JP3531028B2 - Printer - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printer that can be used as a hard copy device for recording image data from a computer or the like.

[0002]

2. Description of the Related Art Conventionally, in a printer for recording with binary gradation data, a plurality of recording elements provided side by side in a sub-scanning direction on a recording head respond to the binary data.
It was recording ON and OFF. ON / OFF at this time
The CPU directly sends the image data to the printer head for recording in accordance with the execution timing of the recording operation, and the printer head executes the recording operation at a constant interval at an extremely short interval. Therefore, the CPU needs to execute the data transfer without delaying the operation of the recording head. If the data transfer is not in time for the recording operation of the recording head, a missing image in the output image or a defect such as recording a plurality of pixels in the image data in which one pixel should be recorded is a very important problem. Becomes Therefore, the CPU is configured to transfer the data every time one pixel of one row arranged in the sub-scanning direction is recorded.

For example, in an ink jet printer, image data sent by a personal computer or the like is taken into a memory via an interface. The printer head has a plurality of ejection nozzles arranged in the sub-scanning direction. The CPU transfers, from the image data stored in the memory, image data for each nozzle of the printer head, which is ejected once, to the drive IC of the head each time one pixel is recorded, and ink is ejected by the transferred image data. Then, image formation was performed.

In such a printer, a program switching time is required for the interrupt for each transfer. However, as the development of printer heads capable of high-speed recording progressed and the printing speed of printers increased,
The load on the CPU for data transfer increases, and it becomes difficult to allocate time for executing other processing. The printing speed of the printer is not determined only by the speed of data transfer, but is a comprehensive reflection of the balance of the time distribution with processing other than data transfer, such as paper transport processing, timing, and the like. Therefore, in a printer such as a conventional printer in which a CPU directly transfers a plurality of image data lined up in a sub-scanning direction from a memory to a recording head line by line, if the print speed is increased, the load on the CPU is extremely high and an interrupt occurs. Occurs, the time consumed for switching becomes large, the balance of time distribution with other processing, the timing, etc. cannot be set efficiently, and as a result, the printing speed is not as fast as expected, There was a problem that the timings of various operations would vary.

In recent years, gradation recording has been performed by various printers, and inkjet printers have also been performed in the same manner as other printers. In gradation recording, the number of data per pixel is large, so if an attempt is made to achieve a printing speed equivalent to that of a binary recording printer, an interrupt will occur as easily as the printing speed will increase, and the printing speed will not be as high as expected. There were problems that it would not be quick and that the timing of various operations would vary.

In order to solve the various problems described above, a large-capacity memory (RAM) is used as a FIFO, and the recording head performs recording by one scanning operation in the main scanning direction. It is expected that the problem can be solved by storing the minute image data so that interrupt switching does not occur, discharging the stored data sequentially, and transferring the data to the printer head for recording. The FIFO is first
This is an in-first-out (first-in first-out) method, and is a method of reading the data written in the memory from the oldest data in time, that is, the data written first.

However, there is a problem that it is difficult to adopt a large-capacity memory for realizing such an operation because it is expensive. Further, in a printer having a high pixel density in the main scanning direction or a printer corresponding to a large recording sheet that requires a large number of pixels in the main scanning direction, the memory capacity is insufficient and
There is a problem that a memory that can store image data to be printed in one scan may not be available. In particular, in an inkjet printer having a configuration in which recording elements are arranged in the sub-scanning direction and lines in the main scanning direction are printed in parallel,
When gradation recording is performed, the number of pixels to be recorded in one scan is large and the amount of image data to be transferred is large, so that a memory having a required capacity cannot be obtained. Therefore, the existing memory with insufficient capacity will be used, and eventually interrupt switching will occur, the printing speed will not be as fast as expected, and the timing of various operations will vary. The problem is foreseen.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and a printer which does not cause a loss due to interrupt switching during one scan operation even if a small-capacity and inexpensive memory is adopted. The purpose is to provide.

[0009]

A first memory for storing captured image data, and a second memory for executing a write operation and a read operation independently and asynchronously and performing a FIFO operation, A printer head that records a plurality of pixels in parallel by image data read from the second memory while moving in the main scanning direction, and a command to start transfer of image data from the second memory to the printer head And an event indicating that the number of transferred image data has reached a predetermined number, an interrupt is generated to cause at least the plurality of pixels to be recorded in parallel in the main scanning direction. Image data to be continuously recorded a plurality of times, the image data not exceeding the predetermined number are collectively transferred from the first memory to the second memory. Second control means, the second memory stores a part of the image data recorded in one main scan of the printer head, and when the second control means starts the transfer, the memory is stored. Space addresses are sequentially allocated, and after the last address, the start address is automatically specified and a write operation is executed, and when the first control means generates an interrupt, the memory space addresses are sequentially allocated, This is achieved by a printer characterized in that a read operation is executed by automatically designating a start address after the final address.

That is, according to the printer of the present invention, the image data for a plurality of pixels lined up in the main scanning direction from the image data stored in the first memory are collectively transferred to the second memory and stored. Then, the data can be collectively transferred from the second memory to the printer head. Moreover, since the second memory operates as a FIFO, the CPU transfers the image data from the second memory to the printer head, that is, reads the image data once at the start of the recording operation of the printer head in the main scanning direction. All that is required is to give a read command to the second memory.

In addition, in this printer, since the CPU executes the transfer of a large amount of image data every time the number of transferred image data reaches a predetermined number, the image data that has been read and is no longer needed is saved. The image data newly transferred from the first memory is written in the designated area.
Therefore, new image data will not be overwritten in the area where necessary image data is stored. Moreover, since the interrupt occurs only when a plurality of pixels are collectively transferred from the first memory to the second memory, the number of interrupt switching occurrences can be significantly reduced as compared with the conventional case.

Since the writing process and the reading process can be independently and asynchronously executed, there is a degree of freedom in setting the execution timing of the writing process and the reading process. Therefore, the timing for transferring the image data from the first memory to the second memory can be controlled by the second control means.

Further, the number of times of occurrence of switching decreases as the capacity of the second memory increases. Therefore, it becomes possible to adopt the memory having the optimum capacity in consideration of the burden on the CPU, and it is no longer necessary to use the memory having a large capacity by mistake. As a result, it is possible to use a small-capacity and inexpensive memory, and it is also possible to reduce the burden on the CPU due to the increase in printing speed.

Further, since the image data is transferred collectively over a plurality of pixels, it is not necessary to execute the transfer of the image data corresponding to the timing of the recording operation of the printer head as in the conventional case, and the transfer timing is set. The degree of freedom has increased.

Further, in the printer of the present invention, the second control means may perform data transfer from the first memory to the second memory by a direct memory access controller.

According to this printer, since the CPU can concentrate on the internal processing, the load on the CPU can be further reduced.

Further, in the printer of the present invention, the CPU may transfer the image data of an amount corresponding to about half the storage capacity of the second memory from the first memory to the second memory when the interrupt occurs.

According to this printer, the frequency of interrupt switching can be minimized with respect to the capacity of the memory used as the second memory.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to FIG.
4 to FIG. 4, an inkjet printer will be described as an example.

FIG. 1 is a perspective view showing the main part of the ink jet printer 1.

The carriage 2 is a resin case containing a head 17 and a head driver 16. Carriage 2
The head driver 16 installed in is composed of an IC,
Flexible cable 5 pulled out from the carriage 2
Is connected to the control board 9.

The carriage 2 is reciprocated by the carriage drive mechanism 6 in the main scanning direction indicated by arrow X in the figure.
The carriage drive mechanism 6 includes a motor 6a, a pulley 6b, a toothed belt 6c, and a guide rail 6d, and the carriage 2 is fixed to the toothed belt 6c.

When the pulley 6b is rotated by the motor 6a, the carriage 2 fixed to the toothed belt 6c is moved in the direction of arrow X in the figure. Guide rail 6
d is two round bars parallel to each other, and penetrates the insertion hole of the carriage 2 so that the carriage 2 slides. Therefore, the toothed belt 6c is not bent by the weight of the carriage 2, and the reciprocating movement direction of the carriage 2 is on a straight line. The direction in which the carriage 2 moves can be changed by reversing the rotation direction of the motor 6a, and the moving speed of the carriage 2 can be changed by changing the number of rotations.

The ink cartridge 4 has an ink tank inside. The ink supply port of the ink tank opens when the ink cartridge 4 is set on the carriage 2 and is connected to the ink supply pipe, and is closed when the connection is released, and ink is supplied to the head 17. Carriage 2
Is provided with a mounting portion for the ink cartridge 4,
Ink cartridges containing Y, M, C, and K inks for ejection can be attached and detached. In this embodiment, only the K (black) ink tank of the four colors is stored in another cartridge, and the other three color ink tanks are stored in one cartridge.

The flexible cable 5 is formed by printing a wiring pattern including a data signal line, a power supply line, etc. on a flexible film, and transfers data between the carriage 2 and the control board 9 so as to transfer the data to the carriage 2. Follow the movement.

The encoder 7 is a transparent resin film provided with graduations at predetermined intervals, and the graduations are detected by an optical sensor provided on the carriage 2 to detect the graduation.
Detects the moving speed of.

The paper transport mechanism 8 is a mechanism for transporting the recording paper P in the sub-scanning direction indicated by an arrow Y in the figure, and the transport motor 8a,
It is configured to include a pair of transport rollers 8b and 8c. The transport roller pair 8b and the transport roller pair 8c are driven by a transport motor 8a and are substantially equal by a gear train (not shown), but the transport roller pair 8c is a roller pair that rotates at a slightly higher peripheral speed. The recording paper P is sandwiched by a pair of transport rollers 8b which are fed from a paper feed mechanism (not shown) and then rotated at a constant speed, and are fed in a sub-scanning direction by a paper feed guide (not shown). After being corrected, it is sandwiched by the pair of transport rollers 8c and transported. Since the peripheral speed of the transport roller pair 8c is slightly higher than that of the transport roller pair 8b, the recording paper P passes through the recording portion without causing slack. The speed at which the recording paper P moves in the sub-scanning direction is set to a constant speed.

In this way, while moving the recording paper P at a constant speed in the sub-scanning direction, the carriage 2 is moved at a constant speed in the main-scanning direction, and the ink ejected from the head 17 is adhered and colored to make the recording paper P. The image is recorded in a predetermined range on one side of.

FIG. 2 is a circuit block diagram of the ink jet printer 1.

A CPU 11 for controlling the entire ink jet printer 1 is mounted on the control board 9, and is connected to the head driver 16 of the carriage 2 by the flexible cable 5 as described above. CPU11
Is C that serves as both the first control means and the second control means of the present invention.
It is an example of PU.

The page memory 12 is an example of the first memory of the present invention, and stores image data received from a personal computer or the like which uses the ink jet printer 1 itself as a peripheral device. The storage capacity of the page memory 12 may be determined by the number of bits of gradation image data handled by a personal computer, the number of dots, the signal transfer speed, the CPU processing speed, and the like. However, 1 of head 17
Since the recording operation cannot be stopped during the scanning operation, the number of pixels recorded during at least one movement of the head 17 in the main scanning direction (hereinafter also referred to as the scanning operation) has a storage capacity which is sufficient for storage. is necessary. Between each scanning operation, the recording paper P is conveyed and the operation of returning the printer head 17 to the home position is executed. Therefore, the image data of the page memory 12 becomes the image data to be recorded in the next scanning operation. It is possible to update.

Since the printer according to the present invention enables very high speed recording, the parallel interface SCSI (14a) and IEEE1 are used for the purpose of speeding up image data transfer without using the serial interface.
284 (14b) was made available.

The memories 13a and 13b are examples of the second memory of the present invention. The image data of each pixel, which is recorded in a line in the main scanning direction when being recorded on the recording paper P, is stored, and each image data is transferred from the page memory 12 as gradation data of several bits. In the present embodiment, two 8-bit processing line memories 13a and 13b are used in parallel, but one line memory for 16-bit processing may be used. The data signal line from the page memory 12 has 16 bits and is branched to each line memory 13 by 8 bits. The image data in the line memories 13a and 13b is transferred to the head driver 16 via the flexible cable 5. The process of writing and reading the image data to and from the memories 13a and 13b will be described later in detail.

The head drivers 16a to 16d are composed of ICs, and one driver is provided for each color. Each IC is connected to a shift register of 128 bits × 4, and the image data from the line memories 13a and 13b is temporarily stored in this shift register. It should be noted that the head driver 16 may be plural in number for each color, and the size can be further reduced by packaging the drivers for four colors in one IC.
The head driver 16 has a 4-bit data signal line, and when the head driver 16 is serially connected by this signal line, image data that could not be stored in the shift register in the previous stage is stored in the shift register in the subsequent stage. it can.

Each of the heads 17Y, M, C and K has 128 nozzles, and the nozzles constituting each head are arranged side by side in the sub-scanning direction so that a plurality of lines can be recorded simultaneously.

In this embodiment, the yellow image data is transferred from the line memory 13a to the head driver 16a via a 4-bit data signal line. The 128 yellow image data transferred to the head driver 16a are processed in parallel, and recording by the head 17Y is executed. Similarly, the magenta image data is transferred from the line memory 13a to the head driver 16b and is recorded by the head 17M. Cyan is transferred from the line memory 13b to the head driver 16c for recording by the head 17C, and black is transferred from the line memory 13b to the head driver 16e for recording by the head 17K. Head driver 16
The detailed operation of will be described later.

Based on the information detected by the encoder 7, the AND gate 22 sends a TRGIN signal to start ink ejection when the carriage 2 starts one reciprocating movement and reaches a predetermined position on the forward path. Output to the driver 16. The head driver 16 receives the TRGIN signal and sends a drive signal to cause the head 17 to eject ink.

The head driver 16 supplies a drive signal to the electromechanical conversion element provided in each nozzle of the head 17 by a 128-bit data signal line, and the electromechanical conversion element is deformed in response to the drive signal, whereby the head is changed. The ink inside is ejected. There are various electromechanical conversion elements, but in the present embodiment, a piezo element will be described as an example.

Generally, in an ink jet printer, a droplet is ejected from a nozzle according to a drive signal to perform recording.
Ink droplets are sequentially recorded on the recording paper P, and it becomes possible to record an area corresponding to the number of droplets, and gradation recording can be performed.

If the environmental conditions are constant, the speed of the droplets ejected from the nozzle head 17 can be increased by increasing the driving voltage of the piezo element. On the contrary, by using a drive signal having a different waveform depending on the environment around the inkjet printer 1, stable image quality can be obtained. In this embodiment, the temperature near the head 17 is measured by the thermistor 19, and the waveform is changed according to the measured temperature. With this configuration, even if the ink viscosity changes with temperature, the head can be driven correspondingly. It is more preferable to set the humidity condition and the like as parameters for changing the waveform of the drive signal.

Since the high-quality output image can be obtained by changing the waveform of the drive signal depending on the environment, various waveforms of the drive signal are stored in the SRAM (not shown) in the drive waveform generation circuit 15 as digital data. , Which are transferred from the CPU 11 and stored. This SRAM can be configured using a FIFO or the like.

Since the waveform data of this embodiment stored in this SRAM outputs data of 4 bits and 16 gradations per color, the data stored in the SRAM in the drive waveform generation circuit 15 has an amplitude of the basic waveform of 16 bits. This is a digital data of the repeating waveform. Just before starting printing,
The CPU 11 transfers the content of the waveform data to the SRAM so that the optimum applied voltage is applied depending on the temperature condition detected by the thermistor 19, and rewrites the waveform data as appropriate. CPU
In 11, some waveform data for each temperature condition is prepared, or the waveform data is calculated from the temperature variable corresponding to the temperature detected each time. In the drive waveform generation circuit 15, the waveform data of this drive signal is demodulated and amplified into an analog waveform by D / A conversion and output to the head driver 16.

The constituent members such as the CPU 11, the page memory 12, the memory 13 and the head driver 16 are synchronized by a common reference clock.

Next, the concept of the operation of the memory 13 will be described with reference to FIG. 3 and 4 are conceptual diagrams conceptually showing the operation of writing the image data to the memory 13 and the operation of reading the image data. The memories 13a and 13b described with reference to FIG. 2 operate in the same manner, and will be described as the memory 13. Figure 3
In (a) to (c) of FIG. 4 and (a) to (c) of FIG. 4, a boundary line m represented by an alternate long and short dash line is a virtual line indicating a half capacity of the memory space of the memory 13. The write pointer WP is a pointer corresponding to the write start address, and the read pointer RP is a pointer corresponding to the read start address. The pointer has a function of sequentially allocating addresses in the memory space from the initial value, and the read pointer R
Both P and the write pointer WP are functions provided in the semiconductor chip of the memory 13. When the CPU 11 which is an example of the second control means issues a transfer start instruction, the write pointer WP sequentially allocates the addresses of the memory space from the initial value to store the image data in the memory 13, and the read pointer R
When the CPU 11, which is an example of the first control means, generates an interrupt, P outputs image data in which addresses are sequentially allocated from the initial value and stored. In addition, the read pointer R
P and the write pointer WP automatically specify the head address after the last address. In addition, the read pointer R
When P and the write pointer WP are reset, the address of the memory space is assigned from the initial value. In the present embodiment, the CPU 11 outputs the reset signal to the read pointer RP and the write pointer WP to issue the reset instruction.

In this embodiment, the memories 13a and 13b each have a capacity of 64 kBytes.

FIG. 3A shows a state where the read pointer and the write pointer are returned to the head address, that is, reset. When it is confirmed that the image data recorded by one scan of the head 17 is stored in the page memory 12, the CPU starts the transfer of the image data from the page memory 12 to the memory 13. At this time, the image data is transferred by the direct memory access controller (DMA
It is preferable to use C) because the load on the CPU can be reduced.
Further, when the image data at the beginning of each scan is transferred, an amount of image data that does not exceed the capacity of the memory 13 is transferred from the page memory 12.

FIG. 3B shows the result of the data transfer, that is, the memory 1
Write pointer W to the last address of the memory space of 3
P has arrived, that is, a state in which the image data is stored in the memory 13 at the full capacity. Light pointer W
If P is not reset and more data than the capacity is transferred, P moves from the final address to the start address. Further, the image data stored in the memory 13 is a part of the image data recorded by one scan of the head 17, and in the present embodiment, it corresponds to recording of several mm in the main scanning direction on the recording paper. .

FIG. 3C shows a state where the image data is being transferred from the memory 13 to the head driver 16. When the read pointer RP reaches the boundary line m, among the image data stored in the memory 13, 32 KBytes of image data is already transferred to the head driver 16 and is no longer needed. is there. 3A to 3C and FIG. 4A.
In (c), the memory space in which the image data that has become unnecessary after being read once is stored is shown by hatching.

In FIG. 4A, since the image data is transferred from the page memory 12 to the memory 13 without resetting, the write pointer WP moves to the head address and the image from the memory 13 to the head driver 16 is moved. This shows a state in which data transfer is being executed.

As the memory 13, a memory 13 which can independently execute a write operation (also called a write processing) and a read operation (also called a read processing) is adopted. Also CP
From U11, the write operation and the read operation to the memory 13 are performed without specifying the address of the memory space. However, since the memory 13 operates as a FIFO until the read pointer RP and the write pointer WP are reset, the automatic operation is performed. The image data at the addresses indicated by both pointers are sequentially processed.

When the read pointer RP reaches the boundary line m during execution of the read processing, the CPU 11 (FIG. 3C).
(Indicated by 1), the transfer of the image data from the page memory 12 to the memory 13, that is, the writing process of the image data of a plurality of pixels to the memory 13 at once is started. At this time, the amount of image data to be collectively written is set to approximately half the capacity of the memory 13. When this writing process ends, the write pointer WP reaches the boundary line m. Therefore, the new image data is replaced and saved in the area shown by the diagonal lines in the drawing in which the unnecessary image data is already saved.

In this embodiment, the motor 6a is a stepping motor, and the number of steps of the motor 6a corresponds to the moving distance of the carriage 2. Since the number of pixels with respect to the moving distance is determined from the pixel density, the moving amount of the read pointer RP in the memory space can be detected by counting the number of steps of the motor 6a. Then, it is determined whether the read pointer RP reaches the boundary line m according to the result of the counting operation. A trigger signal Trg (see FIG. 5) is output every time the read pointer RP reaches the boundary line m. CPU
Upon receiving the trigger signal Trg, the device 11 generates an interrupt, and image data corresponding to a plurality of pixels is collectively written in the memory 13.

FIG. 4B shows a state in which the write pointer WP reaches the boundary line m after both the write processing and the read processing proceed and the read pointer RP reaches the final address of the memory space after that. Read pointer R
Whether or not P has reached the final address is determined by counting the number of steps of the motor 6a. Then, when the read pointer RP reaches the final address, the trigger signal Trg is output in the same manner as when the read pointer RP reaches the boundary line m, so that an interrupt occurs and the capacity of the memory 13 is batched again. Image data corresponding to half the data amount is written.

In FIG. 4C, since the image data is transferred from the memory 13 to the head driver 16 without resetting, the read pointer RP moves to the head address and further read processing is performed, and at the same time, the page memory is read. 12 shows a state in which the image data writing process from 12 to the memory 13 is being executed. The writing process and the reading process are continued as they are to return to the state of FIG.

In this way, the front and rear of the memory space are divided into approximately half, and the writing process of the image data transferred from the CPU is executed in one of the divided memory spaces, and the reading operation is performed in the other of the memory spaces. The data is transferred to the head drivers 16a to 16d. Then, the CPU finishes reading and collectively transfers the image data to the memory space in which the unnecessary image data is stored.

Since the CPU 11 does not reset the read pointer RP and the write pointer WP until the end of one scan operation, the memory 13 is stored in the memory 13 as shown in FIGS. 3A to 3C and 4A to 4C. Repeat the state indicated by. The writing process is executed so as not to exceed the address of the read pointer RP determined from the number of steps of the motor 6a. That is, since unnecessary image data is stored in the first half of the memory space when the read pointer RP reaches the boundary line m and in the second half of the memory space when the read pointer RP reaches the final address, these unnecessary data are stored. The image data of a data amount that does not exceed the capacity of this area is transferred to the area in which various image data are stored. In this way, the operation of reading a certain amount of image data from one memory and writing a certain amount of image data is repeated to perform image recording corresponding to one scan.

When data is transferred from a personal computer or the like, not only the image data but also the information such as the image size and the recording paper size which are indicated by the product of the number of pixels in the main scanning direction and the sub scanning direction are transferred. The CPU 11 obtains the number of steps of the motor 6a corresponding to the image size, executes the image recording operation, and resets the read pointer RP and the write pointer WP when the recording of the number of pixels in the main scanning direction is completed. The CPU 11 also reverses the motor 6a to return the carriage 2 to the home position. Further CPU1
1 confirms whether or not the image data corresponding to one scan operation is already stored in the page memory 12. If the image data corresponding to the one-scan operation has already been saved, the transfer of the image data to the memory 13 is started, and if it has not been saved yet, the transfer of the image data to the memory 13 waits.

Next, a timing chart showing execution timings of the writing process and the reading process of FIG. 5 will be described.

In FIG. 5, the write execution periods W1 and W2 are
It shows the period during which the writing process is being executed. Each trigger signal Trg is a signal output every time the read pointer RP reaches the boundary line m or the final address of the memory 13.

In the write execution period W1, the write pointer W
After P and the read pointer RP are reset (see FIG.
This is the period during which the image data writing process that is first executed in (a) is performed. In the write execution period W1, as shown in FIG. 3B, image data having the same capacity as the entire memory space of the memory 13 is transferred.

When the write execution period W1 ends, the read process starts. The read process is continuously executed until the read process corresponding to one scan operation is completed. When the read process corresponding to the one scan operation is completed, the read pointer RP is reset (not shown). If the configuration for executing the next scan operation without resetting the read pointer RP is adopted,
If the image data remains in the memory 13 after the end of the scan operation or if there is an abnormality such that all the image data is output before the end of the one scan operation, the image shift occurs. This image shift is accumulated in the area recorded by the scanning operation executed after the occurrence of the abnormality, and is observed as a skew shift with respect to the main scanning direction. In the present embodiment, the read pointer RP and the write pointer WP are reset when the reading process corresponding to the one-scan operation is completed. Therefore, even if this abnormality occurs,
The adverse effect on the output image can be limited to only the line being recorded when the abnormality occurs.

During the write execution period W2 to W3, the read pointer RP and the reset of the read pointer RP are completed.
This is the period during which the writing process executed after the second time is being performed. After the write execution period W2, the trigger signal Trg
Is started when is output.

In the above embodiment, the configuration has been described in which an interrupt is generated in accordance with the number of steps of the motor 6a, which is a stepping motor, and the writing process from the page memory 12 to the memory 13 is executed. However, in the printer of the present invention, the writing process to the second memory may be executed by detecting another event.

For example, the encoder 7 outputs a detection signal each time the carriage 2 moves a certain distance, and an interrupt is generated in accordance with the detection signal of the end coder 7 to execute the writing process from the page memory 12 to the memory 13. May be adopted.

Further, the CPU 11 monitors the number of data transferred from the memory 13 to the head driver 16, and when the number of data reaches a predetermined number, an interrupt occurs and the writing process from the page memory 12 to the memory 13 is executed. A configuration may be adopted.

Since the carriage 2 moves at a predetermined recording speed, the head 17 writes each pixel at a constant recording speed. Therefore, the CPU 11 monitors the elapsed time from the start of data transfer from the memory 13 to the head driver 16, and when a predetermined time elapses, an interrupt occurs and a writing process from the page memory 12 to the memory 13 is executed. May be adopted.

The number of data transferred from the page memory 12 to the memory 13 and the elapsed time of data transfer from the page memory 12 to the memory 13 are determined by a counter built in the CPU 11. Further, this counter may be a counter on a chip different from the CPU 11.

In this embodiment, the CPU 11 is DM
Although the AC is built in, the image data may be transferred by the DMAC of another chip.

Further, if the CPU 11 is configured to transfer the image data in an amount equivalent to about half the storage capacity of the memory 13 from the page memory 12 to the memory 13, the occurrence frequency of interrupt switching when the same amount of memory is adopted is minimized. This is preferable because it can be suppressed.

[0070]

According to the printer of the present invention, even if a small-capacity and inexpensive memory is adopted, a loss due to the occurrence of interrupt switching does not occur during one scan operation.

Further, the number of times of occurrence of switching decreases as the capacity of the second memory increases. Therefore, it becomes possible to adopt the memory having the optimum capacity in consideration of the burden on the CPU, and it is no longer necessary to use the memory having a large capacity by mistake. As a result, it is possible to use a small-capacity and inexpensive memory, and it is also possible to reduce the burden on the CPU due to the increase in printing speed.

Further, since the image data is collectively transferred over a plurality of pixels, it is not necessary to transfer the image data in correspondence with the timing of the recording operation of the printer head as in the conventional case, and the transfer timing can be set. The degree of freedom has increased.

[Brief description of drawings]

FIG. 1 is a perspective view showing a main part of an inkjet printer 1.

FIG. 2 is a circuit block diagram of the inkjet printer 1.

FIG. 3 is a conceptual diagram conceptually showing an operation of writing image data to a memory 13 and an operation of reading image data.

FIG. 4 is a conceptual diagram conceptually showing an operation of writing image data to a memory 13 and an operation of reading image data.

FIG. 5 is a timing chart showing execution timings of a writing process and a reading process.

[Explanation of symbols]

1 inkjet printer 2 carriage 5 flexible cable 6a motor 7 encoder 9 Control board 11 CPU 12 page memory 13 memory 14 Interface 15 Drive waveform generation circuit 16 head driver 17 heads 19 Thermistor 23 Control circuit m border WP write pointer RP read pointer

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Yutaka Aoki Yutaka Aoki, 1st Konica stock company, Sakura-cho, Hino-shi, Tokyo (72) Inventor, Tatsuro Oishi 1st-Konica stock company, Sakura-machi, Hino-shi, Tokyo (56) References JP-A-2-24158 (JP, A) JP-A-4-170857 (JP, A) JP-A-7-81140 (JP, A) JP-A-7-40604 (JP, A) JP-A-2-279359 (JP, A) JP 1-198364 (JP, A) JP 7-304213 (JP, A) JP 64-53226 (JP, A) JP 59-121432 (JP, A) Kai 60-100872 (JP, A) JP 61-189953 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B41J 2/01 B41J 2/51 B41J 5/30 H04N 1/21

Claims (9)

(57) [Claims] 1. A first memory for storing captured image data, a second memory capable of executing a write operation and a read operation independently and asynchronously and operating as a FIFO, and the above-mentioned memory while moving in a main scanning direction. A printer head for recording a plurality of pixels in parallel by the image data read from the second memory; first control means for instructing start of transfer of image data from the second memory to the printer head; When an event indicating that the number of transferred image data has reached a predetermined number occurs, an interrupt is generated to reduce at least
Also in the main scanning direction, the plurality of pixels recorded in parallel are
Image data for continuous recording multiple times,
Second control means for collectively transferring image data not exceeding the predetermined number from the first memory to the second memory, wherein the second memory is used for one main scan of the printer head.
When a part of the image data to be recorded is saved and the second control means starts the transfer, addresses in the memory space are sequentially allocated, and the start address is automatically designated after the final address. Write operation is performed, and when the first control means generates an interrupt, addresses of the memory space are sequentially allocated, and next to the last address, the start address is automatically specified and the read operation is performed. Characteristic printer. 2. A CPU having a CPU that doubles as the first control unit and the second control unit.
The printer described in. 3. The encoder according to claim 1, further comprising an encoder that outputs a detection signal each time the printer head moves a predetermined distance, and the event is that the detection signal is output. The listed printer. 4. A stepping motor that is a drive source for moving the printer head, and a counter that outputs a count end signal when the number of steps of the stepping motor reaches the predetermined number, and the event is the counter The printer according to claim 1, wherein the printer outputs a count end signal. 5. An elapsed time monitoring means for monitoring the elapsed time from the start of data transfer from the second memory to the printer head and outputting a detection signal when the elapsed time reaches a predetermined time. The printer according to claim 1 or 2, wherein the event is that the elapsed time monitoring means outputs a detection signal. 6. The printer head records each pixel at a predetermined recording speed, the CPU monitors the elapsed time from the start of data transfer from the second memory to the printer head, and the occurrence of the event occurs. The printer according to claim 2, wherein the elapsed time is a predetermined time. 7. The direct memory access controller causes the second control means to transfer data from the first memory to the second memory. Or the printer according to 6. 8. The CPU transfers from the first memory to the second memory an amount of image data corresponding to approximately half the storage capacity of the second memory when the interrupt occurs. The printer according to 2, 3, 4, 5, 6 or 7. 9. The printer head moves a plurality of times in the main scanning direction to execute the recording each time, and the second memory stores an address of a memory space when the second control means starts the transfer. Are sequentially assigned from the initial value to execute the write operation, and when the first control means generates an interrupt, the addresses of the memory space are sequentially assigned from the initial value to execute the read operation, and the printer head performs the main scanning. 9. The read operation and the write operation are performed by reallocating the address from an initial value every time it moves in the direction once, and the read operation and the write operation are performed. Printer.