JP3646458B2 - Printing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a serial scan type printing apparatus that performs reciprocal printing by reciprocating a carriage mounted with a print head in a main scanning direction (line direction) via a belt, and in particular, every time the carriage reciprocates. In particular, the present invention relates to a printing apparatus having a mechanism for determining print timings in the forward direction and the backward direction on a line.
[0002]
[Prior art]
A printing apparatus capable of reciprocating printing, for example, a serial printer, has a carriage drive mechanism that reciprocates a carriage equipped with a print head in the main scanning direction (line direction), and print paper in a sub-scanning direction (a direction orthogonal to the main scanning direction). ) And a controller for controlling each of the mechanisms.
[0003]
The main configuration of this type of serial printer is shown in FIG. In this serial printer, the carriage drive mechanism is slidable on a guide bar 93 disposed in parallel with the traveling direction on a carriage 92 in which the end of one belt 94 is fixed at each opposite end in the traveling direction. The belt 94 is supported between the driven pulley 95 and the drive pulley 96 attached to the rotating shaft of the carriage motor (CR motor) 97, and is parallel to the guide rod 93. The CR motor By driving 97, the carriage 92 reciprocates in the main scanning direction via the belt 94. Further, the paper feed mechanism has a paper feed motor (PF motor) 98 for driving a paper holding portion for temporarily holding printing paper (not shown) in the sub-scanning direction, and drives the PF motor 98. As a result, the printing surface of the printing paper is displaced relative to the carriage 92.
[0004]
The controller 99 in FIG. 9 is, for example, a programmed computer, and controls the carriage drive mechanism and the paper feed mechanism, and controls the print head mounted on the carriage 92.
[0005]
The content of the control of the carriage drive mechanism is mainly to supply power to the CR motor 97 and to rotate the CR motor 97 in the normal direction or the reverse direction, and thereby the main scanning direction of the carriage 92 via the belt 94 and the guide rod 93. Can be reciprocated. On the other hand, the control of the paper feed mechanism is to supply power to the PF motor 98 at regular intervals in conjunction with the power supply to the CR motor 97 and to rotate the PF motor 98 at a constant pitch in the sub-scanning direction. Thus, it is possible to feed the printing paper set at a constant interval from the carriage 92.
[0006]
The print head control is performed by outputting a print timing signal (hereinafter referred to as PTS) to the print head every time the carriage 92 travels forward and backward, and print data (print request command or Printing based on data (hereinafter the same). In other words, if the serial printer is of an inkjet type, characters are formed by ejecting ink onto the printing paper, and if it is of a thermal type or thermal transfer type, the characters are printed directly on the printing paper or via a ribbon. Etc. are formed. The PTS output time is the time when the CR motor 97 is in a constant speed rotation state after a certain time has elapsed from the start of rotation of the CR motor 97 in both the forward path and the return path. In the conventional printing apparatus, the carriage 92 at this time The speed was treated as the same during forward travel and during backward travel.
[0007]
[Problems to be solved by the invention]
By the way, the belt 94 used in the carriage driving mechanism shown in FIG. 9 is always deformed (expanded) when the carriage 92 travels regardless of the material. Although the amount of deformation depends on the material and shape of the belt 94, it varies depending on the travel direction and travel position of the carriage 92, that is, how far the carriage 92 is from the drive pulley 96. Specifically, the difference in the deformation amount of the belt 94 appears as a difference in carriage traveling speed between the forward direction and the backward direction. However, since the controller 99 outputs the PTS to the print head at the same timing in the forward direction and the backward direction, the print position in the sub-scanning direction does not match during reciprocal printing, and this print position is used for precise printing. This is a problem.
[0008]
This problem will be specifically described with reference to FIGS.
[0009]
FIG. 10A is a schematic diagram showing a state where the carriage 92 in the vicinity of the driven pulley 95 travels in the direction of the drive pulley 96 via the belt 94, that is, the forward direction in the carriage mechanism shown in FIG. FIG. 11A is a schematic diagram showing a state in which the carriage 92 travels from the vicinity of the drive pulley 96 in the direction of the driven pulley 95, that is, in the return path direction. In the figure, FR is a driving force required when the carriage 92 travels in the forward path, and FL is a driving force required when the carriage 92 travels in the backward path. k11 and k21 are the elastic strength of the belt 94 on the side where the carriage 92 is present when viewed from the drive pulley 96 to the driven pulley 95 (degree of difficulty of deformation (also referred to as a spring constant, hereinafter the same), k12, k22. Is the elastic strength of the belt 94 on the side where the carriage 92 is not present, Lp is the printing scheduled area, ΔxL is the amount of deformation of the belt 94 when starting forward travel, and ΔxR is when starting backward travel This is the deformation amount of the belt 94.
[0010]
The schematic diagram in FIG. 10A is mechanically equivalent to that in FIG. That is, the driving force FR at the time of starting the forward traveling is substantially equal to the belt length of the elastic strength k11 portion and the elastic strength k12 portion, so that the deformation amount ΔL is applied to the belt 94 having the elastic strength 2k11 (or 2k12). Which can be approximated by the expression “FR = 2k11 · ΔxL”. Similarly, the schematic diagram of FIG. 11 (a) is equivalent to that of FIG. 11 (b), and the driving force FL when starting the return road is the belt length of the portion where the elastic strength is k21, and the elastic strength is Since it is much shorter than the portion of k22, it can be approximated by the expression “FL = k21 · ΔxR” (k21 is a maximum value than k22). At this time, the relationship between the position of the carriage 92 (CR position) and the elastic strength of the belt 94 is normally as shown by a solid line in FIG. 12, that is, the elastic strength is weakest in the scheduled print area Lp during forward travel. The carriage 92 is displaced in the direction in which the elastic strength is increased from the location (the location where the deformation amount is the maximum), while the elastic strength is weak from the location where the elastic strength is the highest (the location where the deformation amount is minimum) when traveling on the return path. In this direction, the carriage 92 is displaced.
[0011]
Since the actual travel distance of the carriage 92 when performing printing is a distance in consideration of the deformation amounts ΔxL and ΔxR in the scheduled print area Lp, the travel distance in the forward direction is “Lp + ΔxL−ΔxR”, The travel distance in the return direction can be approximated as “Lp + ΔxR−ΔxL”. For convenience, if “ΔxL−ΔxR” is a constant α determined according to the type of the belt 94, the traveling distance in the forward direction is represented by “Lp + α”, and the traveling distance in the backward direction is represented by “Lp−α”. . This means that the traveling distance in the forward direction is always longer than the traveling distance in the backward direction. On the other hand, since the time for the forward trip and the return trip is common, the travel speed in the forward direction is eventually faster than the travel speed in the backward direction.
[0012]
As described above, the traveling speed of the carriage 92 is different between the forward direction and the backward direction. However, since the conventional serial printer has the same PTS output timing in the reciprocating direction, as shown in FIG. At this time, the relative printing positions (p11 and p21, p12 and p22,...) In the sub-scanning direction are shifted. Such a problem commonly occurs in printing apparatuses having the carriage drive mechanism as described above.
[0013]
SUMMARY OF THE INVENTION An object of the present invention is to reduce printing position deviation in the sub-scanning direction in a printing apparatus having elements that make the traveling speeds of the carriage in the forward and backward directions different.
[0014]
[Means for Solving the Problems]
The printing apparatus of the present invention that solves the above-described problems includes a carriage drive mechanism that reciprocally travels a carriage on which a print head is mounted in the main scanning direction, and a print that generates a PTS for determining the print timing of the print head during travel. In the printing apparatus having the timing signal generating means and having different traveling speeds in the forward direction and the backward direction of the carriage, the following points are improved.
[0015]
(1) The printing timing signal generation means supplies at least one PTS in the forward direction and the backward direction of the carriage to the print head at a timing for reducing a relative printing position shift caused by a reciprocating speed difference of the carriage. It was configured as follows. As an example of the configuration, a PTS determined for each carriage traveling direction and each scheduled print position is stored in a data storage memory, and when the carriage traveling direction is detected, the corresponding PTS is retrieved from the data storage memory. Control means, and the relative print positions of the carriage in the forward and backward directions are changed by the searched PTS.
[0016]
(2) In place of the configuration of (1) above, the means for detecting the traveling direction of the carriage and the PTS generated at a fixed timing according to the detected traveling direction are corrected to perform the reciprocating traveling by the print head. Timing correction means for bringing the relative print positions close to the same is provided. The timing correction means includes, for example, a signal correction coefficient storage memory storing a PTS correction coefficient determined for each of the carriage traveling direction and a scheduled print position, and the signal correction coefficient storage when the carriage traveling direction is detected. And a memory control means for searching out a corresponding correction coefficient from the memory, and correcting the PTS by the searched correction coefficient to change the relative print positions in the forward and backward directions of the carriage. Constitute.
[0017]
(3) Instead of the configuration of the above (1), means for detecting the traveling direction of the carriage, and the printing timing signal generated at a fixed timing by correcting the traveling speed of the carriage according to the detected traveling direction. And a speed correction means for bringing the relative printing position during reciprocating travel close to the same. The speed correction means includes, for example, a speed correction coefficient storage memory that stores a correction coefficient for the carriage travel speed determined for each travel direction of the carriage and a scheduled print position, and when the travel direction of the carriage is detected. And a memory control means for finding out the corresponding correction coefficient from the speed correction coefficient storage memory, and configured to change the traveling speeds of the carriage in the forward direction and the backward direction in accordance with the found correction coefficient. .
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment when the present invention is applied to a serial printer will be specifically described with reference to the drawings. The carriage drive mechanism and paper feed mechanism of the serial printer of this embodiment are the same as those shown in FIG. In other words, the carriage on which the print head is mounted is slidably supported on the guide rod, a part of the belt that runs parallel to the guide rod is fixed to the carriage, and the belt is driven by a CR motor to reciprocate the carriage. It is designed to run.
[0019]
FIG. 1 is a block diagram of the main part of the control system of this serial printer, and mainly shows the coupling relationship between the controller 1 and peripheral elements.
[0020]
The controller 1 is a programmed computer (CPU) that controls output of print data and PTS to the print head 2, and controls the CR motor driver 3 for driving the CR motor and drives the PF motor. The PF motor driver 4 is controlled. In the RAM 5, for example, print data based on a print job sent from the host computer is recorded, and the controller 1 can read it at any time. The ROM 6 stores PTS common to the same type of serial printers or various necessary correction coefficient data, and the EEPRPM 7 stores data unique to each printer so that the stored data can be read out at any time when the control processing is executed. It has become.
[0021]
The program for giving the control function to the controller 1 can be recorded and distributed on a machine-readable recording medium such as a flexible disk, and any program after the printer is assembled or after the printer is assembled. At this point, it is installed in the internal memory of the printer so that a computer (CPU) that can access the memory can read and execute it as needed.
[0022]
【Example】
(First embodiment)
FIG. 2 is a diagram showing an example of functional blocks of the controller 1 when the PTS output timing is made independent in the forward direction and the backward direction in the serial printer having the configuration shown in FIG. In this case, the controller 1 functions as a print timing signal generation unit.
[0023]
The controller 1 in this embodiment includes a main control unit 11 that performs overall control inside the controller while interlocking the carriage drive mechanism and the paper feed mechanism, a main scanning control unit 12 that controls the CR motor driver 3, and a PF motor driver 4. A sub-scan control unit 13 for controlling the PTS, a PTS output unit 14 for outputting the PTS to the print head 2, a print data output unit 15 for outputting the print data acquired from the RAM 5 to the print head 2, and a main scan control unit 12 includes a movement detection unit 16 that detects the traveling direction of the carriage from the control contents of 12, and a memory control unit 17 that reads out data stored in the ROM 6 and the EEPROM 7 based on the detection result of the movement detection unit 16 and outputs the data to the PTS output unit 14. ing.
[0024]
The ROM 6 stores a PTS corresponding to the printing speed, that is, the carriage traveling speed. FIG. 3 is a diagram showing an example of the contents of the ROM 6, in which PTSd11 to d1n and d21 to d2n determined according to the traveling speed of the carriage are stored.
[0025]
The EEPROM 7 stores a PTS correction coefficient for each relative print position. The relative print positions L1 to Ln are individual print scheduled positions in the print planned area Lp described above. This correction coefficient is for individually correcting the stored data in FIG. 3 in accordance with the characteristics of the individual carriage drive mechanisms, such as the elastic strength of the belt, and is relative to “1”, which is a reference value that does not require correction, for example. Represented by value. FIG. 4 shows an example of contents of data stored in the EEPROM 7. Note that individual PTSs may be regenerated based on the correction coefficient and stored in the EEPROM 7 in advance. Further, since the data stored in the EEPROM 7 can be rewritten, the contents of the EEPROM 7 may be individually updated as necessary to appropriately match the actual characteristics of the carriage drive mechanism.
[0026]
Next, the operation of the serial printer according to this embodiment will be specifically described.
[0027]
When the CR motor driver 3 and the PF motor driver 4 are controlled by the main scanning control unit 12 and the sub scanning control unit 13, the traveling direction detection unit 16 detects the traveling direction of the carriage. The memory control unit 17 reads the PTS and correction coefficient corresponding to the traveling direction of the carriage from the ROM 6 and the EEPROM 7 and sends them to the PTS output unit 14. The PTS output unit 14 supplies the input PTS to the print head 2 and performs printing based on print data on a print sheet (not shown).
[0028]
In this way, even if there is a difference between the carriage traveling speed and the backward traveling speed when performing reciprocal printing, the PTS set according to the speed difference is supplied to the print head. As described above, the relative print positions (p11 and p21, p12 and p22,...) In the sub-scanning direction at the time of reciprocal printing can be matched. In FIG. 5, the wavy line is the relative printing position in the conventional printer, and the solid line is the relative printing position according to this embodiment.
[0029]
It should be noted that the PTS during the reciprocating travel may be generated in the same manner as before (at a fixed timing), and the PTS may be corrected for each travel direction and print position of the carriage. In this case, the controller 1 is caused to function as timing correction means. For this purpose, the data stored in the ROM 6 and the EEPROM 7 is stored not with the contents of FIGS. 3 and 4, but with signal correction coefficients for correcting the PTS so as to approach the contents of FIGS. Then, the corresponding signal correction coefficient is read by the memory control unit 17 in accordance with the traveling direction of the carriage, and the PTS corrected by the PTS output unit 14 is output to the print head 2.
[0030]
In this embodiment, the relative print position in each direction is made to coincide by adjusting the output timing of the PTS when traveling in both the forward and backward directions, but only the forward direction or only the backward direction is adjusted. By doing so, the relative printing position in one direction may be matched with the relative printing position in the other direction.
[0031]
(Second embodiment)
FIG. 6 is a schematic diagram of the serial printer configured as shown in FIG. 1 on the assumption that the PTS is the same (fixed timing) when the carriage is reciprocating. A configuration example in the case where the print positions are brought close to each other is shown. In this case, the controller 1 is caused to function as speed correction means. The main control unit 11, the main scanning control unit 12, the sub-scanning control unit 13, the PTS output unit 14, and the movement detection unit 16 are the same as those in the first embodiment, and the PTS output unit 24 and the memory control unit 27 are the same as those in the first embodiment. The PTS output unit 14 and the memory control unit 17 prepared in one embodiment basically have the same function.
[0032]
In this embodiment, a carriage speed data value corresponding to the printing speed is stored in the ROM 6 for each carriage speed. The EEPROM 7 stores a speed correction coefficient unique to the printer. Then, the memory control unit 27 sends the data read from the ROM 6 or the EEPROM 7 to the main scanning control unit 12, and the main scanning control unit 12 performs CR processing based on the carriage speed data based on the printing speed and the speed correction coefficient based on the printing position and the printing direction. The control amount of the motor driver 3 is corrected. At this time, the speed correction coefficients e11 to e1n and e21 to e2n in both directions may be read out and sent to the main scanning control unit 12. Normally, however, a speed correction coefficient in only one direction is adopted, and the carriage in that direction is used. The traveling speed is made closer to the traveling speed in the other direction.
[0033]
The speed correction coefficient can be obtained as follows, for example.
[0034]
As described above, the travel distance of the carriage in the forward direction is “Lp + α”, the travel distance of the carriage in the backward direction is “Lp−α”, and the carriage travels at the same time T in these travel distances. The relational expression “T = (Lp + α) / v1 = (Lp−α) / v2” is established between the traveling speed v1 in the direction and the traveling speed v2 in the return direction. Therefore, the parameter coefficient K satisfying “v1 = Kv2” is stored in the EEPROM 7 as the correction coefficient of the printer.
[0035]
Next, the operation of the serial printer according to this embodiment will be specifically described.
[0036]
When the CR motor driver 3 and the PF motor driver 4 are controlled by the main scanning control unit 12 and the sub scanning control unit 13, the traveling direction detection unit 16 detects the traveling direction of the carriage. The memory control unit 27 reads out the speed correction coefficient corresponding to the traveling direction of the carriage or the speed correction coefficient and the correction coefficient and sends them to the main scanning control unit 12. The main scanning control unit 12 controls the CR motor driver 3 based on the speed correction coefficient, and corrects the traveling speed of the carriage in the forward direction and the traveling speed of the return path. The PTS output unit 24 outputs the PTS to the print head at a time point delayed by a certain amount (time) from the phase switching timing of the CR motor acquired from the main scanning control unit 12 or the main control unit 11 in both the forward direction and the backward direction.
[0037]
According to such a control procedure, as shown in FIG. 8, the forward traveling speed and the backward traveling speed of the carriage can be made close to each other, so even if the output timing of the PTS remains as before, the sub-scanning direction Relative print positions (p11 and p21, p12 and p22...) Can be matched.
[0038]
In each of the above embodiments, the relationship between the carriage position and the elastic strength of the belt is the relationship indicated by the solid line in FIG. 12, that is, when traveling forward, the elastic strength increases from the weakest portion in the scheduled print area Lp. This is an example in which the carriage 92 is displaced in the direction in which the carriage 92 is displaced in the direction in which the carriage 92 is displaced from the highest elastic strength to the direction in which the elastic strength decreases. When the elastic coefficient can be approximated by linear conversion between p1 and pn, the correction coefficient shown in FIGS. 4 and 7 does not need to be provided for each relative printing position, and only needs to be provided for each carriage speed. The control content is further simplified.
[0039]
【The invention's effect】
As is clear from the above description, according to the printing apparatus of the present invention, even when the carriage has traveling elements in the forward direction and the backward direction, the printing is performed according to the traveling speed difference in each direction. Since the output timing of the PTS to the head is automatically corrected or the traveling speed is controlled to approach the same, there is an effect of reducing the relative printing position shift in the sub-scanning direction. This enables high-quality printing.
[0040]
In addition, PTS and various correction data are stored in the memory in advance, and the stored data is read according to the traveling direction of the carriage, so that necessary data can be quickly acquired and used for control. Benefits that can be generated.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a main part of a control system of a serial printer to which the present invention is applied.
FIG. 2 is a diagram illustrating a functional block configuration example of a controller when adjusting the output timing of PTS during reciprocal printing.
FIG. 3 is an explanatory diagram showing an example of contents stored in a ROM when adjusting the output timing of a PTS.
FIG. 4 is an explanatory diagram showing an example of contents stored in an EEPROM.
FIG. 5 is an explanatory diagram of reciprocal printing timing when the output timing of PTS is adjusted, and the upper part shows an example during forward travel and the lower part shows an example during backward travel.
FIG. 6 is a diagram illustrating an example of a functional block configuration of a controller when adjusting the traveling speed of a carriage during reciprocal printing.
FIG. 7 is an explanatory diagram showing an example of contents stored in a ROM when adjusting the traveling speed.
FIG. 8 is an explanatory diagram of reciprocal printing timing when the traveling speed of the carriage is adjusted, in which the upper part shows an example during forward travel and the lower part shows an example during backward travel.
FIG. 9 is a schematic explanatory diagram of a carriage drive mechanism of a serial printer to which the present invention is applied.
10A is a schematic diagram showing a state of a carriage drive mechanism at the start of forward traveling, and FIG. 10B is a diagram dynamically replacing this state.
11A is a schematic diagram showing a state of the carriage drive mechanism at the start of backward travel, and FIG. 11B is a diagram dynamically replacing this state.
FIG. 12 is a diagram showing the relationship between the position of the carriage and the elastic strength of the belt.
FIG. 13 is an explanatory diagram of reciprocal printing timing in this type of conventional serial printer, in which the upper part shows an example during forward travel and the lower part shows an example during backward travel.
[Explanation of symbols]
1,99 Controller 2 Print head 3 CR motor driver 4 PF motor driver 5 RAM
6 ROM
7 EEPROM
11 Main control unit 12 Main scanning control unit 13 Sub scanning control unit 14, 24 PTS output unit 15 Print data output unit 16 Travel direction detection unit 17, 27 Memory control unit 92 Carriage 93 Guide rod 94 Belt 95 Drive pulley 96 Drive pulley 97 CR motor 98 PF motor

Claims (2)

A carriage drive mechanism that reciprocates the carriage on which the print head is mounted in the main scanning direction; and a print timing signal generation unit that generates a print timing signal for determining a print timing of the print head during the travel, In a printing apparatus in which the traveling speed of the carriage in the forward direction and the backward direction are different from each other,
Means for detecting a traveling direction of the carriage;
And a feed rate correcting means for correcting the traveling speed of the carriage according to the detected traveling direction and bringing the relative printing position during the reciprocating traveling close to the same based on the printing timing signal generated at a fixed timing. A printing device. The speed correction means includes a speed correction coefficient storage memory that stores a correction coefficient of the carriage travel speed determined for each travel direction of the carriage and a scheduled print position, and the speed correction when the travel direction of the carriage is detected. And a memory control means for finding out the corresponding correction coefficient from the coefficient storage memory, and configured to change the traveling speeds of the carriage in the forward direction and the backward direction in accordance with the found correction coefficient. The printing apparatus according to claim 1 .

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