JP4298805B2 - Printer system and operation 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 (this node is a cycle master as will be described later) to another node in each isochronous cycle. 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 in which when a receiving device receives transmission data, it sends back a message indicating that it has been received.
[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, and transfer of image data A means for outputting the request is provided.
[0008]
The printer controller includes image data transmission control means for transmitting image data to the printer in units of packets in response to the output of the transfer request.
[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 has a storage capacity for image data smaller than the amount of image data representing an image for one frame, and outputs a buffer memory for temporarily storing the supplied image data and an image data transfer request. Means are provided.
[0011]
In response to the output of the transfer request from the printer, image data is transmitted from the printer controller in packet units. The printer receives image data transmitted from the printer controller and receives the buffer The image data stored in the memory and stored in the buffer memory is read, and 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 to the printer in units of packets is performed in response to the output of a transfer request from 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]
For example, the transfer request may be output from the printer for each print of approximately one line of an image for one frame.
[0017]
Further, the continuity of the image data can be maintained by outputting the image data transfer request from the printer so that the image data stored in the buffer memory is not lost.
[0018]
Further, the image data may be transmitted from the controller while changing the amount of image data included in the packet so that the image data stored in the buffer memory is not lost. Also in this case, the continuity of the image data can be maintained.
[0019]
In response to the output of the transfer request by the printer controller, the transmission of empty data is repeated in units of packets after the image data is transmitted by the image data transmission control means until the next transfer request output. May be.
[0020]
As a result, the amount of image data stored in the buffer memory can be adjusted.
[0021]
Preferably, the printer prepares for printing (heating the printer, positioning the printing paper, positioning the printing head, etc.) by inputting the print preparation setting request command. In this case, the transfer request will be output after completion of preparation for printing. It is possible to prevent image data from being transferred from the printer controller before the preparation for printing is completed.
[0022]
The print preparation setting request command may be output from a printer controller. In this case, the printer controller repeats transmission of empty data in units of packets from the output of the print preparation setting request command to the output of the transfer request.
[0023]
A predetermined routine can be used without changing the routine for transmitting image data.
[0024]
A plurality of the printers may be connected to the printer controller. In this case, the printer will transmit image data to the printer in units of packets in response to the output of the transfer request from all the printers.
[0025]
Furthermore, the printer and the printer controller that constitute the printer system can be configured independently.
[0026]
[Explanation of Examples]
(1) Data transfer based on IEEE standard 1394 Before describing the printer system according to this embodiment, data transfer based on IEEE standard 1394 will be described.
[0027]
FIG. 9 shows a state where 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 (all devices have three ports in the example of FIG. 9). 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.
[0028]
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.
[0029]
FIG. 12 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.
[0030]
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. It includes priority, transmission source ID, read / write address offset, data length, extended transaction code, cycle time data, and data CRC (Cyclic Redundansy Check).
[0031]
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. .
[0032]
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.
[0033]
The asynchronous data packet format shown in FIG. 13 is used when data is transmitted by asynchronous transfer. This format differs from the cycle start packet format only in that transmission data is included in the packet instead of data representing the cycle start delay time.
[0034]
14 and 15 show the format of a packet used in isochronous transfer. FIG. 14 shows the format of an isochronous command packet used when sending a command, and FIG. 15 shows the format of an isochronous data packet used when sending image data.
[0035]
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.
[0036]
Returning to FIG. 9, according to the IEEE standard 1394, the parent-child relationship between the devices connected by the bus is determined. The method for determining this parent-child relationship is as follows.
[0037]
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.
[0038]
When the parent-child relationship is determined for all devices, the whole becomes a tree structure as shown in FIG. In the example of FIG. 10, 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.
[0039]
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.
[0040]
FIG. 11 is a time chart of isochronous transfer.
[0041]
Isochronous transfer control is performed by a device called a cycle master. The root becomes the cycle master.
[0042]
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.
[0043]
After the cycle start packet is transmitted, transfer of isochronous data starts.
[0044]
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.
[0045]
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.
[0046]
In the example shown in FIG. 10, request signals requesting use of the bus are transmitted from the devices A, C, and F, and these request signals are received by the device B that is the route. A permission signal for permitting use of the bus is transmitted from the device B as a route to the device C, and data transmission from the device C is enabled. 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.
[0047]
Returning to FIG. 11, 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. 14 or FIG. 15), and end data indicating the end of the data is added after the packet.
[0048]
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 the 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 within 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).
[0049]
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.
[0050]
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. 12).
[0051]
(2) Printer System The printer system according to this embodiment is configured 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.
[0052]
FIG. 1 is a block diagram showing the electrical configuration of the printer controller 10.
[0053]
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 12.
[0054]
FIG. 2 is a block diagram showing the electrical configuration of the printer 20.
[0055]
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.
[0056]
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.
[0057]
The printer 20 includes a FIFO memory 26. The FIFO memory 26 has a capacity capable of storing two lines of image data representing image data printed by the printer 20.
[0058]
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.
[0059]
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.
[0060]
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.
[0061]
In this embodiment, an image data transfer request is output from the printer 20 and given to the printer controller 10. When the transfer request is input by the printer controller 10, print data is transmitted from the printer controller 10 to the printer 20 by the communication control circuit 13 in response to the transfer request.
[0062]
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 21 refers to the RAM 22 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.
[0063]
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. Between the transmission of the second printer specification data request command and the reception of the second printer specification data, the printer controller 10 sends empty data to the printer 20 (empty data is the asynchronous data packet format shown in FIG. 12). The transmission data may be empty data or the image data may be empty in the isochronous data packet format shown in FIG.
[0064]
Transmission / reception of data or commands 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.
[0065]
Subsequently, in order to perform isochronous transfer between the printer controller 10 and the printer 20, channel numbers are set in the printer controller 10 and the printer 20. 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.
[0066]
When the channel number is set, according to the packet format shown in FIG. 15, 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. 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 the printer 20 completes the print preparation, the print preparation completion and transfer request data are output from the printer 20 and given to the printer controller 10. The empty data is transmitted from the printer controller 10 to the printer 20 from the transmission of the print standby command to the completion of the print preparation and the transfer request data.
[0067]
When print preparation completion and transfer request data are output from the printer 20, transmission print data (image data) having a data amount that can be transmitted in one packet is read from the main memory 12 and included in the communication control circuit 13. It is given to the memory 13A and temporarily stored. The communication control circuit 13 generates a packet according to the format of FIG. When print data representing the first part of the image is transmitted, the synchronization bit Sy is set to "1" to indicate that fact. The print data generated in this way is transmitted from the printer controller 10 and received by the printer 20 after the print preparation is completed and the transfer request data is output.
[0068]
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.
[0069]
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 or not 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.
[0070]
The print data stored in the FIFO memory 26 is read 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.
[0071]
When a transfer completion interrupt is input from the FIFO memory 26 to the system controller 21 in the printer 20, a transfer request command is output from the system controller 21. This transfer request command is given from the communication control circuit 25 to the printer controller 10. When the transfer request command is given to the printer controller 10, a packet is generated again according to the format shown in FIG. 15, and the print data is transmitted from the printer controller 10 to the printer 20. As described above, the transmission timing of print data from the printer controller 10 to the printer 20 is defined by the transfer request command given from the printer 20 to the printer controller 10. The empty data is transmitted from the printer controller 10 to the printer 20 until the transfer request command is input after the print data is transmitted.
[0072]
Since print data is transmitted from the printer controller 10 to the printer 20 in response to the input of the transfer request command, 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.
[0073]
When the image data representing the last part of the image is read from the main memory 12, the synchronization bit Sy is set to "2" so as to represent the last part of the image, and the communication control circuit 13 receives the packet data. Generated. 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.
[0074]
When the transmission of the print 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.
[0075]
Further, when transmitting empty data, the synchronization bit Sy may be set to “4”. Thus, it is possible to detect whether or not the data is empty by reading the contents of the synchronization bit Sy. Detection of empty data eliminates the need to transfer data received by the printer 20 to the FIFO memory 26.
[0076]
In the above-described embodiment, the system controller 21 of the printer 20 outputs a transfer request command by inputting the transfer completion interrupt output from the FIFO memory 26 and gives it to the printer controller 10. However, the system controller 21 monitors the amount of data stored in the FIFO memory 26 and outputs a transfer request command from the system controller 21 when the amount of data stored in the FIFO memory 26 decreases. May be.
[0077]
5 and 6 show another embodiment. FIG. 5 is a time chart when image data is transmitted from the printer controller 10 to the printer 20, and FIG. 6 is a time chart when the print data is transmitted from the printer controller 10 to the printer 20. This shows a part of command and data transmission / reception performed between and.
[0078]
In the embodiment shown in FIGS. 5 and 6, a transfer rate representing a print data transmission period is given from the printer 20 to the printer controller 10. The printer controller 10 transmits print data to the printer 20 at a transmission cycle according to the transfer rate given from the printer 20.
[0079]
When the print data transmission process from the printer controller 10 to the printer 20 is repeated, the FIFO memory 26 may become empty because the print data reception cycle (transmission cycle) is long. In the embodiment shown in FIGS. 5 and 6, the system controller 21 of the printer 20 monitors the FIFO memory 26 and determines whether the FIFO memory 26 becomes empty when the current transfer rate is maintained. When the FIFO memory 26 becomes empty, the system controller 21 outputs a transfer rate shortening request command indicating that the transfer rate is shortened and gives it to the printer controller 10. When the printer controller 10 inputs a transfer rate reduction request command, the print data transmission cycle is shortened. As a result, the FIFO memory 26 can be prevented from being emptied, and the continuity of the image data can be maintained.
[0080]
In addition, when print data transmission processing from the printer controller 10 to the printer 20 is repeated, the received print data overflows from the FIFO memory 26 because the print data reception cycle is short, and the FIFO data 26 is received. You may not be able to remember. In the embodiment shown in FIGS. 5 and 6, the system controller 21 of the printer 20 monitors the FIFO memory 26 and determines whether the print data overflows from the FIFO memory 26 if the current transfer rate is maintained. When the print data received from the FIFO memory 26 overflows, the system controller outputs a transfer rate extension request command indicating that the transfer rate is extended and gives it to the printer controller 10. When the printer controller 10 inputs a transfer rate extension request command, the printer controller 10 lengthens the print data transmission cycle. As a result, the print data received by the printer 20 can be prevented from overflowing from the FIFO memory 26, and the continuity of the image data can be maintained.
[0081]
In the above-described embodiment, when the FIFO memory 26 is likely to be empty and when print data is likely to overflow from the FIFO memory 26, the transfer rate of print data transmission is changed. However, this may be dealt with by adjusting the data amount of the print data included in the packet without changing the transfer rate. That is, when the FIFO memory 26 is likely to be empty, a command is given from the printer 20 to the printer controller 10 to increase the amount of print data included in one packet, and the print data is transferred from the FIFO memory 26. If it is likely to overflow, a command for reducing the amount of print data contained in one packet is given from the printer 20 to the printer controller 10.
[0082]
7 and 8 show still another embodiment. FIG. 7 shows an example of connection between a printer controller and a printer. FIG. 8 shows a case where print data is transmitted from the printer controller 10 to the printer 20. The figure shows how commands and data are sent and received between the printer controller 10 and the printer 20.
[0083]
As shown in FIG. 7, a plurality of printers 30, 40 and 50 are connected to the printer controller 10 by cables based on IEEE1394.
[0084]
In the embodiment shown in FIGS. 7 and 8, print data is transmitted from the printer controller 10 when transfer requests are output from all the printers 30, 40 and 50 connected to the printer controller 10. Even if a transfer request is output from one of the printers 30, 40, and 50 connected to the printer controller 10, it is transferred from all the printers 30, 40, and 50 connected to the printer controller 10. Until the request is output, the printer controller 10 outputs empty data.
[0085]
In the embodiment shown in FIG. 7, print data is transmitted from the printer controller 10 when a transfer request is output from all the printers 30, 40 and 50 connected to the printer controller 10, so that the broadcast ( Transmitting the same data to all nodes).
[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 when image data is transmitted from the printer controller to the printer.
FIG. 6 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. 7 shows an example of connection between a printer and a printer controller.
FIG. 8 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. 9 is a block diagram of devices connected by IEEE1394.
FIG. 10 is a block diagram showing devices connected by IEEE 1394 in a tree structure.
FIG. 11 is a time chart of isochronous transfer.
FIG. 12 shows a cycle start packet format.
FIG. 13 shows a packet format of data transferred asynchronously.
FIG. 14 shows an isochronous command packet format.
FIG. 15 shows an isochronous data packet format.
[Explanation of symbols]
10 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, 30, 40, 50 printer
21 System controller
26 FIFO memory
28 Printer engine

Claims (14)

A printer controller connected to the bus and a printer are provided. 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. In the printer system that prints with
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, and transfer of image data Means to output the request,
The printer controller above
Image data transmission control for transmitting image data to the printer by storing image data in response to the output of the transfer request in a packet transmitted at a constant cycle based on isochronous transfer for transmitting the packet at a constant cycle And, in response to the output of the transfer request, after the image data is transmitted by the image data transmission control means until the next transfer request output in response to the output of the transfer request. Empty data transmission control means for repeating the transmission of empty data to the printer for printing the image represented by the image data supplied from the printer controller at a constant speed by storing empty data;
The above printer
Storage control means for receiving image data stored in a packet transmitted at a constant cycle based on isochronous transfer from the printer controller and storing it in the buffer memory, and image data stored in the buffer memory And printing control means for printing an image represented by the read image data at a constant speed,
Printer system.   2. The printer system according to claim 1, wherein the printer outputs a transfer request for the image data so that the image data stored in the buffer memory is not lost.   The image data transmission control means changes the amount of image data included in the packet so as not to lose the image data stored in the buffer memory, and transmits the image data. Printer system.   2. The printer system according to claim 1, wherein the printer prepares for printing by inputting a print preparation setting request command, and outputs the transfer request after completion of the preparation. The print preparation setting request command is output from the printer controller.
The printer controller above
It further comprises empty data transmission control means for repeating the transmission of empty data in units of packets from the output of the print preparation setting request command to the output of the transfer request.
The printer system according to claim 4. A plurality of printers are connected to the printer controller.
The printer system according to claim 1, wherein the printer transmits image data to the printer in units of packets in response to the output of the transfer request from all the printers. A printer controller connected to the bus and a printer are provided. 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. 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 image data supplied from the printer controller; A printer controller used in a printer system provided with means for outputting a transfer request for image data;
Image data transmission control for transmitting image data to the printer by storing image data in response to the output of the transfer request in a packet transmitted at a constant cycle based on isochronous transfer for transmitting the packet at a constant cycle And, in response to the output of the transfer request, after the image data is transmitted by the image data transmission control means until the next transfer request output in response to the output of the transfer request. It further comprises empty data transmission control means for repeating empty data transmission to the printer for storing the empty data to print the image represented by the image data supplied from the printer controller at a constant speed. Is,
Printer controller. A printer controller connected to the bus and a printer are provided. 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. In the printer system that prints with
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, and transfer of image data Means to output the request,
The printer controller above
The image data is transmitted to the printer by storing the image data in response to the output of the transfer request in a packet transmitted at a constant cycle based on isochronous transfer for transmitting the packet at a constant cycle.
In response to the output of the transfer request, empty data is transmitted from the image data transmission control means to the next transfer request output in response to the output of the transfer request in a packet transmitted at a constant period based on isochronous transfer. By storing, the transmission of empty data to the printer for printing the image represented by the image data supplied from the printer controller at a constant speed is repeated in units of packets,
The above printer
Receives image data stored in a packet transmitted at a constant cycle based on isochronous transfer from the printer controller, stores it in the buffer memory,
Reading the image data stored in the buffer memory and printing the image represented by the read image data at a constant speed;
An operation control method for a printer system. As the image data stored in the buffer memory is not eliminated, the printer, and outputs the transfer request of the image data, the operation control method for a printer system of claim 8. 9. The printer according to claim 8 , wherein the printer controller changes the amount of image data included in the packet so that the image data stored in the buffer memory is not lost, and transmits the image data. -System operation control method. The printer is to perform the preparation relating to printing by entered the printing preparation setting request command and outputs the transfer request after completion of this preparation, operation control of the printer system according to claim 8 Method. The print preparation setting request command is output from the printer controller.
12. The operation control of the printer system according to claim 11 , wherein the printer controller repeats transmission of empty data in units of packets from the output of the print preparation setting request command to the output of the transfer request. Method. A plurality of printers are connected to the printer controller.
9. The operation of the printer system according to claim 8 , wherein the printer transmits image data to the printer in units of packets in response to the output of the transfer request from all the printers. Control method. A printer controller connected to the bus and a printer are provided. 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. 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 image data supplied from the printer controller; An operation control method for a printer controller used in a printer system provided with means for outputting a transfer request for image data,
The image data is sent to the printer by storing the image data in response to the output of the transfer request in the packet transmitted at a constant cycle based on the isochronous transfer that transmits the packet at a constant cycle, and the isochronous transfer is performed. In response to the output of the transfer request, empty data is stored in the packet transmitted at a constant cycle based on the time until the next transfer request output after the image data is transmitted by the image data transmission control means. Thus, transmission of empty data to the printer for printing an image represented by the image data supplied from the printer controller at a constant speed is repeated in units of packets.
Printer controller operation control method.

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