JP3874297B2 - Printer - Google Patents

Description

  The present invention relates to a printer suitable for high-speed printing.

A printer generally used in a computer system receives a series of print commands described in a predetermined printer control language from a host computer, interprets the print commands in order, and performs a printing operation based on the interpretation result. A conventional printer has a microcomputer composed of a CPU, ROM, RAM, etc., which exclusively receives a print command from a host, interprets it, and configures a mechanism such as a print head based on the interpretation result. Drive and control.
Japanese Patent Laid-Open No. 9-30058

  Inevitably, the processing speed of the microcomputer in the printer is an important factor affecting the printing speed of the printer. Therefore, a conventional high-speed printer is equipped with a high-speed and high-performance CPU, but as a result, its price is very high.

  Accordingly, an object of the present invention is to provide a printer that is inexpensive and capable of high-speed printing.

  The present invention provides a technology that radically breaks away from the conventional method of processing all commands by a CPU. In general, a series of print commands received by a printer includes a wide variety of print commands such as commands for specifying various parameters relating to print conditions and the like, and commands for sending image data to be printed. Since most of this series of print commands is occupied by image data, most of the processing performed by the printer is also processing of image data. This image data processing typically takes out image data that is normally compressed in a predetermined format and embedded in a print command, extracts from the command, decompresses it, and drives a print mechanism such as a print head. Data operations such as conversion to a specific format suitable for the printer (so-called “development of print image”) and transfer of the print image to the print mechanism are performed in accordance with the operation timing of the print mechanism. . In the prior art, this image data processing is exclusively performed by the CPU, but this is not a particularly complicated process for the CPU, but rather is a huge repetition of simple data operations. However, the CPU is originally an apparatus suitable for complicated processing and general-purpose usage, and cannot perform sufficiently high speed in operations that repeatedly perform simple data operations. In such a work, much of the CPU's work is to put data in and out of the memory, and it repeats enormous numbers of data in and out through one CPU bus. High speed processing cannot be expected due to the limitation of the occupation time. On the other hand, among the print commands, commands that notify various parameters related to printing conditions and the like have a small processing amount of each command, but the processing contents differ for each command, and there are various commands. It is suitable for processing by a CPU.

  Based on such reflection, in the present invention, a dedicated hardware circuit for performing image data processing is mounted on the printer, and the CPU is released from the repeated operation of simple data manipulation. Since image data processing is performed by a dedicated hardware circuit, it is naturally possible to perform high-speed printing as compared with the prior art in which it is performed by a CPU. However, this is not the only advantage of the present invention, and further, there is an advantage that the price increase due to this improvement is small. That is, since the processing content of the image data processing is relatively simple, the dedicated hardware circuit does not need to have a very complicated structure and can be inexpensive. Also, since the printer CPU is released from the image data processing, it does not need to be so fast and may be inexpensive. Therefore, it is possible to achieve high-speed printing performance without increasing the price as compared with the prior art that introduces a high-speed CPU.

  Although it is not impossible for a dedicated hardware circuit to perform all command processing, in the preferred embodiment, the dedicated hardware circuit understands print commands that send image data and a few other print commands. The CPU processes a variety of other print commands. As a result, the hardware circuit does not become unnecessarily complicated, and the CPU can perform the kind of command processing that it is good at, and can achieve the above-mentioned objectives of high speed and low cost most effectively. .

  In a preferred embodiment, the dedicated hardware circuit communicates with the host computer to receive data, determines whether the data is a predetermined command that can be processed by itself, and sends data that cannot be processed to the CPU. For this reason, the CPU is not involved in the communication interface with the host computer, which leads to higher speed.

  In a preferred embodiment, the dedicated hardware circuit has its own memory different from the RAM of the CPU, and the print image is developed in this memory and sent to the printing mechanism without going through the CPU. It has become. This configuration is also a device for releasing the CPU from image processing. Also, as described later, the CPU may exceptionally generate a print image. In this case as well, the dedicated hardware circuit receives the print image generated by the CPU, develops it in its own memory, and sends it to the print mechanism. send. This also reduces the burden on the CPU and leads to higher speed.

  The order in which print commands are received from the host is usually that for each page, a command group for specifying print conditions etc. comes first, followed by a command for sending image data. In the preferred embodiment of the present invention, this order is also employed. However, the dedicated hardware circuit sends the command group specifying the printing conditions and the like to the CPU without understanding this (dedicated hardware). This state of the circuit is referred to as “give-up mode”) so that the CPU understands and processes these commands. Then, the host-side printer driver wakes up the dedicated hardware circuit from the give-up mode prior to the end of the command group for specifying the printing conditions and the start of sending the next command for sending image data. A special command (“restart command”) is sent to the CPU, and a considerable amount (for example, several tens of bytes) of meaningless data (NULL data) is sent after this restart command. With this command structure, the dedicated hardware circuit wakes up from the give-up mode by the restart command immediately before receiving the command of the image data, but only meaningless data is sent until it completely wakes up. You will receive an image data command for the first time after waking up. As a result, the dedicated hardware circuit can reliably enter the image data processing.

  Furthermore, in the preferred embodiment, the CPU firmware is fully prepared to understand all commands that may come from the host and to perform all processing including image data processing. As a result, even if the printer driver on the host side is an old version and the image is sent with an old version print command that the dedicated hardware circuit cannot understand, the printer understands the print command with the CPU and prints it. The image can be expanded and printed normally. For example, when the printer is connected to the network and receives image data (for example, a banner image) from the network OS of the network server instead of the printer driver, the printer processes the image with the CPU and prints it. Is possible.

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

  A printer 3 is connected to the host computer 1 via a local interface or a network. The host computer 1 is equipped with a printer driver 5 for the printer 3, and the printer driver 5 generates a series of print commands described in a predetermined printer control language that can be understood by the printer 3, and the series of print commands. The command is sent to the printer 3 through the OS. The breakdown of this series of print commands is simply that, for each page, a print command group for specifying a print condition or the like is sent first, followed by a print command group for sending image data.

  In this embodiment, the image data incorporated in the print command is a data format (typically, for each pixel that has already undergone rasterization, color conversion, halftoning, interlace processing, etc. on the printer driver 5 side. It is assumed that the number of gradations of each color component value is CMYK raster image data (2 gradations or several gradations that is the same as the expression capability of the printer 3) and is compressed by a certain method. However, this is not necessarily the case, and other image data forms (for example, full-color RGB raster data before color conversion, halftoning, or interlace processing) may be used. The complexity of image data processing to be performed on the printer 3 side differs depending on the form of the image data in the print command. In the present embodiment, color conversion, halftoning, Since there is no need to perform interlace processing, the image data processing is the simplest.

  The printer 3 is equipped with a dedicated hardware circuit 9 for performing image data processing. The dedicated hardware circuit is, for example, an ASIC (Application Specific IC), and is not a computer that executes software on a CPU. On the other hand, a microcomputer 17 including a CPU 11, a ROM 13, a RAM 15 and the like is also mounted, and a dedicated hardware circuit 9 is connected to the bus of the CPU 11. The microcomputer 17 is mainly used for processing that is not performed by the dedicated hardware circuit 9 among the processing that needs to be performed by the printer 3 (for example, print command processing related to printing conditions). Is programmed so that it can process all types of print commands that the printer 3 may receive. Further, a printing mechanism 19 such as a print head for actually printing a print image on a sheet using a colorant is also connected to the dedicated hardware circuit 9.

  The dedicated hardware circuit 9 performs a communication interface process with the host computer to receive the data from the printer driver 5, and a command analysis circuit 13 to analyze the received data and switch the transfer destination. have. A small number of predetermined print commands are registered in advance in the command analysis circuit 23, and the command analysis circuit 23 determines whether or not the received data is the registration command. As a registration command, firstly, there is a print command (hereinafter referred to as “raster image command”) for sending CMYK raster image data that has undergone rasterization, color conversion, halftoning, and interlace processing, and secondly, There are a few commands such as FF (form feed) and paper feed control. When the received command is a registration command, the command analysis circuit 13 transfers the raster image command to the print image development circuit 15 and transfers the FF and paper feed control commands to the CPU 11. When the received data does not correspond to the registration command (that is, the received data cannot be understood), the command analysis circuit 13 stops analyzing the data and the subsequent received data, and all the data is transferred to the CPU. (This state is called "Give-up mode").

  The dedicated hardware circuit 9 further includes a print image development circuit 25, a memory for the image buffer 29, and a print image transfer circuit 31. The print image development circuit 25 interprets the raster image command received from the command analysis circuit 23, extracts the CMYK raster image, decompresses it from the compression, and uses a format suitable for driving the printing mechanism 19 from the format in the command. Are rearranged into CMYK raster images (hereinafter referred to as “print images”), an image buffer 29 is secured on the memory, and the print image is developed in the image buffer 29. The print image transfer circuit 31 transfers the print image in the image buffer 29 to the printing mechanism 19 in accordance with the operation timing of the printing mechanism 31.

  In the present embodiment, the image data processing in the print image development circuit 25 is as simple as the above-described decompression of decompression and rearrangement of formats, and this is intended to develop the dedicated hardware circuit 9 at low cost. It is preferable from the viewpoint of. However, it is also possible to configure so that part or all of the color conversion, halftoning, and interlace processing performed by the printer driver 5 can be performed by the print image development circuit 25. In such a configuration, the burden on the printer driver 5 is reduced, which leads to further increase in speed.

  The dedicated hardware circuit 9 further includes a CPU image expansion circuit 27 for expanding the print image generated by the CPU 11 in the image buffer 29. The case where the CPU image development circuit 27 works is that the printer driver 5 on the host side is an old version that is not compatible with the printer 3 and uses an old version print command that is not registered in the dedicated hardware circuit. This is the case when image data is sent, or when the printer 3 is connected to a network and image data such as a banner is received from the network OS instead of from the printer driver on the network. In such a case, since the command analysis circuit 23 cannot understand the received data, it enters the give-up mode and transfers all the received data to the CPU 11. Therefore, the CPU 11 interprets the command of the received data and generates a print image. become. The print image generated by the CPU 11 is developed in the image buffer 27 by the CPU image development circuit 27 and transferred to the printing mechanism 31 in the same manner as described above.

  As described above, the microcomputer 17 including the CPU 11, the ROM 13, the RAM 15, and the like is programmed so that all command processing can be performed. Perform processing. Also, as described above, the processing of image data sent by an old version of the print command that cannot be understood by the dedicated hardware circuit 9 or image data sent from the network OS is exceptionally performed.

  Further, the microcomputer 17 gives a restart signal to the command analysis circuit 23 of the dedicated hardware circuit 9 in response to a predetermined restart command from the host computer 1, thereby setting the command analysis circuit 23 in the give-up mode. (Ie, returning to a state in which command analysis can be performed (“normal mode” in the present invention)). Typically, this restart is used in the following situations. That is, as described above, a series of print commands from the printer driver 5 is preceded by a command group for specifying a print condition or the like for each page, followed by a raster image command group. Since the command analysis circuit 25 of the dedicated hardware circuit 9 is in the give-up mode while a command group for designating printing conditions, etc., it is restarted at the end of the command group and the subsequent raster image command is sent. Let it be processed.

  The operation of the printer 3 under the above configuration will be further described with reference to FIGS. FIG. 2 is a state transition diagram of the command analysis circuit 23 of the dedicated hardware circuit 9, and FIG. 3 is a state transition diagram of the CPU 11.

  When the printer 3 is turned on, a reset signal is input to the dedicated hardware circuit 9 and the CPU 11, and both are in an idle state (waiting for commands) 41 and 51. Thereafter, the printer driver 5 of the host sends a series of print commands. As described above, a command group for specifying print conditions and the like comes first for each page, and then a raster image command group and A command group for paper feed control and the like come, and an FF command comes at the end of each page. At this time, when the command group for specifying the first printing condition and the like is completed, the printer driver 5 sends the restart command described above before sending the subsequent raster image command group and the like. The restart command is added with NULL data in an amount (for example, several tens of bytes) that can sufficiently cover the time required for restart (wakeup) of the command analysis circuit 25.

  When such a series of print commands arrives, the command analysis circuit 25 of the dedicated hardware circuit 9 analyzes the received data. However, when the first command specifying the print conditions is received, the command cannot be understood. Since it is not a registered command, the process shifts to the state 47 shown in FIG. Thereafter, the command analysis circuit 25 enters the state 49, stops the command analysis, and transfers all subsequent received commands as they are to the CPU. The states 47 and 49 are the give-up mode 50 (the state other than the give-up mode 50 is the “normal mode” in the present invention).

  As shown in FIG. 3, when the CPU 11 is in the idle state 51 at the time of start-up, when a command group designating a printing condition or the like is transferred from the command analysis circuit 25, the CPU 11 enters the state 53 and performs processing of the command. Do. When each command processing is completed, the CPU 11 returns to the idle state 51 and repeats the operation of receiving another command and processing it again. When the command group related to the printing conditions is completed, the restart command is received as described above. Therefore, the CPU 11 shifts to the state 59, outputs a restart signal to the command analysis circuit 23, and returns to the idle state 51 again.

  As shown in FIG. 2, the command analysis circuit 23 in the give-up mode 50 receives a restart signal from the CPU 11 and returns (wakes up) to the idle state 41. During the delay time from the restart signal to the idle state 41, NULL data attached to the restart command is transferred to the CPU 11, but the CPU 11 enters the state 55 when receiving NULL data as shown in FIG. Read and discard NULL data. When the command analysis circuit 23 enters the idle state 41, the remaining NULL data is received and the command analysis circuit 23 enters the state 45 and reads and discards the NULL data. When the NULL data is finished, the command control unit 23 receives a registration command such as a raster image command, a command related to FF or paper feed control, and enters the state 43 to process each received command. In this case, the raster image command is sent to the print image development circuit 25, and the paper feed control and FF commands are transferred to the CPU 11. The print image development circuit 25 interprets the raster image command and develops the print image. When the CPU 11 receives a paper feed control or FF command, the CPU 11 enters a state 53 to process each command.

  As described above, high-speed printing is realized by the dedicated hardware circuit 9 and the CPU 11 sharing the processes suitable for each.

  As mentioned above, although one Embodiment of this invention was described, these embodiment is an illustration for description of this invention to the last, and is not the meaning which limits this invention only to these embodiment. Therefore, the present invention can be implemented in various forms other than the above-described embodiment.

The block diagram which shows the structure of one Embodiment of this invention. The state transition diagram of the command analysis circuit 23 of the dedicated hardware circuit 9. The state transition diagram of CPU11.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Host computer, 3 ... Printer, 5 ... Printer driver, 9 ... Dedicated hardware circuit, 11 ... CPU, 17 ... Microcomputer, 19 ... Printing mechanism, 21 ... Host interface circuit, 23 ... Command analysis circuit, 25 ... Printing Image development circuit 27 ... CPU image development circuit 29 ... Image buffer 31 ... Print image transfer circuit

Claims (2)

In a printer that receives a print command and executes control based on the print command,
A microcomputer capable of processing other print commands other than a predetermined print command of the print commands;
A dedicated hardware circuit capable of processing the predetermined print command,
The predetermined print command includes an image data command indicating that image data compressed in a predetermined format is sent.
The microcomputer includes a CPU and a first memory,
The dedicated hardware circuit is:
A second memory,
Interface means for receiving the print command;
Image processing means for decompressing the image data compressed in the predetermined format;
The image data command is pre-registered, and comprises a command analysis means for analyzing whether the print command received by the interface means is the pre-registered image data command,
When the received print command is the pre-registered image data command, the command analysis unit analyzes the received print command as the pre-registered image data command, The image data command is transferred to the image processing means, whereby the image processing means decompresses the image data compressed in the predetermined format of the transferred image data command, and the decompressed Stored image data in the second memory,
If the received print command is an image data command but not the pre-registered image data command, the command analysis means uses the unregistered image data command as the received print command. The image data command which is the received print command is transferred to the microcomputer, and the CPU of the microcomputer compresses the received image data command in another form of the transferred image data command. Decompress the image data
Printer. The dedicated hardware circuit further includes image expansion means for expanding image data decompressed by the CPU of the microcomputer into the second memory.
The printer according to claim 1.

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