JPH08339273A - Data transmitter, data transfer device and method therefor and printing system and controlling method therefor - Google Patents

Abstract

PURPOSE: To rationalize the transfer of data by transmitting compressed data or non-compressed data so as to be advantageous as a whole. CONSTITUTION: A step S301 is the step for starting a host computer. In the step S302, the compression function of the host computer and the expansion function of a printer which is the transfer destination of printing data are confirmed. Also, it is defined that the function indicates the processing rate of compression/expansion. In the step S303, the transfer rate of the host computer and the printer is confirmed. Thereafter, in the step S304, an application or the like for document preparation for instance is executed. Thereafter, in the step S305, the printing data are generated corresponding to the instructions of a user or the like. In the step S306, whether or not it is advantageous to compress and transfer the printing data to the printer is judged based upon the content confirmed in the step 302 and the step 303, and when it is advantageous to compress and transfer them, the printing data are compressed. In the step S307, the generated printing data are transmitted to the printer 307.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data transmission device, a data transfer device and a method thereof, a printing system and a control method thereof, and more particularly to a data transmission device capable of compressing and transferring data, a data transfer device and the same. The present invention relates to a method, a printing system and a control method thereof.

[0002]

2. Description of the Related Art FIG. 1 is a diagram for explaining the configuration of a general printer system. In the figure, the printer 120
Is the printer controller 121 and the printer engine 1
22 is provided. The printer controller 121 receives drawing data supplied from an external device such as the host computer 100 via the interface 110, analyzes the received data string by software using an internal CPU, and displays the analysis result. Image data is generated using the image data, stored in the internal drawing image data memory, and sent to the printer engine 122. The printer engine 122 is a laser beam printer (LBP),
As represented by a bubble jet printer (BJ) or the like, image data received from the printer controller 121 is fixed on a medium such as recording paper.

In recent years, due to the increase in the output resolution of the printer engine 122 and the increase in the communication data amount accompanying the sophistication of data handled by the printer 120, the communication data is sent to the printer 120 in a compressed form from the data supply source. The printer 120 decompresses the received data and then performs a predetermined process to perform printing to reduce the communication data amount, reduce the communication time, reduce the buffer memory, etc., and improve the efficiency of the entire printer system. Realized models have also appeared.

In order to specifically support such a compression / expansion function, a processor such as a CPU is used on both the data supply source side and the printer device side, and processing is performed by software or compression by the processor is performed. / In order to reduce the load of the decompression process itself, the compression / decompression process is realized using dedicated hardware.

[0005]

However, in order to perform compression / expansion at high speed, it is necessary to provide dedicated hardware for compression / expansion as described above, which increases the cost. However, not all devices have been equipped with the dedicated hardware described above. That is, for example, compression /
A device that has different compression / expansion capabilities (mainly processing speed), such as a system that consists of a device that implements decompression by software, a device that implements decompression by hardware, or a device that does not have a compression / decompression function. The current situation is to connect and build a system.

Specifically, for example, when both the host computer 100 and the printer 120 realize the compression / decompression function by hardware, when either one is realized by software, both are realized by software. There is a case where it is realized, or one of them does not have a compression / expansion function.

When the system is constructed by connecting the devices having different compression / expansion functions in this way, it is not always necessary to compress and transfer the print data, which shortens the overall time required for the printing process. It is not always possible to speed up the process.

That is, the data transfer speed at the interface means between the print data supply source and the printer device differs depending on the interface means between the actually connected devices, and the compression / expansion capability as described above is also applied to the devices. The amount of print data to be transferred is different each time. Therefore, without compressing the print data,
It goes without saying that the entire processing time required for printing may be shorter if it is directly transferred to the printer device.

For example, when data is transferred from a data supply source that realizes a compression function by hardware to a printer device that realizes a decompression function by software using high-speed interface means, high-speed processing is required for data compression at the data supply source. Although possible, it takes a lot of time to decompress with software on the printer device side that receives the compressed data. In such a case, it may be possible to reduce the overall printing time by transferring non-compressed data using a high-speed interface means (although the relationship between the received data buffer capacity and the compressed data quantity on the printer device side may be reduced). Depends also,
It is faster to release the data source from the printing process).

On the other hand, even when data is transferred from a data supply source realizing a compression function by software to a printer apparatus realizing a decompression function by hardware by using a high-speed interface means, a great deal of time is required for compression processing. Therefore, it may be advantageous to directly transfer the uncompressed data from the data supply source to the printer device from the viewpoint of release from the print processing on the data supply source side or reduction of the overall print processing time.

Further, the compression / expansion capability (for example, processing speed) in the data supply source or the printer device, the interface means (for example, data transfer speed), the contents of transfer data (for example, data amount), etc. It can be said that the optimum processing method differs depending on the combination of the respective elements.

The present invention has been made in view of the above problems, and an object thereof is to rationalize data transfer.

[0013]

[Means for Solving the Problems] and

In order to solve the above problems, a data transmitting apparatus according to the present invention is a data transmitting apparatus capable of compressing and transmitting data to a receiving apparatus, the compressed data being transmitted to the receiving apparatus. Necessary time calculating means for calculating a necessary time required for transmission, transmission time calculating means for calculating a transmission time required for transmitting uncompressed data to the receiving device, the necessary time and the transmission Comparing the time with the determining means for determining whether to compress the data to be transferred to the receiving device based on the result, and the data to be transmitted to the receiving device based on the determination. Compression means for compressing, and transmitting means for transmitting data to the receiving device,
If it is advantageous to compress and send the data as a whole, send the compressed data, and if it is advantageous to send the uncompressed data as a whole, send the uncompressed data. The overall processing time provided can be rationalized.

Further, the data transfer apparatus according to the present invention is a data transfer apparatus capable of compressing and transferring data, and a necessary time calculating means for calculating a necessary time required for transferring the compressed data. , A transfer time calculating means for calculating a transfer time required when transferring uncompressed data, and the necessary time and the transfer time are compared, and based on the result, it is determined whether or not the data to be transferred is compressed. Determining means, a compressing means for compressing the data to be transferred, a transmitting means for transmitting the data, a receiving means for receiving the transmitted data, and a receiving means for receiving the compressed data when the received data is compressed data. A decompression means for decompressing the compressed data is provided, and the compressed data is transmitted when it is advantageous to compress the data and transmit the data as a whole,
When it is advantageous to send uncompressed data as a whole, by sending uncompressed data, it is possible to rationalize the entire processing time for a series of processing.

Further, the printing system according to the present invention is a printing system capable of compressing and transferring print data from a printing device to an external device thereof, which is required when transferring the compressed print data. Required time calculation means for calculating the time, transfer time calculation means for calculating the transfer time required when transferring the uncompressed print data, and the necessary time and the transfer time are compared, and transfer is performed based on the result. Determining means for determining whether or not to compress the print data to be compressed, compression means for compressing the print data to be transferred based on the determination, transmitting means for transmitting the print data from the external device, and external device A receiving unit that receives the transmitted print data in the printing apparatus; a decompressing unit that decompresses the compressed print data when the received print data is compressed data; An image forming unit for forming an image based on the received print data is provided, and if it is advantageous to compress the print data and transmit the compressed data, the compressed data is transmitted, and the uncompressed data is transmitted. When it is more advantageous to do so, by transmitting the non-compressed data, it is possible to rationalize the overall processing time for the printing process.

[0016]

【Example】

[First Embodiment] An embodiment according to the present invention will be described below with reference to the drawings. FIG. 2 is a block diagram showing a schematic configuration of the printing system according to this embodiment.

Reference numeral 201 is a display such as a CRT used for an interface with the user. Reference numeral 202 denotes an interface (hereinafter referred to as I / O) that connects the display 201 and the host computer main body 101. Reference numeral 203 denotes a communication port (hereinafter referred to as I / O) which is connected to the printer 120 and controls transmission / reception of print data and the like. A control unit 204 controls the entire host computer 100 based on the application 206. Two
Reference numeral 05 is a memory that functions as a main storage device of the host computer 100. Reference numeral 206 denotes an application program that describes a procedure of processing in the control unit 204, and its substance is a program instruction sequence stored in a ROM or a hard disk device (including a program according to a flowchart described later and O / S). It is explained as a thing). A compression unit 207 compresses print data. 110 is the host computer 100.
It is a bidirectional interface (for example, a serial bidirectional network, a parallel network, a network such as Ethernet) for exchanging data with the printer 120, and the interface itself is not particularly limited.

Reference numeral 209 receives the data transferred from the host computer 100, and the host computer 1
Communication port for transmitting data to 00 (hereinafter, I / O
It is called O). Reference numeral 210 is, for example, an interface (hereinafter referred to as I / O) that supplies image data to the printer engine 215. 212 is the printer 120
Is a memory that functions as the main storage device of the. 213 is
It is a rasterizer that generates a bitmap image according to the data received from the host computer 100.
A decompression unit 214 decompresses the compressed data received from the host computer 100. A printer engine unit 215 realizes print fixing on a medium such as recording paper according to the bitmap image data generated by the printer controller 121, and is represented by, for example, a laser beam printer (LBP), a bubble jet printer (BJ), or the like. However, the present invention does not specifically limit the printer engine format.

The control procedure of the host computer 100 and printer 120 according to this embodiment will be described below.

FIG. 3 is a flow chart for explaining the operation flow of the host computer 100. First, in step S301, the host computer 100 starts up. That is, each hardware asset (including a device (not shown)) and software included in the host computer 100 are initialized.

In step S302, the compression function (compression unit 207) of the host computer 100 and the decompression function (decompression unit 214) of the printer 120 are confirmed. Specifically, in this step, the compression / decompression method of each device (for example, by hardware, by software, without compression / expansion function, etc.) and compression for the scale of print data to be processed / Acquire the processing time required for decompression processing as parameters.

To obtain such parameters relating to the printer 120, for example, a request for transmitting the above parameters is issued to the printer 120 via the interface 110, and the printer 120 recognizing the request causes the decompression unit 214 of its own. It may be realized by controlling the information indicating the function to be transmitted to the host computer 100 via the interface 110 as a parameter (for example, stored in a nonvolatile memory (not shown)).
Other methods may be used. Regarding the function of the compression unit 207, for example, a method of storing corresponding information in a non-volatile memory (not shown) or the like may be used.

In step S303, the host computer 100 confirms the transfer rate of the interface 10. In this embodiment, the transfer rate is I / O2.
03, the interface 110, the I / O 209, the control unit 211, the rasterizer 213, and the like. For example, when the capacity of the transmission / reception buffer included in the I / O 209 is small, it is necessary to wait for the transmission / reception buffer to become receivable before transmitting the print data from the I / O 203, which is the transfer rate. Will be one factor that determines. Further, the processing by the control unit 211 and the rasterizer 213 also affects the speed at which the received data is processed (for example, if the read speed of the transmission / reception buffer is slow, it naturally hinders the transfer speed from becoming high).

The method of acquiring the information regarding the transfer rate is not particularly limited, and for example, the printer 12
A method may be used in which a parameter indicating a transfer rate is held in advance in 0 and a response is issued by issuing a parameter transmission request to the printer 120 as in the case of step S302 described above, or a dummy data May be used to measure the transfer rate.

The I / O 203 and I / O each have a transmission / reception buffer, and these have a control unit 204.
Alternatively, since the transfer rates viewed from 211 are averaged, it is appropriate to give the above-mentioned parameters relating to the transfer rates in the form of an average transfer rate.

In step S304, a specific application in the application 206 (for example, a document creating application) is executed in accordance with a user's instruction, for example. For example, the user operates a pointing device such as a keyboard and a mouse (not shown) provided in the host computer 100 to execute the application. Here, for example, when the printing process is executed according to a user's instruction (not shown in other cases), the process proceeds to step S305.

In step S305, print data is generated according to the print instruction.

In step S306, step S305
The printer 120 based on the print data generated in
Generate data to send to. In this step, if it is advantageous to compress the print data based on the above-mentioned parameters (parameters indicating the compression function and the transfer speed), it is compressed, and if not, it is not compressed. (For example, a flag indicating that the data is non-compressed data is added), and the transmission data is generated. Details of this processing will be described later.

In step S307, the transmission data is transmitted to the printer 120 via the interface 110.

Incidentally, in the flow chart of FIG.
Although various other operations are not mentioned for better understanding of the present invention, it is not intended that the host computer 100 perform only the above operations, and they follow conventional techniques.

Next, the transmission data generation process in step S306 will be described. FIG. 4 is a flowchart showing the flow of a transmission data generation process. First, in step S401, the amount of transmission data when uncompressed (that is,
(Scale of print data generated in step S305)
To calculate. Further, in step S402, the transfer time of the print data at the time of non-compression is calculated with reference to the above-mentioned parameter indicating the amount of transmission data at the time of non-compression and the above-mentioned transfer speed. The transfer time can be calculated by dividing the transmission data amount by the transfer rate.

In step S403, for example, the compression unit 2
07 and the compression ratio (for example, an average compression ratio) according to the compression algorithm supported by the decompression unit 214 and the transmission data amount calculated in step S401 are referred to, and the transmission data amount at the time of compression is calculated. The compression ratio may be acquired together with the confirmation of the compression function in step S302, or the information may be stored in advance in a non-volatile memory or the like.

In step S404, the processing time when the print data is compressed is calculated. This processing time depends on the time required to compress the print data in the host computer 100, the time to transfer the compressed print data to the printer 120, and the time to decompress the compressed data received by the printer 120. Therefore, the total value of these values may be used as the above processing time, or when depending on other factors, the processing time may be calculated by taking it into consideration. Note that the transfer time can be calculated by dividing the amount of data to be actually transmitted (transmitted data amount at the time of compression) by the transfer rate.

At step S405, step S402.
The transfer time calculated in step S404 is compared with the processing time calculated in step S404, and when it is determined that it is advantageous to compress the print data, the process proceeds to step S406 to control the compression unit 207 to compress the print data. To do. In this embodiment, at this time, a flag indicating whether or not the print data is compressed is added to the head portion of the print data (however, such a flag may be added to the compressed data, (It may be added to the uncompressed data, or appropriate flags may be added to both). Further, this processing may be executed by securing a predetermined work area on the memory 205 functioning as a main storage device.

As is apparent from the above description and the gist of the present invention, the transfer time at the time of non-compression and
It is sufficient to determine whether or not it is advantageous to compress and transfer print data without calculating and comparing the processing time in the case of compression with the above method.

The operation of the printer 120 corresponding to the operation of the host computer 100 will be described below. FIG. 5 is a flowchart showing the operation flow of the printer 120. Note that steps S302 and S30
The description of the process of responding to the parameter request in 3 is omitted because it is redundant, and only the process corresponding to “data transmission” in step S307 will be described.

In step S501, the print data transmitted from the host computer 100 via the interface 110 (step S307) is received by the I / O 209. As described above, the I / O 209 includes the transmission / reception buffer, and the received print data is sequentially stored in the reception buffer and is sequentially read according to the control of the control unit 211.

In step S502, it is determined whether or not the print data is compressed data based on the flag indicating the presence or absence of compression included in the received print data.
As a result, when the print data is compressed data, the process proceeds to step S503, and the decompression unit 214 and the memory 2 are used.
Extend using 12 predetermined work areas. The expanded print data is sequentially stored in the memory 212.

Normally, the content of print data received (meaning of data) is a command group of a language system or command system peculiar to the printer device, but the present invention is not particularly limited to these.

In step S504, the control unit 211 interprets the decompressed print data or the print data determined to be uncompressed data in step S502, and the memory 2
An expansion area is secured in 12, and the rasterizer 213 is used to expand the expansion area. Needless to say, if the received print data is already expanded data, such a process is unnecessary, and a process adapted to it may be performed.

In step S505, step S504
The image data generated in the printer engine 2
15 to the printer engine 215 via the I / O 210.

In step S506, the printer engine 215 is controlled to visualize the image data.

As described above, by determining whether to compress and transfer the print data according to the characteristics of the system, it does not contribute to the speeding up of the printing process as a whole, or the printing process is delayed. It is possible to delete unnecessary unnecessary compression processing, and as a result, it is possible to speed up the printing processing as a whole.

In calculating the transfer time,
Transfer capability on the host computer 100 side (I / O 203
(Depending on the capacity of the transmission / reception buffer included in, the processing capacity of the control unit 204, etc.) is inferior to the transfer capacity of the printer 120 on the I / O side, Needless to say.

If the host computer 100 is equipped with an O / S for performing multitask processing, if spool data is to be sent or compressed, step S4 is performed.
At the time of 04, by considering the load average etc. that can be devoted to compression processing, and calculating each transfer time,
A more efficient system can be constructed. When calculating in consideration of the load average, there is no limitation on the method such as calculating the predicted load average at the time of data transmission from the average of the load averages up to that point.

Further, in the above calculation, a flexible system may be constructed in which the user can specify the weight of the above-mentioned parameter.

In the above embodiment, for convenience of explanation, the host computer 100 side mainly decides whether or not to compress the print data.
The present invention is not intended to be limited to this. For example, the printer 120 may take the initiative in making the above determination, and either the host computer 100 or the printer 120 takes the initiative depending on the situation. The above decision may be made. [Second Embodiment] In the first embodiment, a case where the compression / expansion functions and transfer rates of the host computer 100 and the printer 120 are confirmed immediately after the host computer 100 (the printer 120 depending on the configuration) is started up As explained, this is the device (eg, host computer) that has the initiative to decide whether or not to perform compression.
Does not have a special problem when it is started up after another device (for example, a printer), but in the opposite case, the device having the initiative takes steps until the other device is started up. There is a problem in that the processing cannot proceed to S302 and thereafter.

This is, for example, the host computer 10.
Although there is a slight problem when 0 and the printer 120 correspond one-to-one (the other device should be started up), it is hard to say that it is preferable on a network in which a plurality of devices are connected. .

Therefore, the present embodiment shows that the present invention can be preferably implemented in a network or the like by modifying the first embodiment as follows.

FIG. 6 is a flow chart showing the flow of processing of the host computer 100 according to this embodiment. It should be noted that steps that perform the same processing as the flowchart shown in FIG. 3 showing the flow of processing of the host computer 100 according to the first embodiment are assigned the same step numbers and description thereof is omitted. Regarding other processing (flowcharts shown in FIGS. 4 and 5), similar processing is performed in this embodiment.

The characteristic part of this embodiment is step S302.
And the process according to step S303 will be performed after the execution of the application.

After the print data is generated in step S305, the process proceeds to step S601. Step S601
Then, for example, the other party to be transmitted is specified based on the information instructed by the user during the execution of the application. Then, the subsequent process is
Similar to the first embodiment, steps S302, S303, S
306 and S307 are executed.

As described above, steps S302 and S
The present invention can be applied to the network by performing the processing of 303 after the application is executed.

In this embodiment, the case where the host computer 100, which is the supply source of the print data, determines whether or not the compression is mainly performed, is described as an example.
It goes without saying that another device (reception side) on the network such as the printer 120 may make the determination.

It should be noted that the configurations of the host computer 100 and the printer 120 in the first and second embodiments described above are only embodiments of the present invention, and are within the scope of the present invention. The constituent elements can be changed or deleted, and other constituent elements may be added. For example, the compression unit 207 and the decompression unit 214 may be exchangeable so that the system can be upgraded or the transmission / reception buffer provided in the I / O unit can be exchanged.

Further, although the compression / decompression algorithm is not mentioned in the above description, this is because the present invention does not limit the algorithm, and as described above, the data amount after compression is determined by some means. Any algorithm can be supported as long as it has means for calculating (including predicting).

Further, it is needless to say that the present invention is not limited to the transfer of print data between a data supply source such as a host computer and a printer, but is widely applicable to the field of data communication.

The present invention may be applied to a system composed of a plurality of devices or an apparatus composed of a single device. Further, it goes without saying that the present invention can be applied to the case where it is achieved by supplying a program to a system or an apparatus.

[0059]

As described above, according to the present invention, when it is advantageous to compress and transmit data as a whole, it is advantageous to transmit compressed data and to transmit uncompressed data as a whole. In some cases, by transmitting uncompressed data, it is possible to rationalize the overall processing time used for a series of processes.

[0060]

[Brief description of drawings]

FIG. 1 is a diagram illustrating a configuration of a general printer system.

FIG. 2 is a block diagram illustrating a schematic configuration of a printing system according to a first embodiment.

FIG. 3 is a flowchart illustrating a flow of operations of the host computer 100.

FIG. 4 is a flowchart showing a flow of a transmission data generation process.

FIG. 5 is a flowchart showing a flow of operations of the printer 120.

FIG. 6 is a host computer 100 according to the second embodiment.
3 is a flowchart showing the flow of the processing of FIG.

Claims (18)

[Claims] 1. A data transmitting device capable of compressing and transmitting data to a receiving device, wherein a required time is calculated for calculating a required time when transmitting the compressed data to the receiving device. Means, a transmission time calculating means for calculating a transmission time required when transmitting uncompressed data to the receiving device, and comparing the required time with the transmission time, and based on the result, the receiving device Deciding means for deciding whether or not to compress data to be transferred, compression means for compressing data to be transmitted to the receiving device based on the decision, and transmitting data to the receiving device A data transmission device comprising: 2. A compression / decompression function confirmation means for confirming a function of the compression means and a decompression function of the reception device, and a transmission / reception capacity confirmation means for confirming a transmission capacity of the transmission means and a reception capacity of the reception means. And the required time calculation means calculates the required time based on the confirmation result by the compression / expansion function confirmation means and the transmission / reception capability confirmation means, and the transmission time calculation means The transmission time is calculated based on the confirmation result by the reception capability confirmation means.
The data transmission device described. 3. The data transmission according to claim 2, wherein the transmission / reception capability confirmation means is a means for confirming the transmission / reception capability by exchanging predetermined dummy data with the reception device. apparatus. 4. The necessary time calculating means is a sum of a time for compressing data to be transmitted to the receiving device, a time for transmitting the compressed data, and a time for expanding the data received by the receiving device. 4. The method according to claim 2 or claim 3, characterized in that
The data transmission device described. 5. The data transmitting apparatus according to claim 1, wherein the data is print data. 6. A data transfer device capable of compressing and transferring data, wherein necessary time calculating means for calculating a necessary time required for transferring compressed data, and for transferring uncompressed data. A transfer time calculating means for calculating the required transfer time, a deciding means for comparing the necessary time with the transfer time and deciding whether or not to compress the data to be transferred based on the result, and based on the decision A compression means for compressing the data to be transferred, a transmission means for transmitting the data, a reception means for receiving the transmitted data, and a decompression means for decompressing the compressed data when the received data is compressed data, A data transfer device comprising: 7. A compression / decompression function confirmation means for confirming the function of the compression means and the function of the decompression means, and a transmission / reception capacity confirmation means for confirming the transmission capacity of the transmission means and the reception capacity of the reception means. The required time calculating means calculates the necessary time based on the confirmation result by the compression / expansion function confirmation means and the transmission / reception capability confirmation means, and the transfer time calculation means 7. The transfer time is calculated based on the confirmation result by the reception capability confirmation means.
The described data transfer device. 8. The transmission / reception capability confirmation means is means for confirming the transmission / reception capability by exchanging predetermined dummy data between the transmission side and the reception side. The described data transfer device. 9. The required time calculating means is a means for determining the required time by summing a time for compressing data to be transferred, a time for transferring compressed data, and a time for expanding received data. The data transfer device according to claim 7 or 8, characterized in that. 10. The data transfer device according to claim 6, wherein the data is print data. 11. A printing system capable of compressing and transferring print data from a printing device to an external device thereof, and a necessary time calculating means for calculating a necessary time required to transfer the compressed print data. A transfer time calculating means for calculating a transfer time required for transferring uncompressed print data, and comparing the necessary time with the transfer time and compressing the print data to be transferred based on the result. Determining means for determining whether the print data to be transferred is compressed based on the determination, transmitting means for transmitting the print data from the external device, and print data transmitted from the external device. And a decompression unit that decompresses the received print data when the received print data is compressed data, based on the received print data. Printing system comprising: an image forming means for forming an image. 12. The printing system according to claim 11, wherein the required time calculating unit, the transfer time calculating unit, and the determining unit are included in the external device side. 13. The printing system according to claim 11, wherein the required time calculating unit, the transfer time calculating unit, and the determining unit are included in the printing apparatus side. 14. A compression / decompression function confirmation means for confirming the function of the compression means and the function of the decompression means, and a transmission / reception capacity confirmation means for confirming the transmission capacity of the transmission means and the reception capacity of the reception means. The required time calculating means calculates the necessary time based on the confirmation result by the compression / expansion function confirmation means and the transmission / reception capability confirmation means, and the transfer time calculation means 2. The transfer time is calculated based on the confirmation result by the reception capability confirmation means.
The printing system according to any one of 1 to 13. 15. The transmission / reception capability confirmation means is means for confirming the transmission / reception capability by exchanging predetermined dummy data between the printing device side and the external device side. The printing system according to claim 14. 16. The required time calculating means is means for determining the required time by adding the time required to compress the data to be transferred, the time required to transfer the compressed data, and the time required to decompress the received data. 15. The method according to claim 14,
Alternatively, the printing system according to claim 15. 17. A data transfer method capable of compressing and transferring data, comprising: a necessary time calculating step of calculating a necessary time required when transferring compressed data; and a non-compressed data transferring step. A transfer time calculating step of calculating a required transfer time, a determining step of comparing the required time with the transfer time, and determining whether or not to compress data to be transferred based on the result, and a determining step based on the determination A compression step of compressing the data to be transferred, a transmission step of transmitting the data, a reception step of receiving the transmitted data, and a decompression step of decompressing the compressed data when the received data is compressed data, A data transfer method comprising: 18. A method of controlling a printing system, wherein print data can be compressed and transferred from a printing device to an external device, and a necessary time required to transfer the compressed print data needs to be calculated. A time calculation step, a transfer time calculation step for calculating a transfer time required for transferring uncompressed print data, a comparison between the necessary time and the transfer time, and the print data to be transferred is compressed based on the result. A determination step of determining whether or not to perform, a compression step of compressing the print data to be transferred based on the determination, a transmission step of transmitting the print data from the external device, and a print data transmitted from the external device. A receiving step of receiving in the printing device; a decompressing step of decompressing the received print data when the received print data is compressed data; and a received print data Method for controlling the printing system comprising: the image forming step of forming an image, a based on.