JP4163266B2 - Printer and control method thereof - Google Patents

Description

[0001]
【Technical field】
The present invention comprises a printer controller connected to a bus and a printer. The printer controller supplies image data to the printer through a bus, and the printer transmits an image represented by the image data supplied from the printer controller at a constant speed. The present invention relates to a printer system that prints images. The present invention also relates to a printer and a printer controller constituting the printer system. The present invention further relates to a printer system operation control method, a printer operation control method, and a printer controller operation control method.
[0002]
BACKGROUND OF THE INVENTION
In order to transmit image data from the printer controller to the printer, parallel communication such as Centronics, SCSI (Small Computer System Interface), or serial communication such as RS232C, RS422, USB (Universal Serial Bus) is used. In any of these communication systems, image data is transmitted from the printer controller to the printer regardless of the printing speed of the printer. The printer needs to be provided with an image memory having a capacity capable of storing image data representing an image for at least one frame (an image printed on one sheet of paper). For this reason, it is difficult to reduce the cost of the printer.
[0003]
DISCLOSURE OF THE INVENTION
An object of the present invention is to make it possible to configure a printer using a relatively small-capacity image memory.
[0004]
The present invention is an IEEE standard 1394 (IEEE Standard 1394, IEEE = The Institute of Electrical and Electronic Engineers, Inc.) for high-speed serial transmission that is currently being studied to supply image data from a printer controller to a printer. Is to be used. According to the IEEE standard 1394, isochronous transfer and asynchronous transfer are possible.
[0005]
In isochronous transfer, data called cycle start packet data is generated in an isochronous cycle (125 μs period) from any of a plurality of nodes connected by a bus. Data is transmitted from one node in each isochronous cycle (this node is a cycle master as described later) to another node. In isochronous transfer, data transmission can always be performed within an isochronous cycle. Isochronous transfer is a transfer in which data is unilaterally transmitted from a transmission device to a reception device. Asynchronous transfer is a transfer that sends back a receipt when the receiving device receives the transmission data.
[0006]
The present invention provides a printer system comprising a printer and a printer controller. In this printer system, the printer and the printer controller are connected by a bus, and the printer controller supplies image data to the printer through the bus. The printer prints an image represented by image data supplied from a printer controller at a constant speed.
[0007]
The printer has a storage capacity for image data smaller than the amount of image data representing an image for one frame, and a buffer memory for temporarily storing image data supplied from the printer controller. , Means for generating a start signal indicating the start of the supply of image data is provided in one of the printer and the printer controller.
[0008]
The printer controller includes image data transmission start control means for starting transmission of image data to the printer in units of packets after a predetermined period has elapsed since the start signal is generated, and an image stored in the buffer memory. Image data transmission control means for repeating transmission of image data to the printer in units of packets is provided so that data is not lost.
[0009]
The printer receives the image data transmitted from the printer controller and stores it in the buffer memory, reads out the image data stored in the buffer memory, and represents the read image data. The image forming apparatus further includes print control means for printing the image to be printed at a constant speed.
[0010]
The present invention also provides an operation control method suitable for the printer system. That is, a printer controller and a printer connected by a bus are connected, and image data is supplied from the printer controller to the printer through a bus, and an image represented by the image data supplied from the printer controller in the printer is displayed. This is a method for controlling the operation of a printer system for printing at a constant speed. The printer is provided with a buffer memory having a storage capacity of image data smaller than the amount of image data representing an image for one frame, and temporarily storing the supplied image data. A start signal is generated from one of the printer controllers.
[0011]
Then, after a predetermined period from the generation of the start signal, the printer controller starts transmission of image data from the printer controller, and the printer controller does not lose the image data stored in the buffer memory. The image data is repeatedly transmitted in units of packets, and the printer receives the image data transmitted from the printer controller, stores it in the buffer memory, and reads the image data stored in the buffer memory. , The image represented by the read image data is printed at a constant speed.
[0012]
According to the present invention, the printer stores image data smaller than the data amount of image data representing one frame image (an image for one frame means an image printed on one sheet as described above). A buffer memory having a capacity is provided.
[0013]
In the printer controller, transmission of image data in packets is started after a predetermined period of time has elapsed from the generation of the start signal, and image data stored in the buffer memory is not lost in packet units. Are repeatedly transmitted to the printer.
[0014]
The printer receives the transmitted image data in packet units and temporarily stores it in the buffer memory. The image data stored in the buffer memory is read, and the image represented by the read image data is printed at a constant speed.
[0015]
The printer does not need to be provided with a memory having a large capacity capable of storing the amount of image data representing an image for one frame, and it is sufficient to provide a buffer memory with a small capacity, thereby reducing the cost.
[0016]
Since the next data is transmitted from the printer controller before the data in the buffer memory is lost, the continuity of the image data can be maintained. Therefore, a printer that prints an image at a constant speed can be used.
[0017]
The printer may store printing speed data representing the printing speed and storage capacity data representing the storage capacity of the buffer memory. In this case, the stored printing speed data and the storage capacity data are transmitted to the printer controller.
[0018]
The printer controller receives the printing speed data and the storage capacity data transmitted from the printer, and determines the amount of image data included in the packet based on the received printing speed data and the storage capacity data.
[0019]
In the printer controller, the printing speed and the storage capacity of the buffer memory may be input. In this case, the amount of image data included in the packet will be determined based on the input print speed data and the storage capacity data.
[0020]
In any case, the amount of image data included in the packet can be determined optimally.
[0021]
Prior to the start of the printing operation by the printer, a print preparation command may be transmitted from the printer controller to the printer. In this case, in response to the print preparation command transmitted from the printer controller, the print preparation including the positioning of the print paper to the home position is performed, and the completion of the print preparation indicating the end of the print preparation is completed. After the data is transmitted to the printer controller and the print preparation completion data is transmitted, the start signal will be generated.
[0022]
Since the image data is sent from the printer controller to the printer after the print preparation is completed, it is possible to prevent the image data from being transmitted while the printer is not ready for printing. Can be prevented.
[0023]
Command identification data indicating a command may be added to the print preparation command, and image data identification data indicating image data may be added to the image data transmitted from the printer controller. In this case, the printer determines whether the received data is the print preparation command or the image data based on the command identification data or the image data identification data. If it is determined that the image data is determined, the image represented by the image data may be printed.
[0024]
As a result, it is possible to quickly recognize whether the received data is a command or image data, so that print preparation and printing can be performed quickly.
[0025]
The printer controller comprises first control means and second control means, and the first control means performs transmission control relating to transmission of image data to the printer, and the second control means. In addition, operations other than the above transmission control may be controlled.
[0026]
Thereby, the burden of the control operation by the second control means is reduced.
[0027]
There may be a plurality of the printers, each printer may be assigned a unique printer identification symbol, and printer identification data representing the unique printer identification symbol may be added to the image data output from the printer controller.
[0028]
In this case, the printer determines whether or not the printer identification symbol represented by the printer identification data added to the received image data matches the assigned printer identification symbol. Printing by the print head is performed based on image data to which printer identification data representing an identification symbol is added.
[0029]
Even when a plurality of printers are connected to the printer controller, desired image data can be transmitted only to the desired printer. Of course, the same image data can be transmitted to all printers.
[0030]
Furthermore, the printer and the printer controller that constitute the printer system can be configured independently.
[0031]
[Explanation of Examples]
(1) Data transfer based on IEEE standard 1394
Before describing the printer system according to this embodiment, data transfer based on the IEEE standard 1394 will be described.
[0032]
FIG. 10 shows a state in which a plurality of devices (computer, printer, digital video tape recorder, etc.) A, B, C, D, E, and F are connected using a bus. Each device can have one or more ports (in the example of FIG. 10, all devices have three ports). By connecting the ports of each device, up to 63 devices can be connected. IEEE standard 1394 allows devices to be connected as long as the daisy chain connection does not exceed 16. There is no loop connection.
[0033]
In the IEEE standard 1394, two types of data transfer, isochronous transfer and asynchronous transfer, are possible. Data transfer is performed in packet units in both isochronous transfer and asynchronous transfer.
[0034]
FIG. 13 shows the format of the cycle start packet. The cycle start packet data indicates the start of an isochronous cycle period (this period is in principle 125 μs) and is transmitted from the cycle master by isochronous transfer as described later.
[0035]
The cycle start packet indicates the transmission destination ID (which is unique to the device), transaction label, retry code, t code indicating whether the data is asynchronous transfer data or isochronous transfer data, and the priority of the transmission data. The priority, source ID, offset of the address to be read / written, cycle time data, and data CRC (Cyclic Redundancy Check) are included.
[0036]
According to the IEEE standard 1394, a cycle master described later starts measuring time from when the power is turned on. Data representing this measurement time is cycle time data. Each node described later has a counter and can measure time. The counter of each node is reset when the cycle start packet data transmitted from the cycle master is received. In principle, the cycle start packet is output every 125 μs as described above, but it is allowed to be delayed (details will be described later). This delay time is called cycle start delay time. The cycle start delay time is calculated at each node based on the difference between the measurement time of the cycle master represented by the cycle time data and the measurement time of each node. For example, if the measurement time of the cycle master is 130 μs and the measurement time of each node when the cycle start packet data is given is 125 μs, the cycle start delay time is 130 μs−125 μs = 5 μs. .
[0037]
The asynchronous data packet format shown in FIG. 14 is used when data is transmitted by asynchronous transfer. This format differs from the cycle start packet format only in that the data length, extended transaction code, and transmission data are included in the packet instead of the data representing the cycle start delay time.
[0038]
When there are two or more control devices for controlling one controlled device, only one control device can control the controlled device, which is called exclusive control. The extended transaction code specifies the operation used to check whether this exclusive control is in effect.
[0039]
15 and 16 show the format of a packet used in isochronous transfer. FIG. 15 shows the format of an isochronous command packet used when sending a command, and FIG. 16 shows the format of an isochronous data packet used when sending image data.
[0040]
These packet formats include a data length indicating the length of data, a channel number given to a command or image data, a t code, Sy indicating a synchronization bit, and an error detection code for data from the data length to the synchronization bit Sy. Header CRC, command or image data, and data CRC which is an error detection code of the command or image data. As will be described later, in isochronous transfer, a channel number is assigned to each device, and when the channel number assigned to the device matches the channel number included in the transmitted packet, the matching channel number is assigned. The received device receives the transmitted command or image data. The purpose of use of Tg is not defined in the current IEEE standard 1394 standard, and "00" is recorded.
[0041]
Returning to FIG. 10, according to the IEEE standard 1394, a parent-child relationship between devices connected by a bus is determined. The method for determining this parent-child relationship is as follows.
[0042]
When the power of each device is turned on, an inquiry about the parent-child relationship is made from one device to another device. The device that inquires about the parent-child relationship becomes a child, and the device that receives the parent-child relationship inquiry becomes the parent.
[0043]
When the parent-child relationship is determined for all devices, the whole has a tree structure as shown in FIG. In the example of FIG. 11, the device B is a parent (root). Devices A and C are children of device B, devices D and F are children of device A (grandchild when viewed from device B), and device E is a child of device C (grandchild when viewed from device B). Yes.
[0044]
In the IEEE standard 1394, as described above, a channel number is assigned to each device in order to receive isochronous transfer data, and an ID is assigned to each device in order to receive asynchronous transfer data. In the illustrated example, channel number A and IDa are assigned to device A, channel number B and IDb are assigned to device B, channel number C and IDc are assigned to device C, and channel number D and IDd are assigned to device D. The device E is assigned channel numbers E and IDe, and the device F is assigned channel numbers F and IDf.
[0045]
FIG. 12 is a time chart of isochronous transfer.
[0046]
Isochronous transfer control is performed by a device called a cycle master. The root becomes the cycle master.
[0047]
The cycle period starts when a cycle start packet is output from the cycle master (root). The cycle start packet is given to all devices (including grandchild devices) connected to the route.
[0048]
After the cycle start packet is transmitted, transfer of isochronous data starts.
[0049]
When the first period (short gap period) Sg has elapsed after the transmission of the cycle start packet, arbitration is performed between all the devices to be isochronously transferred. Arbitration is to obtain permission to use the bus and is performed as follows.
[0050]
First, a request signal for using the bus is transmitted from the device that is to perform isochronous transfer to its parent device. This request signal is transmitted in order from the device closest to the route. The parent device that has received the request signal further relays the request signal to the parent device. As a result, request signals from all devices that wish to perform isochronous transfer reach the cycle master. The cycle master stores which devices can use the bus preferentially, and the devices that can use the bus are determined when the short gap Sg elapses according to the priority. Only for the determined device, a signal permitting the use of the bus is output from the cycle master at the timing when the short gap Sg has elapsed. To the other devices, a signal for refusing to use the bus is transmitted from the cycle master at the timing when the short gap Sg has elapsed. A device that receives a signal permitting use of the bus can transmit data.
[0051]
In the example shown in FIG. 11, request signals requesting the use of the bus are transmitted from the devices A, C, and F, and these request signals are received by the device B as a route. A permission signal for permitting the use of the bus is transmitted from the device B as the route to the device C, and data can be transmitted from the device C. The device A and the device F are transmitted with a rejection signal for refusing to use the bus, and the device A and the device F cannot transmit data at that time. The device A and the device F perform arbitration again after the device C transmits one packet of data, and transmit data when receiving a permission signal permitting use of the bus.
[0052]
Returning to FIG. 12, isochronous transfer data is transmitted in units of packets from a device which has obtained the right to use the bus at the time when the short gap Sg has elapsed after the transmission of the cycle start packet. Prefix data indicating the start of data is added before the data of this packet (having the format shown in FIG. 15 or FIG. 16), and end data indicating the end of the data is added after the packet.
[0053]
End data is given to all devices. As a result, all devices recognize that the bus is free. When the short gap Sg period elapses after the end data is received, the device that wishes to transmit isochronous transfer data again transmits the bus use request signal as described above (arbitration) (within the isochronous cycle period). A device that has obtained the right to use the bus once does not output a request signal again during the isochronous cycle period, and all devices that perform isochronous transfer transmit data for one packet at any time within the isochronous cycle period. it can).
[0054]
When isochronous transfer ends within the isochronous period, the right to use the bus for asynchronous transfer is secured when the second period (long gap lg) elapses. Asynchronous transfer data is transmitted in units of packets from the device that has obtained the right to use the bus. Also in asynchronous transfer, prefix data indicating the start of data is added before the packet, and end data is added after the packet. In the asynchronous transfer, an acknowledge data ACK indicating that the asynchronous transfer data has been received is output from the device that has received the asynchronous transfer to the device that has transmitted the asynchronous transfer data. Prefix data and end data are also added before and after the acknowledge data.
[0055]
If the amount of data to be transferred asynchronously is large, the cycle start packet transmission interval will be delayed more than 125μs. When the cycle start packet transmission interval exceeds the 125 μs period, the delay time Δt of the transmission cycle start packet is based on the measurement time represented by the cycle time data and the measurement time of each node as described above. Calculated (see FIG. 13).
[0056]
(2) Printer system
The printer system according to this embodiment is constituted by connecting a printer 20 and a printer controller 10 for controlling printing by the printer 20 to each other by a cable based on the IEEE standard 1394.
[0057]
FIG. 1 is a block diagram showing the electrical configuration of the printer controller 10.
[0058]
The overall operation of the printer controller 10 is controlled by the main CPU 11. The printer controller 10 includes a main memory 12. The main memory 12 stores an operation program of the printer controller 10, image data representing an image to be transmitted to the printer 20 and printed by the printer 20, and other data. The printer controller 10 includes a communication control circuit 13 for performing the above-described isochronous transfer and asynchronous transfer. The communication control circuit 13 includes a transmission transfer memory 13A for temporarily storing data for one packet to be transmitted, and a reception transfer memory 13B for temporarily storing data for one packet transmitted from the printer 20. And a register 13C for storing data representing the ID of the printer controller 10 and data representing the channel number. When isochronous transfer is performed, an interruption is performed from the communication control circuit 13 to the main CPU 11 every isochronous period. In response to this interruption, the main CPU 11 reads image data from the main memory.
[0059]
FIG. 2 is a block diagram showing the electrical configuration of the printer 20.
[0060]
The overall operation of the printer 20 is controlled by the system controller 21. The system controller 21 includes a RAM 22 for temporarily storing data representing the current state of the printer 20 including the presence or absence of printing paper, an operation program for the printer 20, a printing speed of the printer 20, a transmission transfer memory 25A, which will be described later, and a reception A ROM 23 storing printer specification data and other data including the memory capacity of the transfer memory 25B and FIFO (first in first out) memory 26 is connected. Further, the printer 20 includes operation keys and a status display circuit 24. A signal representing setting by the operation keys is given to the system controller 21 and the status of the printer 20 is displayed on the status display circuit 24.
[0061]
The printer 20 also includes a communication control circuit 25 for performing the above-described isochronous transfer and asynchronous transfer. The communication control circuit 25 includes a transmission transfer memory 25A for temporarily storing data for one packet to be transmitted, and a reception for temporarily storing data for one packet transmitted from the printer controller 10. A transfer memory 25B and a register 25C for storing data representing the ID of the printer 20 and a channel number are included. When the communication control circuit 25 receives one packet of data, a communication interrupt is generated and given to the system controller 21. In response to this interrupt, the received data is transferred to the FIFO memory 26.
[0062]
The printer 20 includes a FIFO memory 26. The FIFO memory 26 has a capacity capable of confirming image data for two lines of image data representing an image printed by the printer 20.
[0063]
The print engine 28 includes a print head, and starts printing in response to a print start request signal from the system controller 21. When a print start request signal is given from the system controller 21 to the print engine 28, a data request signal is generated from the print engine 28 and given to the FIFO memory 26. In response to a data request signal from the print engine 28, the stored image data is output from the FIFO memory 26. When image data for one line is output from the FIFO memory 26, a transfer completion interrupt signal is given from the FIFO memory 26 to the system controller 21. As a result, the system controller 21 recognizes that one line of image data has been output from the FIFO memory 26.
[0064]
The data output from the FIFO memory 26 is applied to the data processing circuit 27, where data processing including color conversion processing based on the color conversion coefficient set by the system controller 21 is performed and output. The image data output from the data processing circuit 27 is given to the print engine 28, and is printed at a constant speed by the print head included in the print engine 28.
[0065]
3 is a time chart when image data is transmitted from the printer controller 10 to the printer 20. FIG. 4 is a time chart when image data is transmitted from the printer controller 10 to the printer 20. It shows the state of command and data transmission / reception performed between the two. Here, for simplicity, it is assumed that one printer controller 10 and one printer 20 are connected. As described above, a total of 63 devices can be connected in the IEEE standard 1394. Therefore, a total of 63 devices including a printer controller and a printer are connected, and image data is transmitted to a desired printer and printed. You can also. In the example of FIGS. 1 and 2, for example, the printer controller 10 is a parent (cycle master), and the printer 20 is a child.
[0066]
First, a ready signal output request command is output from the printer controller 10 and given to the printer 20. When the printer 20 receives a ready signal output request signal, the system controller 20 refers to the RAM 21 and outputs a ready signal if it is in a ready state. When the ready signal is received by the print controller 10, a first printer specification data request command is output from the printer controller 10 and given to the printer 20. When the printer 20 receives the first printer specification data request command, the system controller 21 reads the printer 20 fixed specification data including the printing speed of the printer 20 and the storage capacity of the FIFO memory 26 from the ROM 23. This fixed specification data is given from the printer 20 to the print controller 10.
[0067]
Subsequently, printer reservation data is given from the printer controller 10 to the printer 20. The printer reservation data is data for setting the printer so that the printer 20 accepts transmission of image data from the printer controller 10, and is written in the RAM 22 of the printer 20. Further, a second printer specification data request command is output from the printer controller 10 and given to the printer 20. When the second printer specification data request command is received at the printer, the system controller 21 reads data representing the current state of the printer 20 from the RAM 22. Data representing the current state is supplied from the printer 20 to the print controller 10.
[0068]
Data / command transmission / reception between the printer controller 10 and the printer 20 so far is performed by asynchronous transfer according to the format shown in FIG. However, isochronous transfer may be used instead of asynchronous transfer. Transfer data after the print standby command described below is isochronous transfer.
[0069]
Subsequently, in order to perform isochronous transfer between the print controller 10 and the printer 20, channel numbers are set in the printer controller 10 and the printer. Data representing the channel number set in the printer controller 10 is stored in the register 13C, and data representing the channel number set in the printer 20 is also stored in the register 25C.
[0070]
When the channel number is set, a printer standby command is generated in the communication control circuit 13 under the control of the main CPU 11 and transmitted from the printer controller 10 to the printer 20 in accordance with the packet format shown in FIG. The When the printer standby command is received by the printer 20, preparation for printing such as positioning of the printer paper to the home position starts. When print preparation is completed in the printer 20, print preparation completion data is output from the printer 20 and given to the printer controller 10.
[0071]
When the printer controller 10 receives print preparation completion data, a print start command is generated. In the print start command, the content of the synchronization bit Sy is set to “3” to indicate the print start command. This print start command is given from the printer controller 10 to the printer 20.
[0072]
When the print start command is output from the printer controller 10, transmission data having a data amount that can be transmitted in one packet is read from the main memory 12 and given to the transmission transfer memory 13 A included in the communication control circuit 13. Remembered. The communication control circuit 13 generates a packet according to the format of FIG. When image data representing the first part of the image is transmitted, the synchronization bit Sy is set to "1" to indicate that fact. The packet data generated in this way is transmitted from the printer controller 10 and received by the printer 20 after a certain delay period has elapsed after the output of the print start command. Since a certain delay time is secured, image data is sent when the print head included in the printer 20 actually starts moving. A small capacity FIFO memory 26 can be used.
[0073]
In the example shown in FIG. 1 and FIG. 2, since one printer 20 is connected to one printer controller 10, only the print controller 10 and the printer 20 transmit and receive data within the isochronous cycle period. Can be used in The amount of image data transmitted from the print controller 10 to the printer 20 can be increased to an allowable range for isochronous transfer. Transfer of image data is quick.
[0074]
The data for one packet transmitted from the printer controller 10 is temporarily stored in the reception transfer memory 25B included in the communication control circuit 25. The communication control circuit 25 determines whether the data is transmitted to itself by comparing the data representing the channel number included in the data for one packet with the data representing the channel number stored in the register 25. When it is determined that the data has been transmitted to itself, a communication interrupt is generated and sequentially written into the FIFO memory 26 under the control of the system controller 21.
[0075]
Subsequently, the image data is transmitted from the printer controller 10 to the printer 20 at regular intervals for each packet. Up to the image data representing the last part of the image, the synchronization bit Sy of the packet is set to “0”, indicating that the image data still continues.
[0076]
Image data received by the printer 20 is sequentially stored in the FIFO memory 26, read out in accordance with a data request signal from the print engine 28, and supplied to the print engine 28 via the data processing circuit 27. As a result, an image is printed at a constant speed by the print head included in the print engine 28.
[0077]
Since image data is always transmitted from the print controller 10 at a constant cycle, the printer 20 does not need to have a large-capacity image memory for storing image data for one frame. It is possible to print at a constant speed only by providing the FIFO memory 26 that can store image data for only a few lines.
[0078]
When image data representing the last part of the image is read from the main memory 12, the synchronization bit Sy is set to "2" and packet data is generated in the communication control circuit 13. This last image data is transmitted from the printer controller 10 to the printer 20, and the transmission of the image data for one frame is completed.
[0079]
When the transmission of the image data is completed, data indicating the end of printing is given from the printer 20 to the printer controller 10. When the printer controller 10 receives data indicating the end of the printer, a printer operation release command is given from the printer controller 10 to the printer 20. When the printer operation cancel command is received by the printer 20, the printer data stored in the RAM 22 is erased and the printer 20 is initialized.
[0080]
Alternatively, the synchronization bit Sy may be set to “4” when transmitting an empty packet (packet whose transmission data is 0). Thus, it is possible to detect whether or not the packet is an empty packet by reading the contents of the synchronization bit Sy. Due to the detection of the empty packet, the transfer of the data received by the printer 20 to the FIFO memory 26 becomes unnecessary.
[0081]
FIG. 5 is a time chart showing a specific transfer rate of image data.
[0082]
Here, it is assumed that an image is represented by R (red), G (green), and B (blue) data. An image to be printed requires 2560 bytes per line of one color. Therefore, for the three colors R, G, and B, image data of 7680 bytes per line is required. Further, it is assumed that the time required for printing one line (printer line cycle) is 7 (ms), and image data of 512 bytes per packet can be sent by isochronous transfer. Dividing 7680 bytes of image data required per line by 512 bytes of image data that can be sent per packet, the number of packets required for 1 line (7680 bytes / 512 bytes = 15 packets) is calculated. it can.
[0083]
Further, the number of isochronous transfer cycles in one line cycle of the printer 20 can be calculated by dividing one line cycle (7 ms) of the printer 20 by the isocycle cycle (125 μs) (7 ms / 125 μs = 56 cycles).
[0084]
The isochronous cycle included in one line cycle of the printer 20 is 56 cycles, and it is sufficient if 15 packets can be transmitted during the 56 cycles. Therefore, 56 cycles are divided by 15 packets (56 cycles / 15 packets = 3.733 cycles). The image data for one packet may be transmitted from the printer controller 10 to the printer 20 for each cycle. In the cycle between the 3.733 cycles, empty data is transmitted from the printer controller 10 to the printer 20.
[0085]
FIG. 6 is a time chart showing other transfer rates of image data.
[0086]
As described above, since image data for one line requires 7680 bytes per 7 ms, 137.1 bytes of image data is required per 125 μs isocycle (7680 bytes / 7 μs = 137.1 bytes / 125 μs). Therefore, 137.1 bytes of image data is read from the main memory 12 in a cycle of one isocycle and given to the transmission transfer memory 13A included in the communication control circuit 13, and one packet of 512 bytes is sent to the transmission transfer memory 13A. The image data may be transferred from the printer controller 10 to the printer 10 after the image data is accumulated.
[0087]
FIG. 7 is a time chart showing still another transfer rate of image data.
[0088]
In FIG. 7, image data for one packet is read from the main memory 12 every other isochronous cycle and stored in the transmission transfer memory 13A included in the communication control circuit 13. The image data stored in the transmission transfer memory 13A is transmitted from the printer controller 10 to the printer 20 every other isochronous cycle.
[0089]
As shown in FIGS. 5 to 7, image data for one packet is continuously transmitted from the printer controller 10 to the printer 20 every isochronous cycle as described above without transferring the image data. Also good.
[0090]
FIG. 8 shows how image data is transferred from the printer controller to the printer, and corresponds to FIG.
[0091]
In the transfer of image data shown in FIG. 8, in order to print one frame image, the transfer of image data shown in FIG. 3 is performed a plurality of times for each color. When the transfer of image data for one frame for one color is completed, the printing paper is returned to the home position again, and image data for one frame for the next color is transferred. Image data for one frame is transmitted from the printer controller to the printer for each color. As a result, a high-definition color image is printed.
[0092]
FIG. 9 shows another embodiment and is a block diagram showing the electrical configuration of the printer controller 10A. In FIG. 9, the same components as those shown in FIG.
[0093]
In the printer controller 10A shown in FIG. 9, a sub-process circuit 15 is newly provided. This sub-process circuit 15 performs data transfer with the main CPU 11 via a PCI (peripheral component interconnect) 14. A command register 16 for temporarily storing commands transferred between the main CPU 11 and the sub-process circuit 15 is also provided.
[0094]
The image data stored in the main memory 12 is read by the sub-process circuit 15 and transferred to the temporary buffer memory 17. The image data stored in the buffer memory 17 is given to the transmission transfer memory 13 A included in the communication control circuit 13 and transmitted to the printer 20.
[0095]
In the printer controller 10A shown in FIG. 9, image data is read from the main memory 12 by the sub-process circuit 15, so that the burden on the main CPU 11 is reduced.
[0096]
Further, an operation key 18 is provided in the printer controller shown in FIG. The operation key 18 allows the user to input the specifications of the printer to which image data is to be transmitted. Thereby, the number of data transmission / reception between the printer controller 10A and the printer 20 can be reduced. Alternatively, the printer controller 10A may be provided with a memory for storing the printer specifications for each printer, and the printer specifications may be read from the memory and selected by the operation key 18.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating an electrical configuration of a printer controller.
FIG. 2 is a block diagram illustrating an electrical configuration of the printer.
FIG. 3 is a time chart when image data is transmitted from the printer controller to the printer.
FIG. 4 shows commands and data transmitted and received between the printer controller and the printer when image data is transmitted from the printer controller to the printer.
FIG. 5 is a time chart showing an example of a transfer rate of image data.
FIG. 6 is a time chart showing another example of the transfer rate of image data.
FIG. 7 is a time chart showing another example of the transfer rate of image data.
FIG. 8 is a time chart when image data is transmitted from the printer controller to the printer.
FIG. 9 is a block diagram illustrating an electrical configuration of a printer controller.
FIG. 10 is a block diagram of devices connected by IEEE1394.
FIG. 11 is a block diagram showing a tree structure of devices connected by IEEE1394.
FIG. 12 is a time chart of isochronous transfer.
FIG. 13 shows a cycle start packet format.
FIG. 14 shows a packet format of data transferred asynchronously.
FIG. 15 shows an isochronous command packet format.
FIG. 16 shows an isochronous data packet format.
[Explanation of symbols]
10, 10A Printer controller
11 Main CPU
12 Main memory
13, 25 Communication control circuit
13A, 25A Transfer memory for transmission
13B, 25B Reception transfer memory
20 Printer
21 System controller
26 FIFO memory
28 Printer engine

Claims (2)

Temporarily store image data for one packet that is transmitted from the printer controller at a transmission cycle determined based on the time required to print one line and that includes data representing the channel number in the packet. Transfer memory for receiving,
A buffer memory that temporarily stores image data, with a storage capacity for image data that is less than the amount of image data that represents one frame of image data,
A register that stores data representing the channel number assigned to the printer,
A comparison is made between the data representing the channel number contained in the packet of image data for one packet temporarily stored in the transfer memory for reception and the data representing the channel number stored in the register. If it is determined that the data is transmitted to the storage memory, storage control means for storing the stored image data for one packet in the buffer memory, and reading and reading the image data stored in the buffer memory Printing control means for printing one line of the image represented by the image data obtained at a constant speed over the required time ;
With printer. Receives image data for one packet that is transmitted from the printer controller at a transmission cycle determined based on the time required to print one line , and that includes data representing the channel number in the packet. Temporarily store in transfer memory,
Store data representing the channel number assigned to the printer in the register,
A comparison is made between the data representing the channel number contained in the packet of image data for one packet temporarily stored in the transfer memory for reception and the data representing the channel number stored in the register. If it is determined that the image data is transmitted to the memory, the image data for one packet stored in the transfer memory for reception is stored in an amount smaller than the amount of image data representing the image for one frame. Stored in a buffer memory with a capacity,
Reading the image data stored in the buffer memory and printing one line of the image represented by the read image data at a constant speed over the required time;
Printer operation control method.

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