JP2002292943A - Printer and data transfer method in printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem of requiring many command execution such as the pointer collation of the writing and reading addresses, confirmation of the reading address, real reading execution of printing command data, and update of the reading address at the time of reading data from a receiving buffer in a printer comprising the same. SOLUTION: A DMA transferable FIFO 20 is provided on a transmission line, linking a receiving buffer 6 and an image buffer 8. In a receiving controlling part 11 of a printing controller 10, in the case image data included in a printing command are judged to be uncompressed data of a certain size or more by an identifying part 112, a writing operation is executed directly for the image buffer 8 from the FIFO 20 by a transmission line determining part 113.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a data transmission technique for transmitting print data received by a printer from a host computer in the printer.

[0002]

2. Description of the Related Art In recent years, printers used in computer systems have tended to increase in size of print data as print quality has improved. In recent printers, therefore, even when handling large print data as described above, the host computer can be quickly released from operations related to printing, or the printing speed can be improved, or the print data can be transmitted without interruption. For this purpose, it is common to use a buffer storage device.

FIG. 1 is a diagram showing a general configuration of a printer having such a buffer storage device. In the printer 1, a CPU (Central Pr
ocessing Unit: Central processing unit 3, ROM (Read)
Only Memory: read-only storage element) 4, main storage device 5
Are connected via a bus to form a computer-structured control mechanism. This control mechanism realizes a function as a print controller described later.

The print command data sent from the host computer 2 is temporarily stored in the reception buffer memory 6 from the interface device 7 via the bus. The image data included in the print command data is bit-mapped and stored in the image buffer memory 8. The data transfer and the extraction of the image data are realized by the function of the print controller embodied by the control mechanism described above.

FIG. 2 is a diagram for explaining the state of data transmission control between the two buffers. When print instruction data is received from the interface device 7, the reception control unit 11 specifies an address of a free area of the reception buffer memory 6 and sequentially writes data of a fixed length (for example, 1 byte). As a result, data is accumulated in the reception buffer memory 6. The bitmap data developing unit 13 periodically checks the contents of the reception buffer memory 6, extracts the image data if data exists, and writes the extracted data into the image buffer memory 8.

The bitmap data developing section 13 stores, as a pointer, area information (address 05 in FIG. 2) of an address at which data was last read from the reception buffer memory 6 last time. Then, the area last written in the reception buffer memory 6 by the reception control unit 11 (FIG. 2)
Is different from the pointer at address 0B). As a result of the comparison, when the two pointers do not match (in the case of address 05 and address 0B in FIG. 2), it is determined that new data has been written to the reception buffer memory 6.

FIG. 3 is a flowchart showing the flow of the procedure at this time. The bitmap data developing unit 13 calculates the number of data in the reception buffer memory 6 from the difference between the two pointers (S101). Then, one-byte data is read (S102). After reading data,
The read destination address pointer is updated (S10).
3 and address 06 in FIG. 2).

Further, a bitmap data developing unit 13
Writes the read 1-byte data into the image buffer memory 8 (S104). Then, the write destination address pointer in the image buffer memory 8 is updated (S105).

Thus, one data reading procedure is completed. This operation is repeated as long as data exists in the reception buffer memory 6 (YES in S106). When reading and writing are completed for all data (S1)
(NO at 06), the process ends.

Now, as described above, the size of print command data tends to increase, and the speed of data transmission and reception between the host computer and the printer tends to be a bottleneck in improving the speed of the entire printing system. is there. Therefore, bit image data actually used for printing is often transmitted after being compressed. Under such conditions, the print command data must be once taken into the bitmap data developing unit 13, expanded into the original bit image data, and then written into the image buffer memory 8.

On the other hand, if the print command data includes the uncompressed bit image data as it is, there is no need to perform the above-described decompression work. Therefore, it cannot be said that the print command data needs to be read by the bitmap data developing unit 13.

Conventionally, a printer connected to a computer system often uses a Centronics parallel interface (Centronics company standard). However, recently, by using a Centronics parallel upward compatible interface such as an IEEE1284 interface (American Electrical and Electronic Engineers Association standard), the data transfer speed between the host computer and the printer has been dramatically improved. USB (Univer
Sal interface (general serial bus) interface is being used for data transfer between a host computer and a printer, and the interface environment is changing.

In addition, the price of the DRAM module used in the buffer memory device as described above has been reduced.
A buffer memory, which previously could only be mounted in a small capacity due to cost considerations, is now available in a large capacity.

[0014]

Under the above-described environment, even if the print image data transmitted from the host computer to the printer is in an uncompressed format, a buffer memory having a sufficient capacity is used. In some cases, the data transfer between the outside of the printer and the printer can be executed without delay.

On the other hand, when data transfer inside the printer is considered, for example, in the data reading and writing sequence by the bitmap data
The process is time consuming to go through many steps.

Further, these data transfers are performed by a PCI
(Processor Controlled Input / Output), there is a problem that the CPU 3 has to read and write data one by one.

An object of the present invention is to reduce the load on the bitmap data developing unit 13 as described above, that is, the load on the control mechanism constituting the print controller, especially the CPU. For this purpose, the present invention provides a technique for simplifying the above-described read and write procedures (FIG. 3) and reducing the involvement of the CPU in data transfer between both buffers.

[0018]

According to the present invention, a direct memory (DMA) is provided on a transmission line connecting a reception buffer memory and an image buffer memory.
Access) A configuration including a first-in first-out circuit element having a function as a device is adopted.

That is, a printer according to a first aspect of the invention stores a reception buffer memory for storing print command data received from a host computer, and stores bit image data obtained based on the print command data. And a data transfer control means for controlling data transfer on a transmission path connecting the reception buffer memory and the image buffer memory using a processor. In the printer having such a configuration, both direct writing to the image buffer memory, that is, DMA transfer, and program control writing by the processor constituting the data transfer control means, that is, PCIO transfer, are performed on the transmission path. A first-in first-out circuit element that can be controlled by a transfer method is provided. The data transfer control means determines whether the image data included in the print command data stored in the reception buffer memory is compressed image data or uncompressed image data. Depending on the data format identification means for identification and the format of the image data related to the identification, the first-in first-out circuit element directly writes to the image buffer memory, or performs the program-controlled writing by the processor. Characterized in that it has a transmission path selecting means for selecting the above.

Further, in the printer according to the present invention, the data format identification means is configured to be able to detect the size of image data included in the print command data stored in the reception buffer memory. I have. And the transmission path selecting means performs direct writing from the first-in first-out circuit element to the image buffer memory according to the size of the data relating to the detection,
Alternatively, the processor is configured to select whether to perform program control writing by the processor.

Further, according to the data transfer method of the present invention, a reception buffer memory for storing print command data received from a host computer and bit image data obtained based on the print command data are stored and stored. A printer having a first-in first-out circuit element capable of direct writing to the image buffer memory, that is, DMA transfer, and writing under program control by a processor, that is, PCIO transfer, on a transmission path connecting an image buffer memory for storing This is a data transfer method. In the present data transfer method, it is determined whether the image data included in the print command data stored in the reception buffer memory is compressed image data by the data transfer control unit configured using the processor. Or the format of uncompressed image data and the size of the image data, and as a result of the identification, the image data is in an uncompressed format and exceeds a predetermined size. In this case, writing is directly performed from the first-in first-out circuit element to the image buffer memory.

A computer program for implementing the above-described printer control procedure can be recorded and held on a specific medium. That is, the recording medium storing the program of the present invention includes a memory for storing the program, and stores the print command data received from the host computer in a computer that executes processing according to the program using a processor. A reception buffer memory, an image buffer memory for storing image data obtained by developing the print command data into a bitmap, and an image buffer memory interposed between the reception buffer memory and the image buffer memory. The computer-readable recording medium stores a program for directly writing in a buffer memory and controlling a printer including a first-in first-out circuit element capable of writing under a program control by the processor. Then, the program causes the print command data to be written from the reception buffer memory to the first-in first-out circuit element, and whether the image data included in the print command data is compressed image data or Whether the format is compressed image data, and identify the size of the image data, as a result of the identification, if the image data is in an uncompressed format and exceeds a predetermined size, The computer is controlled so that writing is directly performed from the first-in first-out circuit element to the image buffer memory.

[0023]

[Embodiment of the present invention will be described with reference to the drawings one embodiment of the present invention. FIG. 1 shows a hardware configuration of a printer 1 to which the present invention is applied. A print controller 10 represented by a chain line in FIG. 1 performs a printing operation according to data input from the interface device 7.
The print engine 9 is executed. That is, the CPU 3
Executes the program stored in the ROM 4 while appropriately using the main storage device 5, thereby controlling each unit in the printer 1.

The printer 1 has a receiving buffer memory 6 for temporarily storing print command data sent from the host computer 2 and an image for expanding image data contained in the print command data. A buffer memory 8 is provided. In FIG. 1, the reception buffer memory 6 and the image buffer memory 8 are depicted as independent memory modules, respectively.
This is an example, and each buffer may be configured by a normal pool management method using a part of the memory space of the main storage device 5 as a buffer area.

A feature of this embodiment is that a first-in first-out circuit element (hardware FIFO) having a function as a DMA device is provided on a transmission line connecting the reception buffer memory 6 and the image buffer memory 8. It is in. FIG. 4 is a diagram for describing a state of data input / output control relating to the first-in first-out circuit element 20.

As already described in the description of the prior art, input / output control between these storage elements is performed by the print controller 10. In the embodiment, the print controller 10 is described as a control mechanism of a computer configuration including the CPU 3, the ROM 4, and the main storage device 5. However, this may also be a configuration using a custom IC chip dedicated to data input / output control, or a configuration using a one-chip CPU.

The printer controller 10 includes a reception control unit 11 for managing reception of print command data provided from the interface device 7 and a bitmap data development unit 13 for extracting image data from the print command data. It is not different from the conventional one in that a functional block is provided.

A feature of the embodiment is a function of the reception control unit 11. The reception control unit 11 in the present embodiment has at least the following functional blocks. That is, in the received print command data, a command interpreting unit 111 for interpreting identification information or the like included as a header or the like, and whether the bit image data to be printed is compressed or uncompressed based on the interpretation. The reception control unit 11 includes an identification unit 112 for determining information such as the data size or the data size.

Then, the transmission line determining unit 113 determines the first-in first-out
In the data transfer from 0 to the image buffer memory 8, PCI transfer is performed or DMA transfer is performed.
Decide whether to perform the transfer. Further, the transmission path determination unit has a role as a DMA controller for controlling input / output of the first-in first-out circuit element 20 which is a DMA device.

FIG. 5 is a flow chart for explaining the flow of the procedure in the process of the transmission path determination section 113 making the determination. First, the transmission path determination unit 113 determines whether the print command data includes compressed image data according to the determination of the identification unit 112 (S201). If the image data exists in an uncompressed format (NO in S201), a determination is further made according to the size of the image data (S202). This is because if the data to be transferred to the image buffer memory 8 is too small, it is not meaningful to perform the DMA transfer.

When the size of the image data exceeds a predetermined value (YES in S202), the transmission path determination unit 113 performs DMA transfer from the first-in first-out circuit element 20 to the image buffer memory 8 to perform DMA transfer. Perform writing control. That is, the transmission path determination unit 113 performs the first-in first-out circuit element 2 as a DMA device.
In response to the bus occupation request from 0, the data bus is occupied. Then, the write-in pointer of the image buffer memory 8 is designated to the first-in first-out circuit element 20 to instruct how many bytes of data are to be continuously transmitted.

On the other hand, when the image included in the print command data exists in a compressed format, or when the image is uncompressed and has a very small size, the transmission path is determined. The unit 113 causes a PCI transfer to be performed. In that case, the bitmap data developing unit 13
Confirms the input port of the first-in first-out circuit element 20, and when data exists there, once takes it in as normal reading, performs predetermined processing such as decompression of image data, and then writes to the image buffer memory 8. (S204 in FIG. 5, and
S101 to S106 in FIG. 3).

As described above, the bitmap data developing unit 13 is a functional block constituted by the CPU 3, its main storage device 5, and the like. In order for the bitmap data developing unit 13 to detect the presence of data in the first-in first-out circuit element 20, for example, an input port of the first-in first-out circuit element 20 as an I / O device is directly connected to a control bus of the CPU. , May be determined based on whether or not the bit of the input port is set.

Although the first-in first-out circuit element 20 is shown as an independent entity in FIG. 4, it is not necessary that the circuit element 20 also be constituted by one chip. For example, any device may be used as long as it is incorporated in the above-mentioned custom IC chip for data input / output control.

This embodiment is as described above.
The present invention is not necessarily limited to the above configuration. In the description of the embodiment, for simplicity of illustration, the reception buffer memory 6 shows only a 4-bit addressable area, but of course has a capacity corresponding to the amount of data transmitted and received between the printer and the host computer. It goes without saying that a memory may be used.

In the embodiment, the transmission path determination unit 113, which also has a function as a DMA controller,
This is realized by a pre-controller 10 including a CPU 3, a ROM 4, and a main storage device 5 and a controller 10. However, an independent DMA controller chip may control the DMA transfer of the first-in first-out circuit element 20.

[0037]

Conventionally, when reading data from the reception buffer memory, first, pointer comparison of both write and read addresses, second, confirmation of the read address, and third, the actual printing of the print command data are performed. Many instructions such as reading, and fifthly, updating the read address, have been required.

By applying the present invention, the processing performed by the bitmap data developing unit 13 is eliminated,
By causing the first-in, first-out circuit element 20 as the device to perform data transfer, the processing procedure performed by the CPU can be largely omitted, and the time required for data transfer can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a printer hardware configuration according to an embodiment.

FIG. 2 is a diagram for explaining a state of data transmission between buffers in the related art.

FIG. 3 is a flowchart showing a conventional procedure for reading data from a reception buffer.

FIG. 4 is an exemplary view for explaining a state of data transmission via a FIFO in the embodiment.

FIG. 5 is a flowchart illustrating a procedure for reading data from a reception buffer according to the embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 printer 2 host computer 3 CPU 4 ROM 5 main storage device 6 reception buffer memory 8 image buffer memory 10 print controller 11 reception control unit 111 command interpretation unit 112 identification unit 113 transmission path determination unit 20 first-in first-out circuit element (hardware FIFO)

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G06T 1/60 450 G06T 1/60 450F 5C062 H04N 1/00 H04N 1/00 C 107 107A F term (reference) 2C087 AB05 BA03 BC02 BC05 BD01 BD40 5B021 AA01 BB11 DD00 5B047 AA30 EA07 EB01 EB17 5B061 DD09 DD12 5B077 BB07 DD00 5C062 AA05 AA27 AB43 AB46 AC25 AC48 AC49 AC58 AE02 BA04

Claims (4)

[Claims] 1. A receiving buffer memory for storing print command data received from a host computer, and an image buffer memory for storing bit image data obtained based on the print command data. A printer having a data transfer control unit for controlling data transfer on a transmission path connecting the reception buffer memory and the image buffer memory using a processor, wherein direct writing to the image buffer memory is performed on the transmission path, and A first-in, first-out circuit element which can be programmed and written by a processor constituting the data transfer control means, and wherein the data transfer control means includes image data included in print command data stored in the reception buffer memory. But the compressed image Data format identification means for identifying whether the data is data or uncompressed image data; and directly writing from the first-in first-out circuit element to the image buffer memory according to the format of the image data. Or a transmission path selecting means for selecting whether to perform the program control writing by the processor. 2. The data format identification unit is configured to detect the size of image data included in print command data stored in the reception buffer memory, and the transmission path selection unit includes: According to the size of the data related to the detection, it is configured to select whether to write directly from the first-in first-out circuit element to the image buffer memory or to perform program-controlled writing by the processor. A printer characterized by the following. 3. A reception buffer memory for storing print command data received from a host computer, and an image buffer memory for storing bit image data obtained based on the print command data. A data transfer method for a printer including a first-in first-out circuit element capable of directly writing to the image buffer memory and writing under program control by a processor on a transmission path to be connected, wherein the data transfer control is configured by using a processor. Means for determining whether the image data included in the print command data stored in the reception buffer memory is compressed image data or uncompressed image data, and the size of the image data. And identify the Another result is that when the image data is in an uncompressed format and exceeds a predetermined size, the data is directly written from the first-in first-out circuit element to the image buffer memory. Transfer method. 4. A receiving buffer memory for storing a print command data received from a host computer in a computer having a memory for storing a program and executing a process according to the program using a processor; An image buffer memory for storing image data obtained by bitmap-expanding data, interposed between the reception buffer memory and the image buffer memory, and directly writing to the image buffer memory, and A program for controlling a printer including a first-in first-out circuit element that can be written out under program control by the processor, and the print instruction data is written out from the reception buffer memory to the first-in first-out circuit element, The print instruction data And whether the image data included in the image data is compressed image data or uncompressed image data, and the size of the image data. In a compression format, if the size exceeds a predetermined size, a program for controlling the computer is stored such that writing is performed directly from the first-in first-out circuit element to the image buffer memory. The computer-readable recording medium.