JP2001010128A - Page printer and page print system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent overrun error and underrun error. SOLUTION: A host 1 delivers the image data of each page, in units of band, to a page printer 3 and a page printer 3 writes each received band data into a receiving buffer in a DRAM 21 through a DMA. Each band data is then transferred from the receiving buffer to an imaging section 13-19, 27 through the DMA. The host 1 acquires an empty buffer capacity from a printer immediately before each band data is transferred and transmits a band data only when the printer 3 can receive it. The printer 3 permits the DMA to transfer a data after a volume of receiving data, calculated by a CPU 23 not to generate an under error based on the data receiving rate or data transfer rate, is stored in the buffer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a page printer used in a computer system or the like, and more particularly, to a control of an operation of accumulating image data in a buffer memory, reading image data from the buffer memory and transferring the image data to a print engine. About.

[0002]

2. Description of the Related Art In a page printer, the speed at which image data is developed into a bit map and written into a buffer memory is generally different from the speed at which image data is read from the buffer memory and transferred to a print engine. In addition, the capacity of the buffer memory is so small that image data for one page cannot often be stored. Therefore, especially when the image is complicated and has a large amount of data, the expansion of the image data and the writing to the buffer memory cannot be performed in time for the transfer to the print engine, and there is no data to be read from the buffer memory during the printing of the page, and the printing cannot be continued. A missing error may occur (this error is referred to herein as an "underrun error"). On the other hand, an error (hereinafter, referred to as "overrun error" in this specification) may occur in which the expansion and writing of the image data are so fast that the buffer memory becomes full and the subsequent data cannot be written.

[0003] To solve this problem, Japanese Patent No. 2663861
The page printer detects the occurrence of an error by detecting a match between the write address and the read address of the buffer memory, notifies the host of the error, and thereby notifies the user of the occurrence of the error and takes appropriate action. Is made available to the user.

[0004]

However, the advantage of the above-mentioned prior art is that when an error occurs, the user is notified of the error and takes a countermeasure. For the user,
Ideally, printing should always succeed without error. If an error occurs, it is desirable that the system automatically take appropriate measures against it.

An object of the present invention is to prevent an overrun error.

[0006]

According to the present invention, a page printer includes a memory including a buffer, an image output unit that forms and outputs an image based on data, and writes data received from a host to the buffer. A receiving unit, a transfer unit that transfers data in the buffer to the image output unit, and a free buffer capacity notifying unit that notifies the host of information regarding free space of the buffer. The host transmits data of a size that can be received by the printer to the printer based on the notification from the page printer. Thereby, an overrun error is prevented.

In a preferred embodiment, the host sends compressed or uncompressed data in a predetermined unit, for example, a band unit to the printer, and obtains a free buffer capacity from the printer immediately before the start of transmission of each band data. If the free buffer capacity is equal to or larger than the size of the band data, the transmission of the band data is started; otherwise, wait until the free buffer capacity is equal to or larger than the size of the band data, and then wait for the size of the band data. Start sending.

[0008] In a preferred embodiment, the page printer comprises:
Further, it has a function of detecting a printer error such as an underrun error and various printer statuses such as successful printing of each page and notifying the host. In that case, the printer temporarily stores the information of the detection result in the memory, and transmits the information in the memory to the host when requested by the host. Immediately before the host starts to transmit each band data, the host requests the printer to acquire the printer status.

The host of the present invention is typically a computer, and a computer program (eg, a printer driver program) for the host is installed or loaded on the computer via various media such as a disk storage, a semiconductor memory, and a communication network. can do.

[0010]

FIG. 1 shows the configuration of an embodiment of the present invention.

The page printer 3 of the present embodiment is a host-based printer that receives image data bit-developed by the host 1 from the host 1 and prints the image data. The printer 3 is connected to the host 1 via a dedicated interface such as a parallel interface or a network such as a LAN so as to be capable of bidirectional communication. Further, various statuses of the printer (for example, free buffer capacity, error information, printing success information, etc.) can be transmitted to the host 1. A receiving buffer for storing image data received from the host 1 is secured in the DRAM 21 in the printer 3 with a fixed or variable capacity. The capacity of the reception buffer may be smaller than the size of image data for one page. C described later
The work area of the PU 23 is also secured in the DRAM 21, and in this work area, status information to be notified to the host 1 and the like are stored.

The printer 3 has a print engine 27 which is a mechanism for executing an electrophotographic process, and a printer engine 27 which receives image data from the host 1 and performs necessary processing.
Series of processing circuits to be passed to
1, a DMA controller 13, a data expansion circuit 15, a video controller 17, and a post-processing circuit 19. These processing circuits 11 to 19 are configured by, for example, dedicated hardware logic circuits. Further, the printer 3 has a CPU 2 for interpreting requests from the host 1, detecting errors, managing printer status, and the like.
3. A microcomputer including a ROM 25 storing programs and fixed data and the above-described DRAM 21 and the like. The function of each part is as follows.

The interface circuit 11 controls bidirectional communication with the host 1 such as reception of a request and image data from the host 1, transmission of status information to the host 1, and the like. The request received by the interface circuit 11 is directly read by the CPU 23. The CPU 23 interprets the request and executes control based on the request. D
The MA controller 13 performs writing and reading of image data to and from the reception buffer in the DRAM 21 by D.
Performed by MA. DRA of image data by DMA
The input / output path to M21 includes a reception DMA 31 and a transfer DM.
There are two channels, A33. Image data from the host 1 is written to the DRAM 21 through the reception DMA 31. The image data is transferred from the DRAM 21 to the data expansion circuit 15 via the transfer DMA 33.

When the image data from the host 1 has been compressed, the data decompression circuit 15 decompresses the image data to the original data and passes it to the video controller 17 at the subsequent stage.
The data not compressed from the host 1 is passed to the video controller 17 as it is. Video controller 17
Controls the timing of image data transfer to the print engine 27 (referred to as video transfer).

The post-processing circuit 19 adjusts the gradation value in consideration of resolution conversion for adjusting the resolution of the image data to the print engine 27, edge smoothing for smoothing the outline of characters and the like, gamma characteristics, and the like. Post-processing such as gradation control is performed on the image data and sent to the print engine 27. The resolution conversion described above is a function of converting the data received from the host to 300 dpi, for example, if the resolution of the print engine 27 is 600 dpi and the data received from the host is 300 dpi. With this resolution conversion function, as described later, for example, if printing fails when an under error occurs when the host 1 first sends 600 dpi image data, then the resolution of the image data from the host 1 Can be reduced to 300 dpi and printing can be retried.

At the start of printing, the CPU 23 notifies the host 1 of printer information (state information fixed to some extent in one print job such as a communication mode and a RAM size) upon receiving a request from the host 1 or prints. In the meantime, the current status of the printer (status information that fluctuates every moment, such as whether the status of the engine, the free buffer capacity, whether an error has occurred, whether printing has succeeded for each page, etc.) is acquired in real time, and the Record in the work area in the host 1
When a request is received from the host 1, the status is notified to the host 1. Among these functions, the one directly related to the present invention is that the CPU 23
Write address to RAM 21 (received DMA address)
And the read address (transfer DMA address)
The free space of the receiving buffer in the AM 2 is calculated, and this free space is recorded in the work area in the DRAM 21, and when there is a request from the host 1, the free receiving buffer capacity is notified to the host 1.

Next, the operation under the above configuration will be described.

FIG. 2 shows a control flow performed for each page when the host 1 sends image data to the printer 3.

The host 1 first determines whether the page to be printed is the first page or the second and subsequent pages (S1).
If it is the first page, the printer 3 sends the printer information (communication mode (communication mode established between the printer 3 and the host 1; for example, in the case of parallel communication, Co
mpatibility and ECP), DRAM size, etc.
If the printer information has not been prepared, information indicating that the printer is being prepared is acquired (S2), and based on this, the restrictions on the printer 3 are grasped. After the second page, the printer information is not obtained. Further, the printer information is acquired not only for the first page but also after the print error in step S6 occurs, and it is checked whether the printer 3 has recovered from the error.

When printer information is received from the printer 3,
The host 1 determines whether the printer information is valid or invalid, that is, valid printer information indicating the communication mode and the DRAM size described above or invalid printer information indicating preparation is being performed (S3). Is in preparation (invalid), the host 1 repeatedly reads the printer information from the printer 3 until receiving valid printer information. The reason why the printer information is being prepared (invalid) is that the printer 3
Is in the process of initializing the printer or recovering from an error.

Upon acquiring valid printer information, the host 1 determines a transmission mode (resolution, etc.) of image data based on the communication mode of the printer 3 and the RAM size.
Next, the host 1 transmits host information (resolution of image data, total number of bands, etc.) relating to image data to be printed to the printer 3 (S4). The printer 3 performs page settings such as register setting and buffer clear based on the host information.

Next, the host 1 receives the printer status (the state of the engine, the free buffer capacity, whether an error has occurred, whether printing has succeeded for each page, etc.) from the printer 3 (S5), and It is checked whether or not the printer 3 can receive one band of image data based on (S6, S8). That is, if the following conditions are satisfied, it is determined that reception is possible.

The print engine 27 can perform a printing operation. That is, the print engine 27 can receive data, is not in a print-disabled state (no paper, paper jam, cover open, engine abnormality, etc.), and the temperature of the fixing unit is a specified value.

The page setting of the printer 3 has been completed.

There is a free space of one band or more in the reception buffer.

No error has occurred.

The printer 3 sets a success / failure flag each time printing of one page is completed. The host 1 looks at the print success / failure flag included in the status acquired from the printer 3 (S6). If “success”, the host 1 deletes the image data of the page from the host 1; For example, the process returns to step S1, and retransmits the image data from the failed page. In the case of retransmission, if the cause of the printing failure is an underrun error, the resolution of the image data is converted to a lower value (for example, dropped from 600 dpi to 300 dpi).
(S7), and retransmit. Since the data size is reduced by lowering the resolution, as will be described later, underrun errors are less likely to occur in retransmission.

Only when the printer 3 determines in step S8 that one band can be received, the host 1 transmits one band of image data (S9). Thereby, an overrun error is avoided. Before transmitting the band image data, the host 1 determines whether or not the size of the band data is reduced by compression. If the size is reduced, the band data is compressed. If not reduced, the band data is not compressed. Then, before transmitting the band image data, the host 1 asks the printer 3 whether or not the band data is compressed data (compression ON / OFF), the size of the compressed band data (in the case of compression OFF, (Original band data size). The printer 3 stores the band image data in a reception buffer of the DRAM 21,
When data of a predetermined number of bands is stored, video transfer is started.

Next, the host 1 checks whether all the band data of one page has been transmitted (S10), and if not completed, returns to step S5. In this way,
The host 1 transmits the image data to the printer 3 in band units.
Each time, the printer status is checked before transmission to confirm whether the printer 3 can receive one band of data. Therefore, when there is at least one band of free buffer capacity, the printer 3 receives at most one band of data (compression OFF).
For 1 band, and less than 1 band for compression ON). This avoids an overrun error as described above.

FIG. 3 shows an operation flow when the printer 3 receives data from the host 1.

First, when the host 1 requests printer information (YES in S11), the CPU 23 of the printer 3
Transmits printer information such as the communication mode and the RAM size to the host 1 (S13). If the printer information has not been prepared (NO in S12), the host 1 indicates that the printer information is being prepared (specifically, that the printer is being initialized or that it is recovering from an error).
(S14).

After transmitting the printer information to the host 1, the CPU 23 of the printer 3 sends the host information (resolution 300 dpi / 600 dpi) regarding the image data from the host 1.
i, the total number of bands), and based on the information, register setting for data reception and page setting such as buffer clear are performed (S15).

Subsequently, a process for receiving one band of image data from the host 1 is started (S16). This one
FIG. 4 shows a control flow of band reception.

As shown in FIG. 4, when a printer status request is first received from the host 1 (YES in S21), C
The PU 23 notifies the host 1 of the current status of the printer (S22, S23, S24). Specifically, if a print error has occurred at present, the host 1 is notified of an error status such as the type of the print error (S
23), and return to step S11 in FIG. If no errors occurred, free buffer space, engine status,
Whether the page settings have been completed, the page has been printed successfully,
Is sent to the host 1 (S24). The free buffer capacity is calculated from the transfer DMA address and the reception DMA address of the DMA controller 13 as described above. As described above, the host 1 determines whether or not the printer 1 can receive one band of data based on the status information.
Band information such as N / OFF and band compression size, and then image data of the band are sent to the printer 3.

The CPU 23 of the printer 3 performs compression ON / O
D based on band information such as FF and band compression size
The parameters related to the reception DMA of the MA controller 13 (the start point of the reception DMA address, the number of bytes of the band data, etc.) are set (S26), and the DMA controller 13 is allowed to receive data (S27). As a result, the DMA controller 13 receives image data for one band from the host 1 on the path of the
Write to the reception buffer of the RAM 21. Note that host 1
If the band information does not come from (NO in S25), the control returns to step S21.

When the DMA controller 13 that has started receiving data has received the image data of the number of bytes set in step S26, that is, the image data of one band, the DMA controller 13 notifies the CPU 23 of that fact. The process proceeds to step S17 shown in FIG.

The CPU 23 determines in step S17 that the DRAM
It is checked whether or not a predetermined number of bands of image data have been stored in the reception buffer 21. If the data for the predetermined number of bands has not been stored yet, step S16 is performed again.
Then, the reception of the subsequent band data is repeated. If data for a predetermined number of bands has been stored, the CPU 23
Permit video transfer to MA controller 13 (S1)
8). Thus, the video transfer starts. That is,
The DMA controller 13 starts the operation of reading image data from the DRAM 21 and transferring the read image data to the data decompression circuit 15, and the data decompression circuit 15 and the video controller 17
The post-processing circuit 19 also starts the respective processes, and the print engine 27 starts printing. After the video transfer starts,
Data reception from the host 1 in band units is similarly continued (S19) (details are shown in FIG. 4). When the reception of the data for one page is completed (YES in S20),
Control returns to step S11, and data reception of the next page is started in a similar procedure.

The "predetermined number of bands" determined in step S17 is determined by the CPU 23 for each page based on the following principle for the purpose of preventing an underrun error.

That is, the data reception speed from the host 1 is x [byte / sec], and the video transfer speed is y [byte / sec].
Seconds], the data compression rate is α, and the total number of data on one page is T
[Byte], the size of the reception buffer is M [byte], and the data size stored in the reception buffer at the time of starting the video transfer is P [byte]. Normally, the video transfer speed y is higher than the data reception speed x, and if the transfer DMA address of the high-speed video transfer catches up with the reception DMA address of the low-speed data reception, an underrun error occurs. However, if P is set so as to satisfy P ≦ M (1) (α × T−P) / x <T / y (2), the transfer DMA address of the video transfer becomes the data reception reception. Since data reception for one page is completed before catching up with the DMA address, no underrun error occurs. (1), (2)
From the formula, M ≧ P> T (α−x / y) (3) is derived. If P is set so as to satisfy the expression (3), no underrun error occurs. In this embodiment,
Since it is determined not by the number of bytes but by the number of bands, the minimum P [byte] satisfying the expression (3) is divided by the compression band size [byte], and the value obtained by adding 1 to the quotient is calculated as the "predetermined number of bands". It should just be set as.

By starting the video transfer when the "predetermined number of bands" is accumulated in the reception buffer, an underrun error can be avoided. In addition, the printing speed is high because the start of the video transfer is only delayed as little as necessary.

Even if the "predetermined number of bands" is determined at the beginning of the page, an underrun error occurs if the compression ratio α decreases in the middle of the page or if the data reception speed from the host 1 decreases. The possibilities come out. in this case,
It is necessary to secure a larger buffer size M or reduce the resolution of the image to reduce the total data size T of one page. In particular, the effect of the resolution conversion is great. For example, when the resolution is reduced from 600 dpi to 300 dpi, the data size T is reduced to ４. Therefore, performing the resolution conversion at the time of retransmitting the data once the underrun error has occurred (FIG. 2, step S7) has a great effect of preventing the underrun error from occurring again. The print quality is slightly degraded by the resolution conversion, but for the user,
It is preferable to not printing.

FIG. 5 is a control flow performed by the CPU 23 regarding video transfer.

The CPU 23 checks whether video transfer is possible (ie, whether image data has been received by the predetermined number of bands or more) (S31). If received, host information (resolution, total The register setting related to video transfer is performed based on the number of bands (S32). Next, based on band information such as compression ON / OFF and compression band size, parameters relating to transfer DMA of the DMA controller 13 (start point of transfer DMA address, number of bytes of band data, etc.) and parameters of the data expansion circuit 15 (expansion) ON / OFF
Etc.). Currently executing (or starting from now) when setting the start point of the transfer DMA address
The start point of the received DMA address is compared with the start point of the transfer DMA address to be set (S33). If they match, it is determined that an underrun error has occurred, and an underrun error flag is set in the work area of the DRAM 21. It is set (S34). This underrun error is notified to the host 1 by the host 1 reading the printer status prior to each band transmission (S5 in FIG. 2) as described above. When the host 1 reads the status of the printer, the underrun error flag is released. As mentioned above, host 1
Upon detecting an underrun error, retransmits the image data in which the error has occurred with the resolution reduced from the first band, and subsequently transmits the image data of the subsequent band with the resolution reduced.

If no underrun error has occurred, the CPU 23 of the printer 3
In step S35, one band transfer DMA is permitted (S35). Each time the one-band transfer DMA is completed, the DMA controller 1
3 notifies that fact, the CPU 23 proceeds to step S3
Return to 3. Thus, until one page transfer is completed
The transfer DMA setting of one band and the execution of the transfer DMA are repeated. When the transfer of one page is completed (YE in S36)
S), the CPU 23 sets a print success flag in the work area of the DRAM 21 (S37). The print success flag is notified to the host 1 when the host 1 reads the printer status. When the host 1 reads the status of the printer, the print success flag is cleared. As described above, upon receiving the print success flag, the host 1 deletes the image data of the page.

When the video transfer for one page is completed, the control returns to step S31, and the video transfer for the next page is started in the same procedure. When the compression ratio of the image data is high or the reception buffer size is sufficiently large, the image data of a plurality of pages is stored in the reception buffer 43 and is continuously printed at the maximum throughput of the print engine 27.

FIG. 6 shows a configuration of the DRAM 21.

As described above, the work area 41 and the receiving buffer 43 are secured in the DRAM 21. The work area 31 is used as a heap memory and a stack memory. In the example shown in the figure, the reception buffer 4 stores all the areas of the DRAM 21 from the buffer start address BUFTOP to the buffer end address BUFBTM.
3. In the reception DMA, the address point (reception DMA address) RAD is set to the buffer start address B
Proceed in the direction from UFTOP to the buffer last address BUFBTM, and
When it reaches TM, it returns to the buffer start address BUFTOP. Similarly, in the transfer DMA, the address point (transfer DMA address) TAD is changed from the buffer start address BUFTOP to the buffer end address BUFBTM.
To the buffer end address BU
When the FBTM is reached, the buffer top address BUFTOP
Return to Thus, the reception buffer 43 is used as a ring buffer.

The illustrated example shows a state in which data 53 of page B is being stored in the reception buffer 43 and video transfer of data 51 of page A before page B is about to be started. The data 51 and 53 of each page include
Host information (resolution, total number of bands, etc.) on each page image, information on each band (compression ON / OF)
F, compression band size, etc.) and image data of each band.

In this embodiment, in order to prevent an overrun error as described above, the host 1 transmits data in band units, and each time the printer 3 calculates the free space of the reception buffer 43 prior to the transmission. And host 1
, And the host 1 executes transmission only when the free space is one or more bands. Hereinafter, a method of calculating the free space will be described.

FIG. 7 shows two states of the reception buffer 43. That is, FIG. 7A shows a state of “reception DMA address RAD> transfer DMA address TAD”.
(B) shows the state of “reception DMA address RAD <transfer DMA address TAD”. Received data is accumulated in the area indicated by hatching, and the area described as “empty” is an empty area.

The "received DMA address R" shown in FIG.
AD> transfer DMA address TAD ”, free space = (TAD-BUFTOP) + (BUFBTM
−RAD), and the “receiving DMA address RAD” shown in FIG.
When <transfer DMA address TAD ”, the free space = TAD-RAD.

FIG. 8 shows a circuit (or software processing flow) used for calculating the free space.

In FIG. 8, TADST is the start point of the transfer DMA address, and RADT is the reception D address.
These are the start points of the MA address, and as described above, these are set by the CPU 23 when the transfer DMA of each band and the reception DMA of each band are started. TADCNT is a counter indicating the address of a reception buffer for which transfer DMA is to be performed, and radCNT is a counter indicating the address of a reception buffer for which reception DMA is to be performed.

The transfer DMA address counter 61 sets the transfer DMA start address TADST as an initial output value and executes the output value from the buffer start address BUFTOP to the reception buffer end address BUFBTM during the execution of the transfer DMA of each band. Step by step so as to circulate in a ring. The output value of the transfer DMA address counter 61 is the transfer DMA address TAD.

Similarly, the reception DMA address counter 63
Indicates that the reception DMA is executed while the reception DMA of each band is executed.
Using the start address RADT as the initial value of the output value,
The output value is advanced by one so as to circulate in a ring from the buffer start address BUFTOP to the reception buffer end address BUFBTM. The output value of the reception DMA address counter 61 is the reception DMA address RAD
It is.

The comparator 65 sets the transfer DMA address TAD
And the received DMA address RAD, and sets an address comparison flag ADCMPR indicating which is larger. The subtracters 67, 69, and 71 operate as “TAD-BUFTO”.
P = TSUBTP "," TAD-RAD = TSSUB
R "and" BUFBTM-RAD = BTSUBR ", respectively.

The CPU 23 sets the address comparison flag ADC
Looking at the MPR, “Receive DMA address RAD> Transfer DM
In the case of "A address TAD", the free space is set to TSUBTP + BTSUBR, and in the case of "reception DMA address RAD <transfer DMA address TAD", free space is set to TSUBBR.

Next, a second embodiment of the present invention will be described. The overall configuration of this embodiment is the same as that shown in FIG. In this embodiment, the host 1 determines the start timing of the video transfer and instructs the printer 3. Generally, since the host 1 has a higher CPU processing capacity than the printer 3, it is better for the host 1 to determine the start timing.
The start timing can be set more accurately than determined by the printer 3. Further, when the free space of the reception buffer decreases to a predetermined amount (for example, one band) before the start timing instructed by the host 1 comes, the printer 3 starts video transfer voluntarily at that time.
This avoids a situation in which the receiving buffer becomes full and the printer 3 stalls before the start timing specified by the host 1 comes. Even if video transfer is started earlier than the start timing instructed by the host 1, there is a case where printing can be normally performed in practice, so that occurrence of an error can be minimized. If the start timing of the video transfer specified by the host 1 is earlier than the completion of data reception for one page, and an underrun error occurs, the host 1 first sets the start timing to one page. After the completion of the data reception, the data is changed and instructed to the printer 3, and then the data is retransmitted. Still, if an underrun error occurs again, the host 1 resends the next lower-resolution data (for example, the original 600 dpi to 300 dpi data) to the printer 3. The receiving buffer of the printer does not need to be able to store the original high-resolution data for one page, but has a capacity to store one-page data with reduced resolution.

FIG. 9 shows the host 1 in this embodiment.
3 is a flowchart of control performed for each page when image data is transmitted to the printer 3.

Here, only the points different from the control flow of the host of the previous embodiment shown in FIG. 2 will be described. Parts not described are the same as those in the flow of FIG.

The host 1 sends the host information (that is, information on image data) to the printer 3 in step S43.
The host information includes the image data resolution (300/600 dpi), the total number of bands, and the video transfer start timing (the band number). The start timing is determined by the host 1 so that the expression (3) described in the first embodiment, that is, the condition of M ≧ P> T (α−x / y) (3) is satisfied. Here, x is the data reception speed [byte / second] from the host 1, y is the video transfer speed [byte / second], α is the data compression ratio, and T is 1
The total number of bytes [bytes] of the page, M is the size of the receiving buffer [bytes], and P is the data size [bytes] stored in the receiving buffer at the start of video transfer.
When determining the start timing, the host 1 determines the type of the port for transmitting the image data (parallel, USB, Ethernet (registered trademark), etc.) or the communication mode of the port (compatibility, ECP, etc. in the case of parallel). Since the data reception speed x is different, the start timing is changed accordingly. For example, when the reception speed x is fast as in parallel ECP, a fast start timing is set, and when the reception speed x is not stable as in network communication, a slow start timing (for example, all data of one page is received) To start the video transfer after
Set. The printer 3 informs the host 1 of the communication mode established with the host 1 as necessary at step S42 as printer information (for example, the parallel communication mode (Compatibility or E).
Since the host 1 cannot know the CP) unless the printer 3 notifies the host 3, the printer 3 notifies the host 1. ).

The printer 3 determines in step S44 that the host 1
Page setting such as register setting and buffer clear based on the host information sent from. At this time, the start timing included in the host information is also set in a register in the printer 3. Thereafter, the printer 3 stores the data of each page sent from the host 1 in the reception buffer, and, in principle, at the start timing designated by the host 1 for each page (that is, the host 1)
The video transfer is started when the number of bands as the start timing instructed from is received.

The printer 3 sets a print success / failure flag each time printing of one page is completed, and
Sees the print success / failure flag included in the status acquired from the printer 3 (S46), deletes the image data of the page from the host 1 if "successful", Proceeding to the error processing of step S47, data is retransmitted from the failed page.

FIG. 10 shows the flow of this error processing.

First, the contents of the error are checked (S5).
1) If the cause of the error is a paper jam, retransmission is simply performed from the failed page. On the other hand, if the cause of the error is an underrun error, the start timing of the video transfer instructed to the printer 3 at the time of occurrence of the error is checked (S52), and the flying start (that is, all the one page) is started. (Starting video transfer before data reception is completed) is instructed to start video transfer after reception of all data of one page is completed.
The start timing is changed (S53), and the changed start timing is instructed to the printer 3 again (FIG. 9, S
44) Retransmit data from the failed page (FIG. 9, S4)
9). In addition, when an error occurs, the printer 3 starts to "start video transfer after receiving all data of one page".
If the instruction has been given, the data of the failed page is recreated by lowering the resolution (for example, from 600 dpi to 300 dpi) (S53), and the lowered resolution is notified to the printer 3 (S44 in FIG. 9). For the failed page, retransmit the data with reduced resolution (FIG. 9, S
49). Note that the above-described data retransmission may be automatically performed by the host 1, or the user may be notified that an error has occurred, and whether or not to retransmit, and if so, whether to decrease the resolution. The user may make a selection.

FIG. 11 shows an operation flow when the printer 3 receives data from the host 1.

Here, only the parts different from the printer control flow of the first embodiment shown in FIG. 3 will be described. Parts not described are the same as those in the flow of FIG.

At step S65, the printer 3
The host information (resolution, total number of bands, start timing of video transfer, etc.) is received from the server, and based on the information, register setting for data reception and page setting such as buffer clear are performed.

Subsequently, the printer 3 enters a process of receiving one band of image data from the host 1 in a flow as shown in FIG. 4 (S66). Then, while receiving data from the host 1 into the reception buffer, the printer 3 determines whether the number of bytes as the start timing specified by the host 1 has been received, and whether the free space of the reception buffer has become less than one band. Check whether (S6
7). When the specified number of bytes has been received, the printer 3 can start video transfer (S68). When the number of bands specified by the host 1 is the total number of bands for all one pages, that is, when the host 1 has instructed “start the reception of all data of one page”, the process immediately proceeds to step S61 after the start of the video transfer. Return (S71) The operation for receiving data of the next page is started.

If the data compression ratio is unexpectedly bad or the original data is considerably larger than the reception buffer size, the reception buffer becomes vacant before the number of bands specified by the host 1 is received. The capacity may be less than one band. In this case, the free buffer space is 1
The printer 3 starts video transfer when the band becomes less than one band. In this case, the probability of occurrence of an underrun error increases, but there are many cases where printing can be performed normally because the start timing designated by the host 1 includes a sufficiently large margin.

FIG. 12 is a control flow of the video transfer performed by the printer 3.

Here, only the portions different from the video transfer flow of the first embodiment shown in FIG. 5 will be described. Parts not described are the same as those in the flow of FIG.

First, it is checked whether video transfer is possible by checking whether or not the number of bands specified by the host 1 has been received (S71). If received, one-band video transfer is executed in the same procedure as in the flow of FIG. 5 (S72 to S75). Then, the state of the printer engine is checked (S76), and if a paper jam has occurred,
The paper jam error flag is set (S77). When detecting a paper jam error, the host 1 retransmits the data without changing the parameters as shown in FIG.

As described above, one embodiment of the present invention has been described.
These embodiments are merely examples for describing the present invention, and are not intended to limit the present invention only to these embodiments. Therefore, the present invention can be implemented in various forms other than the above-described embodiment.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is a flowchart of control performed for each page when a host 1 sends image data to a printer 3;

FIG. 3 is a flowchart of control of a printer CPU 23 when the printer 3 receives data from a host 1.

FIG. 4 is a flowchart of one-band reception control.

FIG. 5 is a flowchart of control of video transfer.

FIG. 6 is a memory map of a DRAM 21;

FIG. 7 is a diagram showing two states of a reception buffer 43.

FIG. 8 is a configuration diagram of a circuit (or software) used for calculating a free buffer capacity.

FIG. 9 is a flowchart of control performed for each page when the host 1 sends image data to the printer 3 according to the second embodiment of the present invention.

FIG. 10 is a flowchart of error processing of a host according to the second embodiment.

FIG. 11 is a flowchart of control of the printer CPU 23 when the printer 3 receives data from the host 1 in the second embodiment.

FIG. 12 is a flowchart of control of video transfer in the second embodiment.

[Explanation of symbols]

 1 Host 3 Printer 13 DMA Controller 21 DRAM 23 CPU 43 Receive Buffer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazuyuki Onuma 3-3-5 Yamato, Suwa City, Nagano Prefecture Inside Seiko Epson Corporation (72) Inventor Hiroyasu Ogata 3-5-5 Yamato Suwa City, Nagano Prefecture Seiko Epson Inside (72) Inventor Michio Maruyama 3-3-5 Yamato, Suwa City, Nagano Prefecture Seiko Epson Corporation (72) Inventor Kazunori Chihara 3-5-5 Yamato, Suwa City, Nagano Prefecture Seiko Epson Corporation ( 72) Inventor Murata Sunao 3-5-5 Yamato, Suwa City, Nagano Prefecture Inside Seiko Epson Corporation

Claims (5)

[Claims] A memory including a buffer; an image output unit configured to form and output an image based on data; a reception unit configured to write data received from a host into the buffer; A transfer unit that transfers the data to an output unit; and a free buffer capacity notifying unit that notifies the host of information about the free space of the buffer to cause the host to transmit data of a size receivable by the printer. Page printer. 2. The free-buffer-capacity notifying unit notifies the host of information on the free space each time the host attempts to start transmitting data in a predetermined unit, before starting the transmission. 1. The page printer according to 1. 3. A page printing system comprising a host and a page printer for printing data transmitted from the host in page units, wherein the page printer forms a memory based on the data with a memory including a buffer. An image output unit that outputs the data received from the host to the buffer; a transfer unit that transfers the data in the buffer to the image output unit; and information about the free space of the buffer. An empty buffer capacity notifying unit for notifying the host, wherein the host transmits data of a size receivable by the page printer to a printer based on information on the free capacity of the buffer notified from the page printer. A page print system comprising: 4. A page configured to temporarily accumulate data received from a host in a buffer and then transferring the data from the buffer to an image output unit, and having a function of notifying the host of information on the free space in the buffer. A host for transmitting the data to a printer, comprising: a unit for transmitting data of a size receivable by the page printer to the printer based on information on the free space of the buffer notified from the page printer; Host for page printer. 5. A page configured to temporarily accumulate data received from a host in a buffer, and then transfer the data from the buffer to an image output unit, and have a function of notifying the host of information on the free space in the buffer. In a computer-readable recording medium that carries a program for causing a computer to function as a host that transmits the data to a printer, the host stores information on the free space of the buffer notified from the page printer. A computer-readable recording medium comprising means for transmitting data of a size that can be received by the page printer to the printer based on the data.