Image forming apparatus and image forming program

Abstract

To specify a communication delay time occurring due to optical wireless communication between a first module and a second module provided in an image forming apparatus prior to main communication between the first module and the second module.SOLUTION: Prior to main communication between a control module 22 and a print module 20, a delay time acquisition unit 40 transmits a test signal T to the print module 20 through optical wireless communication. In response to the test signal T, the print module 20 transmits a response signal A to the control module 22. The delay time acquisition unit 40 specifies a communication delay time occurring due to the optical wireless communication between the control module 22 and the print module 20 based on the difference between the time at which the test signal T is transmitted and the time at which the response signal A is received.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an image processing device and an image processing program. [Background technology]

[0002] Conventionally, communication between devices has been performed by optical wireless communication. For example, Patent Document 1 discloses a communication system that performs optical wireless communication between devices. In this communication system, one device intermittently converts an intermittent signal (electrical signal) into an optical signal and sends it to another device, and the other device separates and extracts a clock from the electrical signal obtained by photoelectrically converting the optical signal. Then, the other device generates a clock synchronized with the extracted clock, thereby achieving clock synchronization between the devices performing optical wireless communication. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2001-168943 A Summary of the Invention [Problem to be solved by the invention]

[0004] In some image forming apparatuses, multiple modules that control various processes are provided. Conventionally, in such image forming apparatuses, the multiple modules are generally connected to each other by electric cables. As a result, electrical signals such as image signals, sensor signals, and control signals are transmitted between the modules via the electric cables.

[0005] It is conceivable that communication between modules in an image forming apparatus may be performed by optical wireless communication. When performing optical wireless communication, it is necessary to take into consideration that the communication delay time is longer in optical wireless communication than in wired communication via electric cables. The communication delay time is the time from when a first module that transmits a signal starts transmitting an electric signal until when a second module that receives the signal receives the electric signal. In optical wireless communication, the first module needs to convert the electric signal into an optical signal, and the second module needs to convert the received optical signal into an electric signal, so the communication delay time is longer than in wired communication via electric cables.

[0006] In particular, in an image forming apparatus, there are cases where it is necessary to operate each module at an appropriate timing (for example, it is necessary to synchronize the timing of the print medium transport process and the print process on the print medium), and in order to operate the second module at the intended timing, the first module needs to transmit a signal at a timing that takes into account the communication delay time between the first module and the second module. To do this, it is necessary to identify the communication delay time between the first module and the second module. In particular, it is desirable to be able to operate the second module at the intended timing immediately after the start of optical wireless communication between the first module and the second module.

[0007] An object of the present invention is to identify a communication delay time caused by optical wireless communication between a first module and a second module provided in an image forming device prior to actual communication between the first module and the second module. [Means for solving the problem]

[0008] The invention according to claim 1 includes a first module having a processor, and a second module that communicates with the first module via optical wireless communication, and the processor transmits a test signal to the second module via optical wireless communication prior to main communication between the first module and the second module, and identifies a first communication delay time caused by the optical wireless communication between the first module and the second module based on a difference between a time when the test signal is transmitted to the second module and a time when a response signal returned by the optical wireless communication from the second module in response to the test signal is received. death , transmitting a control signal to the second module for causing the second module to execute the process at a time that is earlier than a time at which the second module is to start the process by the first communication delay time; The image forming apparatus is characterized in that: The invention of claim 2 is the image forming apparatus described in claim 1, characterized in that when it is determined that processing using the second module is to be executed, the processor identifies the first communication delay time prior to the processing being executed. The invention of claim 3 is the image forming device described in claim 2, characterized in that the second module is a printing module that controls a printing process that prints on a printing medium in accordance with instructions from the first module, and when it is determined that the printing process is to be executed, the processor identifies the first communication delay time prior to the printing process being executed. The invention of claim 4 is an image forming apparatus as described in any one of claims 1 to 3, further comprising a transport module that controls a transport process for transporting a printing medium in accordance with instructions from the first module, and the processor sends instructions to the transport module at a timing based on a first communication delay time caused by optical wireless communication between the first module and the second module. The invention of claim 5 is the image forming apparatus described in claim 4, characterized in that the first module and the conveying module communicate via optical wireless communication, and the processor transmits a test signal to the conveying module via optical wireless communication prior to the main communication between the first module and the conveying module, and identifies a second communication delay time caused by optical wireless communication between the first module and the conveying module based on the difference between the time the test signal is transmitted to the conveying module and the time a response signal returned by optical wireless communication from the conveying module in response to the test signal is received, and transmits an instruction to the conveying module at a timing based on the first communication delay time and the second communication delay time. The invention according to claim 6 is a method for determining a first communication delay time caused by optical wireless communication between the first module and the second module, the method comprising: causing a computer including a first module and a second module that communicates with the first module via optical wireless communication to transmit a test signal to the second module via optical wireless communication prior to a main communication between the first module and the second module; and determining a first communication delay time caused by optical wireless communication between the first module and the second module based on a difference between a time when the test signal is transmitted to the second module and a time when a response signal returned by optical wireless communication from the second module in response to the test signal is received. and transmitting to the second module a control signal for causing the second module to execute the process at a time that is earlier than a time at which the second module is to start the process by the first communication delay time. The image forming program is characterized in that Effect of the Invention

[0009] According to the invention of claim 1 or 6, it is possible to identify a communication delay time caused by optical wireless communication between a first module and a second module provided in an image forming device prior to the actual communication between the first module and the second module. According to the invention as set forth in claim 2, when it becomes necessary to transmit a signal to the second module, it is possible to identify the communication delay time between the first module and the second module. According to the invention as set forth in claim 3, it is possible to identify the communication delay time between the first module and the printing module. According to the invention as set forth in claim 4, the transport module can be operated at a timing corresponding to the operation timing of the print module. According to the invention as set forth in claim 5, the transport module can be operated at a timing corresponding to the operation timing of the print module while also performing optical wireless communication between the first module and the transport module. [Brief description of the drawings]

[0010] [Figure 1] 1 is a schematic diagram illustrating the configuration of an image processing device according to an embodiment of the present invention. [Diagram 2] 2 is a schematic diagram showing detailed configurations of a transport module, a print module, and a control module according to the embodiment; FIG. [Diagram 3] FIG. 4 is a timing diagram showing the timing of transmission and reception of test signals and response signals. [Figure 4] 5 is a flowchart showing a flow of processing of the image processing apparatus according to the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] 1 is a schematic diagram of the configuration of an image forming apparatus 10 according to the present embodiment. The image forming apparatus 10 is an apparatus that executes processing related to a job in response to the job as a processing command input by a user. A representative example of the image forming apparatus 10 is a multifunction machine equipped with a print function, a scan (image reading) function, a copy function, a fax transmission function, etc., but the image forming apparatus 10 may be other devices.

[0012] The communication interface 12 includes, for example, a network adapter, etc. The communication interface 12 exhibits a function of communicating with other devices (for example, a user terminal used by a user) via a communication line such as a LAN (Local Area Network).

[0013] In particular, the communication interface 12 receives jobs including data to be processed from a user terminal, such as a print job for causing the image forming apparatus 10 to perform a printing process.

[0014] The input / output interface 14 includes an input interface such as a touch panel or buttons, and an output interface such as a display or a speaker.

[0015] The input interface is used by the user to input various instructions to the image forming apparatus 10. For example, the user can set a paper document in a paper tray (not shown) of the image forming apparatus 10 and then input, from the input interface, a scan job for causing a scanner (not shown) of the image forming apparatus 10 to perform a scan process. Similarly, the user can input, from the input interface, a copy job for causing the image forming apparatus 10 to perform a copy process (a process of printing image data obtained by scanning a paper document onto a print medium) or a FAX job for causing the image forming apparatus 10 to perform a FAX transmission process (a process of FAXing image data obtained by scanning a paper document).

[0016] The output interface is used to output various types of information to a user by the image forming apparatus 10. For example, various screens are displayed on a display serving as the output interface.

[0017] The memory 16 includes, for example, a hard disk drive (HDD), a solid state drive (SSD), an embedded multi media card (eMMC), a read only memory (ROM), a random access memory (RAM), etc. The memory 16 stores an image forming program for causing each unit of the image forming apparatus 10 to function, as well as various data necessary for the processing of the image forming apparatus 10.

[0018] The conveying module 18 is a module that controls a conveying process for conveying a print medium such as paper within the image forming apparatus 10. Specifically, the conveying module 18 controls a conveying device that conveys the print medium within the image forming apparatus 10 in response to instructions from a control module 22 described below. The conveying device is configured to include a drive roller that conveys the print medium by rotating. The conveying device may be provided separately from the conveying module 18, or may be incorporated into the conveying module 18.

[0019] The printing module 20 as the second module is a module that controls a printing process that prints on a print medium. Specifically, the printing module 20 controls a printing device that prints on a print medium in response to an instruction from a control module 22 described later. The printing device is configured to include, for example, a photosensitive drum, a charging device that charges the photosensitive drum, an LED that applies light to the photosensitive drum to remove the charge of the print image portion, a toner that is attached to the portion of the photosensitive drum that has a weak charge, and a fixing device that fixes the toner transferred from the photosensitive drum to the print medium. Note that the printing device may be provided separately from the printing module 20, or may be incorporated in the printing module 20.

[0020] The control module 22 as a first module is a module that controls each module (the conveying module 18 and the printing module 20 in this embodiment) provided in the image forming apparatus 10. Note that, in this embodiment, the modules to be controlled by the control module 22 are two, the conveying module 18 and the printing module 20, but the image forming apparatus 10 may have three or more modules to be controlled by the control module 22.

[0021] The communication interface 12, the input / output interface 14, and the memory 16 are connected to a control module 22 via a bus line. In addition, the transport module 18 is connected to the control module 22 so as to be able to communicate with each other, and the print module 20 is connected to the control module 22 so as to be able to communicate with each other.

[0022] 2 is a detailed schematic diagram of the transport module 18, the print module 20, and the control module 22 according to the present embodiment. With reference to FIG. 2, the transport module 18, the print module 20, and the control module 22 will be described in detail, as well as the method of communication between the control module 22 and the transport module 18, and between the control module 22 and the print module 20.

[0023] The transport module 18 includes a transport controller 30 that controls the transport device in response to instructions from the control module 22. The transport controller 30 includes at least one of a general-purpose processor (e.g., a CPU (Central Processing Unit)) and a dedicated processing device (e.g., an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a programmable logic device).

[0024] In this embodiment, the transport module 18 and the control module 22 (specifically, the transport controller 30 and the processor 38 of the control module 22) are communicatively connected by an electric cable. The electric cable includes a first data line for transmitting data from the processor 38 to the transport controller 30, a clock line for transmitting a clock from the processor 38 to the transport controller 30, and a second data line for transmitting data from the transport controller 30 to the processor 38.

[0025] The print module 20 includes a print controller 32 that controls the print device in response to instructions from the control module 22. The print controller 32 includes at least one of a general-purpose processor (e.g., a CPU) and a dedicated processing device (e.g., an ASIC, an FPGA, or a programmable logic device).

[0026] The print module 20 is also configured to include an optical wireless communication IF (Interface) 34 for performing optical wireless communication. The optical wireless communication IF 34 is configured to include a light receiving unit 34a, a light emitting unit 34b, an optical communication processing unit 34c, a demultiplexing processing unit 34d, and a multiplexing processing unit 34e. The light receiving unit 34a is configured with a light receiving element such as an avalanche photodiode, and receives an optical signal from a communication partner. The light emitting unit 34b is configured with a light emitting element such as an infrared light emitting diode, and transmits an optical signal to the communication partner. The optical communication processing unit 34c, the demultiplexing processing unit 34d, and the multiplexing processing unit 34e are configured with, for example, a microprocessor. The optical communication processing unit 34c performs a photoelectric conversion process to convert an optical signal into an electrical signal, and an electrical-to-optical conversion process to convert an electrical signal into an optical signal. The demultiplexing processing unit 34d demultiplexes the electrical signal obtained by the photoelectric conversion of the optical communication processing unit 34c into a clock and data, and sends them to the print controller 32. The multiplexing processor 34e multiplexes the clock and data from the print controller 32 into an electrical signal and sends it to the optical communication processor 34c.

[0027] The control module 22 is also configured to include an optical wireless communication IF 36 for performing optical wireless communication. The optical wireless communication IF 36 is configured to include a light emitting unit 36a, a light receiving unit 36b, an optical communication processing unit 36c, a multiplexing processing unit 36d, and a demultiplexing processing unit 36e, similar to the optical wireless communication IF 34. The light emitting unit 36a, the light receiving unit 36b, the optical communication processing unit 36c, the multiplexing processing unit 36d, and the demultiplexing processing unit 36e of the optical wireless communication IF 36 are similar to the light emitting unit 34b, the light receiving unit 34a, the optical communication processing unit 34c, the multiplexing processing unit 34e, and the demultiplexing processing unit 34d of the optical wireless communication IF 34, and therefore a duplicated description will be omitted.

[0028] The print module 20 and the control module 22 (specifically, the print controller 32 and the processor 38 of the control module 22) communicate with each other via wireless optical communication.

[0029] Specifically, when sending a signal from the control module 22 to the printing module 20, the processor 38 sends a clock and data to the multiplexing processor 36d, which then multiplexes the clock and data and sends an electrical signal to the optical communication processor 36c. The optical communication processor 36c converts the electrical signal into an optical signal. The optical signal is sent from the light emitter 36a to the printing module 20. The light receiver 34a of the printing module 20 receives the optical signal, and the optical communication processor 34c converts the optical signal into an electrical signal. The demultiplexer 34d demultiplexes the electrical signal into a clock and data and sends them to the printing controller 32.

[0030] Furthermore, when sending a signal from the printing module 20 to the control module 22, the printing controller 32 sends a clock and data to the multiplexing processing unit 34e, which then multiplexes the clock and data and sends the electrical signal to the optical communication processing unit 34c. The optical communication processing unit 34c converts the electrical signal into an optical signal. The optical signal is transmitted from the light emitting unit 34b to the control module 22. The light receiving unit 36b of the control module 22 receives the optical signal, and the optical communication processing unit 36c converts the optical signal into an electrical signal. The demultiplexing processing unit 36e demultiplexes the electrical signal into a clock and data and sends them to the processor 38.

[0031] The control module 22 includes a processor 38. The processor 38 refers to a processor in a broad sense and includes at least one of a general-purpose processor (such as a CPU) and a dedicated processing device (such as a GPU (Graphics Processing Unit), ASIC, FPGA, or programmable logic device). The processor 38 may not be a single processing device, but may be configured by the cooperation of multiple processing devices located at physically separate locations. As shown in FIG. 2, the processor 38 functions as a delay time acquisition unit 40 and a transmission processing unit 42 according to an image formation program stored in the memory 16.

[0032] The delay time acquisition unit 40 identifies a communication delay time caused by optical wireless communication between the control module 22 and another module. In particular, the delay time acquisition unit 40 identifies a communication delay time caused by optical wireless communication between the control module 22 and another module prior to the actual communication between the control module 22 and another module by optical wireless communication. Here, the actual communication means communication performed for the actual processing of the image forming apparatus 10, for example, processing related to an input job.

[0033] In this embodiment, the control module 22 performs optical wireless communication with the printing module 20, so the processing of the delay time acquisition unit 40 will be explained using an example of identifying the communication delay time due to optical wireless communication between the control module 22 and the printing module 20 as the first communication delay time.

[0034] The delay time acquisition unit 40 transmits a test signal to the printing module 20 via optical wireless communication prior to actual communication between the control module 22 and the printing module 20. In response to receiving the test signal, the printing module 20 (specifically, the printing controller 32) returns a response signal (i.e., ACK) to the control module 22 via optical wireless communication. The delay time acquisition unit 40 identifies the communication delay time due to optical wireless communication between the control module 22 and the printing module 20 based on the difference between the time when the test signal is transmitted to the printing module 20 and the time when the response signal corresponding to the test signal is received.

[0035] A specific description will be given with reference to FIG. 3. First, the delay time acquisition unit 40 generates a test signal T, which is an electrical signal, and sends it to the optical communication processing unit 36c. The waveform of the test signal T may be any, but in this embodiment, the test signal T is two pulses of a rectangular wave. The delay time acquisition unit 40 starts transmitting the test signal T to the optical communication processing unit 36c at time t1 and completes it at time t2. Here, the delay time acquisition unit 40 holds the transmission completion time t2 of the test signal T. The optical communication processing unit 36c converts the test signal T into an optical signal, and the light emitting unit 36a transmits the optical signal toward the printing module 20.

[0036] The light receiving unit 34a of the print module 20 receives the optical signal, and the optical communication processing unit 34c converts the optical signal into an electrical test signal T and sends the test signal T to the print controller 32. The print controller 32 starts receiving the test signal T at time t3 and completes it at time t4. Here, the reception start time t3 of the test signal T is slightly delayed from the transmission start time t1 of the test signal T, and the reception completion time t4 of the test signal T is slightly delayed from the transmission completion time t2 of the test signal T. This is because it takes time for the electrical-optical conversion process by the optical communication processing unit 36c and the photoelectric conversion process by the optical communication processing unit 34c. The time difference between time t1 and time t3 is the same as the time difference between time t2 and time t4.

[0037] When the print controller 32 completes receiving the test signal T, it generates a response signal A, which is an electrical signal corresponding to the test signal T, and sends it to the optical communication processing unit 34c. The waveform of the response signal A may be any type, but in this embodiment, the response signal A is a single pulse of a rectangular wave. The transmission start time of the response signal A is time t4, which is the time when reception of the test signal T is completed. The optical communication processing unit 34c converts the response signal A into an optical signal, and the light emitting unit 34b transmits the optical signal toward the control module 22.

[0038] The light receiving unit 36b of the control module 22 receives the optical signal, and the optical communication processing unit 36c converts the optical signal into a response signal A and sends the response signal A to the processor 38. The processor 38 starts receiving the response signal A at time t5. Here again, since it takes time for the electrical-to-optical conversion process by the optical communication processing unit 34c and the optical-to-electrical conversion process by the optical communication processing unit 36c, the reception start time t5 of the response signal A is slightly delayed from the transmission start time t4 of the response signal A. Note that the time difference between time t4 and time t5 is the same as the time difference between time t1 and time t3 and the time difference between time t2 and time t4.

[0039] The delay time acquisition unit 40 identifies the communication delay time due to the optical wireless communication between the control module 22 and the printing module 20 based on the differential time DT (seconds) between the transmission completion time t2 of the test signal T and the reception start time t5 of the response signal A. In this embodiment, the differential time DT is the sum of the communication delay time when the test signal T is transmitted from the control module 22 to the printing module 20 and the communication delay time when the response signal A is transmitted from the printing module 20 to the control module 22, so the delay time acquisition unit 40 identifies half of the differential time DT, i.e., (DT / 2), as the communication delay time due to the optical wireless communication between the control module 22 and the printing module 20.

[0040] By the delay time acquisition unit 40 identifying the communication delay time due to optical wireless communication between the control module 22 and the printing module 20, the control module 22 can transmit control signals to the printing module 20 and other modules at a timing that takes into account the communication delay time.

[0041] As described above, the delay time acquisition unit 40 specifies the communication delay time due to the optical wireless communication between the control module 22 and the printing module 20 prior to the actual communication between the control module 22 and the printing module 20. In particular, when it is determined that a process using the printing module 20 is to be executed, the delay time acquisition unit 40 specifies the communication delay time due to the optical wireless communication between the control module 22 and the printing module 20 prior to the execution of the process. As a result, the communication delay time is identified before processing using the printing module 20, and control signals can be transmitted to the printing module 20 and other modules at a timing that takes into account the communication delay time from the point in time when the control module 22 starts controlling the printing module 20.

[0042] In particular, since the printing module 20 is a module that controls the printing process, when it is determined that the printing process is to be executed (for example, when a print job is input to the image forming device 10), the delay time acquisition unit 40 will determine the communication delay time due to optical wireless communication between the control module 22 and the printing module 20 before the printing process is executed.

[0043] Returning to Fig. 2, the transmission processing unit 42 performs processing for transmitting control signals to other modules. In particular, the transmission processing unit 42 transmits control signals to each module at a timing based on the communication delay time identified by the delay time acquisition unit 40. For example, if the communication delay time between the control module 22 and the printing module 20 is (DT / 2) seconds, when the transmission processing unit 42 wants to start control of the printing process by the printing module 20 at time tt, it transmits a control signal for instructing the printing module 20 to perform the printing process at time (tt-DT / 2), which is (DT / 2) seconds earlier than time tt.

[0044] In addition, when it is desired to synchronously control multiple modules including the printing module 20 (i.e., when it is desired to start control of each process by multiple modules simultaneously), the transmission processing unit 42 transmits control signals to modules other than the printing module 20 at a timing based on the communication delay time due to the optical wireless communication between the control module 22 and the printing module 20.

[0045] For example, when a printing process is performed by a printing device on a print medium transported by a transport device, in order to correctly print image data specified in a print job on the print medium, it is necessary to match the timing of the transport process by the print processing transport device and the execution of the print process by the printing device. Therefore, it is necessary to control the transport module 18 and the print module 20 in a synchronous manner. As described above, in this embodiment, since the control module 22 and the transport module 18 are connected by an electric cable, the communication delay time between the two modules is considered to be zero. Therefore, when controlling the transport module 18 and the print module 20 in a synchronous manner, the transmission processing unit 42 first transmits a control signal to instruct the print module 20 to perform the print process, and transmits a control signal to instruct the transport module 18 to perform the transport process after (DT / 2) seconds, which is the communication delay time. As a result, the time when the control signal transmitted by the transmission processing unit 42 is received by the transport module 18 (specifically the transport controller 30) and the time when the control signal is received by the print module 20 (specifically the print controller 32) match, and the transport module 18 and the print module 20 can be controlled in a synchronous manner.

[0046] In this embodiment, the control module 22 and the transport module 18 are connected by an electric cable, but the transport module 18 may also be provided with an optical wireless communication IF so that the control module 22 and the transport module 18 communicate with each other via optical wireless communication. In this case, the delay time acquisition unit 40 can identify the communication delay time caused by the optical wireless communication between the control module 22 and the transport module 18 as the second communication delay time, in a similar manner to the communication delay time caused by the optical wireless communication between the control module 22 and the print module 20.

[0047] Furthermore, the transmission processing unit 42 can determine the transmission timing of the control signal to be sent to the conveying module 18 and the printing module 20 based on a first communication delay time caused by optical wireless communication between the control module 22 and the printing module 20, and a second communication delay time caused by optical wireless communication between the control module 22 and the conveying module 18.

[0048] For example, assume that a first communication delay time caused by optical wireless communication between the control module 22 and the print module 20 is (DT1 / 2) seconds, and a second communication delay time caused by optical wireless communication between the control module 22 and the transport module 18 is (DT2 / 2) seconds. In this case, when the transmission processing unit 42 transmits a control signal to the print module 20 at time tt, the transmission processing unit 42 transmits a control signal to the transport module 18 at time (tt-((DT2 / 2)-(DT1 / 2))). As a result, the time at which the control signal transmitted by the transmission processing unit 42 is received by the transport module 18 matches the time at which the control signal is received by the print module 20, and the transport module 18 and the print module 20 can be controlled in a synchronized manner.

[0049] After the main communication between the control module 22 and the printing module 20 is started, the processor 38 can perform clock synchronization processing to synchronize the clocks used in the optical wireless communication between the control module 22 and the printing module 20 based on the clock signal used in the optical wireless communication that is transmitted from the printing module 20 together with the data. Since a conventional method can be used for the clock synchronization processing method, a description thereof will be omitted here.

[0050] The image forming apparatus 10 according to the present embodiment has been outlined above. The flow of processing performed by the image forming apparatus 10 will now be described with reference to the flowchart shown in FIG.

[0051] In step S10, when a print job (including processing using the print module 20) is input to the image forming apparatus 10, the delay time acquisition unit 40 sends a test signal T, which is an electrical signal, to the optical communication processing unit 36c prior to main communication between the control module 22 and the print module 20. At this time, the delay time acquisition unit 40 holds the transmission completion time of the test signal T (time t2 in FIG. 3). The optical communication processing unit 36c converts the test signal T into an optical signal, and the light emitting unit 36a transmits the optical signal to the print module 20.

[0052] In step S12, the light receiving unit 34a of the print module 20 receives the optical signal transmitted in step S10 and transmits it to the optical communication processing unit 34c. The optical communication processing unit 34c converts the optical signal into an electrical signal and transmits the test signal T, which is an electrical signal, to the print controller 32.

[0053] In step S14, the print controller 32 sends an electrical response signal A to the optical communications processing unit 34c in response to receiving the test signal T. The optical communications processing unit 34c converts the response signal A into an optical signal, and the light emitting unit 34b transmits the optical signal to the control module 22.

[0054] In step S16, the light receiving unit 36b of the control module 22 receives the optical signal transmitted in step S14 and transmits it to the optical communication processing unit 36c. The optical communication processing unit 36c converts the optical signal into an electrical signal and transmits a response signal A of the electrical signal to the processor 38.

[0055] In step S18, the delay time acquisition unit 40 determines a communication delay time due to the optical wireless communication between the control module 22 and the printing module 20 based on the difference between the transmission completion time of the test signal T stored in step S10 and the time at which the response signal A was received in step S16 (time t5 in FIG. 3). When the communication delay time is determined, main communication between the control module 22 and the printing module 20 is started.

[0056] In step S20 after the start of communication, the processor 38 sends a clock and data for optical wireless communication (e.g., a control signal to the print module 20) to the multiplexing processor 36d. The multiplexing processor 36d multiplexes the clock and data and sends them to the optical communication processor 36c, which converts the multiplexed electrical signal into an optical signal. The light emitter 36a transmits the optical signal to the print module 20.

[0057] In step S22, the light receiving unit 34a of the printing module 20 receives the optical signal transmitted in step S20 and transmits it to the optical communication processing unit 34c. The optical communication processing unit 34c converts the optical signal into an electrical signal and transmits the clock and data of the electrical signal to the printing controller 32. The printing controller 32 executes various processes based on the received data. Data is also transmitted from the printing module 20 to the control module 22. Specifically, the printing controller 32 transmits the clock and data for optical wireless communication to the multiplexing processing unit 34e. The multiplexing processing unit 34e multiplexes the clock and data and transmits them to the optical communication processing unit 34c, which converts the multiplexed electrical signal into an optical signal. The light emitting unit 34b transmits the optical signal to the control module 22.

[0058] In step S24, the light receiving unit 36b of the control module 22 receives the optical signal transmitted in step S22 and transmits it to the optical communication processing unit 36c. The optical communication processing unit 36c converts the optical signal into an electrical signal and transmits the clock and data of the electrical signal to the processor 38. The processor 38 adjusts the timing of the clock used when performing optical wireless communication from the control module 22 to the printing module 20, based on the clock transmitted from the printing module 20. As a result, the clocks used for optical wireless communication are synchronized between the control module 22 and the printing module 20.

[0059] Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the present invention. [Explanation of symbols]

[0060] 10 image forming device, 12 communication interface, 14 input / output interface, 16 memory, 18 transport module, 20 printing module, 22 control module, 30 transport controller, 32 printing controller, 34, 36 optical wireless communication IF, 34a, 36b light receiving unit, 34b, 36a light emitting unit, 34c, 36c optical communication processing unit, 34d, 36e demultiplexing processing unit, 34e, 36d multiplexing processing unit, 38 processor, 40 delay time acquisition unit, 42 transmission processing unit.

Claims

1. a first module including a processor; and a second module that communicates with the first module via optical wireless communication; The processor, transmitting a test signal to the second module via optical wireless communication prior to the main communication between the first module and the second module; determining a first communication delay time caused by the optical wireless communication between the first module and the second module based on a difference between a time when the test signal is transmitted to the second module and a time when a response signal transmitted from the second module via optical wireless communication in response to the test signal is received; transmitting a control signal to the second module for causing the second module to execute the process at a time that is earlier than a time at which the second module is to start the process by the first communication delay time; 1. An image forming apparatus comprising:

2. The processor, when it is determined that a process using the second module is to be executed, specifying the first communication delay time prior to the process being executed; 2. The image forming apparatus according to claim 1,

3. the second module is a print module that controls a print process for printing on a print medium in response to an instruction from the first module; The processor, when it is determined that the printing process is to be executed, the first communication delay time is specified before the printing process is executed; 3. The image forming apparatus according to claim 2,

4. a transport module that controls a transport process for transporting the print medium in response to an instruction from the first module; The processor, transmitting an instruction to the transport module at a timing based on a first communication delay time caused by the optical wireless communication between the first module and the second module; 4. The image forming apparatus according to claim 1, wherein the first and second electrodes are arranged in a first direction.

5. the first module and the transport module communicate with each other through optical wireless communication; The processor, transmitting a test signal to the transport module via optical wireless communication prior to the main communication between the first module and the transport module; determining a second communication delay time caused by the optical wireless communication between the first module and the transport module based on a difference between a time when the test signal is transmitted to the transport module and a time when a response signal transmitted from the transport module via optical wireless communication in response to the test signal is received; transmitting an instruction to the transport module at a timing based on the first communication delay time and the second communication delay time; 5. The image forming apparatus according to claim 4.

6. A computer including a first module and a second module that communicates with the first module via optical wireless communication, transmitting a test signal to the second module via optical wireless communication prior to the main communication between the first module and the second module; determining a first communication delay time caused by optical wireless communication between the first module and the second module based on a difference between a time when the test signal is transmitted to the second module and a time when a response signal transmitted from the second module via optical wireless communication in response to the test signal is received; transmitting a control signal to the second module for causing the second module to execute the process at a time that is earlier than a time at which the second module is to start the process by the first communication delay time; 23. An image forming program comprising:

Images