JP2002023972A - Data transmitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform multi-address transmission of print data to a plurality of printing engines, etc., that perform processing in different phases. SOLUTION: A multi-address destination selecting means 140 decides a multi- address destination on the basis of phase information sent from a data receiving part 200 (diagram 9). A transmission controlling means 120 performs multi- address transmission to the selected data receiving part 200 and separately performs data transmission to the other data receiving parts 200. A data multi- address performing means 130 performs multi-address data transmission and also performs data transmission to separate destinations. The means 120 also receives buffer state information from the data receiving parts 200 that currently perform multi-address receiving, separates the part 200 which can not buffer data any more from the multi-address group and separately transmits the data.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for transmitting data from a single data transmitting unit to a plurality of data receiving units for processing a predetermined amount of data at mutually different initial phases and at mutually different periods. The present invention relates to a data transmission device that performs broadcast transmission.

For example, the present invention relates to a printer system that prints a series of image data of the same print job by using a plurality of print engines that perform print processing at different initial phases and at different intervals. The present invention relates to a data transmission system and a device for broadcasting image data from an image generation engine as a data transmission unit to a plurality of print engines as a data reception unit.

In describing the technology to be improved by the present invention, first, a printer having a single print engine
FIG. 1 shows a basic model of the system. In FIG. 1, the image generation engine 10 includes an image generation unit and an image storage unit, and the print engine 20 includes a buffer buffer and an image generation unit. Details of these components are shown in FIG.

Here, when high-speed operation is required for the image printing unit, the inertia of the rotating operation of the mechanical parts increases, and the phase cannot be easily shifted. The data output must be performed in good response in accordance with the operation phase of the image printing unit. In addition, it takes time for the rotation operation cycle of the image printing unit to stabilize to a predetermined value, and it is not possible to stop and restart the operation in a short time. Therefore, it is necessary to continuously perform printing processing for efficient printing. However, there are individual differences in the operation cycle of the image printing unit,
Since there is fluctuation between the cycles of the same individual, the raster image data output from the image storage unit to the buffer buffer is continuously performed so that underflow does not occur in accordance with the data output from the buffer buffer to the image printing unit. It must be made.

As described above, a high-speed printing system is a system on the premise that data transmission is performed in accordance with the phase and cycle of processing on the data receiving side.

The present invention has been devised for a printer system having such required characteristics or a data transmission system having similar required characteristics. There is a purpose of printing out a print job having a large number of pages and copies in a shorter time by using a printer system.

To increase the output throughput of a printer, the throughput (p
Although there is an approach to increase the pm (papers per minutes), here, an approach to multiplying the print engine is adopted.

FIG. 3 shows a model of a multi-print engine printer system. When the same print job is printed by a plurality of print engines in such a multi-print engine printer system, the print processing between the print engines is schematically shown in FIG.

As shown in FIG. 4, in the printer system of the multi-print engine, the image printing units of the respective print engines perform the printing process in different phases and at different periods. In addition, each cycle has individual differences and fluctuations. As described above, in a high-speed printer system, it is necessary to transmit data in accordance with the phase and cycle of such processing on the data receiving side.

On the other hand, when the same data is transmitted from a single data transmitting unit to a plurality of data receiving units, broadcast transmission is conventionally used. This transmission method is based on the premise that received data can be sequentially processed in accordance with data transmission timing.

The technique of the present invention applies broadcast transmission to a printer system of a multi-print engine, which has not been applied conventionally because of the conflicting assumptions.

[0012]

2. Description of the Related Art As described above, in a printer system of a multi-print engine, the image printing units of each print engine perform print processing in mutually different phases and at different periods. As described above, in a high-speed printer system, it is necessary to transmit data in accordance with the phase and cycle of the processing on the data receiving side. On the other hand, independent data transmission is performed. In FIG.
In the prior art, the same print job (number of pages:
9 schematically illustrates a mode of data transmission between an image generation engine and a print engine when printing is performed by a multi-layered print engine.

As shown in FIG. 5, portions of raster image data to be printed by each print engine at a certain time point: t (Pa (t), Pb (t), Pc in the example of FIG. 5).
(T)) is different, and the data transmission is performed in accordance therewith. Therefore, at that time: t, the portion of the raster image data transmitted to each print engine is different.
Therefore, the required value of the data transmission throughput from the image generation engine to the print engine group increases by multiplying the number of multiplied print engines.

As a specific example of a required value for the data transmission throughput from the image generation engine to the print engine group, each page is 600 spi (spots per
inch), 24 bits / pixel, and a print job of A4 paper size, the size of the raster image data of each page is about 144 Mbytes. If this is output by a print engine of 60 ppm each, 144 Mbytes per data transmission to one print engine
/ Sec (approximately 1.1 Giga bits / sec) is required, and due to the multiplexing, excessive performance is required for the data transmission throughput from the image generation engine.

Hereinafter, in the present invention, the difference between the print parts at the same time between print engines (in the example of FIG. 5, | Pa (t) -Pb (t) |, | Pb (t) -Pc
(T) |, | Pc (t) -Pa (t) |) is simply referred to as a print portion difference.

As described above, in the prior art, the problem that the required value for the data transmission throughput from the image generation engine to the print engine group is increased arises from the fact that the image generation engine is independent from the individual print engines. This is for performing data transmission.

This is because the phases of the operations between the print engines are not aligned, but when viewed from a macro (in print job units), each print engine simultaneously prints the same print job. Printing is in progress. Therefore, if broadcast transmission is applied for each print job,
The transmission band can be suppressed. However, for this purpose, it is necessary to provide a buffer buffer having a capacity capable of holding a print job of each print engine. As illustrated above, each page has 600 spi (spots per
inch), 24 bits / pixel, and a print job of A4 paper size, the size of the raster image data of each page is about 144 Mby per page.
tes and big. In the case where these are output by a print engine of 60 ppm each, at least 144 Mbytes / sec (about 1.1 G
iga bits / sec). For this reason, it is desirable that the buffer buffer be constituted by a semiconductor memory with a capacity as small as possible, and an increase in capacity leads to an increase in cost.

Another means of applying the broadcast transmission is to arrange the operations of the print engines so that the portions to be printed at the same time in each print engine are the same. However, since the image printing section of the high-speed print engine is composed of mechanical parts with large inertia of operation, the rotational axes are mechanically connected between multiple print engines to precisely align their operations. Mechanism to do
A new mechanism, such as a mechanism for controlling the synchronous follow-up of the same master clock between the print engines, is required for the purpose of realizing a multi-print engine, which also leads to an increase in cost.

[0019]

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, the present invention applies broadcast transmission while suppressing the printing portion difference between print engines to a range that can be absorbed by a buffer buffer having a smaller capacity. The task is to

[0020]

Broadcast transmission generally involves transmitting the same data collectively to all data receiving units. However, if there is a margin in the data transmission throughput from the image generation engine to the print engine group, it is not necessary to forcibly broadcast the data to all of the plurality of print engines at once. May be performed simultaneously using broadcast transmission or multiple independent data transmissions.

Therefore, in the following, for print engines which can absorb the difference between the printing parts by their buffer buffers,
It is considered that data transmission is independently performed to a print engine in which a print portion difference is distant from the others using broadcast transmission.

First, in the printer system of the multi-print engine, the following three points can be cited when considering the reason why a print portion difference occurs between the respective print engines.

There is a difference in the time until the operation cycle is stabilized in each print engine, and the timing for starting the printing process is different. The operation phase of the image printing unit of each print engine is different at the start of a series of print processing. Since there is an individual difference in the cycle of the operation of the image printing unit of each print engine, and each cycle has fluctuation,
Each phase changes gradually.

Here, for the first reason, it is assumed that the printing operation of the print engine in which the rotation operation of the image printing unit is stable is started.

Next, regarding the second reason, that the initial phase of the image printing unit is different, it is not necessary to know the operation phase of the image printing unit of each print engine or the phase difference itself. The problem is whether the differences can be absorbed by each other's buffer buffers. That is, as shown in FIG. 6, in a print engine in which the operation of the image printing unit is stable, the opportunity of starting the printing process is delayed every operation cycle. Based on the time difference (for example, hereinafter referred to as a print time difference) approaching the print start position at the top of the page, a print engine to be a data transmission destination (broadcast group) by the same broadcast transmission is selected. .

The printing portion difference between the print engines is expressed by the equation 1 with the printing time difference of the same portion (hereinafter, simply referred to as the printing time difference). It is possible to determine whether or not the site difference can be absorbed by the buffer buffer, or simply to compare the magnitude.

[0027]

## EQU00001 ## Printing part difference = printing time difference.times.print processing throughput Equation 1

The third reason, that is, a phase change due to individual differences and fluctuations in the operation cycle of the image printing unit for each print engine, as a result, the same If the difference in print parts between the print engines belonging to the broadcast group cannot be absorbed by the buffer buffer, control such as separating the broadcast group or simply interrupting data transmission is performed. This control is shown in FIG.

The above and other configurations of the present invention are described in the appended claims. These configurations are also described in detail below.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, the present invention is mainly composed of the following two controls. At the start of a series of printing processes, ones that have a small phase difference between each other and that can absorb the printing part difference with a buffer buffer,
Or, a control for simply grouping those having close phase differences to each other. This is hereinafter referred to as static control.

Due to individual differences in the operation cycle of the image printing unit of each print engine and fluctuations in the operation cycle, during a series of print processing, differences in print parts between print engines belonging to the same broadcast group are caused. Control that expands and isolates those that can no longer be absorbed by the buffer buffer, or simply interrupts transmission. This is hereinafter referred to as dynamic control.

Means for realizing static control include the following two:
One is provided.

(A) Each print engine is provided with phase information notifying means for notifying the image generation engine of phase information for calculating an initial phase difference between the print engines. Here, the phase information is a signal that notifies the image generation engine that the image printing unit has approached one base point (for example, the print start position of the top part of the page) in the operation cycle without delay variation. It is.

(B) On the basis of the phase information notified from each print engine, the image generating engines can be configured to print each other's initial print site difference between buffer engines in the buffer buffer or each other's initial print site. Broadcast destination selecting means is provided for selecting print engines having a similar difference and forming a broadcast group.

Means for realizing dynamic control are as follows:
One is provided. (C) For each print engine, the difference between the part of the image data being output (printing) from the buffer buffer and the part of the image data being input to the buffer buffer, that is, the amount of image data retained in the buffer buffer is indicated. A buffer status information notifying unit is provided for monitoring and notifying the image generation engine of buffer status information indicating the status.

(D) The image generation engine is provided with transmission control means for performing flow control based on buffer status information notified from each print engine. The transmission control means suspends the image data transmission during a period in which the buffer retention amount is likely to exceed the capacity, and if the buffer retention amount is likely to become zero while the image data transmission is stopped. When the error occurs, data transmission to the corresponding print engine is started independently from the broadcast group.

It should be noted that these two controls, the static control and the dynamic control, may be performed either alone or in combination.

When the static control and the dynamic control are performed in combination, the dynamic control is applied to each broadcast group according to the result after the completion of the static control.

FIGS. 8 and 9 are block diagrams showing a case where the static control and the dynamic control are performed in combination. 8, the data transmission unit 100 includes an image storage unit 110, a transmission control unit 120, a data broadcast unit 130, a broadcast destination selection unit 140, and the like. Broadcast destination selection means 1
Reference numeral 40 determines a broadcast destination based on the phase information sent from the data receiving unit 200 (FIG. 9). Transmission control means 1
20 performs broadcast transmission to the selected data receiving unit 200, and individually transmits data to the other data receiving units 200. The data broadcasting means 130 broadcasts data transmission and also transmits data to individual destinations. Further, the transmission control means 120 receives the buffer status information from the data receiving unit 200 that is receiving the broadcast, separates the data receiving unit 200 that cannot completely buffer the data from the broadcast group, and transmits the data individually.

In FIG. 9, a data receiving unit 200 includes a data receiving unit 210, a buffer buffer 220, and an image printing unit 2.
30, a phase information notifying means 240, a buffer stay information notifying means 250 and the like. The phase information notifying unit 240 sends the phase information to the data transmission unit 100 based on the phase detection signal of the printing unit 230. This determines whether or not to belong to the broadcast group. The buffer retention information notifying unit 250 transmits the buffer status to the data transmission unit 100 based on the buffer retention amount of the buffer buffer 220. Based on this, it is determined whether to be separated from the broadcast group.

Individual differences in the operation cycle due to the print engine,
If it is not necessary to consider the fluctuation of the operation cycle in a single print engine, the dynamic control is unnecessary. When only static control is performed, data transmission from the image generation engine should be performed at a fixed average print throughput of the print engine group so that data input / output to / from the buffer buffer of each print engine is balanced. I do.

FIGS. 10 and 11 are block diagrams showing a case where only static control is performed. 10 and FIG. 11 and FIG. 8 and FIG. 9 are denoted by corresponding reference numerals, and detailed description thereof will be omitted.

On the other hand, if the initial phase difference between the print engines is sufficiently small and only the individual differences in the operation cycle between the print engines and the fluctuations in the operation cycle in a single print engine are taken into account, the dynamic Only the control needs to be performed. If only dynamic control is performed, broadcast group members
The list shall be given fixedly.

FIGS. 12 and 13 are block diagrams showing a case where only dynamic control is performed. Also in this case, the portions corresponding to those in FIGS. 8 and 9 are denoted by the corresponding reference numerals, and detailed description is omitted.

[0045]

Next, specific examples of each means and signals between the means will be described.

First, means for realizing static control, and
Specific examples of signals between means will be described.

The phase signal notifying means of each data receiving unit (print engine) uses a phase detection signal to indicate that the image printing unit has approached one base point (for example, the print start position at the top of the page) during its operation cycle. It detects and notifies the image generation engine as phase information. Here, the phase detection signal and the phase information do not need to include the time information, and the notification may be performed without delay variation.

As a result, on the image generation engine side, FIG.
As exemplified in FIG. 4, a phase signal from each print engine is periodically notified.

Here, the number of print engines: N, the average operation cycle of the print engine group: T, the reference time: t _base , and the reception time of the phase signal from each print engine (i): t _i (or t ′ _i ). I do.

First, as an embodiment of the broadcast destination selecting means, an algorithm will be described in which, using this signal, print engines whose initial print site differences are close to each other are simply selected to form a broadcast group.

In the broadcast destination selecting means, as a first step, the relative phase of each print engine: p _i (i = 0 to N−
1) is obtained by the following equation.

[0052]

P _i = (t _i −t _base ) mod T Equation 2 where X mod Y is obtained by X−Z × Y, where Z is an integer part of a quotient obtained by dividing the real number X by the real number Y. Value.

Next, as a second step, based on the value of p _i, performs rearrangement in ascending or descending order. The array of the relative phases after the rearrangement is P _j , and the relationship between the array index and the index of each print engine is _ij . FIG.
In the example, when arranged in ascending order, _ij = {a, c, b}.

Next, as a third step, the phase difference between adjacent elements of P _j : D _{j, (j + 1) mod N}
Is determined by the following equation.

[0055]

D _{j, (j + 1) mod N} = (P _{(j + 1) mod N−} P _j + T) mod T Equation 3

Finally, as a fourth step, as the initial number of broadcast groups: M, among the phase differences calculated by the equation 3, M groups (in the case of M = 1, 0 in the order from the largest phase difference)
Index _j (i _j , i)
_{j + 1 mod N} ) is the boundary of the broadcast group. In the example of FIG. 14, since D _2,0 > D _1,2 > D _0,1 , if M = 2, (i ₂ , i ₀ ) = (b, a) and (i ₂ , i ₀ ) = (c, b) as a boundary, two broadcast groups {print engine a, print engine c},
And {Print Engine b} is formed.

Here, the initial number of broadcast groups: M is the maximum data obtained from the following equation from the data transmission rate per broadcast from the image generation engine: r and the maximum data transmission throughput from the image generation engine: R. Number of broadcasts: M
_{It is} assumed to be an integer value equal to or less than _max .

[0058]

M _max = R div r Equation 4 where X div Y is an integer part of a quotient obtained by dividing the integer X by the integer Y.

An example of an algorithm for selecting print engines that can absorb the initial print difference between each other in the buffer buffer and forming a broadcast group is as follows: Buffer buffer capacity: L, print throughput: S The above third and subsequent steps are performed as follows.

Here, in the third step of the second algorithm, an arbitrary variable j (j = 0 to N−1) and a variable E satisfying E = N−1 are set as initial values until the variable E becomes zero. The following processing is repeated.

First, P _j and P determined by equation (5)
_{(J + k)} The phase difference of _{mod N} : D _{j
, (J + k) mod N} are sequentially determined for k = 1 to E, and k whose value first satisfies Expression 6 is determined.

[0062]

D _{j, (j + k) mod N} = (P _{(j + k) mod N−} P _j + T) _mod T Equation 5

[0063]

D _{j, (j + k) mod N} > L / S Equation 6

The initial printing part differences between the print engines from the resulting indexes _ij to i _{(j + k-1) mod N} can be absorbed by the buffer buffer. I do.

Thereafter, in the third step, j = (j +
k) The above process is repeated with mod N, E = EK.

Further, using the values of 0 to N-1 as the initial value of j in the third step, an initial value of j that minimizes the number of divided broadcast groups is obtained. A third algorithm may be used.

The signal representing the member list of each broadcast group obtained as a result of the above grouping process is a signal between means for realizing dynamic control (group member bit list: G). It will be described later.

Next, means for realizing dynamic control;
Specific examples of signals between means will be described.

First, as an embodiment of the buffer state information, a signal representing an event of a change in the amount of staying raster image data in the buffer buffer is used.

That is, the buffer status information notifying means sets an upper level and a lower level as shown in FIG. 15 for the buffer buffer, and monitors the data retention amount.
6 are managed in three states. Then, when the state change shown in FIG. 17 occurs, the state change is notified as buffer state information.

As for the values of the upper level and the lower level in the buffer buffer, optimal values may be determined empirically.
The initial value can be determined based on the following idea.

First, as for the upper level, a period from the notification of the MH event to the stop of the data input to the buffer buffer as a result of the flow control, that is, at least the round-trip signal propagation between the image generation engine and the print engine. During the time period, even if the output from the buffer buffer is stopped and only the input is continued, the margin may be set so that the buffer overflow does not occur. Similarly, for the lower level, the period from the notification of the ML event to the restart of the data input to the buffer buffer, that is, at least the period of the signal propagation time for the round trip between the image generation engine and the print engine, the buffer, Even if the input to the buffer is stopped and only the output continues, the margin may be set so that the buffer underflow does not occur.

Next, an embodiment of the transmission control means will be described.

The sending control means has the following variables for each broadcast engine broadcast group determined as a result of the static control or each predetermined print engine broadcast group.

Group member bit list: G Bit list: The bit length of G is N: the number of print engines or more. Bit list: G, when the index of the group members print engine with i (0 ≦ i <N) , the logical sum of the 2 ⁱ for all members belonging to the group. Also, when data transmission to the print engine with index: i is separated and independent, or when data transmission is stopped in response to an OL event, the exclusive OR of the value of G and 2 ⁱ is calculated and held.

Bit list of group members in state H: A Bit list: The bit length of A is N: the number of print engines or more. The bit list A holds and manages the state so that the bit corresponding to the index of the group member in the state of the state display symbol H becomes 1. In other words, the initial value of 0, an index: when an event MH from the print engine of i is notified, holds calculates the logical sum of the values of A itself and 2 ^i. Further, when the event HM is notified from the print engine of the index: i, the exclusive OR of the value of A itself and 2 ⁱ is calculated and held. Index: spun data transmission to i print engine, or when the data transmission is aborted undergoing OL events, holds calculates the exclusive OR between the value of A itself and 2 ^i.

When the data transmission of the index: i to the print engine is separated and independent, it is set as a single broadcast group and the corresponding bit list: G
(Value is 2 ⁱ ) and A (initial value is 0) are newly provided.

The transmission control means behaves as shown in the state transition table of FIG. 18 for each broadcast group based on the above two variables and the buffer state information from the print engines belonging to the broadcast group.

Next, a raster image data signal addressed to the broadcast group, a raster image data signal addressed to each data receiving unit, and
An embodiment of the data broadcasting means will be described.

The data transmission means or the transmission control means divides the raster image data of each page into data of a predetermined length (divided data) and assigns a serial number (divided data sequence number) in order from the leading divided data. , A data frame of the format illustrated in FIG. 19 is created and sequentially transmitted as a raster image data signal addressed to a broadcast group.

In the example of FIG. 19, it is assumed that the value of the bit list of the aforementioned group members is used as the destination group address of the data frame. Then, the data broadcasting means copies the remaining portion of the data frame after the destination group address, creates a data frame of the format illustrated in FIG. 20, and displays the data of the group members held at the destination group address. The data is transmitted as a raster image data signal to each data receiving unit to the print engine (data receiving unit) of the index corresponding to the bit whose value is 1 in the bit list.

The present invention does not include a data transmission unit for transmitting raster image data (data frames) from a data transmission unit (image generation engine) to each data reception unit (print engine). For those skilled in the art, the data transmission means can be easily realized using existing technology.

[0083]

According to the present invention, a single to a plurality of broadcast transmissions are performed by effectively using the data transmission throughput from the image generation engine, thereby suppressing the difference in the print parts of the print engines in the broadcast group. Therefore, the capacity of the buffer buffer in each image generation engine can be reduced.
That is, even if a plurality of print engines having different initial phases and performing print processing at mutually different cycles are used, a print system of a multi print engine can be realized while suppressing an increase in cost accompanying an increase in the buffer buffer capacity. Make up,
A print job with a large number of pages and copies can be printed out in a shorter time. Further, the present invention provides not only the printer system assumed in the present invention but also a similar effect for a data transmission system having the same required characteristics.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a printer device model.

FIG. 2 is a diagram illustrating each unit in FIG. 1;

FIG. 3 is an explanatory diagram of a multi-print engine in a printer device.

FIG. 4 is an explanatory diagram of a phase difference between print engines.

FIG. 5 is an explanatory diagram of a mode of data transmission between an image generation engine and a print engine.

FIG. 6 is an explanatory diagram of a control method according to the present invention.

FIG. 7 is an explanatory diagram of a control method according to the present invention.

FIG. 8 is an explanatory diagram of a configuration of a data transmission unit that performs a combination of static control and dynamic control.

FIG. 9 is an explanatory diagram of a configuration of a data receiving unit that performs static control and dynamic control in combination.

FIG. 10 is an explanatory diagram of a configuration of a data transmission unit that performs only static control.

FIG. 11 is an explanatory diagram of a configuration of a data receiving unit that performs only static control.

FIG. 12 is an explanatory diagram of a configuration of a data transmission unit that performs only dynamic control.

FIG. 13 is an explanatory diagram of a configuration of a data receiving unit that performs only dynamic control.

FIG. 14 is an explanatory diagram of an example of a phase signal notification.

FIG. 15 is an explanatory diagram of a state management method of a buffer buffer.

FIG. 16 is an explanatory diagram of a buffer buffer status notifying unit.

FIG. 17 is an explanatory diagram of buffer buffer status information.

FIG. 18 is an explanatory diagram of a state transition table of the transmission control means.

FIG. 19 is an explanatory diagram of a broadcast group-addressed raster image data signal.

FIG. 20 is an explanatory diagram of a raster image data signal addressed to each data receiving unit.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 image generation engine 20 print engine 100 data transmission unit 110 image storage unit 120 transmission control unit 130 data broadcasting unit 140 broadcast destination selection unit 200 data reception unit 210 data reception unit 220 buffer buffer 230 image printing unit 240 phase information notification unit 250 Buffer retention information notification means

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04L 13/08 H04L 13/00 307A (72) Inventor Koichi Yoshimura 430 Nakai-cho Sakai, Ashigara-gun, Kanagawa Green Green Naka Fuji F-term (reference) in Xerox Co., Ltd.

Claims (9)

[Claims] 1. A data transmission apparatus for performing broadcast transmission of data from a single data transmission unit to a plurality of data reception units that process a predetermined amount of data at mutually different phases and at different periods. The unit has phase information notifying means for notifying the data transmitting unit of phase information. The data transmitting unit obtains a relative phase difference between the data receiving units based on the phase information, A data transmission device comprising a broadcast destination selection means for selecting a broadcast destination data reception unit based on a phase difference. 2. A data transmission apparatus for performing a broadcast transmission of data from a single data transmission unit to a plurality of data reception units that process a predetermined amount of data at different phases at different periods. The receiving unit includes a data buffer unit that retains the received data until the data is processed, and a buffer state notification that notifies the data transmitting unit of buffer state information indicating a state of data stagnation in the data buffer unit. The data transmission unit, based on the buffer status information, stops the broadcast transmission so that no data overflow occurs in the data buffer unit of any data reception unit of the broadcast transmission destination, Alternatively, a data transmission device having transmission control means for restarting broadcast transmission so that underflow does not occur. 3. A data transmission apparatus for performing broadcast transmission of data from a single data transmission unit to a plurality of data reception units that process a predetermined amount of data at mutually different phases and at different periods. The unit has phase information notifying means for notifying the data transmitting unit of phase information. The data transmitting unit obtains a relative phase difference between the data receiving units based on the phase information, Broadcast destination selection means for selecting a broadcast receiving destination data receiving unit based on the phase difference, selecting a broadcast receiving destination data receiving unit prior to a series of data transmission, and receiving each selected data A data buffer unit for holding received data until processing is performed, and a buffer state for notifying the data transmission unit of buffer state information indicating a state of data retention in the data buffer unit. The data transmission unit stops the broadcast transmission based on the buffer status information so that no data overflow occurs in the data buffer unit of any data reception unit of the broadcast transmission destination. Or a transmission control means for resuming broadcast transmission so as not to cause underflow. 4. A data receiving unit used in the data transmission apparatus according to claim 1, wherein a signal indicating that a process of the data receiving unit is approaching a base point in a processing cycle of the data receiving unit is used as the phase information. A data receiving unit of a data transmission device characterized by using. 5. The data transmission unit used in the data transmission apparatus according to claim 1 or 2, wherein a relative time difference is measured by measuring a time difference when phase information is notified from the data reception unit according to claim 4. A data transmission unit of a data transmission device, wherein a data phase difference is obtained. 6. A data receiving unit used in the data transmission apparatus according to claim 1 or 2, wherein the amount of data stored in the data buffer means is monitored, and the data is stored over a threshold provided for the capacity of the data buffer means. A data receiving unit of a data transmission device, wherein the change in the staying amount is used as buffer status information. 7. A data receiving unit of a data transmission device according to claim 6, wherein the threshold provided for the capacity of the data buffer means is a lower level for early detection of an underflow danger and an overflow danger. A data receiving unit of a data transmission device, wherein a high-level binary threshold value for early detection is used. 8. The data transmission unit of the data transmission device according to claim 1 or 3, wherein buffer status information indicating that the amount of data stored in the data buffer means of the data reception unit according to claim 7 exceeds an upper level. When notified from any of the data receiving units of the broadcast transmission destination, the broadcast transmission is stopped, and thereafter, buffer status information indicating that the amount of data stored in the data buffer means has exceeded the upper level is transmitted. Broadcast transmission is restarted when buffer status information indicating that the amount of data staying in the data buffer means has fallen below the upper level from all of the notified data receiving units is resumed. Department. 9. A data transmission unit of a data transmission device according to claim 8, wherein buffer status information indicating that the amount of data stored in the data buffer means of the data reception unit of claim 7 exceeds a higher level is broadcast. When notified by any of the data receiving units at the transmission destination, the broadcast transmission is stopped, and thereafter, buffer status information indicating that the data retention amount in the data buffer unit has exceeded the upper level is notified. Before receiving the buffer status information indicating that the amount of data stored in the data buffer means has fallen below the upper level from all the data receiving units and resuming the broadcast transmission, any one of the data transmission destinations of the broadcast transmission destination is received. When the buffer status information indicating that the amount of data stored in the data buffer means has fallen below the lower level from the data receiving unit, the corresponding data receiving unit is broadcast. A data transmission unit of a data transmission device, characterized in that data transmission is individually resumed after being removed from a destination.