JP6370685B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus, and can be applied to, for example, an image forming apparatus that forms an image on a medium using a print head.

  Patent Document 1 describes a technique related to a dot line printer that performs density correction of print quality. In the technology described in Patent Document 1, the speed of the ribbon motor is varied depending on the print density in the print section. When the print density is low, the speed of the ribbon motor is decreased, and when the print density is high, the speed of the ribbon motor. Is to make it faster. As a result, the occurrence of local unevenness in the ink impregnation amount of the ink ribbon is suppressed, and unevenness in density of printing is reduced.

JP 2009-119757 A

  However, when the image forming apparatus prints adjacent print patterns on the front and back lines, if printing is performed at different print speeds on the front and back lines, the impact force of the print head in each line fluctuates, so Printing unevenness can occur.

  For example, as shown in FIG. 2, when the first line is printed at a printing duty of 100% and the printing speed is 5 IPS (IPS: Inch Per Second), and the second line is printed at a printing duty of 40% and a printing speed of 15 IPS, the first line is printed. And the second line may be uneven in the printed shading of the adjacent black portion. Then, since the black-painted portions are adjacent to each other, the unevenness of the print density appears remarkably.

  Therefore, in view of the above problems, when printing adjacent print patterns between adjacent lines, it is possible to suppress print density unevenness of the print pattern that may occur depending on the print speed and improve the print quality. There is a need for an image forming apparatus.

To solve the above problem, an image forming apparatus according to the present invention, (1) by moving the conveyor to the print head in the width direction of the medium, to print an image based on inputted print data on a medium printed A mechanism unit; (2) a print duty calculation unit that acquires dot development data based on the print data and calculates a print duty value of the line based on the acquired dot development data for one line; (3) according to the value of the printing Duty of one line calculated by the printing Duty calculation unit, a printing speed determination unit that determines the printing speed of the line, the printing conditions including the printing speed of the line before the printing in (4) medium and before storing the row condition storage unit, and (5) before the line conditions by referring to the storage unit, adjacent portion detection unit for detecting an adjacent portion of the printed pattern between the front row and the row adjacent (6) When the adjacent part detected by the head detection part is detected And a printing speed control unit that matches the printing speed of the adjacent part with the printing speed of the preceding line stored in the preceding line condition storage part .

  According to the present invention, when printing adjacent print patterns between adjacent lines, it is possible to suppress print density unevenness of the print pattern that may occur depending on the print speed and improve the print quality.

2 is a block diagram illustrating a configuration of a control system of the image forming apparatus according to the embodiment. FIG. It is a figure which shows the nonuniformity of the printing shading of the location adjacent to a front line. 1 is an external perspective view showing an external appearance of an image forming apparatus according to an embodiment. FIG. 2 is a block diagram illustrating a printing mechanism of the image forming apparatus according to the embodiment. It is explanatory drawing explaining the detection process of the adjacent pattern by the adjacent pattern detection part which concerns on embodiment. It is explanatory drawing explaining the adjacent position detection process by the adjacent position detection part which concerns on embodiment. 5 is a flowchart illustrating setting processing of a density correction mode in the image forming apparatus according to the embodiment. 6 is a flowchart showing an operation of a density correction process in the image forming apparatus according to the embodiment (part 1). 6 is a flowchart showing an operation of a density correction process in the image forming apparatus according to the embodiment (No. 2). FIG. 10 is a flowchart (part 3) illustrating an operation of density correction processing in the image forming apparatus according to the embodiment. It is a structural diagram showing the structure of the dot pin wire of the print head. It is explanatory drawing explaining the rebound of the armature of a print head. It is explanatory drawing explaining the rebound of the armature of a print head when a printing speed is changed. It is explanatory drawing explaining ensuring of the acceleration / deceleration distance by the printing speed judgment part which concerns on embodiment. FIG. 6 is an explanatory diagram illustrating an operation example in the image forming apparatus according to the embodiment.

(A) Main Embodiment Hereinafter, a main embodiment of an image forming apparatus according to the present invention will be described in detail with reference to the drawings.

  In this embodiment, a case where the present invention is applied to a dot impact printer is illustrated.

(A-1) Configuration of Embodiment FIG. 3 is an external perspective view showing an external appearance of the image forming apparatus 100 according to the embodiment. FIG. 4 is a block diagram illustrating a printing mechanism of the image forming apparatus 100 according to the embodiment. 3 and 4, the same or corresponding components are denoted by the same reference numerals.

  In FIG. 3, the image forming apparatus 100 includes an operation panel 120, a stage 109, a belt 102, a carriage unit 103, a print head 110, and a feed roller 107.

  The image forming apparatus 100 according to the embodiment is a dot impact printer, in which a dot pin wire of a print head 110 protrudes based on print data, and the dot pin wire strikes an ink ribbon to print an image on a medium 108. It is.

  The operation panel 120 receives user operations and has various switches. For example, the operation panel 120 includes a switch for selecting either cut sheet paper or continuous paper as a recording medium, a print start switch, a density correction mode setting switch for correcting unevenness in printing density, and the like.

  This density correction mode is an operation mode for correcting various printing density unevenness. The light / dark correction mode according to the present embodiment is intended to be an operation mode for correcting unevenness of print light / darkness in adjacent print pattern portions (hereinafter also referred to as adjacent portions) between adjacent lines. In this embodiment, the setting of the light / dark correction mode is exemplified through the operation panel 120, but it may be set by a command from a host device connected to the image forming apparatus 100.

  As shown in FIG. 4, the printing mechanism 100A of the image forming apparatus 100 includes a pulley 101, a belt 102, a carriage belt 103, a carriage shaft 104, a space motor 105, a feed motor 106, a feed roller 107, and a stage 109.

  The stage 109 is for placing the medium 108 and transporting it to the medium transport path in the image forming apparatus 100. The stage 109 is installed substantially horizontally and may be detachable from the image forming apparatus 100, or may be a drawer type.

  The feed roller 107 is disposed horizontally in the same manner as the stage 109, and rotates by receiving the driving force of the feed motor 106 to convey the medium 108 to the medium conveyance path.

  The feed motor 106 gives a driving force to the feed roller 107. The feed motor 106 meshes with the gear portion of the feed roller 107 and rotates the feed roller 107.

  The carriage unit 103 is mounted with a detachable print head 110 and moves in the left-right direction in FIG. 4 about the carriage shaft 104. The carriage unit 103 is fixed in the vertical direction by a carriage shaft 104. A belt 102 is fixed to the carriage unit 103.

  The belt 102 is uneven on the inner surface of the belt so as to mesh with the gear portion of the space motor 105, and is stretched horizontally by the pulley 101.

  The pulley 101 serves as a fulcrum between the space motor 105 and the carriage unit 103 and rotates in accordance with the movement of the belt 102.

  The gear portion of the space motor 105 has irregularities that mesh with the belt 102, and the carriage unit 103 moves in the horizontal direction (the width direction of the medium 108) via the belt 102 as the gear portion of the space motor 105 rotates.

  The print head 110 prints on the medium 108 while moving in the left-right direction (width direction of the medium 108) while being mounted on the carriage unit 103. The print head 110 has a plurality of dot pin wires and a wire drive unit that drives each dot pin wire, and the wire drive unit projects or retracts each dot pin wire, and the projected dot pin wire Prints on the medium 108 by hitting the ink ribbon.

  FIG. 1 is a block diagram illustrating a configuration of a control system of the image forming apparatus 100 according to the embodiment. In FIG. 1, the configuration of the control system of the image forming apparatus 100 includes a CPU / LSI (arithmetic processing unit) 1, an interface (hereinafter referred to as I / F) connector 2, an I / F driver 3, a feed driver 4, and a feed. Motor 5, space driver 6, space motor 7, head driver 8, print head 9, print duty calculation unit 10, print speed determination unit 11, preceding condition storage unit 12, adjacent part detection unit 30, print speed control unit 31, An operation panel (OP) driver 17, an LED (Light Emitting Diode) / SW (Switch) 18, and a menu holding unit 19 are provided.

  A CPU / LSI (arithmetic processing unit) 1 manages various functions of the image forming apparatus 100. When the CPU / LSI 1 obtains print data via the I / F driver 3, the CPU / LSI 1 develops dots based on the print data and supplies the dot-developed data to the print duty calculation unit 10.

The I / F connector 2 acquires print data from a personal computer (PC) which is a host device and supplies the print data to the CPU / LSI 1 via the I / F driver 3. I / F driver 3 is controlled by the CPU / LSI 1, and controls the operation processing of the I / F connector 2.

  The print duty calculation unit 10 acquires the dot expanded data based on the print data from the CPU / LSI 1, and calculates the ratio of the number of dots to the print column (print duty) for the acquired data for one line. . The print duty calculation unit 10 gives the calculated print duty for one line to the print speed determination unit 11 via the CPU / LSI 1. The value of the print duty is expressed as “D”.

  The print speed determination unit 11 determines the print speed of the line according to the acquired print duty value for one line. The printing speed of the line is denoted as “S”.

  The previous line condition storage unit 12 has a printing speed “E” immediately before the current line (hereinafter referred to as “previous line”), “L” indicating the possibility of occurrence of an adjacent pattern due to a line feed amount, The final Pin print pattern (dot arrangement) “F” and the line feed amount “Z” are stored.

  The adjacent part detection unit 30 detects the adjacent part of the print pattern between the previous line and the current line with reference to the print condition of the previous line in the previous line condition storage unit 12. The adjacent portion detection unit 30 includes an adjacent pattern detection unit 13 and an adjacent position detection unit 14.

  Based on the line feed amount “Z” of LF (Line Feed), the adjacent pattern detection unit 13 prints the last pin print pattern “F” stored in the previous line condition storage unit 12 and received data (that is, , The presence / absence of a pattern adjacent to the print pattern (dot array) of the first Pin of the line is detected. Also, the adjacent pattern detection unit 13 stores the adjacent pattern occurrence possibility “L” indicating the presence or absence of the adjacent print pattern in the preceding condition storage unit 12. Here, for example, “L = 1” is stored when there is an adjacent print pattern, and “L = 0” is stored without the adjacent print pattern.

  FIG. 5 is an explanatory diagram for explaining adjacent pattern detection processing by the adjacent pattern detection unit 13 according to the embodiment.

  As shown in FIG. 5A, the received data in the first row is assumed to be black on the entire first row. The LF (Line Feed) direction is a direction from top to bottom, with the upper left corner being the position of the first Pin and the lower left corner being the position of the final Pin.

  For example, when printing of the first line is completed, the print pattern (dot array data) of the first line is stored in the previous line condition storage unit 12 (see FIG. 5B).

  The received data in the second row is assumed to include a black convex figure and a character string “ABCDE” as shown in FIG. At this time, the printing pattern (dot arrangement) of the first Pin on the second line is the upper part of the black convex figure as shown in FIG.

  At this time, the adjacent pattern detection unit 13 sets the line feed amount “Z”, the print pattern (dot arrangement) of the last Pin stored in the previous line condition storage unit 12, and two lines of received data. Based on the print pattern (dot arrangement) of the first pin of the eye, it is detected whether the print pattern of the last Pin of the first row and the print pattern of the first Pin of the second row are adjacent (FIG. 5 ( E), and the detection result is stored.

Here, next to Seppa turn detecting unit 13 is, for example, a print pattern of the final Pin in the first row, without having adjacent in all the printing pattern of the top Pin in the second row, adjacent to each other in some It also detects if Further, even if the printing pattern is intermittently adjacent neighbor Seppa turn detecting unit 13 detects a plurality of adjacent patterns. That is, the adjacent pattern detection unit 13 detects a portion that is partially adjacent between the first row and the second row.

  The adjacent position detection unit 14 determines the position where the dot arrangement of the first Pin of the received data is adjacent to the print pattern of the last Pin of the previous line according to the adjacent pattern occurrence possibility “L” by the adjacent pattern detection unit 13, The range of the print pattern adjacent to the dot arrangement of the first Pin is detected.

  FIG. 6 is an explanatory diagram for explaining adjacent position detection processing by the adjacent position detection unit 14 according to the embodiment.

  When the adjacent position detection unit 14 indicates that there is an adjacent pattern occurrence possibility “L” (for example, when L = 1), the dot arrangement of the first Pin of the received data is adjacent to the print pattern of the last Pin of the previous line. Is detected (that is, the adjacent dot position in the dot arrangement of the first Pin of the row), and the dot range of the dot arrangement of the first Pin of the reception data adjacent from that position is detected.

  The printing speed control unit 31 controls the printing speed between the adjacent part and a non-adjacent part other than the adjacent part when the adjacent part is detected by the adjacent part detection unit 30. The printing speed control unit 31 includes an adjacent printing speed setting unit 15 and a printing speed determination unit 16.

  The adjacent part printing speed setting unit 15 compares the printing speed “E” of the preceding line stored in the preceding line condition storage unit 12 with the printing speed “S” set by the printing speed determination unit 11, and Based on the comparison result, the printing speed of the adjacent portion adjacent to the print pattern of the preceding line (adjacent portion printing speed “T”) is set.

  As for the setting method of the printing speed of the line by the adjacent printing speed setting unit 15, when S ≧ E, the adjacent printing speed setting unit 15 sets the adjacent printing speed “T” adjacent to the printing pattern of the previous line to the front. The line printing speed “E” is set to the same printing speed as the previous line in one pass. As a result, since the line is printed at the printing speed of the previous line, it is possible to eliminate uneven printing density between the preceding and following lines.

  In the case of S <E, the adjacent portion printing speed setting unit 15 sets the adjacent portion printing speed “T” as the printing speed “E” of the preceding line, and appropriately sets pass division printing. Thereby, since it is possible to print only at the adjacent portion at the printing speed of the preceding line, it is possible to reduce unevenness in the print density of the adjacent portion with the preceding line.

  Here, the pass division printing means that the data for one line is printed in a plurality of times. For example, when the printing speed is “S = 5 IPS” and the printing speed of the previous line is “E = 20 IPS”, E / S = 20/5 = 4. Therefore, the adjacent portion printing speed setting unit 15 prints the print data for one line by dividing it into four. In this case, for example, the plurality of dot pin wires of the print head 9 are divided into four groups, the first group dot pin wires are used for the first printing, and the second group dots are used for the second printing. A pin wire may be used, a third group of dot pin wires may be used for the third printing, and a fourth group of dot pin wires may be used for the fourth printing.

  The printing speed determination unit 16 determines whether the printing speed “S” set by the adjacent part printing speed setting unit 15 and the adjacent part printing speed “T” can be changed from the printing speed “S” to the printing speed “T”. It is determined whether or not the distance or the inter-character distance that can be changed from the printing speed “T” to the printing speed “S” is secured.

  That is, the adjacent portion printing speed “T” of the portion adjacent to the printing pattern of the previous line is set to the same speed as the printing speed “E” of the previous row, and the printing speed “S” is set for the non-adjacent portion which is not adjacent. Print. In this way, in order to make the printing speed variable, the printing speed determination unit 16 determines whether or not there is a sufficient distance (acceleration / deceleration distance) necessary to obtain a desired printing speed.

  For example, the printing speed determination unit 16 sets a plurality of acceleration / deceleration distances in advance according to the difference value of the printing speed to be changed. The printing speed determination unit 16 reads the acceleration / deceleration distance corresponding to the difference value between the printing speed “S” and the adjacent part printing speed “T” as the distance at which the printing speed varies, and the distance at which the printing speed changes is the above-mentioned acceleration speed. It is possible to apply a method for determining whether or not the deceleration distance is exceeded.

  The menu holding unit 19 holds whether the setting of the density correction mode is valid or invalid. As described above, in this embodiment, the density correction mode can be set through the operation panel 120. When the density correction mode is valid, the density correction menu “X” is set to “X = 1”, and when it is invalid, the density correction menu “X” is held as “X = 0”. As the menu holding unit 19, a nonvolatile storage device can be applied, and it is desirable to store it even after the power is turned off.

  The LED / SW 18 is a light emitting unit or switches mounted on the operation panel 120. For example, when a switch (SW) on the operation panel 120 is pressed, a signal from the switch (SW) is given to the CPU / LSI 1 via the OP driver 17, or under the control of the OP driver 17, the light emitting unit (For example, an LED). In addition, although it is set as LED as an example of a light emission part here, a light emission part is not limited to LED.

  The head driver 8 drives the print head 9 according to a signal acquired from the CPU / LSI 1 to print on the medium 108. The CPU / LSI 1 transmits a signal for the amount of movement of the carriage unit 103 to the space driver 6 in synchronization with the printing operation, and drives the space motor 7. Further, the CPU / LSI 1 transmits a signal for the amount of movement for transporting the medium 108 to the feed driver 4, and the feed motor 5 transports the medium 108.

(A-2) Operation of Embodiment Next, the operation of the printing process in the image forming apparatus 100 according to this embodiment will be described in detail with reference to the drawings.

  In the following, first, the processing for setting the density correction mode in the image forming apparatus 100 will be described with reference to FIG.

  In FIG. 7, the operation panel 120 or the host device shifts to the menu setting mode by the user operation, and various setting modes are selected.

  The CPU / LSI 1 confirms whether or not the density correction mode (printed density correction mode in FIG. 7) is enabled (S101). If the density correction mode is enabled, the CPU / LSI 1 determines the density correction menu. “X” is set to “X = 1” (S102), and is stored in the menu holding unit 19 which is a nonvolatile storage unit (S104). On the other hand, if the density correction mode is not valid, the density correction menu “X” is set to “X = 0” (S103), and is stored in the menu holding unit 19 which is a nonvolatile storage unit (S104).

  Next, the operation of density correction processing in the image forming apparatus 100 according to the embodiment will be described in detail with reference to the drawings.

  In FIG. 8, first, when the power switch of the image forming apparatus 100 is turned on (S200), the CPU / LSI 1 initializes various parameters relating to the density correction (S201). That is, the CPU / LSI 1 prints the duty “D”, the preceding line printing speed “E”, the preceding line printing pattern “F”, the possibility of occurrence of the adjacent pattern “L”, the printing speed “S”, and the adjacent part printing speed “ The values of “T” and the previous line feed amount “Z” are initialized to “0”, respectively.

  When there is no print data, the CPU / LSI 1 maintains a standby state (S202), and when there is print data (S203), the CPU / LSI 1 calculates the print duty of the dot development data for one line based on the print data. Part 10 is given.

  The print duty calculation unit 10 calculates the ratio of the number of dots to a predetermined print column (print duty) for the acquired dot development data for one line, and stores the value of the print duty as the value “D”. (S204).

  Next, the printing speed determination unit 11 stores in advance a printing speed table in which the printing speed “S” corresponding to the printing duty “D” is set. The printing speed determination unit 11 refers to the printing speed table to determine the printing speed “S” corresponding to the printing duty “D” calculated by the printing duty calculation unit 10 (S205).

  Here, an example of the printing speed table will be described. For example, when the print duty “D” <25%, the print speed “S = 20 IPS” is set. When 25% ≦ print duty “D” <50%, the print speed “S = 15 IPS” is set, and 50% ≦ print duty “D”. The print speed is “S = 10 IPS” when “<75%”, and the print speed “S = 5 IPS” when 75% ≦ print duty “D”. In this example, the print speed “S” is set to become slower as the value of the print duty “D” increases.

  The CPU / LSI 1 checks whether the density correction menu “X” stored in the menu holding unit 19 is valid or invalid (S206). If the density correction menu “X” is valid (“X = 1”), the process proceeds to S207. If the density correction menu “X” is invalid (“X = 0”), the process is as shown in FIG. The process proceeds to S217 of FIG.

  In S207, the CPU / LSI 1 checks whether or not the adjacent pattern occurrence possibility “L” stored in the preceding condition storage unit 12 is “possible”. If there is a possibility of occurrence of an adjacent pattern (when “L = 1”), the process proceeds to S208. If there is no possibility of occurrence of an adjacent pattern (when “L = 0”), the process proceeds to S217.

  Here, when the shading correction menu is invalid in S206 (when “X = 0”), or when the shading correction menu is valid in S207, there is no possibility of occurrence of an adjacent pattern (“X = 1 ”and“ L = 0 ”).

  In S217, the value of the printing speed “S” is stored in the adjacent portion printing speed “T”. That is, by setting the value of the adjacent portion printing speed “T” to the printing speed “S”, printing for one line is performed at the predetermined printing speed “S” without changing the printing speed of the line. To do.

  In S220, the CPU / LSI 1 determines whether or not the line feed amount stored in the preceding line condition storage unit 12 is equal to or less than one column. That is, it is determined whether or not the line feed amount is greater than the amount of the dot pin wire of the print head 9 arranged in the LF direction.

  When the line feed amount is greater than one column, that is, when the line feed amount is greater than one column of the dot pin wire of the print head 9, the CPU / LSI 1 determines that the print patterns of the adjacent lines are not adjacent to each other. Then, “0” is stored in the adjacent pattern occurrence possibility presence / absence “L”, and the process proceeds to S203 in FIG. 8 to enter a state of waiting for reception of the next print data (S221).

  On the other hand, when the line feed amount is equal to or less than one column, that is, when the line feed amount is equal to or less than one column of the dot pin wire of the print head 9, the CPU / LSI 1 determines that the print patterns of the lines before and after may be adjacent to each other. Then, “1” is stored in the adjacent pattern occurrence possibility “L” (S222). Since there is a possibility that the print pattern is adjacent when the next line is printed, the CPU / LSI 1 stores the value of the adjacent portion print speed “T” in the previous line print speed “E” (S223). The print data for one line printed in the print pattern “F” is stored (S224), and the value of the line feed amount is stored in the previous line feed amount “Z” (S225). Thereafter, the process proceeds to S203 in FIG. 8, and the CPU / LSI 1 waits for reception of the next print data.

  Next, in S206 and S207, processing when the density correction menu is valid and there is a possibility of occurrence of an adjacent pattern (in the case of “X = 1”, “L = 1”) will be described.

  In S208 of FIG. 9, the adjacent pattern detection unit 13 prints the last Pin of the previous line based on the previous line feed amount “Z”, the previous line print pattern “F”, and the dot arrangement of the first Pin of the received data. It is detected whether the pattern and the print pattern of the first Pin of the line are adjacent to each other.

  Then, the CPU / LSI 1 checks whether or not the print pattern of the last Pin of the previous line and the print pattern of the first Pin of the line are adjacent (S209). If the print pattern is adjacent in the preceding and following lines, the process proceeds to S210. If not, the process proceeds to S217 in FIG.

  In S210, based on the data detected by the adjacent pattern detection unit 13, the adjacent position detection unit 14 determines that the dot arrangement of the first Pin of the received data is adjacent to the print pattern of the last Pin of the previous row, and the first Pin. And the range of the print pattern adjacent to the dot arrangement.

  The adjacent portion printing speed setting unit 15 compares the preceding line printing speed “E” with the printing speed “S” determined by the printing speed determination unit 11 (S211).

  When the printing speed “S” ≧ the preceding line printing speed “E”, the process proceeds to S213, and the adjacent part printing speed setting unit 15 sets the preceding line printing speed “E” to the adjacent part printing speed “T”. The value is stored (S213), and the same printing speed as the previous line is set in one pass.

  On the other hand, if the printing speed “S” <the preceding line printing speed “E”, the process proceeds to S212, and the adjacent part printing speed setting unit 15 sets the preceding line printing speed “E” to the adjacent part printing speed “T”. The value is stored (S214), and pass division printing is set as appropriate.

  Here, the meaning of setting the adjacent portion printing speed “T” by the adjacent portion printing speed setting unit 15 will be described with reference to the drawings.

  FIG. 11 is a structural diagram showing the structure of the dot pin wire of the print head 9. As shown in FIGS. 11A and 11B, the print head 9 of the dot impact printer has a structure in which when the current flows through the coil 95, the magnetism of the core 96 is demagnetized, the armature 92 is released, and the spring The dot pin wire 91 protrudes by the urging force of 93. When the current to the coil 95 is turned off, the armature 92 is attracted to the core 96 by the magnetic force of the core 96 and the dot pin wire 91 is retracted. Thereby, the dot pin wire 91 can strike an ink ribbon and print an image on a recording medium.

  When a current flows through the coil 95 and the dot pin wire 91 protrudes and then the current to the coil 95 is turned OFF, the armature 92 is attracted by the magnetic force of the core 96, but the spring 93 is interposed between the armature 92 and the spacer 94. Therefore, when the armature 92 collides with the core 96, the armature 92 and the core 96 come into contact with each other while the armature 92 rebounds as shown in FIG.

  When the printing speed is relatively high, if the dot pin wire 91 is protruded after the rebound of the armature 92 is completely converged, the impact cycle becomes long and the speed specification of the image forming apparatus 100 (printer) may be satisfied. Can not. Therefore, as shown in FIG. 13A, the impact cycle is shortened by utilizing the rebound of the armature 92.

  On the other hand, when printing a high-density print duty, the printing speed may be relatively slow due to the current capacity. In such a case, as shown in FIG. 13B, the dot pin wire 91 protrudes after the rebound of the armature 92 is completely eliminated (that is, after the spring 93 is completely returned). In such a case, the impact force of the dot pin wire 91 on the ink ribbon is increased.

  As shown in FIG. 13A and FIG. 13B, when the printing speed is different between the lines before and after each other, the impact force of the dot pin wire 91 fluctuates, which may cause uneven printing density. It becomes. In particular, when there are print patterns that are adjacent to each other in front and back lines, unevenness in print density becomes noticeable.

  Therefore, in this embodiment, the adjacent portion printing speed setting unit 15 sets the impact force of the dot pin wire 91 to the preceding line by setting the preceding line printing speed “E” for the portion adjacent to the preceding line printing pattern. As a result, the unevenness of the print density between the previous line and the corresponding line is reduced.

  Next, in S215, the printing speed determination unit 16 determines the distance between characters necessary for changing the printing speed “S” from the printing speed “S” to the adjacent printing speed “T” based on the received data, or the adjacent printing speed “ It is confirmed whether or not the distance between the characters necessary for changing the printing speed from “T” to “S” is secured.

  FIG. 14 is an explanatory diagram for explaining the securing of the acceleration / deceleration distance by the printing speed determination unit 16. As shown in FIG. 14, the first line is a black portion printed at a print duty of 100% and a print speed of 5 IPS, and the second line is a character string “ABCDE”, a convex figure, A character string of “ABCDE” (print duty: 50%, print speed: 15 IPS). For the adjacent part where the print pattern is adjacent between the first line and the second line, the adjacent part printing speed “T” is set to the same speed (5 IPS) as the preceding line printing speed “E”.

  In such a case, the printing speed determination unit 16 determines whether or not the distance from the printing speed “S = 15IPS” on the second line to the change to the adjacent part printing speed “T = 5IPS” is equal to or greater than the acceleration / deceleration distance. To do.

  The distance between the characters necessary for changing the printing speed “S” to the adjacent portion printing speed “T”, or the distance between the characters necessary for changing the adjacent portion printing speed “T” to the printing speed “S”. If the distance is secured, the process proceeds to S218. If not, the process proceeds to S219.

  In S218, only the adjacent portion adjacent to the print pattern of the previous line is printed at the preceding line printing speed “E” set to the adjacent portion printing speed “T”, and the printing speed “S” is set for the other non-adjacent portions. "Is printed.

  In step S219, printing is performed by pass division printing set by the printing speed determination unit 16. At this time, pass division printing is performed at the preceding line printing speed “E” set to the adjacent portion printing speed “T”, and printing for one line is performed.

  When the line is printed, the CPU / LSI 1 determines whether or not the line feed amount stored in the previous line condition storage unit 12 is equal to or less than one column (S220).

  If the amount of line feed is greater than one column, the CPU / LSI 1 determines that the print patterns of adjacent lines are not adjacent to each other, stores “0” as the value of the adjacent pattern occurrence possibility “L”, Then, the process shifts to S203 in FIG. 8 and waits for reception of the next print data (S221).

  On the other hand, when the line feed amount is equal to or less than one column, the CPU / LSI 1 determines that there is a possibility that the print patterns of adjacent lines are adjacent to each other, and stores “1” in the value “L” of the possibility of adjacent pattern occurrence. (S222). Then, the CPU / LSI 1 stores the value of the adjacent portion printing speed “T” in the preceding line printing speed “E” (S223), and stores the printing data for one line printed in the preceding line printing pattern “F”. (S224), the value of the line feed amount is stored in the previous line feed amount “Z” (S225). Thereafter, the process proceeds to S203 in FIG. 8, and the CPU / LSI 1 waits for reception of the next print data.

  FIG. 15 is an explanatory diagram illustrating an operation example in the image forming apparatus 100 according to the embodiment.

  Here, the case where the first line receives the print data of the print duty “D”: 100% and the second line illustrates the case where the print data of the print duty “D”: 50% is received. Further, the case where the density correction mode is enabled in the menu item is illustrated.

  First, the print data reception process, print process, and storage process of the first line will be described. Description will be made along the numbers in [] in FIG.

  [1] For the received data on the first line, the print duty calculation unit 10 calculates the print duty “D” (D = 100% in FIG. 15). [2] The printing speed determination unit 11 sets the printing speed “S” in accordance with the printing duty “D” (S = 5 IPS because D = 100%). [3] Density correction menu: Effective when X = 1, but [4] Because of the first line (because it is initialized), the possibility of adjacent pattern occurrence is set to “L = 0” . [5] The adjacent portion printing speed setting unit 15 sets the value of the printing speed “S” to the adjacent portion printing speed “T”. [6] The CPU / LSI 1 sets the printing speed “S”: 5 IPS to the print head driver 8. Print one line.

  Next, a process of storing the previous line condition in the previous line condition storage unit 12 after printing the first line will be described.

  [7] The CPU / LSI 1 detects the line feed amount “Z”, and if the line feed amount “Z” is less than or equal to one column, stores the value “1” in the adjacent pattern occurrence possibility “L”. . [8] The CPU / LSI 1 stores the adjacent line printing speed “T” in the preceding line printing speed “E”. [9] The print pattern for the first line is stored in the print pattern “F” for all lines. [10] The CPU / LSI 1 stores the previous line feed amount in Z.

  Next, the print data reception process, print process, and storage process for the second line will be described.

  [11] For the received data on the second line, the print duty calculation unit 10 calculates the print duty “D” (in the example, D = 50%). [12] The printing speed determination unit 11 sets the printing speed “S” in accordance with the printing duty “D” (S = 15 IPS because D = 50%). [13] Density correction menu: Effective when X = 1, and the condition of the first row is stored in the previous row condition storage unit 12. [14] The possibility of occurrence of the adjacent pattern is set to “L = 1”. Is set. [15] Previous line print pattern [F] The adjacent pattern detection unit 13 determines whether there is an adjacent print pattern between the preceding and following lines based on the print pattern of the first line and the print pattern of the received data of the second line. To detect.

  [16] When the print patterns are adjacent, the adjacent position detector 14 detects the position and print range of the adjacent print pattern. [17] The adjacent portion printing speed setting unit 15 compares the printing speed of the second line: S = 15 IPS with the preceding line printing speed: E = 5 IPS, and determines that S ≧ E holds.

  [18] The adjacent portion printing speed setting unit 15 stores the preceding line printing speed: E = 5 IPS in the adjacent portion printing speed “T”. [19] The printing speed determination unit 16 determines that the distance from the printing speed S = 15 IPS to the adjacent part printing speed T = 5 IPS, or the distance from the adjacent part printing speed T = 5 IPS to the printing speed S = 15 IPS is the acceleration / deceleration distance. Confirm that it is secured.

  [20] If the acceleration / deceleration distance can be ensured, the CPU / LSI 1 performs printing only at the adjacent portion at the adjacent portion printing speed: T = 5 IPS (the same speed as the first line), and the non-adjacent portion that is not the adjacent portion. Printing speed: Printing is performed at S = 15 IPS.

(A-3) Effects of the Embodiment As described above, according to this embodiment, when the print pattern is adjacent based on the print pattern of the previous line and the received data, the same portion is printed as the previous line. Print at speed. Thereby, since the unevenness of the print density in the adjacent portion can be suppressed, the print quality is improved.

  Furthermore, according to this embodiment, there is provided control for printing only the print pattern portion adjacent to the previous line at the same speed as the previous line. As a result, it is possible to suppress a decrease in throughput as much as possible while ensuring print quality.

  DESCRIPTION OF SYMBOLS 100 ... Image forming apparatus, 1 ... CPU / LSI 10 ... Print duty calculation part, 11 ... Print speed determination part, 12 ... Previous condition storage part, 13 ... Adjacent pattern detection part, 14 ... Adjacent position detection part, 15 ... Adjacent part Print speed setting unit, 16... Print speed determination unit, 19.

Claims (4)

Moving the transport to the print head in the width direction of the medium, the printing mechanism unit for printing an image based on inputted print data on the medium,
A print duty calculation unit that acquires dot development data based on the print data and calculates a value of the print duty of the line based on the acquired dot development data for one line;
A printing speed determination unit that determines the printing speed of the line according to the value of the printing duty for one line calculated by the printing duty calculation unit;
A previous line condition storage unit for storing print conditions including the printing speed of the line before the print on the medium,
And the adjacent portion detection unit for detecting an adjacent portion of the printed pattern with the with reference to the previous line condition storage unit, front row and the row,
Wherein when said adjacent portions which are detected by the adjacent portion detecting portion is detected, the printing speed of the adjacent portions, the front row condition storage unit in the printing speed control to match the printing speed memorized the previous row was And an image forming apparatus. The adjacent portion detection unit is
At least, based on the print pattern of the print pattern and the line of the previous line, and the adjacent pattern detection unit for detecting the presence or absence of said adjacent section,
In response to said adjacent pattern detection unit by that detection result, to have a neighboring position detection unit dot arrangement data of the line to detect the position and adjacent ranges of the adjacent portions adjacent to the printing pattern of the previous row The image forming apparatus according to claim 1, wherein: Said adjacent pattern detection unit, and the line feed amount from the previous row, and print pattern of the last pin of the front row, on the basis of the printing pattern of the top pin of the row, to detect the adjacent portion The image forming apparatus according to claim 2. When the said adjacent portion by the adjacent portion detection unit and said non-adjacent portion is detected, the printing speed control section is pressurized when changing the printing speed between the non-adjacent portion and the adjacent portion the image forming apparatus according to claim 1, characterized in that it comprises a printing speed determining section for determining secure deceleration distance.

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