JP3997697B2 - Data transmission device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a data transmission apparatus that performs broadcast transmission of data from a single data transmission unit to a plurality of data reception units that process a predetermined amount of data with different initial phases and different periods. It is about.
[0002]
For example, according to the present invention, data transmission is performed in a printer system that prints a series of image data of the same print job using a plurality of print engines having initial phases different from each other and performing print processing at different periods. The present invention relates to a data transmission method and apparatus for broadcasting image data from an image generation engine serving as a printing unit to a plurality of print engines serving as data receiving units.
[0003]
In describing the technique to be improved by the present invention, first, a basic model of a printer system having a single print engine is shown in FIG. In FIG. 1, the image generation engine 10 is provided with an image generation unit and an image storage unit, and the print engine 20 is provided with a buffer buffer and an image generation unit. Details of these parts are shown in FIG.
[0004]
Here, when high speed is required for the image printing unit, the inertia of the rotation operation of the mechanical parts becomes large and the phase cannot be easily shifted. Therefore, the raster image data output from the buffer buffer to the image printing unit is Therefore, it must be performed with good response in accordance with the phase of operation of the image printing unit. Also, it takes time for the rotation period of the image printing unit to stabilize at a predetermined value, and it is not possible to stop and restart the operation in a short time. Therefore, it is necessary to continuously print for efficient printing. However, since there are individual differences in the operation cycle of the image printing unit, and there are fluctuations between cycles of the same individual, raster image data output from the image storage unit to the buffer buffer is performed from the buffer buffer to the image. In accordance with the data output to the printing unit, it must be performed without interruption to prevent underflow.
[0005]
Thus, 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.
[0006]
The present invention has been devised for a printer system having such required characteristics or a data transmission system having similar required characteristics. The background of the present invention is such a printer system. Is used to print out a print job with a large number of pages / copies in a shorter time.
[0007]
In order to increase the output throughput of the printer, there is an approach of increasing the throughput (ppm: papers per minute) of a single print engine. Here, a multi-print engine approach is taken.
[0008]
A model of a printer system of a multi-print engine is shown in FIG.
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 represented as shown in FIG.
[0009]
As shown in FIG. 4, in a printer system of a multi-print engine, the image printing units of each print engine perform print processing with different phases and with different cycles. 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.
[0010]
On the other hand, when the same data is transmitted from a single data transmission unit to a plurality of data reception units, conventionally, broadcast transmission is used, but the data reception unit side performs data transmission. This is a transmission method based on the premise that received data can be sequentially processed in accordance with the timing.
[0011]
As described above, the technology of the present invention applies broadcast transmission to a printer system of a multi-print engine that has not been applied in the past because of the conflicting assumptions.
[0012]
[Prior art]
As described above, in the printer system of the multi-print engine, the image printing units of the print engines perform print processing at different phases and at different cycles. As described above, in a high-speed printer system, since it is necessary to transmit data in accordance with the phase and cycle of processing on the data receiving side, in the prior art, from the image generation engine to each print engine, On the other hand, independent data transmission is performed.
FIG. 5 schematically shows a state of data transmission between the image generation engine and the print engine when the same print job (number of pages: N) is printed by a multi-printed print engine in the prior art.
[0013]
As shown in FIG. 5, the raster image data portions (Pa (t), Pb (t), Pc (t) in the example of FIG. 5) to be printed by each print engine at a certain time point: t are different. Since the data transmission is performed in accordance with the data transmission, the portion of the raster image data transmitted to each print engine is different at the time point t. Therefore, the required value for the data transmission throughput from the image generation engine to the print engine group increases by multiplying the number of print engines.
[0014]
As an example of a specific value for the data transmission throughput from the image generation engine to the print engine group, when each page is a print job of 600 spi (spots per inch), 24 bits / pixel, A4 paper size, The size of the raster image data of each page is about 144 Mbytes. When each of these is output by a print engine of 60 ppm, a bandwidth of 144 Mbytes / sec (about 1.1 Giga bits / sec) is required for data transmission to one print engine. Excessive performance is required for transmission throughput.
[0015]
From this point onward, in this patent, the difference between the print parts at the same time between the 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 part difference.
[0016]
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 increases is that independent data transmission from the image generation engine to each print engine. Is to do.
[0017]
This is because the phases of operation between the print engines are not aligned. However, when viewed macroscopically (in units of print jobs), each print engine prints the same print job at the same time. ing. Therefore, if broadcast transmission is applied in units of print jobs, the transmission band can be suppressed. However, for that purpose, it is necessary to provide a buffer buffer having a capacity capable of holding a print job of each print engine. As exemplified above, in the case of a print job in which each page is 600 spi (spots per inch), 24 bits / pixel, and A4 paper size, the size of raster image data of each page is as large as about 144 Mbytes per page. . Further, when each of these is output by a 60 ppm print engine, the buffer buffer is required to have an input / output throughput of at least 144 Mbytes / sec (about 1.1 Giga bits / sec). For this reason, it is desirable that the buffer buffer is formed of a semiconductor memory with the capacity reduced as much as possible, and the increase in capacity leads to an increase in cost.
[0018]
Another means for applying the broadcast transmission is to align the operations of the print engines so that the portions to be printed at the same time point in each print engine are the same. However, since the image printing part of a high-speed printing engine is composed of mechanical parts with a large inertia of operation, a mechanically rotating shaft is mechanically connected in order to precisely align the operations among multiple printing engines. A new mechanism is required for the purpose of multi-print engine, such as a mechanism to perform synchronization and control of synchronous follow-up to the same master clock between print engines. I will.
[0019]
[Problems to be solved by the invention]
In view of the above-described problems of the prior art, an object of the present invention is to apply broadcast transmission while suppressing a difference in print parts of each print engine to a range that can be absorbed by a buffer buffer having a smaller capacity.
[0020]
[Means for Solving the Problems]
In general, the broadcast transmission is a method in which the same data is transmitted to all data receiving units at once. However, if there is a margin in data transmission throughput from the image generation engine to the print engine group, it is not necessary to forcibly broadcast to all of the multiple print engines at once. Simultaneous broadcast transmission or multiple independent data transmissions.
[0021]
Therefore, in the following, the broadcast transmission is used for print engines that can absorb the difference in the print area by the buffer buffer, and the data transmission is independently performed for the print engine whose print area difference is different from the others. Think about what to do.
[0022]
Here, first, considering the reason why the print site difference occurs between the print engines in the printer system of the multi-print engine, the following three points can be cited.
[0023]
(1) There is a difference in the time until the operation cycle is stabilized in each print engine, and the timing of starting the printing process is different.
(2) The phase of the operation of the image printing unit of each print engine is different at the start of a series of printing processes.
(3) There are individual differences in the operation cycle of the image printing unit of each print engine, and each cycle also has fluctuations, so that each phase gradually changes.
[0024]
Here, for the first reason, it is assumed that the print processing start of the print engine in which the rotation operation of the image printing unit is stable is awaited.
[0025]
Next, regarding the second reason that the initial phase of the image printing unit is different, it is not necessary to know the phase of the operation of the image printing unit of each print engine and the phase difference itself, and the difference in the printed parts is mutually different. It is a problem whether it can be absorbed by other 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 for starting the printing process is lost every operation cycle, so that the image printing unit of each print engine is a single point in the operation cycle. Select a print engine as a data transmission destination (broadcast group) by the same broadcast transmission based on a time difference (hereinafter, referred to as a print time difference) that approaches the print start position (for example, the print start position of the page head portion). .
[0026]
The difference in print area between print engines has the relationship of the print time difference of the same area (hereinafter, simply referred to as “print time difference”) in Equation 1, and therefore, the print area difference between two print engines is calculated using the print time difference. It is possible to determine whether or not the buffer buffer can absorb or to simply compare the size.
[0027]
[Expression 1]
Print site difference = print time difference × print processing throughput Equation 1
[0028]
In addition, for the third reason, that is, the phase change due to individual differences or fluctuations in the operation cycle of the image printing unit for each print engine, the same broadcast is performed during a series of printing processes. When the print site difference between the print engines belonging to the group cannot be absorbed by the buffer buffer, control is performed such as separating the broadcast group or simply interrupting data transmission. This control is shown in FIG.
[0029]
The above configuration and other configurations of the present invention are described in the claims. These configurations will be described in detail below.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
As described above, the present invention is mainly composed of the following two controls.
(1) At the start of a series of printing processes, control is performed to group broadcasts that have a small phase difference and can absorb the difference in print area with a buffer buffer, or simply those that are close to each other. . Hereinafter, this is referred to as static control.
[0031]
(2) Due to individual differences in the operation cycle of the image printing section of each print engine and fluctuations in the operation cycle, there is a difference in print area between print engines belonging to the same broadcast group during a series of printing processes. Controls that expand and isolate what can no longer be absorbed by the buffer buffer, or simply interrupt transmission. This is referred to as dynamic control below.
[0032]
As means for realizing the static control, the following two are provided.
[0033]
(A) Each print engine is provided with phase information notification means for notifying the image generation engine side 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 reached one base point in the operation cycle (for example, the print start position of the page head part) without variation in delay. It is.
[0034]
(B) Based on the phase information notified from each print engine, the image generation engines have print engines whose initial print site differences can be absorbed by the buffer buffer, or the initial print site differences between each other are simply Broadcast destination selection means for selecting a close print engine and making it a broadcast group is provided.
[0035]
As means for realizing the dynamic control, the following two are provided.
(C) For each print engine, the difference between the portion of the image data being output from the buffer buffer (printing) and the portion of the image data being input to the buffer buffer, that is, the retention amount of the image data in the buffer buffer. Buffer state information notifying means for monitoring and notifying the image generation engine of buffer state information indicating the state is provided.
[0036]
(D) The image generation engine is provided with transmission control means for performing flow control based on the buffer status information notified from each print engine. The transmission control means pauses image data transmission during a period when the buffer retention amount is likely to exceed its capacity, and if the buffer retention amount is likely to become zero while image data transmission is stopped If this occurs, data transmission to the corresponding print engine is started separately from the broadcast group.
[0037]
Note that only one of these static control and dynamic control may be performed, or both may be combined.
[0038]
When the static control and the dynamic control are combined, the dynamic control is applied to each broadcast group according to the result after the static control is completed.
[0039]
FIG. 8 and FIG. 9 are block diagrams in the case where the static control and the dynamic control are implemented in combination. In FIG. 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. The broadcast destination selection means 140 determines the broadcast destination based on the phase information sent from the data receiving unit 200 (FIG. 9). The sending control unit 120 performs broadcast transmission to the selected data receiving unit 200 and transmits data to the other data receiving units 200 individually. The data broadcast means 130 broadcasts data transmission and also transmits data to individual destinations. Also, the transmission control means 120 receives buffer status information from the data receiving unit 200 that is receiving the broadcast, separates the data receiving unit 200 that cannot buffer the data from the broadcast group, and transmits the data individually.
[0040]
In FIG. 9, the data receiving unit 200 includes a data receiving unit 210, a buffer buffer 220, an image printing unit 230, a phase information notification unit 240, a buffer retention information notification unit 250, and the like. The phase information notification unit 240 sends the phase information to the data transmission unit 100 based on the phase detection signal from the conflict printing unit 230. This determines whether it should belong to a broadcast group. The buffer retention information notification 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 or not to be separated from the broadcast group.
[0041]
When it is not necessary to take into account individual differences in the operation cycle between the print engines and fluctuations in the operation cycle of a single print engine, dynamic control is not necessary. When only static control is performed, data transmission from the image generation engine is fixed to the average print throughput of the print engine group so that the data input / output from the buffer buffer of each print engine is balanced. To do.
[0042]
10 and 11 show block diagrams when only static control is performed. In addition, the code | symbol corresponding to the part corresponding to FIG.10 and FIG.11 and FIG.8 and FIG.9 is attached | subjected, and detailed description is abbreviate | omitted.
[0043]
Conversely, if the initial phase difference of each print engine is sufficiently small and only the individual differences due to the print engine in the operation cycle or the fluctuations in the operation cycle in a single print engine are considered, only dynamic control is performed. Just do it. When only dynamic control is performed, the member list of the broadcast group is given in a fixed manner.
[0044]
12 and 13 are block diagrams when only dynamic control is performed. Also in this case, portions corresponding to those in FIGS. 8 and 9 are denoted by corresponding reference numerals, and detailed description thereof is omitted.
[0045]
【Example】
Subsequently, specific examples of each means and signals between the means will be shown.
[0046]
First, specific examples of means for realizing static control and signals between the means will be described.
[0047]
In the phase signal notifying means of each data receiving unit (print engine), the image printing unit detects from the phase detection signal that the image printing unit has reached one base point in the operation cycle (for example, the printing start position of the page head part), Notify the image generation engine as phase information. Here, the phase detection signal and the phase information do not need to include time information, and notification may be performed without delay variation.
[0048]
As a result, the phase signal from each print engine is periodically notified to the image generation engine side as illustrated in FIG.
[0049]
Here, the number of print engines: N, the average operation cycle of the print engine group: T, the reference time: t _base , Phase signal reception time from each print engine (i): t _i (Or t ' _i ).
[0050]
Next, as an example of the broadcast destination selection means, an algorithm for simply selecting print engines that are close to each other in the initial print region difference from each other and using this signal as a broadcast group will be described.
[0051]
In the broadcast destination selection 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]
[Expression 2]
p _i = (T _i -T _base Mod T Equation 2
However, X mod Y is a value obtained by X−Z × Y, where Z is the integer part of the quotient obtained by dividing real number X by real number Y.
[0053]
Next, as a second step, p _i Sort in ascending or descending order based on the value of. P is the relative phase array after the rearrangement. _j , The relationship between the array index and each print engine index i _j And In the example of FIG. 14, when arranged in ascending order, i _j = {A, c, b}.
[0054]
Next, as a third step, P _j Phase difference between adjacent elements: D _{j, (j + 1) mod N} Is obtained by the following equation.
[0055]
[Equation 3]
D _{j, (j + 1) mod N} = (P _{(J + 1) mod N} -P _j + T) mod T Equation 3
[0056]
Finally, as the fourth step, as the initial number of broadcast groups: M, among the phase differences calculated by Expression 3, M pieces are counted in order from the largest (provided that M is 0 when M = 1). For j, the index (i _j , I _{j + 1 mod N} ) Is the boundary of the broadcast group. In the example of FIG. _2,0 > D _{1, 2} > D _0,1 Therefore, if M = 2, then (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} are formed.
[0057]
Here, the initial number of broadcast groups: M is the maximum number of broadcasts determined by 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. : M _max The following integer values are used.
[0058]
[Expression 4]
M _max = R div r Equation 4
X div Y is an integer part of a quotient obtained by dividing the integer X by the integer Y.
[0059]
Further, as an example of an algorithm for selecting print engines that can absorb each other's initial print region difference in the buffer buffer and making it a broadcast group, the buffer buffer capacity: L, the print throughput: S, the above-mentioned The following steps are performed as follows.
[0060]
Here, in the third step of the second algorithm, an arbitrary j (j = 0 to N−1) and a variable E that becomes E = N−1 are set as initial values, and the following processing is performed until E = 0. repeat.
[0061]
First, P calculated by Equation 5 _j And P _{(J + k) mod N} Phase difference of: D _{j, (j + k) mod N} Are sequentially obtained for k = 1 to E, and k whose value satisfies Equation 6 first is obtained.
[0062]
[Equation 5]
D _{j, (j + k) mod N} = (P _{(J + k) mod N} -P _j + T) mod T Formula 5
[0063]
[Formula 6]
D _{j, (j + k) mod N} > L / S Equation 6
[0064]
The resulting index i _j To i _{(J + k-1) mod N} Since the initial print site difference between the print engines up to 1 can be absorbed by the buffer buffer, they are set as the same broadcast group.
[0065]
Thereafter, in the third step, j = (j + k) mod N, E = E−K, and the above processing is repeated.
[0066]
Further, a third value for obtaining an initial value of j that minimizes the number of broadcast groups to be divided is used by sequentially using the values of 0 to N−1 as the initial value of j in the third step. An algorithm may be used.
[0067]
A signal representing the member list of each broadcast group obtained as a result of the above grouping process will be described later as a signal (group member bit list: G) between means for realizing dynamic control. .
[0068]
Next, specific examples of means for realizing dynamic control and signals between the means will be described.
[0069]
First, as an example of the buffer status information, a signal representing a change event of the retention amount of raster image data in the buffer buffer is used.
[0070]
That is, the buffer status information notifying means provides an upper level and a lower level as shown in FIG. 15 for the buffer buffer, monitors the data retention amount, and manages it in the three states shown in FIG. When the state change shown in FIG. 17 occurs, the state change is notified as buffer state information.
[0071]
Optimum values may be determined empirically for the upper and lower level values in the buffer buffer, but the initial values can be determined based on the following considerations.
[0072]
First, regarding the upper level, a period from when the MH event is notified until data input to the buffer buffer is stopped as a result of flow control, that is, a period of at least a round-trip signal propagation time between the image generation engine and the print engine The margin may be set so that buffer overflow does not occur even when the output from the buffer buffer is stopped and only the input is continued. Similarly, for the lower level, a period from when the ML event is notified until data input to the buffer buffer is resumed, that is, at least a period of signal propagation time between the image generation engine and the print engine. Even if the input from the buffer is stopped and only the output is continued, the margin may be set so that a buffer underflow does not occur.
[0073]
Next, an embodiment of the sending control means will be described.
[0074]
The sending control means has the following variables for each of the print engine broadcast group determined as a result of the static control or the print engine broadcast group determined in advance.
[0075]
(1) Group member bit list: G
Bit list: The bit length of G is N: the number of print engines or more.
Bit list: G is 2 for all members belonging to the group, where i (0 ≦ i <N) is the index of the print engine of the group member. ⁱ The logical sum of
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 value of G itself is set to 2 ⁱ Calculate and hold an exclusive OR with
[0076]
(2) 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.
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. That is, when the initial value is 0 and the event MH is notified from the print engine with the index: i, the value of A itself and 2 ⁱ Calculates and holds the logical OR.
When the event HM is notified from the print engine with the index: i, the value of A itself and 2 ⁱ Calculate and hold an exclusive OR with Index: The data transmission to the print engine of i is separated and independent, or when the data transmission is stopped in response to an OL event, the value of A itself and 2 ⁱ Calculate and hold an exclusive OR with
[0077]
When data transmission to the print engine of index: i is separated and independent, it is made a single broadcast group, and corresponding bit list: G (value is 2 ⁱ ) And A (initial value is 0).
[0078]
For each broadcast group, the sending control means behaves as shown in the state transition table of FIG. 18 based on the two variables and the buffer status information from the print engine belonging to the broadcast group.
[0079]
Next, embodiments of the raster image data signal addressed to the broadcast group, the raster image data signal addressed to each data receiving unit, and the data broadcast means will be described.
[0080]
The data sending means or sending control means divides the raster image data of each page into data of a predetermined length (divided data), and assigns serial numbers (divided data sequence numbers) in order from the first divided data. A data frame having the format shown in FIG. 6 is created and sequentially transmitted as a raster image data signal addressed to the broadcast group.
[0081]
In the example of FIG. 19, the value of the bit list of the group member described above is used as the destination group address of the data frame. Then, in the data broadcast means, the remaining portion of the data frame after the destination group address is copied to create a data frame of the format illustrated in FIG. 20, and the group member held at the destination group address The data is sent as a raster image data signal to each data receiving unit addressed to the print engine (data receiving unit) of the index corresponding to the bit having a value of 1 in the bit list.
[0082]
The present invention does not include data transmission means for realizing transmission of raster image data (data frame) from the data transmission unit (image generation engine) to each data reception unit (print engine). In the same person, the data transmission means can be easily realized by using existing technology.
[0083]
【The invention's effect】
According to the present invention, each image generation is performed in order to suppress a print part difference of the print engines in the broadcast group by performing single to multiple broadcast transmission by effectively using the data transmission throughput from the image generation engine. It is possible to reduce the capacity of the buffer buffer in the engine.
In other words, even if multiple print engines that have different initial phases and perform printing processes at different periods are used, the print system of the multi-print engine can be reduced by suppressing the cost increase associated with the buffer buffer capacity increase. It is possible to print out a print job with a large number of pages / copies in a shorter time.
Further, the present invention is not limited to the printer system assumed in the present invention, and brings about the same effect for a data transmission system having similar required characteristics.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a printer apparatus model.
FIG. 2 is a diagram for explaining each part of FIG. 1;
FIG. 3 is an explanatory diagram of multiple print engines in a printer apparatus.
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 of the present invention.
FIG. 7 is an explanatory diagram of a control method of the present invention.
FIG. 8 is an explanatory diagram of a data transmission unit configuration that implements a combination of static control and dynamic control.
FIG. 9 is an explanatory diagram of a data receiving unit configuration that implements a combination of static control and dynamic control.
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 data transmission unit configuration for performing 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 phase signal notification;
FIG. 15 is an explanatory diagram of a buffer buffer state management method;
FIG. 16 is an explanatory diagram of buffer buffer state notification means.
FIG. 17 is an explanatory diagram of buffer buffer state information.
FIG. 18 is an explanatory diagram of a state transition table of 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 reception unit;
[Explanation of symbols]
10 Image generation engine
20 Print engine
100 Data transmitter
110 Image storage unit
120 Transmission control means
130 Data Broadcast Means
140 Broadcast destination selection means
200 Data receiver
210 Data receiving means
220 Buffer buffer
230 Image printing section
240 Phase information notification means
250 Buffer retention information notification means

Claims (8)

A plurality of print engines that print and output images at different phases and different periods based on raster image data temporarily stored in the buffer means, and raster image data is generated from the print job data and sent to the plurality of print engines. In a printing system comprising a single image generation engine for transmission ,
Each of the print engines has phase information notification means for notifying the image generation engine of phase information of a print output cycle ,
The image generating engine, obtains a relative phase difference between the print engine based on the phase information, based on the relative phase difference, have a broadcast destination selecting means for selecting a broadcast transmission destination of the print engine ,
A printing system, wherein the raster image data is transmitted to the selected print engine by broadcast transmission . A plurality of print engines that print images at different phases and different periods based on raster image data; and a single image that generates raster image data from print job data and transmits the generated raster image data to the plurality of print engines. A printing system comprising a generation engine ;
Each of the print engines has phase information notification means for notifying the image generation engine of phase information of a print output cycle ,
The image generation engine has a broadcast destination selection unit that obtains a relative phase difference between the print engines based on the phase information and selects a data receiving unit of the broadcast transmission destination based on the relative phase difference. And
Prior to a series of data transmissions, select the broadcast transmission destination print engine ,
Each selected print engine notifies the data buffer means that holds the received data for a period until it is processed, and the buffer status information that indicates the data retention state in the data buffer means to the data transmission unit Buffer status notification means for
Based on the buffer status information, the image generation engine stops broadcast transmission so that no data overflow occurs in the data buffer means of any print engine at the broadcast transmission destination, or underflow occurs. A print system comprising a sending control means for restarting broadcast transfer so that there is no transmission. 3. The print system according to claim 1 , wherein each of the print engines uses, as phase information, a signal indicating that the print process of the print engine is about to reach one base point in the print process cycle of the print engine . . 4. The printing system according to claim 3 , wherein the image generation engine obtains a relative phase difference by measuring a time difference in which phase information is notified from the print engine as a relative phase difference. Each of said print engine, according to monitoring the data retention amount to said data buffer means, that the data retention amount over a threshold value provided for the capacity of the data buffer unit is changed to the buffer status information Item 3. The printing system according to Item 2. The print engine has two levels of threshold values for the capacity of the data buffer means: a lower level for early detection of an underflow risk and an upper level binary value for early detection of an overflow risk. 6. A printing system according to claim 5, wherein a threshold is used . When the image generation engine is notified of buffer status information indicating that the data retention amount in the data buffer means of the print engine has exceeded the upper level from one of the data receiving units of the broadcast transmission destination Stops broadcast transmission, and after that, the amount of data staying in the data buffer means from all data receiving units that have notified the buffer status information indicating that the amount of data staying in the data buffer means has exceeded the upper level 7. The printing system according to claim 6, wherein the broadcast transmission is resumed when the buffer status information indicating that the signal is below the upper level is notified. If the buffer status information indicating that the data retention amount exceeds upper level to said data buffer means of the print engine is notified from one of the printing engine of the broadcast transmission destination, stopping the broadcast transmission After that, the amount of data staying in the data buffer means from all the print engines that notified the buffer status information indicating that the amount of data staying in the data buffer means exceeded the upper level The buffer status information indicating that the amount of data staying in the data buffer means from any print engine at the broadcast transmission destination has fallen below the lower level before the broadcast transmission is restarted after the buffer status information is notified. when notified, remove the corresponding print engine from broadcast transmission destination resumes individual data transmission according to claim 7, wherein the print System.

Images