JP4038639B2 - Printer and its image data transfer method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a printer used as a terminal printer or a facsimile terminal of a computer system, and more particularly to a printer having an improved image data transfer method from an image buffer to a head data processing circuit.
[0002]
[Prior art]
Conventionally, in such a printer, every time print timing occurs, an interrupt is generated or DMA is started, so that head data processing in a print control circuit (ASIC) is performed from a buffer (image buffer) storing image data. The necessary amount of print data is transferred to the circuit.
[0003]
For example, in the method using an interrupt, the CPU timer is used (at the rising edge of the timer output pulse) to generate the print head drive timing, and the same timer interrupt (interrupt generated inside the CPU) is used. The print data is transferred from the image buffer to the head data processing circuit and stored.
[0004]
That is, as shown in FIG. 6, the CPU 11 in the printer has a timer 11a, and generates the print head drive trigger 12 at the rising edge of the output pulse of the timer 11a. The drive trigger 12 is input to a head drive circuit 21 a in the ASIC 21, and a drive waveform 24 is applied to the head 25 via the D / A converter 23 by the head drive circuit 21 a. Accordingly, the generation timings of the drive trigger 12 and the drive waveform 24 are shown in FIGS. 7A and 7B.
[0005]
On the other hand, interrupt processing is generated by using the interrupt request by the output pulse of the same timer 11a, and print data is transferred from the image buffer 26B on the RAM (DRAM) 26 to the head data processing circuit in the ASIC 21 as shown in FIG. The data is transferred to 21b and stored in the head data processing circuit 21b. The relationship between the interrupt processing and the drive trigger 12 is as shown in FIGS. 7 (a) and 7 (c). The CPU 11 controls the above processing according to a control program stored in a ROM (program ROM) 27.
[0006]
Hereinafter, a specific description will be given with reference to FIG. For example, conventionally, raster format data used in a color printer has been treated as one byte corresponding to 8 bits in the horizontal direction as shown in FIG. 8, but as shown in FIG. In the case of a structure in which nozzles or impact wires (51a) are arranged in a vertical line, when sending to the print head 51, it is necessary to take out data 53 of a bit string in one byte. The amount of image data has been steadily increasing due to the recent reduction in print density, while the print timing 62 is generated at such short intervals such as the print timing 62 is generated approximately every 70 μs by the timer 61a in the CPU 61. appear. Therefore, in recent years, which has become stricter in terms of time, data for the number of dot forming elements in a dot forming element array of 8 horizontal bits (1 byte) × vertical row (for example, 32 in the illustrated example). 57 is generated at a certain print timing and transferred from the image buffer 63 to the shift register (head data processing circuit) 67 in the print control circuit (ASIC) 65 at a time, and an interrupt is generated at each print timing. Each time, a part of the print control circuit (ASIC) 65, that is, data 53 (32 bits) of a certain bit string is taken out and transferred to the print head 51.
[0007]
[Problems to be solved by the invention]
As described above, since the raster format data is an array of data in the scanning direction, the data for the horizontal 8 bits, 16 bits, or 32 bits.times.vertical one column is collected from the image buffer 63 to the print control circuit (ASIC) 65. Although it is necessary to transfer, the data transfer time is not enough in one interrupt process. For example, in the case of data of 8 bits in the horizontal direction, the data is transferred by dividing into 8 interrupts. . However, as a result of such division processing, the interrupt processing program also becomes complicated, and a long time is required for the data transfer processing, resulting in a decrease in throughput.
[0008]
Accordingly, an object of the present invention is to reduce the need for dividing interrupts in a printer that transfers a required amount of data from an image buffer to the head data processing circuit described above at once, and thus a simple program and a shorter time. In addition to providing a printer that can transfer data in time, it is intended to reduce the total CPU load and thereby improve throughput.
[0009]
[Means for Solving the Problems]
The present inventor noticed that the above-described conventional printer used the CPU timer interrupt, so that the process had to be performed within the drive trigger period. For example, the print control circuit ( The ASIC) is provided with a counter, thereby adding a circuit for controlling the interrupt request so that the interrupt request is controlled from the print control circuit (ASIC) side.
[0010]
Thereby, for example, in the case of data of 8 bits, an interrupt request can be generated only once even if 8 drive triggers are generated. Similarly, once for 16 bits, once every 16 times and once for 32 bits, once every 32 times.
[0011]
That is, according to the first aspect of the present invention, the printer of the present invention includes a CPU, an image buffer, and a print control circuit having a hardware configuration including a head data processing circuit, and outputs a drive trigger signal for the print head. In response, the CPU transfers a required amount of image data from the image buffer to the head data processing circuit, the head data processing circuit holds the image data, and the image data held by the head data processing circuit is partly printed. In the printer for serial transfer to the printer, the printing control circuit is provided with counting means, and a count value is set a plurality of times as the set number of the driving trigger signal by the counting means, and the driving trigger is set by the counting means. When the signal is counted for the set number, an external interrupt request is generated from the print control circuit to the CPU, Upon receiving an external interrupt request, the CPU executes an interrupt process for transferring the required amount of image data to the head data processing circuit, and transfers the required amount of image data in one external interrupt request. The image data can be transferred even when the transfer time is longer than the cycle of the drive trigger signal.
[0012]
According to a second aspect of the present invention, in response to the external interrupt request, the CPU preferably transfers all of the required amount of image data to the head data processing circuit within one interrupt process. is there.
[0013]
Further, as in the printer according to claim 3, the image data is significant when the data is raster graphics data.
[0014]
According to a fourth aspect of the present invention, if the required amount of image data is data corresponding to the number of nozzles of horizontal n (n is an integer of at least 2) × vertical one nozzle row, the n The number n is not limited, but normally, n may be 8, 16, or 32 as in the ink jet printer according to claim 5.
[0015]
7. The printer according to claim 6, wherein the head data processing circuit includes a first RAM and a second RAM capable of storing a required amount of image data transferred from the image buffer, respectively, and the required amount of image data. A write selector for selectively writing data to either the first or second RAM and an mth bit (m is greater than or equal to 1 and less than or equal to n above) from the first or second RAM. And a read selector for reading out data corresponding to the number of nozzles of the mth bit × vertical one nozzle row.
[0016]
Further, in the printer according to claim 7, the print control circuit including the head data processing circuit is provided on a main board constituting the printer controller.
On the other hand, according to the second aspect of the present invention, the printer of the present invention includes a CPU, an image buffer, and a print control circuit having a hardware configuration including a head data processing circuit, and outputs a print head drive trigger signal. In response, the CPU transfers a required amount of image data from the image buffer to the head data processing circuit, held by the head data processing circuit, and performs printing based on the image data held by the head data processing circuit. In the printer, a counting unit that sets a plurality of count values as the set number of the drive trigger signal and counts the drive trigger signal;
External interrupt means for generating an external interrupt request to the CPU when the drive trigger signal is counted by the set number by the counting means;
Upon receiving the external interrupt request generated by the external interrupt generating means, the CPU executes an interrupt process for transferring the required amount of image data to the head data processing circuit, and the required amount of image data is set to 1 The image data can be transferred even when the transfer time is longer than the period of the drive trigger signal when the transfer is performed by the external interrupt request.
[0017]
In this case, the head data processing circuit is provided on a head substrate in a print head included in the print engine.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, printers according to embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the overall configuration of the printer according to the first embodiment of the present invention.
[0019]
The illustrated printer includes a printer controller 1 and a print engine 2. The printer controller 1 stores an interface (hereinafter referred to as “I / F”) 4 that receives print data from the host computer 3, a RAM 5 that stores various data, a routine for various data processing, and the like. A ROM 6, a CPU 7, a print control circuit (printing ASIC) 9 for sending head data and the like to a print (printing) head 12, which will be described later, and an I for sending image data and drive signals to the print engine 2. / F10. The I / F 4, the RAM 5, the ROM 6, the CPU 7, the print control circuit (printing ASIC) 9, the I / F 10, and the like are connected to each other by a bus 11.
[0020]
The I / F 4 receives print command data from the host computer 3. The RAM 5 is used as a reception (data) buffer 5A, an output (image) buffer 5C, a work memory 5B, and the like. In the data buffer 5A, print command data from the host computer 3 received by the I / F 4 is temporarily stored. For example, image data in a raster graphics format after the print command data is analyzed is developed in the image buffer 5C. The ROM 6 stores various control programs executed by the CPU 7 and the like. As shown in FIG. 1, the programs include a main program 6a and an interrupt processing program 6b. The ROM 6 also stores font data and graphic functions (not shown), various procedures, and the like.
[0021]
The print engine 2 includes a print head 12, a carriage mechanism 13, and a paper feed mechanism 14. The paper feed mechanism 14 includes a paper feed motor, a paper feed roller, and the like, and sequentially feeds a print storage medium such as recording paper to perform sub-scanning. The carriage mechanism 13 includes a carriage on which the print head 12 is mounted and a carriage motor that moves the carriage via a timing belt or the like, and causes the print head 12 to perform main scanning. The print head 12 has an inkjet nozzle row 15 made up of, for example, 32 nozzles in the sub-scanning direction, and ejects ink droplets from each nozzle at a predetermined timing.
[0022]
FIG. 2 shows the configuration of the print control circuit (printing ASIC) 9.
[0023]
The printing ASIC 9 constitutes a control unit of a head driver and the like, and as shown in FIG. 2, a head driving circuit 16 for applying a predetermined driving waveform to the print head 12 and print data to the print head 12. A head data processing circuit 17 for sending to the printer side, and an interrupt request control circuit 18 including a counter for controlling an interrupt request from the printing ASIC side.
[0024]
Hereinafter, the operation and action of the printing ASIC 9 will be mainly described with reference to FIG. 3 in addition to FIG. The print head drive trigger 42 [see FIG. 2 and FIG. 3B] is generated by the rising edge of the output pulse of the timer 7b of the CPU 7. The drive trigger 42 is input to the head drive circuit 16 in the printing ASIC 9. A drive waveform is applied to the print head 12 by the head drive circuit 16. Accordingly, the generation timings of the drive trigger 42 and the drive waveform 24 are shown in FIGS. 3 (a) and 3 (b).
[0025]
On the other hand, the drive trigger 42 by the rising edge of the output pulse of the same timer 7 b is also input to the head data processing circuit 17 and the interrupt request control circuit 18 in the printing ASIC 9. The interrupt request control circuit 18 counts this drive trigger 42 with an internal counter, and issues an interrupt request signal 18a as an external interrupt to the CPU 7 when it reaches a predetermined number (for example, 8 times). Upon receiving this interrupt request signal 18a, the CPU 7 performs one interrupt process, and in this one interrupt process, the image buffer 5C transfers all the data for 8 bits horizontal × vertical column to the head data processing circuit 17. Forward. If this one-time interruption process and the generation timing of the drive trigger 42 are shown, they are as shown in FIGS. As a comparative example, as shown in FIGS. 3D, 3E, and 3F, similarly, a driving waveform, a driving trigger, and the like in the case of transferring data of horizontal 8 bits × vertical column by a conventional divided interrupt process, (Division) The generation timing of interrupt processing is shown respectively.
[0026]
As apparent from FIG. 3, even when a required amount of data is transferred from the image buffer to the head data processing circuit at a time, it is not necessary to divide the interrupt.
[0027]
Note that only one column of data that has been bit-selected is serially transferred from the head data processing circuit 17 to the print head 12 (head and head substrate) via a flat cable or the like. The operation of the head data processing circuit 17 including this bit selection will be described below.
[0028]
FIG. 4 is a diagram for explaining the operation of the head data processing circuit 17. That is, the head data processing circuit 17 has two data selectors including a write selector 17a and a read selector 17b, and two RAMs including a first RAM 17c and a second RAM 17d.
[0029]
As described above, all the data of horizontal 8 bits × vertical column is transferred from the image buffer 5C to the head data processing circuit 17 in one interrupt process. Is selectively written into either the first RAM 17c or the second RAM 17d by the write selector 17a. Further, the read selector 17b reads the bit-selected and selected data from either the first RAM 17c or the second RAM 17d, that is, selects and reads the data in one vertical column at a predetermined timing. The data thus transferred is transferred to the print head 12 as shown in FIG.
[0030]
It is assumed that data latched in the second RAM 17d is being printed. Since this second RAM 17d is 8 bits wide and latches data for 8 shots, it is serially transferred to the print head 12 in 8 steps, but during printing for 8 shots, The CPU 7 reads and writes the next print data from the image buffer 5C to the first RAM 17c. When the data in the second RAM 17 is printed, the write selector 17a and the read selector 17b are switched to start printing the data in the first RAM 17c. During the printing, the next printing is performed in the second RAM 17d. Data is read from the image buffer 5C and written. Printing is executed by repeating the above processing.
[0031]
As described above, according to the present embodiment, the drive trigger 42 is counted by the counter in the interrupt request control circuit 18 in the ASIC 9 for printing, and when the predetermined number (eight times) is reached, the CPU 7 is treated as an external interrupt. The interrupt request signal 18a is issued. Upon receiving this interrupt request signal 18a, the CPU 7 performs one interrupt process, and in this one interrupt process, the image buffer 5C transfers all the data for 8 bits horizontal × vertical column to the head data processing circuit 17. Forward.
[0032]
The point of this improvement is that processing that has been divided by eight interrupt processing can be processed eight times by one interrupt.
[0033]
In the past, data transfer was processed by the CPU timer interrupt, so processing longer than the drive cycle of the head could not be performed, but it became an external interrupt, so eight data transfers were performed in one interrupt. It is sufficient to perform the processing within the head driving cycle for 8 times. The image of the data transfer process by this interrupt process is as already shown in FIGS. 3 (a), 3 (b), and 3 (c).
[0034]
FIG. 5 is a block diagram showing the overall configuration of a printer according to the second embodiment of the present invention. The basic configuration of the printer of this embodiment is substantially the same as that of the printer of the first embodiment shown in FIG. 1, and the same reference numerals are given to the same parts and the description thereof is omitted.
[0035]
That is, in the printer of the second embodiment, as shown in FIG. 5, the print control circuit (printing ASIC) 9 ′ is provided not in the printer controller 1 but in the print head 12 of the print engine 2. . Specifically, in the first embodiment described above, the printing ASIC 9 is provided on a main board (not shown) constituting the printer controller 1, whereas in the second embodiment, printing is performed. The ASIC 9 ′ is provided on a head substrate (not shown) in the print head 12.
[0036]
In this embodiment, the CPU 7 that has received the external interrupt request sends, for example, data of 8 bits in width × one column in the vertical direction from the image buffer 5C to the head data processing circuit 17 ′ in the print head 12. Except for transferring all of them, the operation of the head data processing circuit is not significantly different from that of the first embodiment.
[0037]
However, in this embodiment, since the printing ASIC 9 'including the head data processing circuit 17' is arranged on the print head 12 side, the portion of the control circuit related to the number and arrangement of nozzles unique to the head is the main board (printer). If the data transfer specifications (from the image buffer in the printer controller to the head data processing circuit in the print head) are standardized to some extent, the first embodiment will exist. Compared to the above, there is an advantage that the main board (printer controller circuit) can be easily standardized. For example, the printer can be upgraded simply by exchanging the program ROM (ROM 6) and the print head (head substrate). In addition, since the main board (printer controller circuit) can be easily shared, it can quickly respond to various specifications on the head side (4 colors or 6 colors ?, increase in number of nozzles, etc.) (development is possible).
[0038]
As mentioned above, although this invention was described about specific embodiment, this invention is not limited to these, It is applied also about other embodiment within the range of the invention described in the claim.
[0039]
For example, in the above-described embodiment, the raster format image data is processed by transferring the data from the image buffer to the head data processing circuit in one interrupt by collecting 8 bytes in the horizontal direction and 32 bytes in the vertical row (32 nozzles). However, other desired amount of data may be transferred by one interrupt process. That is, the horizontal 16-bit or 32-bit data may be transferred by one interruption, and it is needless to say that the present invention can be similarly applied to one having 64 nozzles in a vertical row.
[0040]
Needless to say, the present invention can be applied not only to inkjet printers, dot impact printers, and the like, but also to other printers.
[0041]
【The invention's effect】
As described above, according to the present invention, a counting unit is provided in a print control circuit (printing ASIC) having a hardware configuration, and when a predetermined number of drive triggers is counted by the counting unit, an external interrupt request is generated. As a result, the interrupt request can be controlled from the hardware print control circuit side, and the interrupt processing program is simpler and the data transfer of the head can be processed at a higher speed than the transfer processing by the conventional divided interrupt. It is possible. As a result, it is possible to provide a printer capable of reducing the burden on the CPU as a whole and improving the throughput.
[Brief description of the drawings]
FIG. 1 is a functional block diagram illustrating an overall configuration of a printer according to a first embodiment of the present invention.
2 is a functional block diagram showing a configuration of a print control circuit of the printer shown in FIG. 1. FIG.
FIGS. 3A and 3B are timing charts showing execution timings of print timing, drive waveforms, and transfer processing by interruption, wherein FIGS. 3A to 3C are according to the first embodiment of the present invention, FIG. -(F) shows what is by a prior art example.
4 is a diagram for explaining the operation of a head data processing circuit in the printer shown in FIG. 1; FIG.
FIG. 5 is a functional block diagram illustrating an overall configuration of a printer according to a second embodiment of the present invention.
FIG. 6 is a functional block diagram showing a simplified overall configuration of a conventional printer.
FIG. 7 is a timing chart showing execution timing of print timing, drive waveform, and transfer processing by interruption in a conventional printer.
FIG. 8 is a diagram showing a data transfer (software transfer) method by a general interrupt of raster format data in a conventional color printer.
[Explanation of symbols]
1 Printer Controller 2 Print Engine 3 Host Computer 4 I / F
5 RAM
5A Reception buffer 5B Work memory 5C Output (image) buffer 6 ROM
6a Main program 6b Interrupt processing program 7 CPU
7a Timer 9 Printing control circuit (ASIC for printing)
9 'Print control circuit (ASIC for printing)
10 I / F
11 Bus 12 Print head 15 Inkjet nozzle row 13 Carriage mechanism 14 Paper feed mechanism 16 Head drive circuit 17 Head data processing circuit 17a Write selector 17b Read selector 17c First RAM
17d second RAM
17 'head data processing circuit 18 interrupt request control circuit 18a interrupt request signal 42 drive trigger

Claims (12)

A CPU, an image buffer, and a print control circuit having a hardware configuration including a head data processing circuit, and upon receiving a print head drive trigger signal, the CPU transfers a required amount of image from the image buffer to the head data processing circuit. In a printer that transfers data and holds it in the head data processing circuit, and further serially transfers image data held in the head data processing circuit to a print head part by part.
In the case where the printing control circuit is provided with a counting unit and a count value is set a plurality of times as the set number of the drive trigger signal by the counting unit, and the driving trigger signal is counted by the set number by the counting unit, An external interrupt request is generated from the print control circuit to the CPU, and upon receiving the external interrupt request, the CPU executes an interrupt process for transferring the required amount of image data to the head data processing circuit. When transferring a large amount of image data by one external interrupt request, the image data can be transferred even if the transfer time is longer than the cycle of the drive trigger signal. Printer.   2. The printer according to claim 1, wherein upon receiving the external interrupt request, the CPU transfers all of the required amount of image data to the head data processing circuit within one interrupt process.   3. The printer according to claim 1, wherein the image data is raster graphics data.   4. The printer according to claim 3, wherein the required amount of image data is data corresponding to the number of nozzles of horizontal n (n is an integer of at least 2) × vertical one nozzle row. Printer.   The printer according to claim 4, wherein the n is 8, 16, or 32.   6. The printer according to claim 4, wherein the head data processing circuit includes first and second RAMs capable of storing a required amount of image data transferred from the image buffer, respectively, and the required amount of image data. And a m-th bit (m is greater than or equal to 1 and less than or equal to n above) from the first or second RAM by selectively writing to one of the first and second RAMs. A printer having a read selector that reads out data corresponding to the number of nozzles of mth bit × vertical one nozzle row.   7. The printer according to claim 1, wherein the print control circuit including the head data processing circuit is provided on a main board constituting a printer controller.   A CPU, an image buffer, and a print control circuit including a head data processing circuit, and upon receiving a print head drive trigger signal, the CPU transfers a required amount of image data from the image buffer to the head data processing circuit; The image data held by the head data processing circuit is further transferred to the head data processing circuit in a printer that performs serial transfer to the print head for part of the image data held by the head data processing circuit. A control device comprising an ASIC (Application Specific Integrated Circuit), having a counting means inside, and setting a count value for a plurality of times as a set number of the drive trigger signal by the counting means. When the drive trigger signal is counted for the set number, an external interrupt request is sent to the print control The CPU generates an interrupt request for causing the CPU to transfer the required amount of image data to the head data processing circuit in response to the external interrupt request. An image data transfer control device that enables transfer of the image data even when the transfer time is longer than the period of the drive trigger signal when transferring by the external interrupt request. A CPU, an image buffer, and a print control circuit having a hardware configuration including a head data processing circuit, and upon receiving a print head drive trigger signal, the CPU transfers a required amount of image from the image buffer to the head data processing circuit. The head data processing from the image buffer in a printer for transferring data and holding it in the head data processing circuit, and further serially transferring image data held in the head data processing circuit to a print head part by part. In a method for transferring image data to a circuit,
Counting the drive trigger signal by a counting means in which a count value of a plurality of times is set as the set number of the drive trigger signal in the print control circuit;
Generating an external interrupt request to the CPU by counting the set number of the drive trigger signals by the counting means;
Receiving the external interrupt request, the CPU executing an interrupt process for transferring the required amount of image data to the head data processing circuit,
When the required amount of image data is transferred by one external interrupt request, the transfer of the image data is enabled even when the transfer time is longer than the cycle of the drive trigger signal. A characteristic image data transfer method. A CPU, an image buffer, and a print control circuit having a hardware configuration including a head data processing circuit, and the CPU receives a print head drive trigger signal from the image buffer to the head data processing circuit to obtain a required amount of image. Transfer of image data by the CPU in a printer that transfers data and holds it in the head data processing circuit, and further serially transfers image data held in the head data processing circuit to a print head part by part. A recording medium on which a program to be controlled is recorded,
The counting means in which the count value is set a plurality of times as the set number of drive trigger signals in the print control circuit has generated an external interrupt request to the CPU by counting the set number of drive trigger signals. When the external interrupt request is received, the CPU executes an interrupt process for transferring the required amount of image data to the head data processing circuit, and sends the required amount of image data to the external interrupt request once. A recording medium on which is recorded a program that enables transfer of the image data even when the transfer time is longer than the cycle of the drive trigger signal. A CPU, an image buffer, and a print control circuit having a hardware configuration including a head data processing circuit, and upon receiving a print head drive trigger signal, the CPU transfers a required amount of image from the image buffer to the head data processing circuit. In a printer that transfers data and is held by the head data processing circuit and performs printing based on image data held by the head data processing circuit.
Counting means for setting the count value for a plurality of times as the set number of the drive trigger signal, and counting the drive trigger signal;
An external interrupt means for generating an external interrupt request to the CPU when the drive trigger signal is counted by the set number by the counting means;
Upon receiving the external interrupt request generated by the external interrupt generating means, the CPU executes an interrupt process for transferring the required amount of image data to the head data processing circuit, and the required amount of image data is set to 1 A printer which makes it possible to transfer the image data even when the transfer time is longer than the cycle of the drive trigger signal when the transfer is performed by the external interrupt request.   12. The printer according to claim 11, wherein the head data processing circuit is provided on a head substrate in a print head included in a print engine.

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