfer film 46 is increased during printing, the tension of the transfer film 46 is such that the pinch rollers 32a and 23b are separated from the film conveying roller 46, and the peeling roller 25 and the platen roller from the peeling member 28 and the thermal head 40. 45 in the direction of separating them. However, as described above, since the tension of the transfer film 46 is received by the tension receiving members 52 and 52A, the pressure contact force of the pinch rollers 32a and 32b is not weakened, and accurate film conveyance can be performed. Since the pressure contact force between the thermal head 40 and the platen roller 45 and the pressure contact force between the peeling member 28 and the peeling roller 25 are not weakened, accurate printing and peeling can be performed. The ink ribbon 41 after completion of printing is peeled off from the transfer film 46 and taken up on the take-up roll 44.

  The amount of movement of the transfer film 46 conveyed, that is, the length in the conveyance direction of the printing area where printing is performed, is detected by a sensor (not shown) provided on the film conveyance roller 49, and the film conveyance roller 49 accordingly. , And the winding by the winding roll 44 due to the operation of the motor Mr2 is also stopped. Thereby, the printing of the 1st color to the said printing area | region of the transfer film 46 by the thermal head 40 is complete | finished.

  When the cam 53 and the cam 53A further rotate in conjunction with each other and the state shown in FIG. 5 is reached, the image forming section B moves to the transport position shown in FIG. 8, and the platen roller 45 is retracted from the thermal head 40. Return. In this state, the pinch rollers 32a and 32b still wind the transfer film 46 around the film transport roller 49, the tension receiving member 52 is in contact with the transfer film 46, and the transfer film 46 is rotated by the reverse rotation of the film transport roller 49. Reversely conveyed to the initial position. At this time as well, the moving amount of the transfer film 46 is controlled by the rotation of the film transport roller 49, but the length in the transport direction of the print area on which printing has been performed is transported in reverse. The ink ribbon 41 is stopped and is in a state in which the panel for the next color to be printed is kept waiting at the initial position.

  Then, the control state by the cams 53 and 53A becomes the state shown in FIG. 4 again and becomes the printing position shown in FIG. 7, the platen roller 45 is brought into pressure contact with the thermal head 40, and the film transport roller 49 again rotates in the forward direction. When the transfer film 46 is moved by the length of the printing area, printing with the next color is performed by the thermal head 40.

  Thus, the operations at the print position and the transport position are repeated until printing of all colors is completed. When the printing (primary transfer) by the thermal head 40 is completed, the primary transfer area of the transfer film 46 is conveyed to the heat roller 33. At this time, the cams 53 and 53A move to the state shown in FIG. The pressure contact with the transfer film 46 is released. Subsequent secondary transfer is performed by transferring the film onto the card while the transfer film is conveyed by driving the take-up roll 47.

  Such an image forming unit B is divided into three units 90, 91, 92 and integrated.

  A first unit 90 shown in FIG. 9 has a drive shaft 70 that is rotated by driving a motor 54 (see FIG. 10) mounted on a unit frame 75, and a film transport roller 49 is attached to the drive shaft 70. Yes. Below the film transport roller 49, a bracket 50A and a pair of platen support members 72 are disposed, and these members are rotatably supported by shafts 71 mounted on both side plates of the unit frame 75. Yes.

  In FIG. 9, a pair of cam receiving support portions 85 that are a part of the bracket 50 </ b> A appear from the perforated portions 72 a and 72 b formed in the platen support member 72. The cam receiver support portion 85 holds a pair of cam receivers 84 disposed on the rear side thereof. A cam 53 </ b> A that is attached to the cam shaft 83 that is inserted through the unit frame 75 is disposed further rearward of the cam receiver 84. The cam shaft 83 is mounted on both side plates of the unit frame 75.

  The thermal head 40 is disposed at a position facing the platen roller 45 with the transfer path between the transfer film 46 and the ink ribbon 41 interposed therebetween. As shown in FIG. 11, the thermal head 40, the member related to heating, and the cooling fan 39 are integrated with the third unit 92 and are arranged to face the first unit 90.

  The first unit 90 holds the platen roller 45, the peeling roller 25, and the tension receiving member 52A whose positions are changed by a printing operation in a movable bracket 50A so as to adjust the position between these members. Is no longer necessary. Moreover, by moving the bracket 50 </ b> A by the rotation of the cam 53, these members can be moved to a predetermined position. Further, since the bracket 50A is provided, it can be accommodated in the same unit as the fixed film conveyance roller 49, and a transfer driving portion by the film conveyance roller 49 that must convey the transfer film with high accuracy, and a transfer position by the platen roller 45 are provided. Since the restriction part is included in the same unit, the position adjustment between them is not necessary.

  In the second unit 91 shown in FIG. 10, the cam shaft 82 on which the cam 53 is mounted is inserted through the unit frame 55, and the cam shaft 82 is connected to the output shaft of the drive motor 54. The second unit 91 supports the bracket 50 movably on the unit frame 55 so as to come into contact with the cam 53, and the pinch roller support member 57 is rotatably supported on the bracket 50. The support shaft 58 and the tension receiving member 52 are fixed.

  The pinch roller support member 57 has spring members 51a and 51b attached to the support shaft 58, and the end portions thereof are brought into contact with both ends of the pinch roller support member 57 supporting the pinch rollers 32a and 32b, respectively. The film is urged in the direction of the film conveying roller 49. The pinch roller support member 57 has a support shaft 58 inserted into the long holes 76 and 77, and the support shaft 58 is fixedly supported by the bracket 50 at the center.

  A spring 89 is provided between the bracket 50 and the pinch roller support member 57 to urge the pinch roller support member 57 toward the bracket 50. Since the pinch roller support member 57 is urged by the spring 89 in the direction of retreating from the film transport roller 49 of the first unit 90, when the transfer film cassette is set in the printing apparatus 1, The transfer film 46 can be easily passed between the second units 91.

  The second unit 91 holds the pinch rollers 32a and 32b and the tension receiving member 52 whose positions change according to the printing operation by the bracket 50A, and moves the bracket 50A by the rotation of the cam 53. In order to move the rollers 32a and 32b and the tension receiving member 52, the position adjustment between them and the position adjustment between the pinch rollers 32a and 32b and the film transport roller 49 are simplified. Such a second unit 91 is arranged to face the first unit 90 with the transfer film 46 interposed therebetween.

  By unitizing in this way, the first unit 90, the second unit 91, and the third unit 92 are each pulled out from the main body of the printing apparatus 1 in the same manner as the cassettes of the transfer film 46 and the ink ribbon 41. Will also be possible. Therefore, if the units 90, 91, and 92 are removed as necessary when the cassette is replaced due to the consumption of the transfer film 46 and the ink ribbon 41, the transfer film 46 and the ink ribbon 41 when the cassette is inserted can be easily installed in the apparatus. It can be mounted on.

  As described above, the first unit 90 in which the platen roller 45, the bracket 50A, the cam 53A, and the platen support member 72 are integrated, the pinch rollers 32a and 32b, the bracket 50, the cam 53, and the spring member 51 are integrated. In combination with the second unit 91, the third unit 92 to which the thermal head 40 is attached is arranged so as to face the platen roller 45, and is adjusted during assembly and maintenance during the production of the printing apparatus. Can be performed easily and accurately. In addition, since it is integrated, it can be easily detached from the apparatus, and handling as a printing apparatus is improved.

  Next, the control and electrical system of the printing apparatus 1 will be described. As shown in FIG. 12, the printing apparatus 1 includes a control unit 120 that controls the operation of the entire printing apparatus 1, and a power supply unit that converts a commercial AC power source into a DC power source that can drive / operate each mechanism unit and the control unit. 130.

<Control unit of printing apparatus>
As shown in FIG. 12, the control unit 120 includes a microcomputer 122 (hereinafter simply referred to as a microcomputer 122) that performs overall control processing of the printing apparatus 1. The microcomputer 122 is a CPU that operates as a central processing unit with a high-speed clock, a ROM that stores basic control operations (programs and program data) of the printing apparatus 1, a RAM that functions as a work area of the CPU, and an internal bus that connects these. It is configured.

  An external bus is connected to the microcomputer 122. On the external bus, an interface (not shown) for communication with the host device 100, print data to be printed on the card, recording data to be magnetically or electrically recorded on the magnetic stripe portion of the card or built-in IC, etc. Is temporarily connected to the buffer memory 121.

  The external bus includes a sensor control unit 123 that controls signals from various sensors, an actuator control unit 124 that controls a motor driver that sends drive pulses and drive power to each motor, and a heating element that constitutes the thermal head 40. The thermal head energization control circuit 125 for controlling the heat energy to the operation panel, the operation display control unit 126 for controlling the operation panel unit 5, and the information recording unit A described above are connected. Physically, the thermal head energization control circuit 125 is disposed on the thermal head 40.

  The power supply unit 130 supplies operating / driving power to the control unit 120, the thermal head 40, the operation panel unit 5, and the information recording unit A.

<Thermal head energization control circuit>
Next, the thermal head energization control circuit 125 of the printing apparatus 1 according to the present embodiment will be described with reference to FIG.

  As described above, the thermal head 40 includes 1344 heating elements arranged in the main scanning direction. A printing process for one printing line by one heating element constitutes one pixel (one dot) of an image formed on the transfer film 46. In FIG. 13, this heating element is represented by R as a resistor. In the present embodiment, corresponding to IC1 to IC7, 1344 heating elements are divided into 7 blocks (first block to seventh block) of 192 pieces each.

  As shown in FIG. 13, one end of each heating element R is connected to a thermal head applied voltage Vhead (power supply voltage), and the other end is connected to an IC corresponding to the block to which the heating element R belongs. Each IC has, for example, 192 AND circuits and NOT circuits. For example, the other end of each heating element R belonging to the first block is connected to the output side of the NOT circuit connected to the output side of the AND circuit (see also FIG. 14).

  One input side of each AND circuit is connected to one of seven strobe signal input ports STB1 to STB7 to which a strobe signal is input. For example, one input side of each AND circuit of IC1 is connected to the first strobe signal STB1 input port, and one input side of each AND circuit of IC2 is connected to the second strobe signal STB2 input port ( (See also FIG. 14). The other input side of each AND circuit is connected to the shift register SR. The other input side of each AND circuit and the shift register SR are connected by a bus. The first strobe signal STB1 input port, the third strobe signal STB3 input port, the fifth strobe signal STB5 input port, and the seventh strobe signal STB7 input port are input with a first strobe signal described later at the same timing, The second strobe signal STB2 input port, the fourth strobe signal STB4 input port, and the sixth strobe signal STB6 input port receive a second strobe signal described later at the same timing.

  The shift register SR receives a print line data signal (DATA), a clock signal (CLK), and a latch signal (LATCH) for taking in the print line data signal from the microcomputer 122. An electrolytic capacitor Ca is inserted between the thermal head applied voltage Vhead and the thermal head ground voltage VGND to alleviate the voltage drop of the thermal head applied voltage Vhead due to energization of each heating element. With such a configuration, only the heating element R in which the print line data signal is input and the STB is turned on is energized.

<First and second strobe signals>
Next, the first strobe signal and the second strobe signal input to each strobe signal input port will be described. The thermal head applied voltage Vhead (power supply voltage), the energy supplied to the heating element by the first strobe signal and the second strobe signal (integrated value of energization current) will also be described.

As shown in FIG. 15, for the printing process of the first print line, the first strobe signal STB1 is turned on at time t1, and the second strobe signal STB2 is turned on at time t2. Thereafter, the first strobe signal STB1 is turned off at time t3, and the second strobe signal STB2 is turned off at time t4. Next, for the printing process of the second print line, the second strobe signal STB2 is turned on at time t5, and the first strobe signal STB1 is turned on at time t6. Thereafter, the second strobe signal STB2 is turned off at time t7, and the first strobe signal STB1 is turned on at time t8. The printing process for odd-numbered printing lines after the third printing line is the same as the printing process for the first printing line, and the printing process for even-numbered printing lines after the third printing line is the second printing line. Similar to the printing process, ON / OFF of the first strobe signal STB1 and the second strobe signal STB2 is controlled.

  Since the first strobe signal STB1 is turned on at time t1, a voltage drop occurs in the thermal head applied voltage Vhead, and the second strobe signal is obtained at time t2 before the thermal head applied voltage Vhead returns to the original voltage. STB2 is turned on. Further, since the second strobe signal STB2 is turned on at time t5, a voltage drop occurs in the thermal head applied voltage Vhead, and the first time t6 before the thermal head applied voltage Vhead returns to the original voltage. The strobe signal STB1 is turned on. As a result, there is a difference between the energy supplied to the heating element by the first strobe signal STB1 (integrated value of energization current) and the energy supplied to the heating element by the second strobe signal STB2 (integrated value of the energizing current). The first strobe signal STB1 and the second strobe signal STB2 that are turned on first differ for each print line (for example, the first strobe signal STB1 and the first strobe signal STB1 and the second printline The first strobe signal STB2 is turned on first.) Therefore, for example, the energy supplied to the heating element (the energization current) by the first strobe signal STB1 in the printing process of the first printing line and the printing process of the second printing line. And the second strobe signal in the printing process for the first printing line and the printing process for the second printing line. STB2 becomes also the supply energy to the heating element (integrated value of electric current) by.

Therefore, the first strobe signal STB1 and the second strobe signal STB2 shown in FIG. 15 satisfy the following three energization conditions.
(1) Energizing the heating elements belonging to the odd-numbered blocks (first, third, fifth, and seventh blocks) and even-numbered blocks (second, fourth, and sixth blocks) shown in FIG. The energization time to be turned on partially overlaps (for example, time t2 to time t3, time t6 to time t7),
(2) Energization start timing (time t1, t2, t5, t6) for switching energization to the heating elements belonging to the odd-numbered blocks and the heating elements belonging to the even-numbered blocks shown in FIG. The energization stop timings (time t3, t4, t7, t8) for switching the energization to the heating elements belonging to the odd-numbered blocks and the heating elements belonging to the even-numbered blocks shown in FIG. And (3) when the same density data is printed over a plurality of lines in the odd-numbered blocks and the heating elements belonging to the even-numbered blocks shown in FIG. 13, the odd-numbered print lines (for example, the first print line) ) And the even-numbered print line and the integrated value of the energizing current flowing through the heating elements belonging to the odd-numbered blocks shown in FIG. For example, the sum of the integrated values of the energization currents flowing through the heating elements belonging to the odd-numbered blocks and the odd-numbered print lines (for example, the first print line) shown in FIG. The integrated value of the energization current flowing through the heating elements belonging to the even-numbered blocks shown in FIG. 13 during the printing process and the odd-numbered blocks shown in FIG. 13 during the printing process for the even-numbered print lines (for example, the second print line) And the sum of the energized currents flowing through the heating elements belonging to the same value.

(Operation)
Next, a printing process operation on the transfer film 48 of the printing apparatus 1 of the present embodiment will be described mainly with a CPU of the microcomputer 120 (hereinafter simply referred to as a CPU). Since the entire operation of the printing apparatus 1 has already been described, the duplication is avoided here, and the one-color printing process and the generation of the strobe signal by the thermal head 40 are described and shown in FIG. 15 for better understanding. The relationship with the time on the timing chart is also mentioned.

  As shown in FIG. 16, the CPU executes print line data processing in step 202. In this print line data processing, the CPU confirms dots that meet the heating conditions based on the print data transmitted from the host apparatus 100 and creates each print line data. The first print line data is stored in the thermal head 40. To the shift register SR. The image data is separated into color components (original data is R, G, B) on the host device 100 side, converted from R, G, B to Y, M, C by the printing device 1 and used as print data. The Bk data set on the upper apparatus 100 side is also used as the Bk print data in the printing apparatus 1.

  In the next step 204, it is determined whether or not odd-numbered printing lines are printed. If the determination is affirmative, the first strobe signal STB1 is turned on in the next step 206 (for example, time t1 in FIG. 15). Next, in step 208, it is determined whether or not it is an energization start timing for turning on the second strobe signal STB2 (for example, time t2 in FIG. 15). In step 210, the second strobe signal STB2 is turned on.

  Next, at step 212, it is determined whether or not it is an energization end timing (for example, time t3 in FIG. 15) at which the first strobe signal STB1 is turned off. If negative determination is made, the process waits. , The first strobe signal STB1 is turned off. In the next step 216, it is determined whether or not it is an energization end timing (for example, time t4 in FIG. 15) in which the second strobe signal STB2 is turned off. At 218, the second strobe signal STB2 is turned off and the routine proceeds to step 234.

  On the other hand, if the determination in step 204 is negative, the second strobe signal STB2 is turned on in step 220 (for example, time t5 in FIG. 15) for printing even-numbered print lines. Next, in step 222, it is determined whether or not it is an energization start timing (for example, time t6 in FIG. 15) for turning on the first strobe signal STB1, and if a negative determination is made, the process waits. In step 224, the first strobe signal STB1 is turned on.

  Next, at step 226, it is determined whether or not it is an energization end timing (for example, time t7 in FIG. 15) at which the second strobe signal STB2 is turned off. When negative determination is made, the process waits. When positive determination is made, the next step 228 is performed. The second strobe signal STB2 is turned off. In the next step 230, it is determined whether or not it is an energization end timing (for example, time t8 in FIG. 15) at which the first strobe signal STB1 is turned off. At 232, the first strobe signal STB1 is turned off and the routine proceeds to step 234.

  In step 234, it is determined whether or not printing is completed. If the determination is negative, the process returns to step 202 to output the next print line data to the shift register SR of the thermal head 40. If the determination is affirmative, the printing process is terminated. .

  Incidentally, FIG. 14 schematically shows a part of the block circuit diagram shown in FIG. In the block circuit diagram of FIG. 14, the heating elements R of the first block to the seventh block are each composed of only one resistor, and IC1 to IC7 are composed of only one AND circuit and NOT circuit, This is different from the block circuit diagram shown in FIG. 13 in that a heating element R8 is added. In the block circuit diagram shown in FIG. 13, the first strobe signal STB1 is input to the odd-numbered strobe signal (STB1, STB3, STB5, STB7) input port among the first to seventh strobe signal input ports. Since the first strobe signal STB2 is input to the strobe signal (STB2, STB4, STB6) input port, the first strobe signal STB1 input port and the second strobe signal STB2 input port are simplified. .

  FIG. 20B schematically shows a printing state from one printing line to four printing lines by the heating elements R1 to R8 when the energization control shown in FIG. 15 is performed according to the block circuit diagram of FIG. It is shown. Density unevenness occurs at the pixel (dot) level, but since the shades are mixed evenly, it appears that there is no density unevenness when viewed with the human eye. Note that FIG. 20A described above schematically shows a printing state when the energization control shown in FIG. 22 is performed, based on the block circuit diagram of FIG.

  According to the printing apparatus 1 of the present embodiment, the printing speed can be increased by the above-described energization condition (1), and the thermal head applied voltage when the heating element is energized by the above-described energization condition (3). It is possible to reduce the occurrence of density unevenness due to the voltage drop of Vhead.

(Second Embodiment)
Next, a second embodiment in which the present invention is applied to a printing apparatus will be described. In the second embodiment, the first strobe signal STB1 and the second strobe signal STB2 have the heating elements belonging to the odd-numbered blocks and the even-numbered blocks shown in FIG. This is a mode having a plurality of energization pulses for turning on energization to the ON state. In the second and subsequent embodiments, the description of the same configuration and the like as those of the above-described first embodiment will be omitted, and only different points will be described below.

  As shown in FIG. 17, for the printing process of the first print line, the first strobe signal STB1 is turned on at time t1, and the second strobe signal STB2 is turned on at time t2. The first strobe signal STB1 is turned off at time t3, and the second strobe signal STB2 is turned on at time t4. Thereafter, the second strobe signal STB2 is turned on again at time t5, and the first strobe signal STB1 is also turned on again at time t6. The second strobe signal STB2 is turned off at time t7, and the first strobe signal is turned off at time t8. Also for the printing process of the second and subsequent printing lines, on / off of the first strobe signal STB1 and the second strobe signal STB2 is controlled as in the printing process of the first printing line.

  The timing chart of FIG. 17 differs from the timing chart shown in FIG. 15 in the following two points. (A) The first strobe signal STB1 and the second strobe signal STB2 are applied to the heating elements belonging to the odd-numbered blocks and the even-numbered blocks shown in FIG. (B) Regardless of the print line, the first strobe signal STB1 and the second strobe signal STB2 that are turned on first are the first strobe signals that are turned on. 1 strobe signal STB1. However, it is the same in that the three energization conditions (1) to (3) described in the first embodiment are satisfied.

  In the second embodiment, the CPU executes a printing process different from the printing process shown in the flowchart (FIG. 16) shown in the first embodiment. However, referring to FIG. Since the printing process executed by the CPU in the timing chart is clear, the description thereof is omitted.

(Third embodiment)
Next, a third embodiment in which the present invention is applied to a printing apparatus will be described. In the third embodiment, the first strobe signal STB1 and the second strobe signal STB2 have the heating elements belonging to the odd-numbered blocks and the even-numbered blocks shown in FIG. There are a plurality of energization pulses for turning on the energization of the first strobe signal STB1 and the second strobe signal STB2 to which the energization pulse that is first turned on belongs to each print line. It is a different form and is a form suitable for gradation expression. In the following, a case where the first strobe signal STB1 and the second strobe signal STB2 each have three energization pulses for the printing process of one printing line will be described.

  As shown in FIG. 18, for the printing process of the first print line, the first strobe signal STB1 is turned on at time t1, and the second strobe signal STB2 is turned on at time t2. The first strobe signal STB1 is turned off at time t3, and the second strobe signal STB2 is turned on at time t4. That is, the first energization pulse of the first strobe signal STB1 is turned on at time t1 and turned off at time t3, and the first energization pulse of the second strobe signal STB2 is turned on at time t2. It is turned off at time t4. These two energization pulses are odd-numbered energization pulses of odd-numbered print lines. Thereafter, the second strobe signal STB2 is turned on again at time t5, the first strobe signal STB1 is turned on again at time t6, the second strobe signal STB2 is turned off again at time t7, and the first strobe signal STB2 is turned on again. The signal STB1 is also turned off again at time t8. That is, the second energization pulse of the second strobe signal STB2 is turned on at time t5 and turned off at time t7, and the second energization pulse of the first strobe signal STB1 is turned on at time t6. It is turned off at time t8. These two energization pulses are the even-numbered energization pulses of the odd-numbered print lines. Furthermore, the first strobe signal STB1 is turned on three times at time t9, the second strobe signal STB2 is also turned on three times at time t10, and the first strobe signal STB1 is turned off three times at time t11. The second strobe signal STB2 is also turned off three times at time t12. That is, the third energization pulse of the first strobe signal STB1 is turned on at time t9 and turned off at time t11, and the third energization pulse of the second strobe signal STB2 is turned on at time t10. It is turned off at time t12. These two energization pulses also correspond to the odd-numbered energization pulses of the odd-numbered print lines.

  For the printing process of the second print line, the second strobe signal STB2 is turned on at time t13, and the first strobe signal STB1 is turned on at time t14. The second strobe signal STB2 is turned off at time t15, and the first strobe signal STB1 is turned on at time t16. That is, for the printing process of the second print line, the first energization pulse of the second strobe signal STB2 is turned on at time t13 and turned off at time t15, and the first strobe signal STB1 of the first strobe signal STB1 is turned on. The energization pulse is turned on at time t14 and turned off at time t16. These two energization pulses are odd-numbered energization pulses of even-numbered print lines. Thereafter, the first strobe signal STB1 is turned on again at time t17, the second strobe signal STB2 is also turned on again at time t18, the first strobe signal STB1 is turned off again at time t19, and the second strobe signal STB1 is turned on again. The signal STB2 is also turned off again at time t20. That is, for the printing process of the second print line, the second energization pulse of the first strobe signal STB1 is turned on at time t17 and turned off at time t19, and the second strobe signal STB2 of the second strobe signal STB2 is turned on. The energization pulse is turned on at time t18 and turned off at time t20. These two energization pulses are even-numbered energization pulses of even-numbered print lines. Further, the second strobe signal STB2 is turned on three times at time t21, the first strobe signal STB1 is also turned on three times at time t22, and the second strobe signal STB2 is turned off three times at time t23, The first strobe signal STB1 is also turned off three times at time t24. That is, for the printing process of the second print line, the third energization pulse of the second strobe signal STB2 is turned on at time t21 and turned off at time t23, and the third strobe signal STB1 of the first strobe signal STB1 is turned on. The energization pulse is turned on at time t22 and turned off at time t24. These two energization pulses also correspond to the odd-numbered energization pulses of the odd-numbered print lines. The printing process for the third and subsequent print lines is repeated as described above.

  The timing chart of FIG. 18 differs from the timing chart shown in FIG. 15 in that the first strobe signal STB1 and the second strobe signal STB2 are odd-numbered blocks shown in FIG. 17 and a plurality of energization pulses for turning on energization to the heating elements belonging to the even-numbered blocks and the timing chart shown in FIG. The first strobe signal STB1 and the second strobe signal STB2 are different in the strobe signal that is first turned on.

  Next, print processing executed by the CPU of the printing apparatus 1 according to the third embodiment will be described. In addition, in order to deepen understanding, the relationship with the time of the timing chart shown in FIG. 18 is also mentioned.

  As shown in FIG. 19, the CPU executes print line data processing in step 252. In this print line data process, the CPU creates each print line data as in the process of step 202 in FIG. Then, pulse data for each dot in the print line is created for gradation expression and output to the shift register SR of the thermal head 40 (step 253). By repeating the process of creating and printing the pulse data 256 times, 256 gradations can be expressed. Even when 256 gradations are expressed in one pixel (dot), the number of energized pulses is not necessarily 256, and for example, the maximum number of energized pulses may be 20. In that case, a table defining the relationship of gradation / pulse number may be referred to determine the number of energized pulses in accordance with the gradation, or the number of energized pulses may be calculated by applying a mathematical formula. Good. In this case, for example, the energization pulse number is determined / calculated as 10 (about) for an intermediate gradation. In the following description, a case where the number of energization pulses in the first print line is three will be described, corresponding to FIG.

  In the next step 254, it is determined whether or not there is an odd-numbered print line and an odd-numbered energization pulse, or an even-numbered print line and an even-numbered energization pulse. Thus, since the first strobe signal STB1 is turned on before the second strobe signal STB2, the first strobe signal STB1 is turned on in the next step 256 (for example, time t1 in FIG. 18). Note that odd-numbered print lines and odd-numbered energization pulses are shown in [1] and [3] of FIG. 18, and odd-numbered print lines and even-numbered energization pulses are shown in [2] of FIG. The line and odd-numbered energization pulses correspond to [1] 'and [3]' in FIG. 18, and the even-numbered print line and even-numbered energization pulses correspond to [2] 'in FIG. Next, in step 258, it is determined whether or not it is an energization start timing for turning on the second strobe signal STB2 (for example, time t2 in FIG. 18). In step 260, the second strobe signal STB2 is turned on.

  Next, in step 262, it is determined whether or not it is an energization end timing for turning off the first strobe signal STB1 (for example, time t3 in FIG. 18). If negative determination is made, the process waits. If positive determination is made, the next step 264 is performed. , The first strobe signal STB1 is turned off. In the next step 266, it is determined whether or not it is the energization end timing (for example, time t4 in FIG. 18) at which the second strobe signal STB2 is turned off. If the determination is negative, the process waits; At 268, the second strobe signal STB2 is turned off and the routine proceeds to step 284.

  On the other hand, if the determination in step 254 is negative, the second strobe signal STB2 is turned on prior to the first strobe signal STB1 as is apparent from FIG. Is turned on (for example, time t5 in FIG. 18). Next, in step 272, it is determined whether or not it is an energization start timing (for example, time t6 in FIG. 18) for turning on the first strobe signal STB1, and if the determination is negative, the process waits. In step 274, the first strobe signal STB1 is turned on.

  Next, at step 276, it is determined whether or not it is an energization end timing (for example, time t7 in FIG. 18) at which the second strobe signal STB2 is turned off. When negative determination is made, the process waits. When positive determination is made, the next step 278 is performed. The second strobe signal STB2 is turned off. In the next step 280, it is determined whether or not it is an energization end timing (for example, time t8 in FIG. 18) at which the first strobe signal STB1 is turned off. At 282, the first strobe signal STB1 is turned off and the routine proceeds to step 284.

  In step 284, it is determined whether printing of the print processing target line is completed. In this example, since there are three energization pulses for one print line, the processing from step 254 to step 282 is repeated three times. If a negative determination is made, the process returns to step 254 to perform processing for the next energization pulse. If an affirmative determination is made, whether or not printing has been completed in step 286, that is, whether all print lines have been processed. If the determination is negative and the determination is negative, the process returns to step 252 to output the next print line data to the shift register SR of the thermal head 40 and determine / calculate the number of energization pulses to perform the print processing of the next print line. If the determination is affirmative, the printing process is terminated.

  Incidentally, the first strobe signal STB1 and the second strobe signal STB2 in the timing chart shown in FIG. 18 are suitable for gradation expression as described above. Therefore, the number of energization pulses may be intentionally varied for each print line for gradation expression. However, as described above, in the case of the same number of energization pulses for each printing line, as shown in FIG. 20B, density unevenness occurs at the pixel (dot) level, but the lightness and darkness are evenly entered. Therefore, it appears that there is no density unevenness when viewed with human eyes. For this point, refer to the supply energy to the heating element by the first strobe signal STB1 shown in FIG. 18 (integrated value of energization current) and the supply energy to the heating element by the second strobe signal STB2 (integration value of energization current). This is clear. Therefore, the third embodiment basically satisfies the three energization conditions (1) to (3) described in the first embodiment.

  FIG. 20C schematically shows a printing state from one printing line to four printing lines by the heating elements R1 to R8 when the energization control shown in FIG. 18 is performed according to the block circuit diagram of FIG. It is shown. When this is seen, since the density is more finely and evenly mixed as compared with FIG. 20B, it appears that there is no density unevenness when viewed with human eyes.

  In the above-described embodiment, an example in which the present invention is applied to the indirect printing type printing apparatus 1 has been described. However, the present invention is not limited thereto, and is applicable to a direct printing type printing apparatus. Further, although the card is exemplified as the recording medium, the present invention is not limited to this. For example, the recording medium is long, (elliptical), polygonal, film-like, paper-like, or thick. The present invention can also be applied to a recording medium.

  In the above embodiment, seven strobe input ports are provided corresponding to IC1 to IC7 and the heating elements are divided into the first block to the seventh block. However, the present invention is not limited to this, and the thermal element is not limited to this. The head 40 only needs to have two or more strobe input ports so that the first strobe signal STB1 and the second strobe signal STB2 are input. Also, the number of ICs is not limited to seven. For example, if one IC can handle, there is no need to divide the first block to the seventh block.

  Further, although not within the scope of the present invention, as shown in FIG. 23, for the printing process of the first print line, the first strobe signal STB1 is turned on at time t1, and the second strobe signal STB2 is turned on at time t2. The first strobe signal STB1 is turned off at time t3, the second strobe signal STB2 is turned off at time t4, and the on / off energization control is similarly performed for the second and subsequent print lines. Good. In this reference example, although (1) and (2) are satisfied among the three energization conditions shown in the first embodiment, an odd-numbered print line (for example, the first print line) is printed for (3). Sometimes, the integrated value of the energization current flowing through the heat generating elements belonging to the odd-numbered blocks shown in FIG. 13 and the even-numbered print lines (for example, the second print line) belong to the odd-numbered blocks shown in FIG. Integration of the sum of the energization currents flowing through the heating elements and the integration of the energization currents flowing through the heating elements belonging to the even-numbered blocks shown in FIG. 13 during the printing process of odd-numbered print lines (for example, the first print line). The sum of the current value and the integrated value of the energization currents flowing through the heating elements belonging to the odd-numbered blocks shown in FIG. From Rukoto, but results in a slight inferiority in density unevenness, looks like there is not much of concentration unevenness when viewed by the human eye (see FIG. 25).

  Similarly, although not within the scope of the present invention, the thermal head energization control circuit may be configured as shown in FIG. In this reference example, the example of eight heating elements R1 to R8 shown in FIG. 14 is increased to 192, for example, and 192 is processed as one block by one IC.

  As described above, the present invention provides a printing apparatus capable of increasing the printing speed and reducing density unevenness, and thus contributes to the manufacture and sale of the printing apparatus. Have

1 Printing device 40 Thermal head 41 Ink ribbon 122 Microcomputer (energization control means)
R, R1 to R8 Heating element STB1 First strobe signal STB2 Second strobe signal

Claims (5)

In a printing apparatus that prints on a recording medium with a thermal head via an ink ribbon,
A thermal head having a plurality of heating elements arranged in the main scanning direction;
An energization control means for switching energization timings of the plurality of heating elements,
The energization control means includes
A first strobe signal for switching on / off of energization of a part of the plurality of heating elements; and a second strobe signal for switching on / off of energization of another part of the plurality of heating elements;
Energization time for turning on energization to a part of the plurality of heating elements and the other part partially overlaps, and
An energization start timing for switching energization to a part of the plurality of heating elements to an on state and an energization start timing for switching energization to another part of the plurality of heating elements to an on state are different in time. control and,
After turning on the first strobe signal, turning on the second strobe signal;
After turning on the second strobe signal, turning off the first strobe signal and turning off the second strobe signal;
Then, after the second strobe signal is turned on, the first strobe signal is turned on,
The energization timing for a part of the plurality of heating elements and the other part so that the second strobe signal is turned off and the first strobe signal is turned off after the first strobe signal is turned on. Switch
A printing apparatus characterized by that.   The energization control means has a time period for energizing to switch off energization to some of the plurality of heating elements and an energization end timing to switch off energization to other parts of the plurality of heating elements. The printing apparatus according to claim 1, wherein the first strobe signal and the second strobe signal are controlled so as to be different from each other. The plurality of heating elements are composed of a plurality of blocks divided in the main scanning direction,
The heating elements of the odd-numbered blocks are energized and controlled by the energization control means at the same timing as the first strobe signal,
Numbered the heating elements of the block printing apparatus according to claim 1 or claim 2, characterized in that it is energized controlled by the energization control means at the same timing as the second strobe signal. The first strobe signal and the second strobe signal include a plurality of energization pulses for turning on energization of a part of the plurality of heating elements and the other part of the printing process for one print line. printing apparatus according to any one of claims 1 to 3, characterized in that it has. The first strobe signal and the second strobe signal include a plurality of energization pulses for turning on energization of a part of the plurality of heating elements and the other part of the printing process for one print line. And the energization control means performs control so that the strobe signal to which the energization pulse that is first turned on differs among the first strobe signal and the second strobe signal for each print line. The printing apparatus according to any one of claims 1 to 3 .

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