Image forming apparatus

Abstract

To enable a page on which an image is formed again to be easily specified in the event of a failure in a control unit which instructs transfer of image data.SOLUTION: A printer engine control unit 150 switches a synchronization signal from the first state to the second state when predetermined processing about partial image data is completed, switches the synchronization signal from the second state to the first state after a printer controller control unit 140 recognizes the switching of the synchronization signal, and instructs the printer controller control unit 140 to transfer the partial image data of the next page. When the synchronization signal is switched from the first state to the second state and then switched from the second state to the first state, the printer controller control unit 140 transfers the partial image data of the instructed page to the printer engine control unit 150.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an image forming apparatus. [Background Art]

[0002] Conventionally, image forming apparatuses that form an image on a medium have been used. In an image forming apparatus, when forming an image, image data for forming the image is transferred to a printer engine control unit that actually controls image formation.

[0003] Specifically, when the image forming apparatus detects that the leading edge of the medium has reached the write sensor, it sets FSYNC, which is a synchronization signal indicating print start timing, to ON and starts transferring image data (see Patent Document 1). [Prior Art Documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2009-3215 [Summary of the Invention] [Problem to be Solved by the Invention]

[0005] However, in conventional control methods, when DMA (Direct Memory Access) is employed to achieve higher speed and lower power consumption for the image data transfer interface to the printer engine control unit, there has been a problem that reprinting becomes difficult when a failure occurs.

[0006] This problem arises because the speed of data transfer to the printer engine control unit is higher than the speed of data transfer from the printer engine control unit to an exposure unit. Specifically, if an error such as a paper jam occurs during data transfer from the printer engine control unit to the exposure unit, the printer controller control unit, which generally controls the overall processing of the image forming apparatus, cannot determine from which page reprinting should be performed.

[0007] Therefore, one or more aspects of this disclosure aim to enable a control unit that instructs the transfer of image data to easily identify the page on which to form the image again in the event of a failure. [Means for solving the problem]

[0008] An image forming apparatus according to a first aspect of the present disclosure comprises a first control unit that controls the process of forming an image represented by image data on a medium, and a second control unit that transfers the image data to the first control unit page by page according to a synchronization signal from the first control unit, wherein the first control unit switches the synchronization signal from a first state to a second state when a predetermined process is completed with respect to a portion image data which is the image data for one page, and after the second control unit recognizes the switch of the synchronization signal, it switches the synchronization signal from the second state to the first state, thereby instructing the second control unit to transfer the portion image data for the next page, and after the synchronization signal has been switched from the first state to the second state and then switched back from the second state to the first state, the second control unit transfers the portion image data for the instructed page to the first control unit.

[0009] An image forming apparatus according to a second aspect of the present disclosure comprises a first control unit that controls the process of forming an image represented by image data on a medium, and a second control unit that transfers the image data to the first control unit page by page in accordance with a synchronization signal from the first control unit, wherein if a predetermined error occurs during the transfer of partial image data, which is one page of the image data, the first control unit sends a transfer stop instruction to the second control unit to stop the transfer, and the second control unit stops the transfer of the partial image data during the transfer in response to the transfer stop instruction. [Effects of the Invention]

[0010] According to one or more aspects of this disclosure, a control unit that instructs the transfer of image data can easily identify the page on which to re-form the image in the event of a failure. [Brief explanation of the drawing]

[0011] [Figure 1] This is a longitudinal cross-sectional view schematically showing the configuration of the image forming apparatus according to Embodiments 1 and 2. [Figure 2] This is a block diagram schematically showing the configuration of the control system of the image forming apparatus in Embodiments 1 and 2. [Figure 3] This is a timing chart of the control system's operation in Embodiment 1. [Figure 4] This is a timing chart of the control system's operation in Embodiment 2. [Figure 5] (A) and (B) are block diagrams showing hardware configuration examples. [Modes for carrying out the invention]

[0012] Embodiment 1. Figure 1 is a longitudinal cross-sectional view schematically showing the configuration of the image forming apparatus 100 according to Embodiment 1. Here, we will describe a monochrome image forming apparatus 100 that forms black and white images using an electrophotographic method as an example, but Embodiment 1 is not limited to such an example. It may also be a color image forming apparatus.

[0013] The image forming apparatus 100 has a printing mechanism 101, which is an independent image drum unit, arranged in a transport path that moves from the insertion side to the discharge side of the medium.

[0014] The printing mechanism 101 is an electrophotographic LED printing mechanism (image forming mechanism) for forming a black (K) image. The printing mechanism 101 includes a photosensitive drum 102, a charging roller 103, a developing roller 104, a developing blade 105, a supply roller 106, a static elimination light irradiation unit 107, and a toner cartridge 108.

[0015] The photosensitive drum 102 is an image carrying portion (image carrying member) that carries an image. For example, the photosensitive drum 102 carries an electrostatic latent image and a toner image, which is a developer image formed by attaching developer to the electrostatic latent image. The charging roller 103 is a charging portion that uniformly charges the surface of the photosensitive drum 102. The developing roller 104 is a developing portion that forms a toner image as a developer image by causing toner, which is a developer, to adhere to the electrostatic latent image formed on the photosensitive drum 102.

[0016] The developing blade 105 is a regulating portion that thins the toner on the surface of the developing roller 104. The supply roller 106 is a supply portion that supplies the toner stored in the toner cartridge 108 to the developing roller 104.

[0017] The static elimination light irradiation unit 107 eliminates static charge from the photosensitive drum 102 by irradiating the photosensitive drum 102 with static elimination light. The toner cartridge 108 is a toner storage portion (developer storage portion) that stores toner. The toner cartridge 108 stores black toner.

[0018] An LED (Light Emitting Diode) head 109 is disposed above the photosensitive drum 102 of the printing mechanism 101. The LED head 109 is an exposure portion that forms an electrostatic latent image by exposing the surface of the photosensitive drum 102.

[0019] Then, the LED head 109 causes the LED array to emit light in accordance with image data, whereby the surface of the photosensitive drum 102 is exposed, and an electrostatic latent image is formed on the surface of the photosensitive drum 102. A toner image is formed when toner from the developing roller 104 adheres to the electrostatic latent image by electrostatic force.

[0020] Further, the image forming apparatus 100 includes a paper feeding mechanism (medium feeding mechanism) 110 for feeding paper as a medium. The paper feeding mechanism 110 includes a paper storage cassette 111, a hopping roller 112, and transport roller groups 113 and 114.

[0021] The paper storage cassette 111 is a paper storage section (media storage section) for storing paper. The hopping roller 112 takes out the paper stored in the paper storage cassette 111 one sheet at a time.

[0022] The transport roller groups 113 and 114 correct the skew of the single sheet of paper picked up by the hopping roller 112 and transport that single sheet of paper to the printing mechanism 101. Sensors 115, 116, and 117 are positioned along the paper transport path to detect the position or jam of a single sheet of paper. Since the transfer of image data to the LED head 109 begins when sensor 117 detects the beginning of the paper, this sensor 117 is also referred to as the write sensor 117.

[0023] A transfer roller 120 is positioned below the photosensitive drum 102 of the printing mechanism 101. A transfer voltage is applied to the transfer roller 120, and the toner image formed on the surface of the photosensitive drum 102 is transferred to a sheet of paper that has been transported by the transfer roller 120. In other words, the transfer roller 120 functions as a transfer unit that transfers the toner image formed on the photosensitive drum 102 to a medium.

[0024] After the toner image is transferred, the sheet of paper separated from the printing mechanism 101 is sent to the fixing mechanism 130, which acts as the fixing unit. The fixing mechanism 130 includes a heat roller 131, a pressure roller 132 that pressurizes the heat roller 131, a heater 133 that heats the heat roller 131, and a thermistor 134 that detects the temperature of the heat roller 131.

[0025] This fixing mechanism 130 heats and melts the toner on a single sheet of paper that has been transported, thereby fixing the toner image onto that sheet of paper. The heat roller 131 is driven by a heater motor (not shown), and the pressure roller 132 rotates in accordance with the rotation of the heat roller 131.

[0026] The heater 133 is a halogen lamp positioned inside the heat roller 131 and serves as a heat source. A thermistor 134 is positioned near the surface of the heat roller 131. Furthermore, a sensor 1135 is located downstream of the heat roller 131 to detect the paper position or jam.

[0027] A sheet of paper on which the toner image has been fixed by the fixing mechanism 130 is discharged outside the image forming apparatus 100 by the discharge roller groups 136 and 137.

[0028] Figure 2 is a block diagram schematically showing the configuration of the control system of the image forming apparatus 100. The control system of the image forming apparatus 100 includes a printer controller control unit 140 and a printer engine control unit 150. The printer engine control unit 150 is also referred to as the first control unit, and the printer controller control unit 140 is also referred to as the second control unit.

[0029] The printer controller control unit 140 and the printer engine control unit 150 are connected by a first signal path 160, a second signal path 161, and a third signal path 162. Furthermore, the printer engine control unit 150 and the LED head 109 are connected by a fourth signal path 163.

[0030] Each of the first signal path 160, the second signal path 161, the third signal path 162, and the fourth signal path 163 may be at least partially wireless, but here we will describe them as being wired.

[0031] The printer controller control unit 140 includes an image data storage unit 141, a transfer controller 142, and an image processing controller 143.

[0032] The image data storage unit 141 stores image data representing the image to be formed. The image data is separated by page. The image data for one page is also called partial image data.

[0033] The transfer controller 142 transfers the image data stored in the image data storage unit 141 to the printer engine control unit 150 in response to instructions from the image processing controller 143. Here, the transfer controller 142 reads the image data from the image data storage unit 141 one page at a time in response to instructions from the image processing controller 143, and transfers the image data for one page that has been read to the printer engine control unit 150.

[0034] Specifically, the transfer controller 142 functions as a DMA controller, reading image data page by page from the image data storage unit 141, which acts as memory, and transferring the image data for each page to the printer engine control unit 150. Here, the transfer controller 142 transfers image data via the third signal path 162 using the video interface LVDS (Low Voltage Differential Signaling).

[0035] The image processing controller 143 operates via CU firmware and primarily performs image data generation, editing, and processing. Furthermore, the image processing controller 143 sends and receives commands via the first signal path 160 using a UART (Universal Asynchronous Receiver Transmitter), which is a command interface for controlling the printer engine control unit 150.

[0036] Furthermore, the image processing controller 143 receives a synchronization signal from the printer engine control unit 150 via the second signal path 161, thereby detecting the timing of image data transmission and understanding which page the printer engine control unit 150 is processing.

[0037] Furthermore, the image processing controller 143 instructs the transfer controller 142 to transfer images. For example, the image processing controller 143 instructs the transfer controller 142 to transfer the image data of the required page to the printer engine control unit 150. Specifically, when the printer engine control unit 150 sets the synchronization signal to ON, the image processing controller 143 instructs the transfer controller 142 to transfer the image data of the next page to be processed.

[0038] As described above, the printer controller control unit 140 transfers image data for forming an image to the printer engine control unit 150 one page at a time, in accordance with the synchronization signal from the printer engine control unit 150. Specifically, when the synchronization signal is switched from a first state (in this case, ON) to a second state (in this case, OFF), and then switched back from the second state to the first state, the printer controller control unit 140 transfers the partial image data of the page instructed by the printer engine control unit 150 to the printer engine control unit 150.

[0039] The printer engine control unit 150 receives image data from the printer controller control unit 140 and controls the process of forming an image on the medium based on the transferred image data.

[0040] The printer engine control unit 150 includes a relay controller 151, a temporary storage unit 152, and an image forming controller 153. Here, the relay controller 151 and the image forming controller 153 are connected by a fifth signal path 154. The fifth signal path 154 can be wireless in part, but here it will be described as being wired.

[0041] The relay controller 151 operates using relay firmware and controls the process of relaying image data between the image forming controller 153 and the printer controller control unit 140.

[0042] For example, the relay controller 151 receives commands from the image processing controller 143 via UART and forwards them to the image forming controller 153. Furthermore, the relay controller 151 receives commands from the image forming controller 153 via an internal bus (not shown) and transmits them to the image processing controller 143 via UART.

[0043] Furthermore, the relay controller 151 receives image data (in this case, partial image data) from the transfer controller 142. For example, when the relay controller 151 receives a print process start command via UART from the image processing controller 143, it sets the synchronization signal of the second signal path 161 to ON and receives image data from the transfer controller 142 using LVDS. The relay controller 151 then stores the received image data in the temporary storage unit 152.

[0044] The temporary storage unit 152 is composed of a storage device such as RAM (Random Access Memory) that can store partial image data, which is image data for at least one page. The temporary storage unit 152 then stores the partial image data received by the relay controller 151.

[0045] The image forming controller 153 controls a series of processes, including transporting a medium, transferring an image to the medium, fixing the transferred image to the medium, and ejecting the medium with the image fixed, by controlling each part shown in Figure 1.

[0046] For example, the image forming controller 153 reads partial image data, which is image data for one page, from the temporary storage unit 152 and sends that partial image data to the LED head 109. Specifically, when paper is transported onto the write sensor 117 shown in Figure 1, the image forming controller 153 sets the internal synchronization signal in the fifth signal path 154 to ON and transfers the image data for one page stored in the temporary storage unit 152 to the LED head 109.

[0047] Figure 3 is a timing chart of the control system operation in Embodiment 1. In this explanation, we will use an example where a jam occurs during printing of the second page in a two-page single-sided print job, and then the jammed second page is reprinted.

[0048] First, after the image processing controller 143 has completed the generation, editing, and deployment of the first page of image data to the image data storage unit 141, it sends an image setup command to the relay controller 151 via UART (S10).

[0049] When the relay controller 151 receives an image setup command, it sends the image setup command to the image forming controller 153 via an internal bus (not shown) (S11).

[0050] When the image forming controller 153 receives an image setup command, it picks up a sheet of paper and starts transporting that sheet of paper, and performs other printing preparations. Once the preparations are complete, it sends an image setup authentication command to the relay controller 151 via an internal bus (not shown) (S12).

[0051] When the relay controller 151 receives an image setup authentication command, it sends the image setup authentication command to the image processing controller 143 via UART (S13).

[0052] When the image processing controller 143 receives the image setup authentication command, it sends a print process start command to the relay controller 151 via UART (S14).

[0053] When the relay controller 151 receives a print process start command, it sets the synchronization signal in the second signal path 161 to ON (S15) and transmits the print process start command to the image forming controller 153 via an internal bus (not shown) (S16).

[0054] When the synchronization signal is set to ON, the image processing controller 143 instructs the transfer controller 142 to transmit the image data for the first page, and the transfer controller 142 transfers the image data to the relay controller 151 using LVDS (S17). At this point, the relay controller 151 stores the image data received via LVDS in the temporary storage unit 152 while transferring the print image data to the image forming controller 153.

[0055] When the leading edge of the paper reaches the write sensor 117, the image forming controller 153 detects a write sensor ON interrupt (S18), sets the internal synchronization signal to ON (S19), and transfers the image data to the LED head 109 (S20).

[0056] At this point, the image processing controller 143 has already completed the generation, editing, and unfolding of the image data for the second page, and, as with the first page, sends an image setup command (S21, S22), receives an image setup authentication command (S23, S24), and sends a print process start command (S25, S26).

[0057] Next, once all the image data on the first page has been transferred to the LED head 109, the image forming controller 153 sets the internal synchronization signal to OFF (S27). Subsequently, an internal signal OFF interrupt occurs (S28), and when the relay controller 151 detects this OFF interrupt, it sets the synchronization signal to OFF (S29).

[0058] After the synchronization signal is set to OFF, the relay controller 151 sets the synchronization signal to ON again after a predetermined time of 50 ms (S30) because the command to start the second page print process has already been sent from the image processing controller 143 in step S21.

[0059] Subsequently, similar to the image data for the first page, the image data for the second page is transferred from the transfer controller 142 to the relay controller 151 at the instruction of the image processing controller 143 (S31). At this point, the relay controller 151 stores the image data for the second page in the temporary storage unit 152 while transferring it to the image forming controller 153.

[0060] When the leading edge of the second page of paper reaches the write sensor 117, the image forming controller 153 detects a write sensor ON interrupt (S32), sets the internal synchronization signal to ON (S33), and transfers the image data of the second page to the LED head 109 (S34), just as it did with the first page of paper.

[0061] Next, let's assume a jam occurs while transferring the second page of image data to the LED head 109 (S35).

[0062] When a jam occurs, the image forming controller 153 sets the internal signal to OFF (S36). When the internal signal is set to OFF, an internal signal OFF interrupt occurs (S37), and the relay controller 151 detects this OFF interrupt and sets the synchronization signal to OFF (S38).

[0063] Furthermore, the image forming controller 153 sends a jam occurrence notification command to the image processing controller 143 via the relay controller 151 (S39, S40).

[0064] When the image processing controller 143 receives a jam notification command, it determines that a jam has occurred in the second page of image data that was transferred immediately before. Specifically, if the image processing controller 143 receives a jam notification command for the second page of image data before the synchronization signal is turned OFF, it can determine that a jam has occurred in the second page of image data, which has not yet been transferred to the LED head 109.

[0065] Therefore, when reprinting after the jam is cleared, the image processing controller 143 sends an image setup command (S41, S42), receives an image setup authentication command (S43, S44), and sends a print process start command (S45, S46), as described above. This allows the image processing controller 143 to instruct the transfer controller 142 to transfer the image data of the second page to the relay controller 151 again using LVDS (S47).

[0066] As described above, when the printer engine control unit 150 completes the predetermined processing (in this case, transfer to the LED head 109) for partial image data, which is image data for one page, it switches the synchronization signal from the first state (in this case, ON) to the second state (in this case, OFF). After the printer controller control unit 140 recognizes this change in the synchronization signal, it switches the synchronization signal back from the second state to the first state, thereby instructing the printer controller control unit 140 to transfer the partial image data for the next page.

[0067] Specifically, after the image forming controller 153 has finished sending partial image data to the LED head 109, the relay controller 151 switches the synchronization signal from a first state (in this case, ON) to a second state (in this case, OFF), and after a predetermined period of time has elapsed, switches the synchronization signal back from the second state to the first state. The switch of the synchronization signal from the first state to the second state allows the image processing controller 143 to recognize that the predetermined processing (in this case, transfer to the LED head 109) of the partial image data of the page that was just transmitted has been completed. The predetermined period here can be any period during which the image processing controller 143 can recognize the switch of the synchronization signal, and can be set from the operating clock of the image processing controller 143, for example. For example, the period can be longer than the period of the operating clock of the image processing controller 143. Then, when the synchronization signal is switched from the second state to the first state, the image processing controller 143 can recognize the timing for transmitting the partial image data of the next page and can instruct the transfer controller 142 to transfer the partial image data of the next page.

[0068] The ON and OFF states of the synchronization signal may be reversed from those described above.

[0069] As described above, according to Embodiment 1, after the synchronization signal is turned OFF, the relay controller 151 sets the synchronization signal ON after a period of time (here, 50 ms) has elapsed in which the image processing controller 143 can reliably recognize that the synchronization signal is OFF, and requests the image processing controller 143 to transfer the image data for the next page. Therefore, even if an error such as a jam occurs during printing, the image processing controller 143 does not yet transfer the image data for the next page. As a result, when reprinting after clearing the jam, the image processing controller 143 can recognize the page that was being processed when the error occurred, and can easily reprint by simply resending the image data of the page that was transferred immediately before.

[0070] Embodiment 2. As shown in Figure 1, the schematic configuration for forming an image in the image forming apparatus 200 according to Embodiment 1 is the same as that of the image forming apparatus 100 according to Embodiment 1. The image forming apparatus 200 according to Embodiment 2 differs from the image forming apparatus 100 according to Embodiment 1 in the configuration of its control system.

[0071] As shown in Figure 2, the control system of the image forming apparatus 200 includes a printer controller control unit 240 and a printer engine control unit 250.

[0072] The printer controller control unit 240 includes an image data storage unit 141, a transfer controller 242, and an image processing controller 243. The image data storage unit 141 of the printer controller control unit 240 in Embodiment 2 is the same as the image data storage unit 141 of the printer controller control unit 140 in Embodiment 1.

[0073] The transfer controller 242 performs the same processing as the transfer controller 142 in Embodiment 1, and also stops the transfer of image data in progress using LVDS in response to a request from the image processing controller 143. The transfer of image data is performed via the third signal path 162, as in Embodiment 1.

[0074] In addition to performing the same processing as the image processing controller 143 in Embodiment 1, the image processing controller 243 sends a data transfer stop command to the transfer controller 242 when it receives a data transfer stop command from the printer engine control unit 250 via the first signal path 160 using the UART.

[0075] The printer engine control unit 250 includes a relay controller 251, a temporary storage unit 152, and an image forming controller 253. The temporary storage unit 152 of the printer engine control unit 250 in Embodiment 2 is the same as the temporary storage unit 152 of the printer engine control unit 150 in Embodiment 1.

[0076] The relay controller 251 performs the same processing as the relay controller 151 in Embodiment 1. In addition, when it receives a paper size error command from the image forming controller 253 via an internal bus (not shown), it transmits the paper size error command to the image processing controller 243 using the UART. Furthermore, when the relay controller 251 receives a data transfer stop command from the image forming controller 253, it transmits a data transfer stop instruction command to the image processing controller 243 using the UART.

[0077] The image forming controller 253 performs the same processing as the image forming controller 153 in Embodiment 1. In addition, when it detects a paper size error as a media size error, it sends a paper size error command to the relay controller 251 via an internal bus (not shown). The image forming controller 253 also sends a data transfer stop command to the relay controller 251 via an internal bus (not shown).

[0078] As described above, in Embodiment 2, if a predetermined error (in this case, a paper size error) occurs during the transfer of partial image data, the printer engine control unit 150 sends a transfer stop instruction to the printer controller control unit 140 to stop the transfer. This transfer stop instruction is notified to the printer controller control unit 140 using UART. Upon receiving a transfer stop instruction, the printer controller control unit 140 stops the transfer of the partial image data midway through the transfer in accordance with the transfer stop instruction.

[0079] Figure 4 is a timing chart of the control system operation in Embodiment 2. In the operation of Embodiment 2, in single-sided printing of one page, image data of a paper size larger than the paper size in the tray (e.g., A3 portrait paper size) is transferred from the printer controller control unit 240, and a paper size error occurs thereafter, resulting in a reprint operation.

[0080] First, once the image processing controller 243 has completed the generation and editing of image data for one A3 portrait page, and the processing of expanding it to the image data storage unit 141, it sends an image setup command to the relay controller 251 via UART (S60).

[0081] When the relay controller 251 receives an image setup command, it sends the image setup command to the image forming controller 153 via an internal bus (not shown) (S61).

[0082] When the image forming controller 253 receives an image setup command, it picks up a sheet of paper and starts transporting that sheet of paper, among other things, to prepare for printing. Once the preparation is complete, it sends an image setup authentication command to the relay controller 251 via an internal bus (not shown) (S62).

[0083] When the relay controller 251 receives an image setup authentication command, it sends the image setup authentication command to the image processing controller 243 via UART (S63).

[0084] When the image processing controller 243 receives the image setup authentication command, it sends a print process start command to the relay controller 251 via UART (S64).

[0085] When the relay controller 251 receives a print process start command, it sets the synchronization signal in the second signal path 161 to ON (S65) and transmits the print process start command to the image forming controller 153 via an internal bus (not shown) (S66).

[0086] When the synchronization signal is set to ON, the image processing controller 243 instructs the transfer controller 242 to send image data for one A3 portrait page, and the transfer controller 242 sends the image data to the relay controller 251 in LVDS (S67). At this point, the relay controller 251 stores the image data received in LVDS in the temporary storage unit 152 and then transfers the print image data to the image forming controller 153.

[0087] When the leading edge of the paper (in this case, A4 portrait size) reaches the write sensor 117, the image forming controller 253 detects a write sensor ON interrupt (S68), sets the internal synchronization signal to ON (S69), and starts transferring the image data to the LED head 109 (S70).

[0088] Subsequently, during data transfer to the LED head 109, when the trailing edge of the paper reaches the write sensor 117, the image forming controller 253 generates an internal signal OFF interrupt (S71).

[0089] Furthermore, the image forming controller 253 detects a paper size error and sends a paper size error command to the image processing controller 243 via the relay controller 251 (S72, S73).

[0090] When the relay controller 251 detects an internal signal OFF interrupt, it sets the synchronization signal to OFF (S74).

[0091] Subsequently, the image forming controller 253 sends a data transfer stop command to the image processing controller 243 via the relay controller 251 in order to stop data transfer using LVDS (S75, S76).

[0092] When the image processing controller 243 receives a data transfer stop command, it issues a transfer stop request to the transfer controller 242 (S77), and when the transfer controller 242 receives the transfer stop request, it stops the data transfer operation using LVDS (S78).

[0093] When the image processing controller 243 receives a data transfer stop command, it determines that an error occurred in the image data for the page that was transferred immediately before. For example, if the image processing controller 243 receives a data transfer stop command for that page of image data before the synchronization signal is turned OFF, it can determine that an error occurred in that image data.

[0094] Therefore, when reprinting after the paper size error has been cleared, the image processing controller 243 sends an image setup command (S79, S80), receives an image setup authentication command (S81, S82), and sends a print process start command (S83, S84), as described above. This allows the image processing controller 243 to have the transfer controller 242 transfer the image data for that one page back to the relay controller 251 using LVDS (S85).

[0095] As described above, according to Embodiment 2, data transfer using LVDS can be stopped immediately after a paper size error occurs, eliminating the need to wait until all LVDS data transfer is complete. This allows for rapid recovery processing after a paper size error occurs.

[0096] The transfer controllers 142, 242, image processing controller 243, relay controllers 151, 251, and image forming controllers 153, 253 in the embodiments 1 and 2 described above can each be configured as a processing circuit 10 such as a single circuit, a composite circuit, a programmable processor, a programmable parallel processor, an ASIC (Application Specific Integrated Circuit), or an FPGA (Field Programmable Gate Array), as shown in Figure 5(A).

[0097] Furthermore, the image processing controller 243, relay controllers 151 and 251, and image forming controllers 153 and 253 can each be configured, for example, as shown in Figure 5(B), with a memory 11 and a processor 12 such as a CPU (Central Processing Unit) that executes the program stored in the memory 11. Such a program may be provided via a network, or it may be provided by being recorded on a recording medium. That is, such a program may be provided, for example, as a program product.

[0098] As described above, the transfer controllers 142 and 242, the image processing controller 243, the relay controllers 151 and 251, and the image forming controllers 153 and 253 can be implemented by a processing network. For example, the printer engine control units 150 and 250 can be implemented by a first processing network, and the printer controller control units 140 and 240 can be implemented by a second processing network.

[0099] Furthermore, the image data storage unit 141 can be implemented using a storage device such as an HDD (Hard Disc Drive), SSD (Solid State Drive), volatile memory, or non-volatile memory.

[0100] While Embodiments 1 and 2 described above primarily describe image forming apparatuses 100 and 200 as printers, Embodiments 1 and 2 are not limited to these examples. For instance, Embodiments 1 and 2 may also be MFPs (Multi-Function Printers). [Explanation of symbols]

[0101] 100,200 Image forming apparatus, 109 LED head, 140,240 Printer controller control unit, 141 Image data storage unit, 142,242 Transfer controller, 143,243 Image processing controller, 150,250 Printer engine control unit, 151,251 Relay controller, 152 Temporary storage unit, 153,253 Image forming controller.

Claims

1. A first control unit that controls the process of forming an image represented by image data on a medium, The system includes a second control unit that transfers the image data to the first control unit page by page according to a synchronization signal from the first control unit, The first control unit, upon completion of predetermined processing with respect to the partial image data, which is the image data for one page, switches the synchronization signal from the first state to the second state, and after the second control unit recognizes the switch in the synchronization signal, switches the synchronization signal back from the second state to the first state, thereby instructing the second control unit to transfer the partial image data for the next page. The second control unit, after the synchronization signal has been switched from the first state to the second state, and then switched back from the second state to the first state, transfers the portion image data of the indicated page to the first control unit. An image forming apparatus characterized by the following.

2. The first control unit is, A relay controller that receives the aforementioned partial image data, A temporary storage unit for storing the aforementioned partial image data, The system includes an image forming controller that reads the partial image data from the temporary storage unit and sends it to an exposure unit that forms an electrostatic latent image on an image carrier, The second control unit is, An image processing controller that instructs the transfer of the aforementioned image data, An image data storage unit that stores the aforementioned image data, The system includes a transfer controller that, in response to instructions from the image processing controller, reads the image data one page at a time and transfers the read-out image data for one page to the first control unit as partial image data, The relay controller, after the image forming controller has finished sending the partial image data to the exposure unit, switches the synchronization signal from the first state to the second state, and then, after a predetermined period of time has elapsed, switches the synchronization signal back from the second state to the first state. The image forming apparatus according to claim 1, characterized by the following:

3. The transfer controller transfers the partial image data using LVDS (Low Voltage Differential Signaling). The image forming apparatus according to claim 2, characterized by the following:

4. If a predetermined error occurs during the transfer of the partial image data, the first control unit sends a transfer stop instruction to the second control unit to stop the transfer. The second control unit shall, in response to the transfer stop instruction, stop the transfer of the partial image data midway through the transfer. An image forming apparatus according to any one of claims 1 to 3, characterized by the following:

5. The first control unit uses UART (Universal Asynchronous Receiver Transmitter) to notify the second control unit of the instruction to stop the transfer. The image forming apparatus according to claim 4, characterized by the following:

6. A first control unit that controls the process of forming an image represented by image data on a medium, The system includes a second control unit that transfers the image data to the first control unit page by page according to a synchronization signal from the first control unit, If a predetermined error occurs during the transfer of the partial image data, which is the image data for one page, the first control unit sends a transfer stop instruction to the second control unit to stop the transfer. The second control unit shall, in response to the transfer stop instruction, stop the transfer of the partial image data midway through the transfer. An image forming apparatus characterized by the following.

Images