JP3586324B2 - Thermal line printer and driving method of thermal line printer - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a thermal line printer that forms an image using a thermal line head and a driving method thereof.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, image information is developed into a bitmap, and image formation is performed line by line on a thermal paper using a thermal line head in which the number of heating resistors corresponding to one line of the developed bitmap are linearly arranged. Thermal line printers for performing such operations are known. Normally, in such a printer, input image information is developed into a bitmap and stored in a memory. Then, the bitmap stored in the memory is transferred to the output buffer, and the bitmap data for one line is transferred from the output buffer to the register of the thermal line head for printing. Normally, a bitmap is developed in a memory for each predetermined amount of image information, and the bitmap data written in the memory is transferred to a buffer as needed.
[0003]
[Problems to be solved by the invention]
In the printer as described above, as the image forming process progresses, the load on the CPU increases, and the speed of bitmap development may be slower than the speed of image formation. That is, the amount of data transferred from the buffer to the thermal line head may exceed the amount of data transferred to the buffer. In this case, the image data is temporarily lost in the buffer, and the image forming process cannot be continued.
[0004]
Normally, the thermal line printer forms an image by coloring the heat-sensitive paper line by line while conveying the recording paper. However, when the data in the buffer runs out, the printing operation is temporarily interrupted. If the printing operation is interrupted, the next data is transferred to the buffer, and when the image formation is restarted, the pitch between the printing lines before and after the stop is shifted or the printing is stopped. There has been a problem that the quality of an image is deteriorated, such as a change in print density due to a decrease in the temperature of the thermal line head. An object of the present invention is to prevent image quality degradation as described above.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, a thermal line printer of the present invention forms an image on recording paper using a thermal line head having a plurality of heating resistors arranged in a line, Expansion means for expanding the bitmap data, storage means for storing the bitmap data, and storage means for storing the bitmap data stored in the storage means for each predetermined amount corresponding to the plurality of heating resistors. To the thermal line head from First A data transfer unit, a detection unit that detects an amount of data stored in the storage unit, and a data amount stored in the storage unit. First Cycle determination means for determining a data transfer cycle by the data transfer means; Storage means for storing the bitmap data included in the expansion means, and second data transfer means for transferring the bitmap data stored in the storage means to the storage means; With The cycle setting means may determine that the transfer speed of the bitmap data transferred from the storage means to the thermal line head by the first transfer means is from the storage means to the storage means by the second data transfer means. The period is set so as not to exceed the transfer speed of the bitmap data transferred to the means. It is characterized by doing.
[0006]
Further, in a thermal line printer driving method according to the present invention, in a thermal line printer for transferring an image to a thermal line head having a plurality of heating resistors arranged linearly and forming an image on recording paper, the image information is bit-mapped. Expand as data, Expanded The bitmap data is stored in storage means. Transfer Storage Let , By the data transfer means, The bitmap data stored in the storage unit is transferred from the storage unit to the thermal line head at predetermined intervals corresponding to the plurality of heating resistors, and the amount of data stored in the storage unit is detected. And setting a data transfer cycle of the data transfer means according to the amount of data stored in the storage means. Wherein the transfer speed of the bitmap data transferred from the storage means to the thermal line head does not exceed the transfer speed of the bitmap data transferred from the storage means to the storage means. Set the data transfer cycle It is characterized by:
[0007]
【Example】
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0008]
FIG. 1 is a perspective view showing the appearance of a thermal line printer 1 as an embodiment of the present invention. The printer 1 of the present embodiment uses thermal paper having a width of A4 size as the recording paper P, and has a housing 3 having a substantially rectangular parallelepiped shape. The housing 3 houses a control circuit, a drive circuit, a drive motor, a thermal line head, a platen, and the like.
[0009]
The housing 2 is provided with a cover 2. The cover 2 is swingably supported at two places 2 </ b> X and 2 </ b> X on the upper surface of the housing 3. In FIG. 1, a solid line indicates a state in which the cover 2 is closed, and a dashed line indicates a state in which the cover 2 is opened.
The recording paper P is introduced into the inside of the printer 1 through a recording paper insertion opening 4 formed between the cover 2 and the upper surface of the housing between the support portions 2X and 2X of the cover 2, and an image is formed. The recording paper P introduced into the printer 1 has an image formed on the paper surface, and is discharged from a recording paper discharge port 5 formed between the cover 2 and the front surface of the housing.
[0010]
The cover 2 is provided with indicators (LEDs) 7, 8, and 9 that indicate the operation state of the printer 1. The display 7 indicates whether power is on or off and whether an error has occurred by turning on / off and blinking. The display 8 indicates whether data can be received. The display 9 displays information on the built-in battery.
[0011]
A power switch 6 is provided on the upper surface of the housing 3. In the printer 1 of the present embodiment, the operation mode such as turning on / off the power of the printer 1 and refresh discharge / charging of the built-in battery is switched according to the operation method (operation time / number of times) of the power switch 6. It has become. The CPU 10 detects the operation state of the power switch 6 based on the signal SW input to the port Port8.
[0012]
FIG. 2 is a block diagram illustrating control of the printer 1 according to the present embodiment.
As a CPU (central processing unit) for controlling the driving of the printer 1, a one-chip CPU 10 having an address space of 16 megabytes is used.
The CPU 10 is connected to an EPROM 21, a DRAM 22, a font ROM 23, and a G / A (gate array) 26 via address ports AB0 to AB23 and data ports DB0 to DB15.
The CPU 10 sends address data specifying an address to the address bus AB via the address ports AB0 to AB23, and transmits and receives data via the data bus DB via the data ports DB0 to DB15.
[0013]
A program for controlling the driving of the printer 1 and various initial data are written in the EPROM 21. The DRAM 22 includes a bitmap area BM for developing a bitmap for image output based on print data transferred from the host computer or the like to the printer 1, and a buffer for transferring data developed in the bitmap area to the thermal head. A dynamic RAM used as a buffer area BF used as a memory area, an area for storing data from an interface, and a work area for various other processes. The font ROM 23 stores character font data used when developing print data into a bit map on the DRAM 22.
[0014]
Further, the CPU 10 exchanges data with the interface (I / F) 27 via the gate array (G / A) 26 and performs processing such as driving the LEDs 7, 8, and 9.
An interface (I / F) 27 is a printer interface (conforming to Centronics specifications) for receiving print data transferred from a host computer or the like, and has eight data lines and three control lines. .
Eight data lines PDATA1 to PDATA8 are used for transfer of print data from the host computer, and three control lines are used for a signal (/ DATASTB) for reading the print data to the printer and for not receiving the data. Signal (BUSY), and a signal (ACK) indicating that the printer has read data, respectively. In this specification, a low-active signal and a port that receives the low-active signal are indicated by adding “/” before a character string representing the signal or the port.
[0015]
The divided voltage V_Batt of the battery voltage (or the external power supply voltage) is applied to the analog port AN2 of the CPU 10. The CPU 10 detects the battery voltage (external power supply voltage) based on the A / D converted value of the voltage value applied to the port AN2.
[0016]
The reset IC 24 outputs a reset signal (/ RESET) to the port / RESET of the CPU 10 when the detected power supply voltage falls below a certain value. Upon receiving the reset signal, the CPU 10 stops operating. Therefore, when the power supply voltage falls below the predetermined voltage value, the printing operation stops.
[0017]
The cover 2 is provided with a recording paper sensor 25, and an output signal of the recording paper sensor is input to a port PTOP of the CPU 10. The recording paper sensor 25 is arranged so as to face the recording paper transport path with the cover 2 closed, and detects the presence or absence of recording paper in the recording paper transport path. When the cover 2 is opened, the recording paper sensor 25 does not always detect the recording paper. Therefore, by monitoring the output signal of the sensor 25, it is possible to know whether the recording paper is set and a printing operation is possible.
[0018]
X'tal 15 is a crystal oscillator which is connected to a clock input terminal of the CPU 10 and forms a reference clock generation circuit together with an oscillator inside the CPU 10. The reference clock is supplied from the clock output terminal φ of the CPU 10 to the gate array G / A 26. In the gate array G / A 26, the reference clock is frequency-divided to generate a transfer clock CLK. The CPU 10 reads the program from the EPROM 21 based on the reference clock, and develops the print data into bits in the bit map area BM of the DRAM 22.
[0019]
The thermal line printer according to the present embodiment is configured such that, after print data for one page is received once, bits are developed by a predetermined amount. When data is expanded in the bitmap area BM, it is transferred to the buffer area BF. The data in the buffer area BF is sequentially transferred by a predetermined amount for each line to a parallel / serial converter incorporated in the G / A 26, and is divided into two divided print data DATA1 and DATA2 in synchronization with the transfer clock CLK. The image is transferred to the thermal head 40. Note that the sizes of the bitmap area BM and the buffer area BF are not particularly limited, but in this embodiment, the size is set to a capacity that can store bitmap data for 100 print lines.
[0020]
The heating energy of the heating resistor (not shown) of the thermal head 40 is controlled by a strobe signal (described later in detail) sent from Port 1 to Port 4 of the CPU 10. In other words, the heating resistor to be driven is specified by the print data DATA1 and DATA2, and the heating resistor is driven by the strobe signal applied after the transfer of the print data so as to generate energy required for image formation.
[0021]
The thermal head 40 is provided with a thermistor 41 for detecting a temperature. The output voltage of the thermistor 41 is applied to the analog input port AN1 of the CPU 10. The CPU 10 detects the temperature of the thermal head 40 based on the A / D converted value of the applied value (analog value).
[0022]
Further, the CPU 10 sends a motor drive control pulse for controlling the drive of the motor 32 to the motor drive circuit 31 from the ports A / A / B / B. The motor drive will be described later in detail.
[0023]
The port PON1 sends out a signal for turning on / off the FET 52 as a switch element. The port PON2 sends out a signal for turning on / off the FET 51 as a switch element. When an external power supply (AC adapter) is connected, the transistor 53 as a switching element is turned on, and the signal / ADPT. IN becomes “L”. The CPU 10 outputs the / ADPT. Based on the level of IN, the FET 51 is selectively turned on when the external power supply is connected, and the FET 52 when the external power supply is not connected.
[0024]
When the power switch 6 is turned on, the FET 51 and the FET 52 are turned on, and a voltage is supplied to the DC-DC converter 50 from an external power supply or a battery. The DC-DC converter 50 outputs a drive power supply Vcc (5 volts) for the CPU 10, the EPROM 21, the DRAM 22, the ROM 23, and the like.
Once the FETs 51 and 52 are both turned off by the signals PON1 and PON2, power is not supplied to the DC-DC converter 50, and the drive voltage Vcc is not supplied to the CPU 10. Therefore, when the FETs 51 and 52 are turned off, the power switch 6 is operated again to restart.
[0025]
The printer 1 uses a built-in nickel-cadmium battery 100 as a driving power source to obtain a voltage of about 14.4 volts. The power supply connector 70 is provided in the printer 1 of the present embodiment, and an AC adapter 80 can be connected thereto. The AC adapter 80 has a constant current circuit 81 in addition to a constant voltage circuit 82 for supplying a drive voltage for the printer 1. The constant voltage circuit 82 is connected to the DC-DC converter 50 via the connector 70 and the FET 51.
[0026]
The constant current circuit 81 is connected to the charge control circuit 60 via the connector 70. Under the control of the printer 1, the built-in battery 100 is charged using the current output from the constant current circuit 81 inside the AC adapter 80.
[0027]
The printer 1 according to the present embodiment has a function of refreshing and charging a built-in battery (nickel-cadmium battery) 100. Refresh / charge control of the built-in battery 100 is performed by the charge control circuit 60. When the / CHARGE signal is output from the Port 5 of the CPU 10 to the charge control circuit 60, the charge control circuit 60 starts charging the battery 100 with the current from the constant current circuit 81. The termination of charging is performed by monitoring the voltage of battery 100.
[0028]
When refreshing is performed, the / REFRESH signal is output from Port 6 of CPU 10, and the current from constant current circuit 81 is not applied to battery 100. Further, despite the AC adapter 80 being connected, the FET 51 is turned off, the FET 52 is turned on, and the battery 100 is refreshed.
[0029]
As shown in FIG. 3, the thermal head 40 of the printer of this embodiment is a line thermal head in which heating resistors of 2560 dots (2560) are arranged in a horizontal line. The bitmap data (data indicating ON / OFF) corresponding to the first to 1280th heating resistors is DATA1, and the bitmap data corresponding to the 1281st to 2560th heating resistors is DATA2. It is sent from the BF to the thermal head 40. As described above, the bitmap data sent to the thermal head 40 is sent as serial data in synchronization with the transfer clock CLK.
[0030]
For printing on thermal paper, 2560 heating resistors are divided into four blocks, and two blocks are simultaneously driven at different timings (two-part drive). By setting the strobe signals / STB1 to / STB4 to "L", the four blocks of the heating resistor are energized according to the print data (dot data) and generate heat.
[0031]
FIG. 3 is a conceptual diagram illustrating the configuration of the thermal line head 40. As described above, when the data DATA1 corresponding to the first to 1280th heating resistors 40H is transferred from the buffer area BF to the thermal line head 40, the data is transferred to the shift register 40A provided in the thermal line head 40. The data is stored in synchronization with the transfer clock CLK. When the data DATA2 corresponding to the 1281st to 2560th heating resistors 40H is transferred from the buffer area BF to the thermal line head 40, the data is stored in the shift register 40B. The heating resistor 40H of the thermal head and each bit of the shift registers 40A and 40B have a one-to-one correspondence, and when the contents of the shift register are "1", they correspond when / STBn becomes "L". The heating resistor generates heat, and if the content is "0", the heating resistor does not generate heat.
[0032]
FIG. 4 is a timing chart showing control of the thermal head 40 and the drive motor 32. In this embodiment, two pulses of the drive control pulse of the motor 32 convey the recording paper P by one line of the image. That is, each time the combination of H and L of the motor drive control pulses A and / A, and B and / B changes, the motor 32 conveys the recording paper by half a line, and two types of images are formed while an image for one line is formed. Is generated.
[0033]
When the bitmap is developed on the bitmap area BM, the bitmap data is transferred to the buffer area BF, and one line of print data is transferred from the buffer area BF to the thermal head 40 as serial data. As described above, first, DATA1 (data corresponding to the first to 1280th heating resistors) is transferred in synchronization with CLK.
[0034]
When the transfer of DATA1 is completed, the motor 32 is driven to start the conveyance of the recording paper. In response to the change in the pattern of the pulse applied to the motor 32, / STB1 and / STB2 are set to "L" to drive the heating resistors (1st to 1280th) for a predetermined time TSTB. When / STB1 becomes "L", the contents of the shift register 40A are not rewritten even if data is written to the shift register 40B. Transfer starts. That is, while the first to 1280th heating resistors are being driven, DATA2 (data corresponding to the 1281st to 2560th heating resistors) is transferred in synchronization with CLK. When the drive by / STB1 and / STB2 is completed, the transfer of DATA2 has already been completed. Then, the next drive control pulse for the motor 32 is output. In response to the application of the drive control pulse, the remaining heating resistors (1281 to 2560 heating resistors) are driven by setting / STB3 and / STB4 to "L" for a predetermined time TSTB. By setting / STB1 to / STB4 to "L" for each predetermined time TSTB, the driving of the heating resistors in one row of the thermal line head is completed (the image formation for one row is completed).
).
[0035]
The pattern of the motor drive control pulses A, / A, B, / B is changed by interrupt processing, as will be described in detail later. At the same time as changing the pattern of the motor drive control pulse, the strobe pulses / STB1 and / STB2 (or / STB3 and / STB4) are set to "L", and the transfer of data DATA2 (or DATA1) is executed. In FIG. 4, while the first to 1280 heating resistors are being driven, A = “H”, / A = “L”, B = “L”, and / B = “H”. This is a pattern during which DATA2 is transferred. Next, the motor drive control pulse changes to the following pattern: A = "H", / A = "L", B = "H", / B = "L", and at the same time, the 1281st to 2560th heating resistors Is driven. At this time, the transfer of DATA1 is performed. Thereafter, similarly, the pattern of the motor drive control pulse is updated, two blocks of the heating resistor divided into four parts are driven at the same time, and data transfer corresponding to the next driven heating resistor is performed. .
[0036]
FIG. 5 is a diagram illustrating a transfer process of the bitmap data.
As described above, the image data input to the printer 1 is bit-developed in the bit map area BM of the DRAM 22. The data in the bitmap area BM is transferred to the buffer area BF in a predetermined order. In the printer of the present embodiment, the bitmap area BM stores bitmap data for 100 rows, and after all the data for 100 rows has been transferred to the buffer area BF, the bitmap data for the next 100 rows is stored. Of the image data is executed.
[0037]
When writing data in the bitmap area BM, the CPU 10 writes the write pointer W.A. indicating the address of the buffer area BF stored in the pointer storage area of the DRAM 22 (not shown). P. , And the data output from the bitmap area BM is the write pointer W. P. Are sequentially written to the address specified by. Write pointer W. P. Is updated to the next write address when data is written to the specified address. Further, when transferring the bitmap data from the buffer area BF to the thermal line head 40 (registers 40A and 40B), the CPU 10 sets the read pointer R.D. indicating the read address of the buffer area BF stored in the above-mentioned pointer storage area. P. See The read pointer R.R. P. The data read from the address designated by (1) is sequentially transferred to the thermal line head 40 as DATA1 and DATA2. Read pointer R. P. Is updated to the next read address when the data at the specified address is read.
[0038]
In the bitmap area BM, the next data is recorded after all the data is transferred. On the other hand, the buffer area BF is subjected to FIFO control, and is sequentially read from the data written first, and new data is transferred from the bitmap area BM to the area where the reading has been completed.
[0039]
FIG. 6 is a main flowchart showing control of the thermal line printer of the present embodiment. In this embodiment, the timing of data transfer from the buffer area BF to the thermal line head 40 (registers 40A and 40B) is controlled so that data in the buffer area BF does not disappear during the image forming process. In the data transfer from the buffer area BF to the thermal line head 40 (registers 40A and 40B), DATA1 and DATA2 are alternately transferred as described above. Therefore, when the amount of data in the buffer area BF decreases, the transfer interval of DATA1 and DATA2 is extended, so that the amount of data transferred from the buffer area BF to the registers 40A and 40B is reduced. The amount is controlled to be less than the amount, and the amount of data in the buffer area BF is controlled so as not to become zero.
[0040]
When the power is turned on, an initialization memory test is performed (S1 to S5). At this time, 0 is set to a flag FLAG which is referred to in a recording paper cueing process described later (S4). When a memory error is found (Y: S7), the printing operation is not performed, an error is displayed (S9), and the operation is stopped.
[0041]
If the recording paper sensor 25 detects the recording paper in S11, the head of the recording paper (conveyance of the recording paper to the printing position) is performed in S13, and the processing in S11 to S15 is performed until data arrives at the interface. Repeated. Note that the cueing of the recording paper in S13 is to convey the recording paper to a predetermined printing position only when the recording paper is detected for the first time, and once cueing is performed, this step (S13 In), nothing is performed, and the process proceeds to the next S15. The recording paper cueing process will be described later in detail.
[0042]
When the data arrives at the interface I / F (Y: S15), the presence of the recording paper is checked again (S17). Here, when a recording sheet is detected, a cueing process is performed (S19). Note that, similarly to S13, the cueing processing is to convey the recording paper to the printing position only when the recording paper is detected for the first time. Since the cueing processing has already been executed, the recording paper is conveyed to the predetermined position. If not, proceed to the next step without doing anything.
[0043]
The processing of S11 to S23 is repeated until the reception of the data of one page is completed. When the data for one page is received, the CPU 70 starts developing a bit map of the print data in the bit map memory BM (S24). When the bitmap is developed in the bitmap memory BM, the data is transferred to the buffer BF, and one row of data is further transferred from the buffer BF to the register 40A. The bitmap development to the bitmap memory BM and the data transfer from the bitmap memory BM to the buffer BF are performed at any time after S29 while the printing process is being executed. Next, recording paper detection and cueing are performed (S25, S27). Here, the process does not proceed unless the recording paper is detected and conveyed to the printing position. In the cueing process of S27, similarly to the cueing processes of S13 and S19, the conveyance process of the recording paper is performed only when the recording paper is detected for the first time.
[0044]
When one page of data arrives and the recording paper is conveyed to the printing position, first, DATA1 is transferred to the register 40A (S29). Next, a timer for executing a motor drive interrupt process for updating the pattern of the drive control pulse of the motor 34 is started (S39). In the motor drive interrupt processing, updating of a motor drive control pulse, control of a strobe pulse, control of data transfer, and the like are performed (details will be described later).
[0045]
When the printing is completed (YES: S41), the timer for the motor drive interrupt processing is stopped, and the recording paper on which the image formation has been completed is discharged (S45), and the printing process for the next page is prepared (S11).
[0046]
FIG. 7 is a flowchart showing details of the recording paper cueing process called in S13, S19 and S27 of the main flowchart of FIG.
The recording paper cueing process is a process of transporting the recording paper only when the recording paper sensor 25 has detected the recording paper and the recording paper has not been transported to the printing position. First, in S81, it is checked whether a flag FLAG indicating whether or not the recording paper has been conveyed is 1 or 0. The FLAG is set to 0 when the power is turned on (S4 in FIG. 6) and after the recording paper is discharged (S46). In the process during that time, the FLAG is set to 1 only when the cue of the recording paper is performed.
[0047]
If it is determined in step S81 that FLAG = 1, the cueing of the recording paper has already been performed, and the process ends without any further processing. If it is determined that FLAG = 0, the recording paper is transported until the leading end of the printing area reaches the printing position of the printer (S82). When the conveyance of the recording paper is completed, FLAG is set to 1 and the processing is terminated.
[0048]
FIG. 8 is a flowchart showing the motor drive interrupt processing.
At S61, a motor drive control pulse is output. The pattern of the motor drive control pulse is updated each time this interrupt processing is executed. In other words, each time this interrupt processing is executed, the recording paper is conveyed by half a line.
[0049]
Next, a strobe pulse is output (S62). This process is performed every time the recording paper is conveyed by a half line. Therefore, in S62, a strobe pulse corresponding to two blocks of the heating resistor divided into four blocks is output. The strobe pulse corresponding to the other two blocks is output when the next interrupt processing is executed.
[0050]
When the strobe pulse is output, the time until interrupt processing for stopping the strobe pulse is executed (predetermined time: TSTB) is set in the timer, and interruption of the strobe pulse interrupt processing is permitted. While half of all the heating elements are being driven in this way, data for driving the other heating elements is transferred from the buffer BF to the register 40A or 40B (S64). After the data transfer, the remaining amount X of the data in the buffer BF is detected (S65), and the time interval until the next processing (motor drive interrupt processing) is executed is determined according to the remaining amount X (S66). . That is, since the data is transferred from the buffer BF to the thermal line head 40 every time the process is performed, the amount of data transferred from the buffer BF is adjusted by changing the time interval at which the process is performed. I have. The determined time interval is set in the timer (S67), and this processing ends.
[0051]
The remaining amount of data in the buffer area BF is calculated as follows.
In FIG. 5, the start address of the buffer area BF is S.P. A. And the end address is E. A. (S.A. <E.A.). R. P. The read address indicated by W. P. If the write address is smaller than the write address indicated by
X = W. P. -R .; P. ... (1)
Is obtained by R. P. The read address indicated by W. P. If the write address is larger than the write address indicated by
X = (WP-SA) + (EA-RP) (2)
Required by
[0052]
Next, a time interval until the next motor drive interruption process is executed is determined according to the remaining data amount. The time interval is a function of the remaining amount X,
Time interval = f (X) (3)
It is expressed as As the function f, a predetermined function is set according to the specifications of the printer.
[0053]
FIG. 9 is a flowchart illustrating an example of a function for determining the time interval of the motor drive interrupt processing.
The remaining data amount X is divided into cases where the remaining capacity is less than 25%, 25% or more and less than 50%, and 50% or more of the total capacity of the buffer area BF, and the pulse width is different in each case. In the flowchart, 1 <K1 <K2.
Equation (3) is obtained by using the definition of the following equation (4).
R = X / capacity of buffer area BF (4)
It can also be described as a function of R as follows: According to this, the time interval f (R) obtained from the flowchart of FIG. 9 until the next motor drive interrupt process is executed is represented by the following equation (5), where STI is the reference time interval. Will be.
f (R) = STI (R <25%)
f (R) = STI × K1 (25 ≦ R <50%)
f (R) = STI × K2 (50 ≦ R) (5)
[0054]
For example, by setting K1 = 2 and K2 = 3, the burden on the CPU 10 can be relatively reduced when the remaining data amount X (that is, the percentage R) decreases. Since the required time per line of printing increases and the load on the CPU 10 decreases, the processing capacity of the CPU 10 during that time can be increased, and the speed can sufficiently cope with the amount of data transferred from the buffer area BF to the thermal line head 40. Enables execution of bitmap expansion.
[0055]
FIG. 10 is a flowchart showing an interrupt process for stopping the strobe pulse.
When a strobe pulse is output in the motor drive interrupt processing of FIG. 8 and a time corresponding to the strobe pulse width set in S63 of the same processing elapses, the strobe pulse interrupt processing of FIG. 10 is executed, and the pulse output ends. (S71). Further, in S72, the interruption of the strobe pulse interruption processing is prohibited. The interruption of this process is permitted in S63 of FIG. By performing such control, the strobe pulse interrupt processing can be executed only when the strobe pulse is being output.
[0056]
As described above, according to the thermal line head printer and the thermal line head driving method of the present invention, even when the image forming process progresses and the load on the CPU increases, control is performed so as to allow the CPU processing time to relax. Therefore, the image forming process can be executed without interrupting the printing process and without deteriorating the quality of the formed image.
[Brief description of the drawings]
FIG. 1 is a perspective view showing the appearance of a thermal line head printer according to an embodiment of the present invention.
FIG. 2 is a block diagram for explaining control of a thermal line head printer.
FIG. 3 is a diagram illustrating a configuration of a thermal head.
FIG. 4 is a timing chart for explaining print control.
FIG. 5 is a conceptual diagram illustrating the transfer of bitmap data.
FIG. 6 is a flowchart illustrating drive control of the thermal line head printer.
FIG. 7 is a flowchart illustrating recording paper cueing processing of the thermal line head printer.
FIG. 8 is a flowchart showing a motor drive interruption process.
FIG. 9 is a flowchart illustrating an example of a process for determining an execution interval of a motor drive interrupt process.
FIG. 10 is a flowchart showing a strobe pulse interrupt process.
[Explanation of symbols]
1 Printer
2 Cover
3 Housing
10 CPU
22 DRAM
BM bitmap area
BF buffer area
40 thermal head
40A, 40B register

Claims (11)

Using a thermal line head having a plurality of heating resistors arranged in a line, to form an image on recording paper,
Expanding means for expanding image information as bitmap data;
Storage means for storing the bitmap data;
First data transfer means for transferring the bitmap data stored in the storage means from the storage means to the thermal line head for each predetermined amount corresponding to the plurality of heating resistors;
Detecting means for detecting the amount of data stored in the storage means;
A period setting means for setting a first cycle of the data transfer by the first data transfer means in response to the amount of data stored in the storage means,
Storage means for storing the bitmap data possessed by the expansion means,
Have a, a second data transfer means for transferring said storage means the bit map data stored in said storage means,
The cycle setting means may determine that the transfer speed of the bitmap data transferred from the storage means to the thermal line head by the first transfer means is from the storage means to the storage means by the second data transfer means. A thermal line printer , wherein the period is set so as not to exceed a transfer speed of the bitmap data to be transferred .   Using a thermal line head having a plurality of heating resistors arranged in a line, to form an image on recording paper,
  Expanding means for expanding image information as bitmap data;
  Storage means for storing the bitmap data;
  First data transfer means for transferring the bitmap data stored in the storage means from the storage means to the thermal line head for each predetermined amount corresponding to the plurality of heating resistors;
  Detecting means for detecting the amount of data stored in the storage means;
  Cycle setting means for setting a cycle of the first data transfer by the first data transfer means according to the amount of data stored in the storage means;
  Storage means for storing the bitmap data possessed by the expansion means,
  A second data transfer unit for transferring the bitmap data stored in the storage unit to the storage unit by a predetermined amount,
  The cycle setting means increases or decreases the cycle so that the bitmap data stored in the storage means is not lost. 3. The thermal line printer according to claim 1, wherein the recording paper is a thermal paper. The thermal line printer further includes a driving unit that drives the recording paper to be transported, and a heating control unit that drives the heating resistor based on the transferred bitmap data in synchronization with the operation of the driving unit. And
4. The apparatus according to claim 1 , wherein the cycle setting unit sets a cycle of the first data transfer by setting a driving speed of the thermal paper by the driving unit. 5. The thermal line printer as described. 5. The thermal line printer according to claim 1, wherein the cycle setting unit sets the cycle to be longer when the amount of data stored in the storage unit decreases. 6. The thermal line printer according to claim 5 , wherein the cycle setting unit sets the cycle in a stepwise manner. The thermal line head has a register to which bits are assigned corresponding to the plurality of heat generating resistors, and is configured to be driven to generate heat in accordance with the value of the bit of the register. 7. The thermal line printer according to claim 1, wherein data is transferred from a storage unit to the register. In a thermal line printer which transfers an image to a thermal line head having a plurality of heating resistors arranged in a line and forms an image on recording paper,
Expand image information as bitmap data,
Is stored by transferring the bit map data developed in the storage means,
Data transfer means for transferring the bitmap data stored in the storage means from the storage means to the thermal line head for each predetermined amount corresponding to the plurality of heating resistors;
Detecting the amount of data stored in the storage means,
Setting a data transfer cycle of the data transfer means in accordance with an amount of data stored in the storage means, wherein a transfer speed of the bitmap data transferred from the storage means to the thermal line head is And setting a cycle of the data transfer so as not to exceed a transfer speed of the bitmap data transferred from the storage means to the storage means .   In a thermal line printer which transfers an image to a thermal line head having a plurality of heating resistors arranged in a line and forms an image on recording paper,
  Expand image information as bitmap data,
  The developed bitmap data is transferred to storage means and stored,
  Data transfer means for transferring the bitmap data stored in the storage means from the storage means to the thermal line head for each predetermined amount corresponding to the plurality of heating resistors;
  Detecting the amount of data stored in the storage means,
  Setting a cycle of data transfer by the data transfer means in accordance with an amount of data stored in the storage means, and increasing or decreasing the cycle so that the bitmap data stored in the storage means is not lost; A method for driving a thermal line printer. Wherein the amount of data stored in the storage means is reduced cycle characterized in that it is longer, the driving method for a thermal line printer according to claim 8 or claim 9. The thermal line head has a register bit corresponding to said plurality of heating resistors is allocated, has a heating driven configuration according to the value of the bit of the register, the data transfer means the 11. The driving method of a thermal line printer according to claim 8 , wherein data is transferred from a storage unit to the register.

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