JPH11225317A - Image data transmitter, image data receiver, image data transmission reception system, image data transmission method, image data reception method, and image data transmission reception method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the image data transmission reception system by which image data are normally transferred by using the IEEE 1394 standards. SOLUTION: Data by one line among image data stored in a 1st storage area of a memory 14 are read by a composition section 12, where dummy data are added to the image data as transmission data. The transmission data are once stored in a 2nd storage storage area of the memory 14 by the composition section 12 and a transmission reception section 16 reads the data from the 2nd storage area and sends it as packets having a prescribed period nearly equal to the period of a line synchronizing signal. The transmission data reached from an image data transmitter 10 are received by a transmission reception section 22. The received transmission data are given to an extract section 24, from which the image data are extracted and stored once in a FIFO memory 26, and then the image forming device 30 reads the data to form an image.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a method and an apparatus for serially transferring packet data of image data.

[0002]

2. Description of the Related Art In an image forming apparatus such as a laser beam printer, input of image data to an image writing unit needs to be performed at a timing synchronized with a drive system of the image writing unit. The synchronizing signal used at this time includes a video clock signal for synchronizing each pixel of image data, a line synchronizing signal for synchronizing each line of image data, and an image for one screen. There is a page synchronization signal for synchronizing each data.

Conventionally, when transmitting image data from an image data source for generating image data to the image forming apparatus, the image forming apparatus sends the synchronization signal to the image data source, and the image is synchronized with the synchronization signal. Image data is sent from the data source to the image forming apparatus side, and different signal lines are used for transmitting and receiving the synchronization signal and the image data, respectively. However, in such a conventional image data transmission / reception method, there is a problem that a transmission line and a connector need to be prepared for each device because standards are not standardized.

In order to solve such a problem, IEEE (The Institute of Electr
It has been considered that image data is transmitted and received using the 1394 standard (for example, see Japanese Patent Application Laid-Open No. Hei 8-79744). In the image data transmission / reception according to the IEEE 1394 standard, image data is divided into packets, and each packet is transmitted isochronously every predetermined time (125 μsec). Serial transmission is performed by a single signal line connecting standardized connectors. I do.

[0005]

SUMMARY OF THE INVENTION However, the IEEE
In image data transmission / reception according to the E1394 standard, a cycle and a transmission clock every 125 μsec, which is a packet cycle, have no synchronous relationship with any of the video clock signal, the line synchronization signal, and the page synchronization signal output from the image forming apparatus side. Therefore, if the IEEE 1394 standard is simply applied to image data transmission / reception, neither image data transmission / reception nor image formation is normally performed.

FIG. 19 is a view for explaining a problem when the IEEE 1394 standard is simply applied to image data transmission / reception. As shown in this figure, the line synchronization signal is a repetitive pulse signal having a fixed period of 599.092 μsec, for example, whereas the packet period in the IEEE 1394 standard is 125 μsec, and there is no synchronization between them. Further, the amount of image data for one line has no relation to the amount of data that can be transferred per packet. Therefore, in the transmission and reception of the image data, the timing difference between the line synchronization signal and the transferred image data for one line is gradually increased even if the timing is initially relatively similar.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an image data transmitting method, an image data receiving method, and an image data transmitting / receiving method capable of normally transferring image data using the IEEE 1394 standard. The purpose is to provide. Another object of the present invention is to provide an image data transmitting device, an image data receiving device, and an image data transmitting / receiving system suitable for realizing such image data transfer.

[0008]

An image data transmitting apparatus according to the present invention is an image data transmitting apparatus for dividing image data into packets and transmitting the packets in a first cycle.
(1) Dummy data is added to a predetermined unit of image data,
A transmission unit that transmits transmission data at a predetermined time substantially equal to the second period longer than the first period, and (2) a transmission unit that transmits the transmission data at the predetermined time. I do.

According to this image data transmitting apparatus, the composition section adds dummy data to the predetermined unit of image data to form transmission data, and the transmission section converts the transmission data into the second data longer than the first cycle. The packet is transmitted in the first cycle at a predetermined time that is substantially equal to the cycle of (1). That is, the second
A predetermined unit of image data is transmitted as a packet in the first cycle per cycle.

An image data receiving apparatus according to the present invention is an image data receiving apparatus for receiving image data that has been transmitted by packet transmission from an image data transmitting apparatus, and (1) transmitted from an image data transmitting apparatus and arrived. A receiving unit that receives transmission data including image data and dummy data,
(2) An extraction unit for extracting image data from the transmission data received by the reception unit.

According to this image data receiving device, the receiving unit receives the transmitted data transmitted from the image data transmitting device and arrives, and the extracting unit extracts the image data from the received transmitted data. That is, a predetermined unit of image data is received in packets in the first cycle per second cycle.

An image data transmitting / receiving system according to the present invention is an image data transmitting / receiving system that divides image data into packets and transmits / receives packets in a first cycle.
(1) Dummy data is added to a predetermined unit of image data,
A composition unit for composing transmission data to be transmitted in a predetermined time substantially equal to the second period longer than the first period, (2) a transmission unit for transmitting the transmission data in the predetermined time, and (3) a transmission unit. It is characterized by comprising: a receiving unit that receives the arrived transmission data; and (4) an extraction unit that extracts image data from the transmission data received by the receiving unit. The image forming apparatus further includes an image forming apparatus that forms an image based on the image data extracted by the extracting unit. The second cycle is a cycle of a line synchronization signal output from the image forming apparatus. Is preferably one line.

According to this image data transmitting / receiving system,
On the transmission side, the composition unit adds dummy data to a predetermined unit of image data to form transmission data, and the transmission unit converts the transmission data to a predetermined time substantially equal to the second period longer than the first period. , In the first cycle. On the receiving side, the receiving unit receives the transmitted data transmitted from the transmitting unit and arrives, and the extracting unit extracts the image data from the received transmitted data. That is, a predetermined unit of image data per second cycle is:
Packets are transmitted and received in the first cycle.

An image data transmitting method according to the present invention is an image data transmitting method for dividing image data into packets and transmitting the packets in a first cycle, wherein dummy data is added to a predetermined unit of image data. The second longer than the first cycle
, Transmission data to be transmitted in a predetermined time substantially equal to the period of the transmission data, and the transmission data is transmitted in the predetermined time.

According to this image data transmitting method, dummy data is added to image data of a predetermined unit to form transmission data, and the transmission data is transmitted at a predetermined time substantially equal to the second period longer than the first period. , In the first cycle. That is, a predetermined unit of image data is transmitted in packets in the first cycle per second cycle.

An image data receiving method according to the present invention is an image data receiving method for receiving image data that has arrived by packet transmission. The image data receiving method comprises the steps of: Image data is extracted from the transmitted data.

According to this image data receiving method, transmission data including image data and dummy data transmitted and arrived is received, and the image data is extracted from the received transmission data. That is, a predetermined unit of image data is received in packets in the first cycle per second cycle.

An image data transmitting / receiving method according to the present invention is an image data transmitting / receiving method for dividing image data into packets and transmitting / receiving packets at a first cycle.
Dummy data is added to a predetermined unit of image data, and the first
The transmission data to be transmitted is transmitted at a predetermined time substantially equal to the second period longer than the period of the transmission data, and the transmission data is transmitted at the predetermined time, and the reception side receives the transmission data arrived from the transmission side, Image data is extracted from the received transmission data. The second cycle is a cycle of a line synchronization signal output from the image forming apparatus provided on the receiving side, and the predetermined unit is preferably one line of image data.

According to this image data transmitting / receiving method, on the transmitting side, dummy data is added to a predetermined unit of image data to form transmission data, and the transmission data is substantially equivalent to a second period longer than the first period. Packets are transmitted in the first cycle at the same predetermined time. The receiving side receives the transmission data transmitted from the transmitting side and arrives, and extracts the image data from the received transmission data. That is, a predetermined unit of image data is transmitted and received in the first cycle in the second cycle.

[0020]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In the description of the drawings, the same elements will be denoted by the same reference symbols, without redundant description.

In order to solve the problems in applying the IEEE 1394 standard to image data transmission / reception,
It is also conceivable to provide a buffer memory for storing received image data on the image forming apparatus side, that is, on the receiving side. However, in this case, a buffer memory having a capacity enough to store at least one screen of image data is required, and the hardware configuration becomes large and complicated. Therefore, the present invention solves the above-mentioned problem without complicating the hardware configuration by adding dummy data to image data to generate transmission data and transferring the transmission data.

First, an image data transmitting apparatus according to the present invention,
One embodiment of each of the image data receiving device and the image data transmitting / receiving system will be described. FIG. 1 is a diagram illustrating the configuration of each of an image data transmitting device, an image data receiving device, and an image data transmitting and receiving system according to the present embodiment. In this figure, arrows between blocks indicate the direction of the flow of image data.

As shown in FIG. 1, an image data transmitting / receiving system 1 includes an image data transmitting device 10, an image data receiving device 20, and an image forming device 30.
The image data transmitting apparatus 10 includes a composition unit 12, a memory 14, and a transmitting / receiving unit 16. The image data receiving apparatus 20 includes a transmitting / receiving unit 22, an extracting unit 24, and an FI.
An FO (First-In First-Out) memory 26 is provided.

The memory 14 of the image data transmitting device 10
It has a first storage area and a second storage area which are different from each other, stores image data to be transmitted in the first storage area, and stores the image data based on the image data.
Is stored in the second storage area.

The composition section 12 of the image data transmitting apparatus 10
Image data is sequentially read from the first storage area of the memory 14, and dummy data is added to each of the image data of one line (predetermined unit), so that line synchronization longer than 125 μsec which is a packet cycle (first cycle) is performed. The transmission data to be transmitted in the packet is composed for a predetermined time substantially equal to the signal period (second period), and the composed transmission data is stored in the second storage area of the memory. That is, 1
The transmission data including the image data for the line and the added dummy data is an amount that can be transmitted by the transmission / reception unit 16 for a predetermined time substantially equal to the cycle of the line synchronization signal. In the initialization between the transmission / reception unit 16 of the image data transmission device 10 and the transmission / reception unit 22 of the image data reception device 20, the other party can be identified from each other. It is possible to know the time of the signal cycle.

Transmission / reception section 16 of image data transmission apparatus 10
Reads the transmission data stored in the second storage area of the memory 14 and transmits the transmission data in a packet at the predetermined time. Further, the transmission / reception unit 22 of the image data reception device 20 receives the transmission data arrived from the transmission / reception unit 16 of the image data transmission device 10. When transmitting and receiving transmission data between the transmission / reception unit 16 and the transmission / reception unit 22,
This is performed according to the EEE1394 standard.

The extraction unit 24 of the image data receiving unit 20 receives the transmission data received by the transmission / reception unit 22, extracts image data from the transmission data, and stores the image data in the FIFO memory 26. The FIFO memory 26 stores one line of image data starting from the head address, and is preferably a memory that can simultaneously perform writing and reading.

Then, the image forming apparatus 30 sequentially reads out image data from the FIFO memory 26 in synchronization with the line synchronization signal, and forms an image based on the image data. The image forming apparatus 30 is, for example, a laser beam printer, but is not limited to this.

The image data transmission / reception system 1 operates as follows. In the image data transmitting apparatus 10, one line of data of the image data stored in the first storage area of the memory 14 is read out by the composition unit 12 and added with dummy data to be transmitted data. You. The transmission data is temporarily stored in the second storage area of the memory 14 by the composition unit 12 and then read out of the second storage area by the transmission / reception unit 16 to obtain a predetermined data that is substantially equal to the cycle of the line synchronization signal. Packets are sent on time.

On the other hand, in the image data receiving device 20, the transmission data arriving from the image data transmitting device 10 is received by the transmitting / receiving unit 22. The received transmission data is input to the extraction unit 24 to extract image data, and the image data is stored in the FIFO memory 26. Then, the image data is transmitted to the
The image is read from the FO memory 26, and an image is formed based on the image.

Therefore, one line of image data is transferred to the image data transmitting apparatus 10 per one cycle of the line synchronizing signal.
Is transmitted to the image data receiving apparatus 20, the image data is transmitted and received normally, and a normal image is formed in the image forming apparatus 30. Further, the memory capacity required on the receiving side is reduced, and the configuration is simplified.

An image data transmission / reception method for adding transmission data to be transmitted for a predetermined time substantially equal to the cycle of a line synchronization signal by adding dummy data to one line of image data, and transmitting the transmission data in packets. As
Various things are possible. Hereinafter, four preferred embodiments will be described. In any of these four embodiments, the image data transmitting device 10, the image data receiving device 2,
0 and the image data transmission / reception system 1.

In the following description of each embodiment, regarding the image data transmission method, a dummy data addition number calculation process for calculating the number of dummy data to be added, and a dummy data addition process for adding transmission data by adding dummy data The processing will be described separately. These processes are performed in the composition unit 12 of the image data transmission device 10. The dummy data addition number calculation process is not limited to the composition unit 12, and may be performed in an arithmetic unit separately provided on the transmission side, may be performed in advance before transmission, or may be sequentially performed in transmission. Is also good. Also, the dummy data adding process may be performed in advance before transmission, or may be performed sequentially upon transmission. Further, examples of suitable packet formats will be described.
Image data receiving method, that is, image data receiving device 2
A method of extracting valid image data in the 0 extraction unit 24 will also be described.

(First Embodiment) Next, a first embodiment will be described. In this embodiment, dummy data is added continuously after one line of image data.

First, the process of calculating the number of added dummy data will be described. FIG. 2 is a flowchart illustrating a dummy data addition number calculation process in the image data transmission / reception method according to the first embodiment.

In step S01, the number of lines of image data is obtained by multiplying the image length by the resolution at the time of image formation. Note that the greater the number of lines, the better the accuracy in subsequent processing. This number of lines is a positive integer. In step S02, the time required to form one image is determined by multiplying the number of lines determined in step S01 by the cycle of the line synchronization signal. This time required for image formation is generally a positive real number.

In step S03, the image forming time determined in step S02 is set to a packet cycle of 125 μs.
By dividing by c, the number of packets required to transmit one image of image data as a packet is obtained, and the result is set as the ideal number of packets. This ideal number of packets is generally a positive real number. In step S04, the number of ideal packets obtained in step S03 is multiplied by the number of image data to be transmitted per packet, and the result is used as the number of ideal image data.
The result is taken as the ideal number of image data per line. The ideal number of image data per line is generally a positive real number.

In step S05, the magnitude of the ideal number of image data per line obtained in step S04 is compared with the actual number of image data per line. If they are equal to each other, the dummy data addition number is set to a value of 0, and the dummy data addition number calculation process ends. On the other hand, if they are different from each other, the process proceeds to step S06, and the number of dummy data additions is obtained by the subsequent processes.

In step S06, the actual number of image data per line is subtracted from the integer part of the ideal number of image data per line obtained in step S04.
The result is set as the first dummy data addition number. This first
Is the number of dummy data to be added at least per line.

In step S07, the decimal part of the ideal number of image data per line obtained in step S04 is set as the value of variable Y. In step S08, the value of a variable X representing the line count value is initialized to zero.

In step S09, the decimal part of the value of the variable Y is multiplied by the number of lines obtained in step S01, and the result of the multiplication is compared with half of the actual number of image data per packet. And the result of the multiplication is the actual 1
If it is equal to or more than half of the number of image data per packet, the process proceeds to step S10; otherwise, the process proceeds to step S12. In the magnitude comparison, the accumulation of the decimal part of the value of the variable Y is set to be smaller than one packet. However, the smaller the decimal part of the value of the variable Y is, the smaller the accumulation is. It is desirable that the fractional part of the value of Y be compared so as to be as small as possible.

In step S10, the current value of the variable Y and the decimal part of the ideal number of image data per line obtained in step S04 are added, and the addition result is newly set as the value of the variable Y. In step S11, the value of the variable X and the value 1 are added, and the addition result is newly set as the value of the variable X. Then, the process returns to step S09.

That is, in the loop consisting of steps S09 to S11, the result of multiplying the decimal part of the value of the variable Y in step S09 by the number of lines obtained in step S01 is less than half the actual number of image data per packet. Repeat until. If the result of the multiplication becomes half or more of the actual number of image data per packet,
The process exits from this loop and proceeds to step S12.

In step S12, the integer part of the value of the variable Y at that time is used as the second dummy data addition number. The value of the variable X at this time is set as a second dummy data addition interval. This second dummy data addition number is the number of dummy data to be further added per X line. Thus, the dummy data addition number calculation processing ends. The first and second dummy data addition numbers and the second dummy data addition interval thus obtained are used in a dummy data addition process described below.

Next, the dummy data adding process will be described. FIGS. 3 and 4 are flowcharts for explaining the dummy data adding process in the image data transmitting / receiving method according to the first embodiment.

In step S13 shown in FIG. 3, the data count value indicating the image data position in one line is initialized to a value 0, and in step S14, the line count value indicating the line position is initialized to a value 0. In step S15,
The image data for one line stored in the original first storage area is transferred to a new second storage area. Step S
At 16, the data count value is counted up by the image data amount transcribed at step S15. Step S
In step 17, the address value of the first storage area is counted up by the image data amount transcribed in step S15, and the address value of the first storage area of the image data to be read next is obtained. In step S18, the address value of the second storage area is counted up by the image data amount transcribed in step S15, and the address value of the second storage area in which data is to be stored next is obtained. In step S19, the data count value is compared with the number of image data per line. If the data count value is smaller than the number of image data per line, the process proceeds to step S20; otherwise, the process proceeds to step S21.

In step S21 shown in FIG. 4, the data count value is initialized to 0, and in step S22, the line count value is increased by one. In step S23, the address value of the second storage area is advanced by the first dummy data addition number obtained in step S06, and the result is newly set as the address value of the second storage area. Thereby, the first
Means that dummy data has been added by the number of dummy data added.

In step S24, the line count value is compared with the second dummy data addition interval obtained in step S12, and if the line count value has reached the second dummy data addition interval, the flow advances to step S25. Otherwise, the process proceeds to step S20. In step S25, the line count value is initialized to 0, and in step S2
In step S6, the address value of the second storage area is stored in step S1.
The process proceeds by the second dummy data addition number obtained in step 2, and the result is newly set as the address value of the second storage area. This means that the dummy data has been added by the second dummy data addition number. Then, the process proceeds to step S20.

In step S20 shown in FIG. 3, it is determined whether or not the address value of the first storage area has reached the end of one screen of image data. If not, the flow returns to step S15. The dummy data adding process is terminated when the end is reached.

FIG. 5 is a timing chart for explaining transmission data in the image data transmission / reception method according to the first embodiment. As shown in the figure, dummy data is added after one line of image data to form transmission data, and the transmission data is transmitted at a time substantially equal to the cycle of the line synchronization signal.

FIG. 6 is a diagram for explaining a packet format example of transmission data in the image data transmission / reception method according to the first embodiment.

The 16-bit data_length shown in FIG.
Is the image data and invalid contained in the packet
Indicates the size of data. The 2-bit tag indicates the format of the isochronous packet, and is fixed to 00b in this case. The 6-bit channel indicates a channel number. The 4-bit tcode indicates that the packet is an isochronous packet, and is fixed to 0xA. The 4-bit sy is a synchronization code and is fixed at 0000b. The total of 32 bits described above is the header portion. The 32-bit header_CRC is
This is a CRC (Cyclical Redundancy Check) of the header part. The above header part and header_CRC are IEEE
It is based on the E1394 standard.

The 4-bit PKTSeq indicates the sequence number of the packet, uses a cyclic value of 0x0 to 0xF, and is used for packet loss detection. 13-bit ValidPixelL
“ength” indicates the effective image data length in the packet. 13
The LHeadOffset bit indicates the head data position of one line of image data in the packet. 1-bit PF
Indicates a status bit of the transmission-side page synchronization signal. A 1-bit LF value of 1 indicates that the value of LHeadOffset is valid, and a value of 0 indicates that the value of LHeadOffset is invalid. 32-bit Logical inv
erse of VDATA HEADER first Quadlet is PKTSeq
Is the logical inversion of each bit value from to LF.
It is used to detect on the receiving side whether the packet transfer has been performed normally. Subsequent image data 0 to image
Each of data n is 8-bit image data. 3
2-bit data_CRC is from image data 0 to image data
Indicates the CRC of n. Here, in a packet including the head or end of one line of image data, image data 0 to i
In some cases, dummy data is included as mage data n.

Therefore, in the present embodiment, in the image data transmitting apparatus 10, the composition unit 12 causes the packet of the packet including the head data of the image data of one line to be included.
The LF value is set to the value 1, and the head data position information of one line is stored in LHeadOffset. Further, the LF value of a packet that does not include the leading data in the image data for one line is set to the value 0. Also, the number of valid image data image data 0 to image data n included in each packet is
Store in lLength. In the image data receiving device 20, the transmission data in the packet format is received by the receiving unit 22, and the image data is extracted by the extracting unit 24.

That is, in the extraction unit 24, the ValidPixelLength value, the LHeadOffset value, and the LF
The value is detected. And if the LF value is 1, then LHead
The data before the head data position of one line indicated by the Offset value is stored sequentially following the current address of the FIFO memory 26, and the data after the head data position of one line indicated by the LHeadOffset value is the head address of the FIFO memory 26. Are stored sequentially. On the other hand, if the LF value is 0, ima
Each data of ge data 0 to image data n is sequentially stored following the current address of the FIFO memory 26. In this case, the FIFO memory 26 stores 1
The effective image data for the line is stored, and subsequently the dummy data is stored. However, only valid image data is read by the image forming apparatus 30.

(Second Embodiment) Next, a second embodiment will be described. In this embodiment, dummy data is added before one line of image data. Note that the process of calculating the number of added dummy data in this embodiment is the same as that described in the first embodiment. Hereinafter, the dummy data adding process will be described. FIGS. 7 and 8 are flowcharts for explaining dummy data addition processing in the image data transmission / reception method according to the second embodiment.

In step S27 shown in FIG. 7, the data count value is set to the number of image data per line, and in step S28, the line count value is initialized to zero.
In step S29, it is determined whether or not the data count value has reached the value 0, that is, whether or not it has reached the line head position, and if it has reached the line head position, it is determined in step S30.
Otherwise, to step S35.

In step S35 shown in FIG. 8, the data count value is set to the number of image data per line, and in step S36, the line count value is increased by one. In step S37, the address value of the second storage area to which the one-line image data stored in the original first storage area is to be transcribed is calculated by the first dummy data addition number obtained in step S06. Proceed. This means that the dummy data has been added by the first dummy data addition number.

In step S38, the line count value is compared in magnitude with the second dummy data addition interval obtained in step S12. If the line count value has reached the second dummy data addition interval, the flow advances to step S39. Otherwise, the process proceeds to step S30. In step S39, the line count value is initialized to 0, and in step S4
0, the address value of the second storage area is stored in step S1
The process proceeds by the second dummy data addition number obtained in step 2.
This means that the dummy data has been added by the second dummy data addition number. Then, the process proceeds to step S30.

In step S30 shown in FIG.
The image data for one line stored in the storage area is transferred to the second storage area. In step S31, the data count value is counted down by the image data amount transcribed in step S30. In step S32, the address value of the first storage area is counted up by the image data amount transcribed in step S30, and the address value of the first storage area of the image data to be read next is obtained. In step S33, the address value of the second storage area is counted up by the image data amount transcribed in step S30, and the address value of the second storage area in which data is to be stored next is obtained. In step S34, it is determined whether or not the address value of the first storage area has reached the end of one screen of image data.
29, the process is repeated, and if the end has been reached, the dummy data addition process ends.

FIG. 9 is a timing chart for explaining transmission data in the image data transmission / reception method according to the second embodiment. As shown in this figure, dummy data is added before one line of image data to form transmission data, and the transmission data is transmitted at a time substantially equal to the cycle of the line synchronization signal.

The packet format of the transmission data in the image data transmission / reception method according to the present embodiment is the first
This is the same as the embodiment. Also, ValidPixelLength, LHead in each of the composition unit 12 and the extraction unit 24
The handling of Offset and LF is the same as in the first embodiment.

(Third Embodiment) Next, a third embodiment will be described. In this embodiment, dummy data is added at the end of each packet.

First, the dummy data addition number calculation processing will be described. FIG. 10 is a flowchart illustrating a dummy data addition number calculation process in the image data transmission / reception method according to the third embodiment.

In step S41, the number of lines of image data is obtained by multiplying the image length by the resolution at the time of image formation. Note that the greater the number of lines, the better the accuracy in subsequent processing. This number of lines is a positive integer. In step S42, the time required to form one image is determined by multiplying the number of lines determined in step S41 by the cycle of the line synchronization signal. This time required for image formation is generally a positive real number.

In step S43, the time required for image formation obtained in step S42 is set to a packet cycle of 125 μs.
By dividing by c, the number of packets required to transmit one image of image data as a packet is obtained, and the result is set as the ideal number of packets. This ideal number of packets is generally a positive real number. In step S44, the number of lines obtained in step S41 is multiplied by the number of image data to be transmitted per packet, the result of the multiplication is divided by the number of image data to be transferred per packet, and the division result is obtained. Is the current number of packets. This current number of packets is generally a positive real number.

In step S45, the ideal number of packets obtained in step S43 is compared with the current number of packets obtained in step S44. If the two are equal, the dummy data addition number is set to 0, and the dummy data addition number calculation process ends. On the other hand, if the two are different from each other, the process proceeds to step S46, and the number of dummy data additions is obtained by the subsequent processes.

In step S46, the current number of packets determined in step S44 is subtracted from the ideal number of packets determined in step S43, the result of subtraction is multiplied by the number of image data per packet, and the result of multiplication is calculated. This is the number of dummy data additions. The number of added dummy data is the number of dummy data to be added per one cycle of the line synchronization signal, and is generally a positive real number.

In step S47, the number of added dummy data obtained in step S46 is divided by the number of ideal packets obtained in step S43, and the division result is used as the number of added dummy data per packet. 1
The integer part of the number of added dummy data per packet is defined as the first number of added dummy data. This first dummy data addition number is the number of dummy data to be added at least per packet.

In step S48, the decimal part of the number of added dummy data per packet obtained in step S47 is set as the value of the variable Y. In step S49, the value of a variable X representing the count value of the line is initialized to 0.

In step S50, the decimal part of the value of the variable Y is multiplied by the ideal number of packets obtained in step S41, and the result of the multiplication is compared with half of the number of image data per packet. If the multiplication result is equal to or more than half of the number of image data per packet, the process proceeds to step S51, and if not, the process proceeds to step S53.
In the magnitude comparison, the accumulation of the decimal part of the value of the variable Y is set to be smaller than one packet. However, the smaller the decimal part of the value of the variable Y is, the smaller the accumulation is. It is desirable that the fractional part of the value of Y be compared so as to be as small as possible.

In step S51, the current value of the variable Y is added to the decimal part of the number of added dummy data per packet obtained in step S47, and the addition result is newly set as the value of the variable Y. In step S52, the value of the variable X and the value 1 are added, and the addition result is newly set as the value of the variable X. Then, the process returns to step S50.

That is, the loop consisting of steps S50 to S52 is repeated until the result of multiplying the decimal part of the value of the variable Y by the ideal number of packets in step S50 is less than half the number of image data per packet. If the multiplication result is equal to or more than half of the number of image data per packet, the process exits this loop and proceeds to step S53.
Proceed to.

In step S53, the integer part of the value of the variable Y at that time is used as the second dummy data addition number. The value of the variable X at this time is set as a second dummy data addition interval. This second dummy data addition number is the number of dummy data to be further added per X line. The dummy data addition number calculation process is completed as described above, and the first and second dummy data addition numbers and the second dummy data addition interval thus obtained are used in the dummy data addition process described below. .

Next, the dummy data adding process will be described. FIGS. 11 and 12 are flowcharts for explaining the dummy data adding process in the image data transmitting / receiving method according to the third embodiment.

In step S54 shown in FIG. 11, the data count value representing the image data position in one line is initialized to a value of 0. In step S55, the packet count value representing the number of packets is initialized to a value of 0. In step S56, the number of image data per packet is calculated in step S56.
The first dummy data addition number obtained in 47 is subtracted, and the subtraction result is set as a packet limit value. Step S5
At 7, the image data stored in the original first storage area is transferred to a new second storage area. Step S58
Then, the data count value is counted up by the image data amount transcribed in step S57. Step S59
Then, the address value of the first storage area is counted up by the image data amount transcribed in step S57, and the address value of the first storage area of the image data to be read next is obtained. In step S60, the address value of the second storage area is counted up by the image data amount transcribed in step S57, and the address value of the second storage area in which data is to be stored next is obtained. In step S61, the data count value is compared with the packet limit value. If the data count value has not reached the packet limit value, the process proceeds to step S62; otherwise, the process proceeds to step S63.

In step S63 shown in FIG. 12, the data count value is initialized to 0, and in step S64, the packet count value is incremented by one. In step S65, 1
The number of first dummy data added obtained in step S47 is subtracted from the number of image data per packet, and the result of the subtraction is set as a packet limit value.

In step S66, the second dummy data addition interval obtained in step S53 is compared with the value obtained by adding 1 to the packet limit value, and the value obtained by adding 1 to the packet limit value is obtained. If the second dummy data addition interval has been reached, that is, if the next packet is to add the second dummy data, step S67
Then, the process proceeds to step S68. Otherwise, the process immediately proceeds to step S68. In step S67, the second packet calculated in step S53 is calculated from the current packet limit value.
Is subtracted, and the result of the subtraction is set as a new packet limit value.

In step S68, the address value of the second storage area is advanced by the first dummy data addition number obtained in step S47, and the result is newly set as the address value of the second storage area. This means that the dummy data has been added by the first dummy data addition number.

In step S69, the size of the packet count value is compared with the second dummy data addition interval obtained in step S53. If the packet count value has reached the second dummy data addition interval, the flow advances to step S70. Otherwise, the process proceeds to step S62. Step S
In step 70, the packet count value is initialized to 0. In step S71, the address value of the second storage area is advanced by the second dummy data addition number obtained in step S53, and the result is newly added to the second storage area. Is the address value of the storage area. This means that the dummy data has been added by the second dummy data addition number. And step S
Proceed to 62.

In step S62 shown in FIG. 11, it is determined whether or not the address value of the first storage area has reached the end of one screen of image data. If not, the flow returns to step S57. The dummy data adding process is terminated when the end is reached.

FIG. 13 is a timing chart for explaining transmission data in the image data transmission / reception method according to the third embodiment. As shown in this figure, dummy data is added to the end of each packet to form transmission data, and the transmission data is transmitted at a time substantially equal to the cycle of the line synchronization signal.

FIG. 14 is a view for explaining a packet format example of transmission data in the image data transmission / reception method according to the third embodiment. Data_length,
tag, channel, tcode, sy, header_CRC, PKTSeq, Va
lidPixelLength, LHeadOffset, PF, LF and Logical
inverse of VDATA HEADER first Quadlet
It is similar to that shown in FIG. Ima following
Each of ge data 0 to image data n is 8-bit effective image data, and dummy data following this effective image data
Each of data 0 to dummy data m is 8-bit dummy data added for each packet in this embodiment. Pa
d data is dummy data added to fix the packet length. 32-bit data_CRC is image data
0 to image data n, dummy data 0 to dummy data m
And CRC of Pad data.

Therefore, in the present embodiment, in the image data transmitting apparatus 10, the composition unit 12 causes the packet of the packet including the head data of the image data for one line to be included.
The LF value is set to the value 1, and the head data position information of one line is stored in LHeadOffset. Further, the LF value of a packet that does not include the leading data in the image data for one line is set to the value 0. Also, the number of valid image data image data 0 to image data n included in each packet is
Store in lLength. In the image data receiving device 20, the transmission data in the packet format is received by the receiving unit 22, and the image data is extracted by the extracting unit 24.

That is, in the extraction unit 24, the ValidPixelLength value, the LHeadOffset value, and the LF
The value is detected. If the LF value is 1, image
Data is extracted from the position of data0 by the number indicated by the ValidPixelLength value, and among the data, the data before the head data position of one line indicated by the LHeadOffset value is F
Stored in order following the current address of the IFO memory 26,
Data after the head data position of one line indicated by the LHeadOffset value is stored in order from the head address of the FIFO memory 26. On the other hand, if the LF value is 0, image data
Each data of 0 to image data n is stored in the FIFO memory 26.
Are stored sequentially after the current address. In this case, FI
The FO memory 26 stores valid image data for one line from the head address.
Pad data is not stored.

(Fourth Embodiment) Next, a fourth embodiment will be described. In this embodiment, dummy data is added at the beginning of each packet. Note that the process of calculating the number of added dummy data in this embodiment is the same as that described in the third embodiment. Hereinafter, the dummy data adding process will be described. FIGS. 15 and 16 are flowcharts for explaining dummy data addition processing in the image data transmission / reception method according to the fourth embodiment.

In step S72 shown in FIG. 15, the first dummy data addition number obtained in step S47 is subtracted from the number of image data per packet, and the subtraction result is used as a data count value. In step S73, the packet count value is initialized to a value of zero. In step S74, the data count value is compared with the value 0, and if the data count value is equal to or less than the value 0, that is, if the data count value has reached the beginning of the packet, the process proceeds to step S75. move on.

In step S80 shown in FIG. 16, the packet count value is incremented by 1. In step S81, the first dummy data addition number obtained in step S47 is subtracted from the number of image data per packet. Is the data count value. In step S82, the second dummy data addition interval obtained in step S53,
The value obtained by adding the value 1 to the packet count value is compared. If the value obtained by adding the value 1 to the packet count value has reached the second dummy data addition interval, that is, the next packet is the second dummy data. If you want to add data,
After step S83, the process proceeds to step S84. Otherwise, the process immediately proceeds to step S84. In step S83, the second dummy data addition number obtained in step S53 is subtracted from the current data count value, and the result of the subtraction is set as a new data count value.

In step S84, the address value of the second storage area to which the image data stored in the original first storage area is transcribed is advanced by the first dummy data addition number obtained in step S47. The result is newly set as the address value of the second storage area. This means that the dummy data has been added by the first dummy data addition number.

In step S85, the packet count value is compared with the second dummy data addition interval obtained in step S53, and if the packet count value has reached the second dummy data addition interval, the flow advances to step S86. Otherwise, the process proceeds to step S75. Step S
In step 86, the packet count value is initialized to 0, and in step S87, the address value of the second storage area is advanced by the second dummy data addition number obtained in step S53, and the result is newly added to the second storage area. Is the address value of the storage area. This means that the dummy data has been added by the second dummy data addition number. And step S
Go to 75.

In step S75 shown in FIG. 15, the image data stored in the original first storage area is replaced with a new second data.
To the storage area. In step S76, the data count value is counted down by the image data amount transcribed in step S75. In step S77, the address value of the first storage area is counted up by the image data amount transcribed in step S75, and the address value of the first storage area of the image data to be read next is obtained. Step S
At 78, the address value of the second storage area is counted up by the image data amount transcribed at step S75, and the address value of the second storage area where data is to be stored next is obtained. In step S79, it is determined whether or not the address value of the first storage area has reached the end of the image data for one screen. If not, the process returns to step S74 and repeats the processing. If it has reached, the dummy data addition processing ends.

FIG. 17 is a timing chart for explaining transmission data in the image data transmission / reception method according to the fourth embodiment. As shown in this figure, dummy data is added first in each packet to form transmission data, and the transmission data is transmitted at a time substantially equal to the cycle of the line synchronization signal.

FIG. 18 is a view for explaining a packet format example of transmission data in the image data transmission / reception method according to the fourth embodiment. Data_length,
tag, channel, tcode, sy, header_CRC, PKTSeq, Va
lidPixelLength, LHeadOffset, PF and LF are the same as those shown in FIG.

DummyPixelLength following these is the number of dummy data added for each packet in this embodiment, and Spare is an unused data area. dummy data
Each of 0 to dummy data m is 8-bit dummy data added for each packet in this embodiment, and each of image data 0 to image data n following this dummy data is 8-bit effective image data. Pad data is
This is dummy data added to fix the packet length. 32-bit data_CRC is image data 0 to image
data n, dummy data 0 to dummy data m and Pad
Indicates the CRC of data.

Therefore, in the present embodiment, in the image data transmitting apparatus 10, the composition unit 12 causes the packet of the packet including the head data of the image data for one line to be included.
The LF value is set to the value 1, and the head data position information of one line is stored in LHeadOffset. Further, the LF value of a packet that does not include the leading data in the image data for one line is set to the value 0. Also, the number of valid image data image data 0 to image data n included in each packet is
Dummy data stored in lLength and included in each packet
DummyPixelL is the number of dummy data 0 to dummy data m
Store in ength. In the image data receiving device 20, the transmission data in the packet format is received by the receiving unit 22, and the image data is extracted by the extracting unit 24.

That is, the extraction unit 24 detects the ValidPixelLength value, LHeadOffset value, LF value, and DummyPixelLength value of each packet. Dummy da
From the position of ta 0, the dummy data is treated as dummy data by the number of DummyPixelLength values, and then extracted as valid image data by the number of ValidPixelLength values. If the LF value is 1, LHeadOf of the effective image data
The data before the head data position of one line indicated by the fset value is stored sequentially following the current address of the FIFO memory 26, and the data after the head data position of one line indicated by the LHeadOffset value is the head address of the FIFO memory 26. Are stored sequentially. On the other hand, if the LF value is 0, the effective image data is stored sequentially following the current address of the FIFO memory 26. In this case, the FIFO memory 26 stores valid image data for one line from the head address, but does not store dummy data and pad data.

[0097]

As described in detail above, according to the present invention, on the transmitting side, dummy data is added to a predetermined unit of image data to form transmission data, and the transmission data is transmitted in the first cycle ( The first period is substantially equal to the second period (the period of the line synchronization signal) longer than the first period (the packet period).
Packets are transmitted at a period of. On the receiving side, transmission data transmitted from the transmitting side and arriving is received, and image data is extracted from the received transmission data.

With this configuration, one line of image data is transferred per one cycle of the line synchronization signal, so that the image data is normally transferred from the transmission side to the reception side. When an image forming apparatus is provided, a normal image is formed in the image forming apparatus.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating configurations of an image data transmitting apparatus, an image data receiving apparatus, and an image data transmitting and receiving system according to an embodiment.

FIG. 2 is a flowchart illustrating a dummy data addition number calculation process in the image data transmission / reception method according to the first embodiment.

FIG. 3 is a flowchart illustrating a dummy data addition process in the image data transmission / reception method according to the first embodiment.

FIG. 4 is a flowchart illustrating a dummy data addition process in the image data transmission / reception method according to the first embodiment.

FIG. 5 is a timing chart illustrating transmission data in the image data transmission / reception method according to the first embodiment.

FIG. 6 is a diagram illustrating an example of a packet format of transmission data in the image data transmission / reception method according to the first embodiment.

FIG. 7 is a flowchart illustrating a dummy data addition process in the image data transmission / reception method according to the second embodiment.

FIG. 8 is a flowchart illustrating a dummy data addition process in the image data transmission / reception method according to the second embodiment.

FIG. 9 is a timing chart illustrating transmission data in the image data transmission / reception method according to the second embodiment.

FIG. 10 is a flowchart illustrating a dummy data addition number calculation process in the image data transmission / reception method according to the third embodiment.

FIG. 11 is a flowchart illustrating a dummy data addition process in the image data transmission / reception method according to the third embodiment.

FIG. 12 is a flowchart illustrating a dummy data addition process in the image data transmission / reception method according to the third embodiment.

FIG. 13 is a timing chart illustrating transmission data in the image data transmission / reception method according to the third embodiment.

FIG. 14 is a diagram illustrating an example of a packet format of transmission data in the image data transmission / reception method according to the third embodiment.

FIG. 15 is a flowchart illustrating a dummy data addition process in the image data transmission / reception method according to the fourth embodiment.

FIG. 16 is a flowchart illustrating a dummy data addition process in the image data transmission / reception method according to the fourth embodiment.

FIG. 17 is a timing chart illustrating transmission data in the image data transmission / reception method according to the fourth embodiment.

FIG. 18 is a diagram illustrating an example of a packet format of transmission data in the image data transmission / reception method according to the fourth embodiment.

FIG. 19 is a diagram illustrating a problem when the IEEE 1394 standard is simply applied to image data transmission / reception.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Image data transmission / reception system, 10 ... Image data transmission apparatus, 12 ... Composition part, 14 ... Memory, 16 ... Transmission / reception part,
20: image data receiving device, 22: transmitting / receiving unit, 24: extracting unit, 26: FIFO memory, 30: image forming device.

Claims (8)

[Claims] 1. An image data transmitting apparatus for dividing image data into packets and transmitting the packets in a first cycle, wherein dummy data is added to a predetermined unit of the image data,
A composition unit for composing transmission data to be transmitted in a predetermined time substantially equal to a second period longer than the first period, and a transmission unit for transmitting the transmission data in the predetermined time. Image data transmission device. 2. An image data receiving apparatus for receiving image data received by packet transmission from an image data transmitting apparatus, the transmission data including image data transmitted from the image data transmitting apparatus and arriving, and dummy data. An image data receiving apparatus, comprising: a receiving unit that receives the image data; and an extracting unit that extracts the image data from the transmission data received by the receiving unit. 3. An image data transmission / reception system which divides image data into packets and transmits / receives packets in a first cycle, wherein dummy data is added to a predetermined unit of the image data,
A composition unit that composes transmission data to be transmitted at a predetermined time substantially equal to a second period longer than the first period; a transmission unit that transmits the transmission data at the predetermined time; and the transmission unit that arrives from the transmission unit. An image data transmission / reception system, comprising: a reception unit that receives transmission data; and an extraction unit that extracts the image data from the transmission data received by the reception unit. 4. An image forming apparatus for forming an image based on the image data extracted by the extracting unit, wherein the second cycle is a cycle of a line synchronization signal output from the image forming apparatus. The image data transmitting / receiving system according to claim 3, wherein the predetermined unit is one line of the image data. 5. An image data transmission method for dividing image data into packets and transmitting the packets in a first cycle, wherein dummy data is added to a predetermined unit of the image data,
An image data transmission method comprising: forming transmission data to be transmitted in a predetermined time substantially equal to a second period longer than the first period; and transmitting the transmission data in the predetermined period. 6. An image data receiving method for receiving image data that has arrived by packet transmission, comprising: receiving transmission data including image data that has arrived and dummy data; and receiving the image data from the received transmission data. Image data receiving method. 7. An image data transmitting / receiving method for dividing image data into packets and transmitting / receiving packets at a first cycle, wherein the transmitting side adds dummy data to a predetermined unit of the image data, and The transmission data to be transmitted at a predetermined time substantially equal to the second period longer than the period is composed, and the transmission data is transmitted at the predetermined time. The reception side receives the transmission data arrived from the transmission side. And extracting the image data from the received transmission data. 8. The second cycle is a cycle of a line synchronization signal output from an image forming apparatus provided on the receiving side, and the predetermined unit is one line of the image data. The image data transmitting / receiving method according to claim 7, wherein: