Image forming system

Abstract

To provide a relay device capable of inhibiting a circuit configuration of an image forming device from being complicated.SOLUTION: An image forming system has an image forming device and a relay device. The relay device relays communication between an external device and the image forming device. In the relay device, a first serial-parallel conversion part outputs a serial signal from a 0-th connection part to a first connection part as a parallel signal. In the relay device, a first parallel-serial conversion part outputs a parallel signal from the first connection part to the 0-th connection part as a serial signal. In the image forming device, a serial signal from an A-th connection part is input to an A-th switching part when the 0-th connection part is connected to the A-th connection part. In the image forming device, an A-th parallel-serial conversion part outputs a parallel signal from the A-th connection part to the A-th switching part as a serial signal when a first external device is connected to the A-th connection part. The A-th switching part outputs a serial signal input to the A-th switching part to a processor.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] FIELD OF THE INVENTION An embodiment of the present invention relates to an imaging system. [Background technology]

[0002] BACKGROUND ART Conventionally, there is known an image forming apparatus that does not include a control unit and can be connected to one or more external devices (see Patent Document 1). The external device is, for example, a large-capacity paper feeder. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-035380 Summary of the Invention [Problem to be solved by the invention]

[0004] An image forming apparatus may be connected to one or more external devices via a relay device that relays communication between each of the external devices and the image forming apparatus. Each of the one or more external devices connected to the relay device communicates with the image forming apparatus via multiple parallel interfaces provided by the relay device. For this reason, the image forming apparatus is often provided with the same number of parallel interfaces as the number of parallel interfaces provided by the relay device. As a result, the circuit configuration of the image forming apparatus can become complex. This is undesirable because it increases the manufacturing cost of the image forming apparatus.

[0005] The problem to be solved by the present invention is to provide an image forming system that can prevent the circuit configuration of the image forming apparatus from becoming complicated. [Means for solving the problem]

[0006] An image forming system according to an embodiment includes an image forming apparatus, and a relay device connected between the image forming apparatus and one or more external devices controlled by the image forming apparatus, for relaying communication between the one or more external devices and the image forming apparatus, wherein the relay device includes a zeroth connection unit connectable to the image forming apparatus, a first connection unit connectable to a first external device among the one or more external devices, a first serial-to-parallel conversion unit that converts a serial signal input from the zeroth connection unit into a parallel signal and outputs the converted parallel signal to the first connection unit, and a first parallel-to-serial conversion unit that converts the parallel signal input from the first connection unit into a serial signal and outputs the converted serial signal to the zeroth connection unit, The image forming device includes a processor, an Ath connection unit to which either the relay device or the first external device is connected, an Ath switching unit to which a serial signal input from the Ath connection unit is input when the Oth connection unit of the relay device is connected to the Ath connection unit, and an Ath parallel-serial conversion unit that converts a parallel signal input from the Ath connection unit into a serial signal when the first external device is connected to the Ath connection unit and outputs the converted serial signal to the Ath switching unit, and the Ath switching unit outputs the serial signal input to the Ath switching unit to the processor, out of the serial signal input from the relay device and the serial signal input from the first external device via the Ath parallel-serial conversion unit. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a diagram showing an example of a configuration of an image forming system 1 according to an embodiment. [Figure 2] 1 is a diagram showing an example of a state in which an image forming apparatus 10 is connected to a first external apparatus 31 without going through a relay apparatus 20. FIG. [Figure 3] 2 is a diagram showing an example of the configuration of a connection unit 100 of the image forming apparatus 10. FIG. [Figure 4] 2 is a diagram illustrating an example of the configuration of a connection unit 200 of a relay device 20. FIG. [Figure 5]2 is a diagram illustrating an example of the configuration of a connection unit 201 of a relay device 20. FIG. [Figure 6] 3 is a diagram showing an example of the configuration of a connection unit 311 of a first external device 31. FIG. [Figure 7] 2 is a diagram illustrating an example of a circuit configuration of a relay device 20. FIG. [Figure 8] FIG. 2 is a diagram illustrating an example of a circuit configuration of an image forming apparatus 10. DETAILED DESCRIPTION OF THE INVENTION

[0008] An image forming system according to an embodiment will be described with reference to the drawings. In each drawing, the same components are denoted by the same reference numerals. As an example of the image forming system according to the embodiment, an image forming system 1 will be described.

[0009] (Configuration of image forming system) The configuration of an image forming system 1 will be described with reference to Fig. 1. Fig. 1 is a diagram showing an example of the configuration of an image forming system 1 according to an embodiment.

[0010] The image forming system 1 includes an image forming apparatus 10 and a relay apparatus 20.

[0011] The image forming apparatus 10 is an apparatus that forms an image on a print medium. For example, the image forming apparatus 10 is a multifunction peripheral, a copier, a printer, etc. As an example, a case where the image forming apparatus 10 is a multifunction peripheral will be described.

[0012] The print medium is the medium on which the image forming device 10 performs processing such as forming an image. The print medium may be any medium on which an image can be formed. For example, the print medium may be printing paper, plastic film, etc., but is not limited to these.

[0013] The image forming apparatus 10 includes a connection unit 100 that can be connected to another device. For example, the connection unit 100 is a connector. For example, other devices that can be connected to the connection unit 100 include a relay device 20, an external device, etc. The external device is a device that is communicatively connected to the image forming apparatus 10 and thereby controlled by the image forming apparatus 10. For example, the external device is a large-capacity paper feeder. Instead of a large-capacity paper feeder, the external device may be another device controlled by the image forming apparatus 10.

[0014] The image forming apparatus 10 can be connected to one external device via the connection unit 100. When the image forming apparatus 10 is connected to one external device via the connection unit 100, it becomes capable of communicating with this one external device.

[0015] The image forming apparatus 10 can be connected to a relay apparatus 20 via a connection unit 100. When the relay apparatus 20 is connected, the image forming apparatus 10 can be connected to one or more external apparatuses via the relay apparatus 20. When the image forming apparatus 10 is connected to the relay apparatus 20, the image forming apparatus 10 can communicate with each of the one or more external apparatuses connected to the relay apparatus 20 via the relay apparatus 20.

[0016] In addition to the connection unit 100, the image forming apparatus 10 may be configured to include one or more other connection units to which other devices can be connected.

[0017] The relay device 20 is connected between one or more external devices and the image forming device 10. The relay device 20 relays communication between the one or more external devices and the image forming device 10. As an example, a case will be described in which the relay device 20 can be connected to two external devices. One of these two external devices will be referred to as a first external device 31. The other of these two external devices will be referred to as a second external device 32. In the example shown in FIG. 1 , the relay device 20 is connected to each of the image forming device 10, the first external device 31, and the second external device 32. In this case, the relay device 20 relays communication between the first external device 31 and the image forming device 10, and also relays communication between the second external device 32 and the image forming device 10. In this case, the image forming system 1 may be configured to include at least one of the first external device 31 and the second external device 32.

[0018] Relay device 20 includes connection unit 200, connection unit 201, and connection unit 202. Connection unit 200 is an example of a 0th connection unit. Connection unit 201 is an example of a first connection unit. Connection unit 202 is an example of a second connection unit.

[0019] The connection unit 200 is a connection unit that can be connected to the image forming apparatus 10. For example, the connection unit 200 is a connector that can be connected to the connection unit 100 of the image forming apparatus 10.

[0020] The connection unit 201 is a connection unit that can be connected to an external device. For example, the connection unit 201 is a connector. In the example shown in FIG. 1, the first external device 31 is connected to the connection unit 201.

[0021] The connection unit 202 is a connection unit that can be connected to an external device. For example, the connection unit 202 is a connector. In the example shown in FIG. 1, the second external device 32 is connected to the connection unit 202.

[0022] The first external device 31 is, for example, a large-capacity paper feeder capable of feeding A4-sized paper. In this case, the relay device 20 relays communication between the image forming device 10 and the first external device 31, and also relays the transport of the paper from the first external device 31 to the image forming device 10. In other words, the relay device 20 transports the paper from the first external device 31 to the image forming device 10 through a transport path formed inside the relay device 20. The paper is an example of the print medium described above. The first external device 31 may be another type of device instead of a large-capacity paper feeder.

[0023] The first external device 31 includes a connection unit 311 that can be connected to any of the connection unit 100 of the image forming device 10, the connection unit 201 of the relay device 20, and the connection unit 202 of the relay device 20. In this example, a case will be described in which the connection unit 311 is connected to the connection unit 201 when the relay device 20 is connected to the image forming device 10.

[0024] The second external device 32 is, for example, a large-capacity paper feed device capable of feeding A3-sized paper. In this case, the relay device 20 relays communication between the image forming device 10 and the second external device 32, and also relays the transport of the paper from the second external device 32 to the image forming device 10. In other words, the relay device 20 transports the paper from the second external device 32 to the image forming device 10 through a transport path formed inside the relay device 20. The paper is an example of the aforementioned print medium. The second external device 32 may be a different type of device from the first external device 31.

[0025] The second external device 32 includes a connection unit 321 that can be connected to any of the connection unit 100 of the image forming device 10, the connection unit 201 of the relay device 20, and the connection unit 202 of the relay device 20. In this example, a case will be described in which the connection unit 321 is connected to the connection unit 202 when the relay device 20 is connected to the image forming device 10.

[0026] As described above, in the image forming system 1, the image forming apparatus 10 can be communicably connected to each of the first external apparatus 31 and the second external apparatus 32 via the relay apparatus 20.

[0027] As described above, the image forming apparatus 10 can also be communicatively connected to either the first external apparatus 31 or the second external apparatus 32 without going through the relay apparatus 20. FIG. 2 is a diagram showing an example of a state in which the image forming apparatus 10 is connected to the first external apparatus 31 without going through the relay apparatus 20. As shown in FIG. 2, the image forming apparatus 10 can be connected to an external apparatus without going through the relay apparatus 20. In the example shown in FIG. 2, the connection unit 311 of the first external apparatus 31 is connected to the connection unit 100 of the image forming apparatus 10. As an example, a case will be described in which the connection unit 311 of the first external apparatus 31 is connected to the connection unit 100 when an external apparatus is connected to the image forming apparatus 10.

[0028] (Configuration of connection part of image forming device) The configuration of the connection unit 100 of the image forming apparatus 10 will be described.

[0029] Fig. 3 is a diagram showing an example of the configuration of the connection unit 100 of the image forming apparatus 10. Each of the multiple circles shown in Fig. 3 represents a terminal. The shape of the connection unit 100 shown in Fig. 3 is merely an example, and other shapes may be used.

[0030] The connection unit 100 is a single connection connector including a signal input unit 1001, a signal input unit 1002, a signal input unit 1003, a signal input unit 1004, and a signal output unit 1005. The connection unit 100 may be configured to include a plurality of connection connectors. In this case, each of the plurality of connection connectors includes some of the signal input unit 1001, the signal input unit 1002, the signal input unit 1003, the signal input unit 1004, and the signal output unit 1005. For example, the connection unit 100 may be configured to include a connection connector including the signal input unit 1001, the signal input unit 1002, and the signal input unit 1003, and a connection connector including the signal input unit 1004 and the signal output unit 1005.

[0031] Each of the three signal input units, ie, signal input unit 1001, signal input unit 1002, and signal input unit 1003, has one terminal to which a serial signal is input.

[0032] The signal input unit 1004 has a plurality of terminals to which parallel signals are input.

[0033] The signal output unit 1005 has a plurality of terminals from which parallel or serial signals are output.

[0034] (Configuration of the connection part of the relay device) The configurations of the connection units 200, 201, and 202 of the relay device 20 will be described.

[0035] 4 is a diagram showing an example of the configuration of the connection unit 200 of the relay device 20. Each of the multiple circles shown in FIG. 4 represents a terminal. The shape of the connection unit 200 shown in FIG. 4 is merely an example, and other shapes are also possible. However, the shape of the connection unit 200 is a shape that allows connection to the connection unit 100.

[0036] The connection unit 200 is a single connection connector including a signal output unit 2001, a signal output unit 2002, and a signal input unit 2003. The connection unit 200 may be configured to include a plurality of connection connectors. In this case, each of the plurality of connection connectors includes a part of the signal output unit 2001, the signal output unit 2002, and the signal input unit 2003. For example, the connection unit 200 may be configured to include a connection connector including the signal output unit 2001 and the signal output unit 2002, and a connection connector including the signal input unit 2003.

[0037] Each of the two signal output units, signal output unit 2001 and signal output unit 2002, has one terminal from which a serial signal is output. The one terminal of signal output unit 2001 is an example of one second terminal. The one terminal of signal output unit 2002 is an example of one third terminal.

[0038] When the connection unit 200 of the relay device 20 is connected to the connection unit 100 of the image forming device 10 , the signal output unit 2001 is connected to the signal input unit 1001 of the connection unit 100 .

[0039] When the connection unit 200 of the relay device 20 is connected to the connection unit 100 of the image forming device 10 , the signal output unit 2002 is connected to the signal input unit 1002 of the connection unit 100 .

[0040] The signal input unit 2003 has a plurality of terminals to which serial signals are input. The plurality of terminals of the signal input unit 2003 are an example of a plurality of first terminals.

[0041] When the connection unit 200 of the relay device 20 is connected to the connection unit 100 of the image forming device 10, the signal input unit 2003 is connected to the signal output unit 1005 of the connection unit 100. In this case, serial signals are input to the multiple terminals of the signal input unit 2003 via the multiple terminals of the signal output unit 1005.

[0042] 5 is a diagram showing an example of the configuration of connection unit 201 of relay device 20. Each of the multiple circles shown in FIG. 5 represents a terminal. The shape of connection unit 201 shown in FIG. 5 is merely an example, and other shapes are also possible. However, connection unit 201 has a shape that allows connection to connection unit 311 or connection unit 321. For example, connection unit 201 has the same shape as connection unit 100.

[0043] The connection unit 201 is a single connection connector including a signal input unit 2011 and a signal output unit 2012. The connection unit 201 may be configured to include two connection connectors. In this case, each of the two connection connectors includes either the signal input unit 2011 or the signal output unit 2012. For example, the connection unit 201 may be configured to include a connection connector including the signal input unit 2011 and a connection connector including the signal output unit 2012.

[0044] The signal input unit 2011 has a plurality of terminals to which parallel signals are input. The signal input unit 2011 is an example of a first parallel signal input unit. The plurality of terminals of the signal input unit 2011 are an example of a plurality of eleventh terminals.

[0045] The signal output unit 2012 has a plurality of terminals to which parallel signals are input. The signal output unit 2012 is an example of a first parallel signal output unit. The plurality of terminals of the signal output unit 2012 are an example of a plurality of twelfth terminals.

[0046] The configuration of connection unit 202 is similar to that of connection unit 201, and therefore a detailed description thereof will be omitted. Of the signal input units included in connection unit 202, signal input unit 2021, which corresponds to signal input unit 2011 of connection unit 201, is an example of a second parallel signal input unit. The multiple terminals of signal input unit 2021 are an example of multiple 21 terminals. Of the signal output units included in connection unit 202, signal output unit 2022, which corresponds to signal output unit 2012 of connection unit 201, is an example of a second parallel signal output unit. The multiple terminals of signal output unit 2022 are an example of multiple 22 terminals.

[0047] (Configuration of external device connection part) The configuration of the connection section of the external device will be described using the connection section 311 of the first external device 31 as an example.

[0048] FIG. 6 is a diagram showing an example of the configuration of the connection unit 311 of the first external device 31. Each of the multiple circles shown in FIG. 6 represents a terminal. The shape of the connection unit 311 shown in FIG. 6 is merely an example, and other shapes are also possible. However, the shape of the connection unit 311 is a shape that allows connection to each of the connection unit 100 of the image forming device 10, the connection unit 201 of the relay device 20, and the connection unit 202 of the relay device 20. For example, the shape of the connection unit 311 is the same as the shape of each of the connection unit 100, the connection unit 201, and the connection unit 202.

[0049] The signal output unit 3111 has a plurality of terminals from which parallel signals are output. When the connection unit 311 of the first external device 31 is connected to the connection unit 201 of the relay device 20, the signal output unit 3111 is connected to the signal input unit 2011 of the connection unit 201. When the connection unit 311 of the first external device 31 is connected to the connection unit 100 of the image forming apparatus 10, the signal output unit 3111 is connected to the signal input unit 1004 of the connection unit 100.

[0050] The signal input unit 3112 has a plurality of terminals to which parallel signals are input. When the connection unit 311 of the first external device 31 is connected to the connection unit 201 of the relay device 20, the signal input unit 3112 is connected to the signal output unit 2012 of the connection unit 201. In this case, parallel signals are input to the plurality of terminals of the signal input unit 3112 via the plurality of terminals of the signal output unit 2012. When the connection unit 311 of the first external device 31 is connected to the connection unit 100 of the image forming apparatus 10, the signal input unit 3112 is connected to the signal output unit 1005 of the connection unit 100. In this case, parallel signals are input to the plurality of terminals of the signal input unit 3112 via the plurality of terminals of the signal output unit 1005.

[0051] The configuration of the connection unit 321 of the second external device 32 is similar to the configuration of the connection unit 311, and therefore a detailed description thereof will be omitted.

[0052] (Circuit configuration of repeater) The circuit configuration of the relay device 20 will be described.

[0053] Fig. 7 is a diagram showing an example of the circuit configuration of the relay device 20. In order to simplify the diagram, Fig. 7 shows only the circuit configuration of the relay device 20 that is related to the exchange of signals between the image forming device 10 and the first external device 31 and the second external device 32. In order to simplify the diagram, the circuit configuration shown in Fig. 7 shows a logical connection mode. Therefore, the connection mode shown in Fig. 7 differs from the actual connection mode.

[0054] The relay device 20 includes, for example, a parallel-to-serial conversion unit PSA, a parallel-to-serial conversion unit PSB, a parallel-to-serial conversion unit PSC, a serial-to-parallel conversion unit SPA, a serial-to-parallel conversion unit SPB, and a connection signal generation unit SGC. Note that the relay device 20 may include other circuits, other devices, etc., as long as they do not impair the functions of the relay device 20 described below.

[0055] The parallel-serial conversion unit PSA has a plurality of parallel signal input terminals ITAA, one serial signal input terminal ITAB, and one serial signal output terminal OTA. The parallel-serial conversion unit PSB has a plurality of parallel signal input terminals ITBA, one serial signal input terminal ITBB, and one serial signal output terminal OTB. The parallel-serial conversion unit PSC has a plurality of parallel signal input terminals ITC and one serial signal output terminal OTC. The serial-parallel conversion unit SPA has a plurality of serial signal input terminals ITD, a plurality of parallel signal output terminals OTDA, and one serial signal output terminal OTDB. The serial-parallel conversion unit SPB has a plurality of serial signal input terminals ITEA, one serial signal input terminal ITEB, a plurality of parallel signal output terminals OTEA, and one serial signal output terminal OTEB.

[0056] One serial signal output terminal OTA of the parallel-serial conversion unit PSA is connected to one terminal of the signal output unit 2001 of the connection unit 200 via a transmission path.

[0057] Each of the plurality of parallel signal input terminals ITAA of the parallel-serial conversion unit PSA is connected to each of the plurality of terminals of the signal input unit 2011 of the connection unit 201 via a transmission line so as not to overlap with each other.

[0058] One serial signal input terminal ITAB of the parallel-serial conversion unit PSA is connected to one serial signal output terminal OTB of the parallel-serial conversion unit PSB via a transmission path.

[0059] Each of the plurality of parallel signal input terminals ITBA of the parallel-serial conversion unit PSB is connected via a transmission line to each of the plurality of terminals of the signal input unit 2021 of the connection unit 202 so as not to overlap.

[0060] One serial signal input terminal ITBB of the parallel-serial conversion unit PSB is connected to one serial signal output terminal OTC of the parallel-serial conversion unit PSC via a transmission path.

[0061] Each of the multiple parallel signal input terminals ITC of the parallel-serial conversion unit PSC is connected via a transmission line to a multiple terminal of a predetermined circuit so as not to overlap with each other. The predetermined circuit is one of the circuits of the relay device 20. The predetermined circuit is, for example, a circuit related to a sensor, a motor, etc. In FIG. 7, the predetermined circuit is omitted.

[0062] The serial-to-parallel conversion unit SPA has a plurality of serial signal input terminals ITD, which are connected to the signal input unit 2003 of the connection unit 200 via transmission paths so as not to overlap with each other.

[0063] The plurality of parallel signal output terminals OTDA of the serial-parallel conversion unit SPA are connected to the plurality of terminals of the signal output unit 2012 of the connection unit 201 via transmission paths so as not to overlap with each other.

[0064] One serial signal output terminal OTDB of the serial-parallel conversion unit SPA is connected to one serial signal input terminal ITEB of the serial-parallel conversion unit SPB via a transmission path.

[0065] The transmission path connecting the signal input unit 2003 and the serial-to-parallel conversion unit SPA is branched and also connected to the serial-to-parallel conversion unit SPB. Therefore, each of the multiple terminals of the signal input unit 2003 of the connection unit 200 is connected to each of the multiple serial signal input terminals ITEA of the serial-to-parallel conversion unit SPB so as not to overlap with each other.

[0066] The plurality of parallel signal output terminals OTEA of the serial-parallel conversion unit SPB are connected to the plurality of terminals of the signal output unit 2022 of the connection unit 202 via transmission paths so as not to overlap with each other.

[0067] One serial signal output terminal OTEB of the serial-parallel conversion unit SPB is connected to one serial signal input terminal of a predetermined circuit via a transmission path.

[0068] The connection signal generation unit SGC is connected to the signal output unit 2002 of the connection unit 200 via a transmission line.

[0069] The parallel-serial conversion unit PSA receives a parallel signal PA from the signal input unit 2011 of the connection unit 201 via a plurality of parallel signal input terminals ITAA. The parallel signal PA is a signal output from the first external device 31 to the image forming apparatus 10. The parallel-serial conversion unit PSA converts the parallel signal PA input from the signal input unit 2011 into a serial signal SA. That is, the serial signal SA is a signal output from the first external device 31 to the image forming apparatus 10. For example, the parallel-serial conversion unit PSA is a parallel-serial conversion IC (Integrated Circuit). Instead of a parallel-serial conversion IC, the parallel-serial conversion unit PSA may be any circuit capable of converting the parallel signal PA input from the signal input unit 2011 into a serial signal SA.

[0070] After converting the parallel signal PA into the serial signal SA, the parallel-serial conversion unit PSA outputs the serial signal SA to the signal output unit 2001 of the connection unit 200. That is, the parallel-serial conversion unit PSA outputs the serial signal SA to the image forming apparatus 10 via the signal output unit 2001.

[0071] The parallel-serial conversion unit PSA receives serial signals SB and SC from the parallel-serial conversion unit PSB via a single serial signal input terminal ITAB. The serial signal SB input from the serial signal output terminal OTB of the parallel-serial conversion unit PSB is the serial signal output from the parallel-serial conversion unit PSB. The serial signal SC input from the serial signal output terminal OTB of the parallel-serial conversion unit PSB is the serial signal output from the parallel-serial conversion unit PSC. The parallel-serial conversion unit PSA outputs the input serial signals SB and SC to the signal output unit 2001 of the connection unit 200. That is, the parallel-serial conversion unit PSA relays the output of the serial signal SB from the parallel-serial conversion unit PSB to the signal output unit 2001. The parallel-serial conversion unit PSA relays the output of the serial signal SC from the parallel-serial conversion unit PSC to the signal output unit 2001. This eliminates the need for relay device 20 to output the serial signals output from parallel-serial conversion unit PSA, parallel-serial conversion unit PSB, and parallel-serial conversion unit PSC from separate terminals. As a result, relay device 20 can prevent the circuit configuration of relay device 20 from becoming complicated, and can also prevent the circuit configuration of image forming device 10 from becoming complicated.

[0072] The parallel-serial conversion unit PSB receives a parallel signal PB from the signal input unit 2021 of the connection unit 202 via a plurality of parallel signal input terminals ITBA. The parallel signal PB is a signal output from the second external device 32 to the image forming apparatus 10. The parallel-serial conversion unit PSB converts the parallel signal PB input from the signal input unit 2021 into a serial signal SB. In other words, the serial signal SB is a signal output from the second external device 32 to the image forming apparatus 10. For example, the parallel-serial conversion unit PSB is a parallel-serial conversion IC. Instead of a parallel-serial conversion IC, the parallel-serial conversion unit PSB may be any circuit that can convert the parallel signal PB input from the signal input unit 2021 into a serial signal SB.

[0073] After converting the parallel signal PB into the serial signal SB, the parallel-serial conversion unit PSB outputs the serial signal SB to the signal output unit 2001 of the connection unit 200 via a relay by the parallel-serial conversion unit PSA. In other words, the parallel-serial conversion unit PSB outputs the serial signal SB to the image forming apparatus 10 via the signal output unit 2001.

[0074] The parallel-serial conversion unit PSB receives a serial signal SC from a serial signal output terminal OTC of the parallel-serial conversion unit PSC via a single serial signal input terminal ITBB. The parallel-serial conversion unit PSB outputs the received serial signal SC to the parallel-serial conversion unit PSA. That is, the parallel-serial conversion unit PSB relays the output of the serial signal SC from the parallel-serial conversion unit PSC to the signal output unit 2001. This eliminates the need for the relay device 20 to output the serial signals output from the parallel-serial conversion unit PSA, the parallel-serial conversion unit PSB, and the parallel-serial conversion unit PSC from separate terminals. As a result, the relay device 20 can prevent the circuit configuration of the relay device 20 from becoming complicated, and can also prevent the circuit configuration of the image forming apparatus 10 from becoming complicated.

[0075] A parallel signal PC is input to the parallel-serial conversion unit PSC from a predetermined circuit via a plurality of parallel signal input terminals ITC. The parallel signal PC is a signal output from the predetermined circuit to the image forming apparatus 10. The parallel-serial conversion unit PSC converts the parallel signal PC input from the predetermined circuit into a serial signal SC. In other words, the serial signal SC is a signal output from the predetermined circuit to the image forming apparatus 10. For example, the parallel-serial conversion unit PSC is a parallel-serial conversion IC. Instead of a parallel-serial conversion IC, the parallel-serial conversion unit PSC may be any circuit that can convert the parallel signal PC input from the predetermined circuit into a serial signal SC.

[0076] The serial-parallel conversion unit SPA receives serial signals SD and SE from a signal input unit 2003 of the connection unit 200 via a plurality of serial signal input terminals ITD. The serial signals SD input from the signal input unit 2003 to the serial-parallel conversion unit SPA are control signals output from the image forming apparatus 10 to the first external device 31 and the second external device 32, respectively. The serial signals SD are serial signals divided into a plurality of signals. Therefore, the serial signals SD are input from the signal input unit 2003 to the serial-parallel conversion unit SPA via a plurality of serial signal input terminals ITD. The serial signals SE input from the signal input unit 2003 to the serial-parallel conversion unit SPA together with the serial signals SD are control signals output from the image forming apparatus 10 to a predetermined circuit. The serial-parallel conversion unit SPA converts the serial signals SD input from the signal input unit 2003 into parallel signals PD. That is, the parallel signal PD is a control signal output from the image forming apparatus 10 to each of the first external device 31 and the second external device 32. The first external device 31 extracts information necessary for controlling the first external device 31 from the parallel signal PD and performs processing according to the extracted information. For example, the serial-parallel conversion unit SPA is a serial-parallel conversion IC. Instead of a serial-parallel conversion IC, the serial-parallel conversion unit SPA may be any circuit that can convert the serial signal SD input from the signal input unit 2003 into the parallel signal PD.

[0077] After converting the serial signal SD into a parallel signal PD, the serial-to-parallel conversion unit SPA outputs the parallel signal PD to the signal output unit 2012 of the connection unit 201. In other words, the serial-to-parallel conversion unit SPA outputs the parallel signal PD to the first external device 31 via the signal output unit 2012.

[0078] After the serial signal SE is input, the serial-to-parallel converter SPA outputs the serial signal SE to the serial-to-parallel converter SPB. That is, the serial-to-parallel converter SPA relays the output of the serial signal SE from the image forming apparatus 10 to a predetermined circuit.

[0079] The serial signal SD is input to the serial-parallel conversion unit SPB from the signal input unit 2003 of the connection unit 200 via a plurality of serial signal input terminals ITEA. The serial-parallel conversion unit SPB converts the serial signal SD input from the signal input unit 2003 into a parallel signal PE. That is, the parallel signal PE is a control signal output from the image forming apparatus 10 to each of the first external device 31 and the second external device 32. The second external device 32 extracts information necessary for controlling the second external device 32 from the parallel signal PE and performs processing according to the extracted information. For example, the serial-parallel conversion unit SPB is a serial-parallel conversion IC. Instead of a serial-parallel conversion IC, the serial-parallel conversion unit SPB may be any circuit capable of converting the serial signal SD input from the signal input unit 2003 into a parallel signal PE.

[0080] After converting the serial signal SD into a parallel signal PE, the serial-to-parallel conversion unit SPB outputs the parallel signal PE to the signal output unit 2022 of the connection unit 202. That is, the serial-to-parallel conversion unit SPB outputs the parallel signal PE to the second external device 32 via the signal output unit 2022.

[0081] The serial signal SE is input to the serial-parallel conversion unit SPB from the serial-parallel conversion unit SPA via one serial signal input terminal ITEB.

[0082] After the serial signal SE is input, the serial-parallel converter SPB outputs the serial signal SE to a predetermined circuit. That is, the serial-parallel converter SPB relays the output of the serial signal SE from the image forming apparatus 10 to the predetermined circuit.

[0083] When the connection unit 200 is connected to the image forming apparatus 10, the connection signal generation unit SGC continues to generate a connection signal SH indicating that the relay device 20 is connected to the image forming apparatus 10, based on the power supplied from the image forming apparatus 10. In this case, the connection signal generation unit SGC outputs the generated connection signal SH to the image forming apparatus 10 via the signal output unit 2002 of the connection unit 200. The connection signal generation unit SGC may be any circuit having such a function.

[0084] With the circuit configuration described above, relay device 20 converts parallel signals output from an external device to image forming device 10 into serial signals. Relay device 20 outputs the converted serial signals to image forming device 10. In other words, relay device 20 exchanges serial signals with image forming device 10, but does not exchange parallel signals. In this case, relay device 20 can prevent the circuit configuration of image forming device 10 from becoming complicated for the following reasons 1 to 3.

[0085] (Reason 1) A single serial interface allows a serial signal to be output from an external device to the image forming apparatus 10. In this example, the signal output unit 2001 of the connection unit 200 is an example of such a single serial interface. (Reason 2) A serial signal can be input from the image forming apparatus 10 to an external device using one parallel interface. In this example, the signal input unit 2003 of the connection unit 200 is an example of such a single parallel interface. (Reason 3) In communication between an external device and the image forming device 10 via the relay device 20, the image forming device 10 does not need to be equipped with multiple parallel interfaces. In other words, the image forming device 10 can be communicatively connected to one or more external devices with just one interface that is communicatively connected to the relay device 20.

[0086] For the above three reasons, the relay device 20 can prevent the circuit configuration of the image forming device 10 from becoming complicated. The relay device 20 is provided with at least a parallel-to-serial conversion unit PSA and a serial-to-parallel conversion unit SPA, so the above three reasons can be realized. In other words, by devising the circuit configuration of the relay device 20, it is possible to simplify the circuit configuration of the image forming device 10. For example, the circuit configuration of the image forming device 10 can be as simple as the circuit configuration shown in FIG. 8.

[0087] (Circuit configuration of image forming device) The circuit configuration of the image forming apparatus 10 will be described.

[0088] FIG. 8 is a diagram showing an example of the circuit configuration of the image forming apparatus 10. As shown in FIG.

[0089] The image forming apparatus 10 includes a processor PR, a switching unit SWA, a switching unit SWB, a parallel-to-serial conversion unit PSD, and a serial-to-parallel conversion unit SPC. The image forming apparatus 10 may include other circuits, other devices, etc., as long as they do not impair the functions of the image forming apparatus 10 described below.

[0090] The processor PR has one serial signal input terminal ITJA, one serial signal input terminal ITJB, one serial signal input terminal ITJC, multiple serial signal output terminals OTJA, and one serial signal output terminal OTJB. The switching unit SWA has one serial signal input terminal ITIA, one serial signal input terminal ITIB, and one serial signal output terminal OTI. The switching unit SWB has one serial signal input terminal ITHA, multiple serial signal input terminals ITHB, and multiple serial signal output terminals OTH. The parallel-serial conversion unit PSD has multiple parallel signal input terminals ITF and one serial signal output terminal OTF. The serial-parallel conversion unit SPC has one serial signal input terminal ITGA, multiple serial signal input terminals ITGB, and multiple parallel signal output terminals OTG.

[0091] One serial signal input terminal ITJA of the processor PR is connected to one serial signal output terminal OTI of the switching unit SWA via a transmission path.

[0092] One serial signal input terminal ITIA of the switching unit SWA is connected to one terminal of the signal input unit 1001 of the connection unit 100 via a transmission line.

[0093] One serial signal input terminal ITIB of the switching unit SWA is connected to one serial signal output terminal OTF of the parallel-serial conversion unit PSD via a transmission path.

[0094] Each of the plurality of parallel signal input terminals ITF of the parallel-serial conversion unit PSD is connected via a transmission line to each of the plurality of terminals of the signal input unit 1004 of the connection unit 100 so as not to overlap.

[0095] One serial signal input terminal ITJB of the processor PR is connected to one terminal of the signal input unit 1003 of the connection unit 100 via a transmission line.

[0096] The transmission path connecting the serial signal input terminal ITJB and the signal input unit 1003 is branched and is also connected to one serial signal input terminal ITGA of the serial-to-parallel conversion unit SPC. In other words, one serial signal input terminal ITJB of the processor PR is also connected to one serial signal input terminal ITGA of the serial-to-parallel conversion unit SPC via the transmission path.

[0097] One serial signal output terminal OTJB of the processor PR is connected to one of the plurality of serial signal input terminals ITHB of the switching unit SWB via a transmission path.

[0098] The plurality of serial signal input terminals ITGB of the serial-parallel conversion unit SPC are connected via transmission paths to the plurality of serial signal output terminals OTJA of the processor PR so as not to overlap with each other.

[0099] Each of the transmission paths connecting the serial-parallel conversion unit SPC and the processor PR is branched and connected so as not to overlap with any of the available terminals among the multiple serial signal input terminals ITHB of the switching unit SWB. These available terminals are the terminals among the multiple serial signal input terminals ITHB of the switching unit SWB that are not connected to the single serial signal output terminal OTJB of the processor PR. In other words, each of the multiple serial signal output terminals OTJA of the processor PR is connected via the transmission path so as not to overlap with any of these available terminals.

[0100] The plurality of parallel signal output terminals OTG of the serial-parallel conversion unit SPC are connected to the plurality of terminals of the signal output unit 1005 of the connection unit 100 via transmission paths so as not to overlap with each other.

[0101] Each of the transmission paths connecting the serial-to-parallel conversion unit SPC and the connection unit 100 is branched and connected so as not to overlap with each of the plurality of serial signal output terminals OTH of the switching unit SWB. In other words, each of the plurality of parallel signal output terminals OTG of the serial-to-parallel conversion unit SPC is connected via the transmission path so as not to overlap with each of the plurality of serial signal output terminals OTH of the switching unit SWB.

[0102] The processor PR has one serial signal input terminal ITJC, which is connected to the signal input section 1002 of the connection section 100 via a transmission line.

[0103] The transmission path connecting the serial signal input terminal ITJC and the signal input unit 1002 is branched and is also connected to one serial signal input terminal ITHA of the switching unit SWB. That is, one serial signal input terminal ITJC of the processor PR is also connected to one serial signal input terminal ITHA of the switching unit SWB via the transmission path.

[0104] When the relay device 20 is connected to the image forming apparatus 10, the aforementioned serial signals SA, SB, and SC are input from the relay device 20 to the signal input unit 1001 of the connection unit 100. After being input to the signal input unit 1001, each of the serial signals SA, SB, and SC is input to one serial signal input terminal ITIA of the switching unit SWA. When the first external device 31 is connected to the image forming apparatus 10, no signal is input to the signal input unit 1001 of the connection unit 100.

[0105] When the first external device 31 is connected to the image forming apparatus 10, the above-mentioned parallel signal PA is input from the first external device 31 to the signal input unit 1004 of the connection unit 100. The parallel signal PA is input to the signal input unit 1004 and then input to the parallel-serial conversion unit PSD. When the relay device 20 is connected to the image forming apparatus 10, no signal is input to the signal input unit 1004 of the connection unit 100.

[0106] The parallel-serial conversion unit PSD converts the parallel signal PA input from the signal input unit 1004 into a serial signal SA. For example, the parallel-serial conversion unit PSD is a parallel-serial conversion IC. Instead of a parallel-serial conversion IC, the parallel-serial conversion unit PSC may be any circuit that can convert the parallel signal PA input from the signal input unit 1004 into a serial signal SA.

[0107] After converting the parallel signal PA into a serial signal SA, the parallel-serial conversion unit PSD outputs the serial signal SA to one serial signal input terminal ITIB of the switching unit SWA.

[0108] The switching unit SWA outputs each of the serial signals SA, SB, and SC, and the serial signal SA that was input, to the processor PR. The switching unit SWA is, for example, an AND circuit. The process by which the switching unit SWA outputs the serial signals to the processor PR is known, so a detailed description will be omitted. Instead of an AND circuit, the switching unit SWA may be any circuit that can selectively output the serial signals to the processor PR.

[0109] In this manner, when the relay device 20 is connected to the image forming apparatus 10, the processor PR acquires signals input from the external devices as serial signals. In this example, these external devices are the first external device 31 and the second external device 32. The processor PR also acquires signals input from the external devices as serial signals when the external devices are connected to the image forming apparatus 10. That is, by providing the image forming apparatus 10 with the switching unit SWA and the parallel-serial conversion unit PSD, the processor PR can always acquire signals acquired from the external devices as serial signals. As a result, the processor PR does not need to process signals acquired from the external devices based on different control programs for each external device. This leads to simplification of the control programs used by the processor PR to control the external devices.

[0110] Furthermore, since the image forming apparatus 10 is provided with the switching unit SWA and the parallel-serial conversion unit PSD, it is not necessary to provide multiple parallel interfaces for inputting signals from external devices. This leads to a simplification of the circuit configuration of the image forming apparatus 10. In other words, the relay device 20 can prevent the circuit configuration of the image forming apparatus 10 from becoming complicated.

[0111] The reason why the circuit configuration of the relay device 20 can simplify the circuit configuration of the image forming device 10 is the similarity of the circuit configurations between the relay device 20 and the image forming device 10. The similarity of the circuit configurations between the relay device 20 and the image forming device 10 means that both the relay device 20 and the image forming device 10 have circuit configurations that can convert parallel signals input from external devices to serial signals. In other words, this similarity means that the relay device 20 includes a parallel-to-serial converter PSA, and the image forming device 10 includes a parallel-to-serial converter PSD. The circuit configuration of the image forming device 10 can be simplified by being configured to have such similarity with the circuit configuration of the relay device 20. In other words, the relay device 20 has the circuit configuration shown in FIG. 7, which allows the relay device 20 to have such similarity with the image forming device 10. As a result, the relay device 20 can prevent the circuit configuration of the image forming device 10 from becoming complicated.

[0112] The above-mentioned similarity is a similarity regarding the input of parallel signals among the similarities in the circuit configurations between relay device 20 and image forming device 10. There is another similarity in the circuit configurations between relay device 20 and image forming device 10. This other similarity will be described below.

[0113] When the relay device 20 is connected to the image forming apparatus 10, the aforementioned connection signal SH continues to be input to the signal input unit 1002 of the connection unit 100 from the relay device 20. The connection signal SH input to the signal input unit 1002 is input to one serial signal input terminal ITHA of the switching unit SWB and one serial signal input terminal ITJC of the processor PR. As described above, the connection signal SH is a serial signal indicating that the relay device 20 is connected to the image forming apparatus 10. In the image forming apparatus 10, the connection signal SH also functions as an enable signal for the switching unit SWB. The switching unit SWB operates while the connection signal SH continues to be input. The switching unit SWB does not operate while the connection signal SH is not input. When the first external device 31 is connected to the image forming apparatus 10, no signal is input to the signal input unit 1002 of the connection unit 100.

[0114] When the first external device 31 is connected to the image forming apparatus 10, a serial signal SG is continuously input from the first external device 31 to the signal input unit 1003 of the connection unit 100. The serial signal SG input to the signal input unit 1003 is input to one serial signal input terminal ITGA of the serial-parallel conversion unit SPC and one serial signal input terminal ITJB of the processor PR. The serial signal SG is a signal indicating that the first external device 31 is connected to the image forming apparatus 10. In the image forming apparatus 10, the serial signal SG also functions as an enable signal for the serial-parallel conversion unit SPC. The serial-parallel conversion unit SPC operates while the serial signal SG is continuously input. The serial-parallel conversion unit SPC does not operate while the serial signal SG is not input. When the relay device 20 is connected to the image forming apparatus 10, no signal is input to the signal input unit 1003 of the connection unit 100.

[0115] The processor PR outputs serial signals SD from multiple serial signal output terminals OTJA to the serial-parallel conversion unit SPA and the switching unit SWB as signals for controlling external devices. After being output from the processor PR, the serial signals SD are input to the serial-parallel conversion unit SPA and the switching unit SWB. When a relay device 20 is connected to the image forming apparatus 10, the processor PR outputs a serial signal SE from one serial signal output terminal OTJB to the switching unit SWB. When a first external device 31 is connected to the image forming apparatus 10, the processor PR does not output a signal from one serial signal output terminal OTJB.

[0116] When the first external device 31 is connected to the image forming apparatus 10, the serial-parallel converter SPC receives the serial signal SD and converts it into a parallel signal PG. For example, the serial-parallel converter SPC is a serial-parallel converter IC. Instead of a serial-parallel converter IC, the serial-parallel converter SPC may be any circuit capable of converting the serial signal SD input from the processor PR into a parallel signal PG. The serial-parallel converter SPC outputs the converted parallel signal PG to the signal output unit 1005 of the connection unit 100. That is, the serial-parallel converter SPC outputs the parallel signal PG to the first external device 31 via the signal output unit 1005. On the other hand, when the relay device 20 is connected to the image forming apparatus 10, the serial-parallel converter SPC receives the serial signal SD and does not operate, so it does not perform any processing.

[0117] When the relay device 20 is connected to the image forming device 10, the switching unit SWB, to which the serial signals SD and SE are input, outputs the serial signals SD and SE to the signal output unit 1005 of the connection unit 100. On the other hand, when the first external device 31 is connected to the image forming device 10, the switching unit SWB, to which the serial signal SD is input, is not operating and therefore does not perform any processing. The switching unit SWB may be any circuit that performs such an operation.

[0118] In this way, when the relay device 20 is connected to the image forming apparatus 10, the processor PR outputs a signal for controlling an external device to the relay device 20 as a serial signal. Even when an external device is connected to the image forming apparatus 10, the processor PR outputs a signal for controlling the external device to the external device as a serial signal. In other words, by providing the image forming apparatus 10 with the serial-to-parallel converter SPC and the switching unit SWB, the processor PR can always output signals to external devices as serial signals. As a result, the processor PR does not need to process signals to be output to external devices based on different control programs for each external device. This leads to simplification of the control programs used by the processor PR to control external devices.

[0119] Furthermore, since the image forming apparatus 10 is equipped with the serial-to-parallel converter SPC and the switching unit SWB, it is not necessary to provide multiple parallel interfaces for outputting signals to external devices. This leads to a simplification of the circuit configuration of the image forming apparatus 10. In other words, the relay device 20 can prevent the circuit configuration of the image forming apparatus 10 from becoming complicated.

[0120] The reason why the circuit configuration of the relay device 20 can simplify the circuit configuration of the image forming device 10 is the other similarity mentioned above. This similarity means that both the relay device 20 and the image forming device 10 have circuit configurations that can convert serial signals output to external devices into parallel signals. In other words, this similarity means that the relay device 20 includes a serial-to-parallel converter SPA, and the image forming device 10 includes a serial-to-parallel converter SPC. The circuit configuration of the image forming device 10 can be simplified by being configured to have this similarity with the circuit configuration of the relay device 20. In other words, because the relay device 20 has the circuit configuration shown in FIG. 7, the relay device 20 can have this similarity with the image forming device 10. As a result, the relay device 20 can prevent the circuit configuration of the image forming device 10 from becoming complicated.

[0121] In summary, as shown in FIG. 8, the image forming apparatus 10 can allocate input signals and output signals to the relay device 20. As a result, the processor PR of the image forming apparatus 10 can control all external devices using a common program. As shown in FIG. 8, the circuit configuration of the image forming apparatus 10 can be simplified. In other words, the relay device 20 can prevent the circuit configuration of the image forming apparatus 10 from becoming complicated.

[0122] As described above, the relay device according to the embodiment is connected between the image forming device and one or more external devices controlled by the image forming device. The relay device relays communication between the one or more external devices and the image forming device. The relay device has a zeroth connection unit, a first connection unit, a first serial-to-parallel conversion unit, and a first parallel-to-serial conversion unit. The zeroth connection unit is a connection unit connectable to the image forming device. The first connection unit is a connection unit connectable to a first external device among the one or more external devices. The first serial-to-parallel conversion unit converts a serial signal input from the zeroth connection unit into a parallel signal and outputs the converted parallel signal to the first connection unit. The first parallel-to-serial conversion unit converts a parallel signal input from the first connection unit into a serial signal and outputs the converted serial signal to the zeroth connection unit. In this way, the relay device can enable communication between the image forming device and one or more external devices simply by being connected to the image forming device via the zeroth connection unit. As a result, the relay device eliminates the need for the image forming device to have any other connectors other than the connector connectable to connector 0. In other words, the relay device can prevent the circuit configuration of the image forming device from becoming complicated.

[0123] An image forming system according to an embodiment includes an image forming apparatus and a relay device. The relay device is connected between the image forming apparatus and one or more external devices controlled by the image forming apparatus. The relay device relays communication between the image forming apparatus and the one or more external devices. The relay device includes a 0th connection unit, a 1st connection unit, a 1st serial-to-parallel conversion unit, and a 1st parallel-to-serial conversion unit. The 0th connection unit is a connection unit connectable to the image forming apparatus. The 1st connection unit is a connection unit connectable to a first external device among the one or more external devices. The 1st serial-to-serial conversion unit converts a serial signal input from the 0th connection unit into a parallel signal and outputs the converted parallel signal to the 1st connection unit. The 1st parallel-to-serial conversion unit converts a parallel signal input from the 1st connection unit into a serial signal and outputs the converted serial signal to the 0th connection unit. This makes it possible for the image forming system to prevent the circuit configuration of the image forming apparatus from becoming complicated.

[0124] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, as well as within the scope of the invention described in the claims and their equivalents. [Explanation of symbols]

[0125] 1...image forming system, 10...image forming apparatus, 20...relay apparatus, 31...first external apparatus, 32...second external apparatus, 100, 200, 201, 202, 311, 321...connection section, 1001, 1002, 1003, 1004, 2003, 2011, 2021, 3112...signal input section, 1005, 2001, 2002, 2012, 2022, 3111...signal output section, PR...processor, PSA, PSB, PSC, PSD...parallel-serial conversion section, SGC...connection signal generation section, SPA, SPB, SPC...serial-parallel conversion section, SWA...switching section, SWB...switching section

Claims

1. an image forming apparatus; a relay device connected between the image forming apparatus and one or more external devices controlled by the image forming apparatus, for relaying communication between the image forming apparatus and the one or more external devices; An image forming system comprising: The relay device a 0th connection unit connectable to the image forming apparatus; a first connection unit connectable to a first external device among the one or more external devices; a first serial-parallel conversion unit that converts a serial signal input from the zero connection unit into a parallel signal and outputs the converted parallel signal to the first connection unit; a first parallel-serial conversion unit that converts a parallel signal input from the first connection unit into a serial signal and outputs the converted serial signal to the zero connection unit; Equipped with the image forming apparatus, a processor; an A-th connection unit to which either the relay device or the first external device is connected; an A-th switching unit to which a serial signal input from the A-th connection unit is input when the O-th connection unit of the relay device is connected to the A-th connection unit; an A-th parallel-serial conversion unit that converts a parallel signal input from the A-th connection unit into a serial signal when the first external device is connected to the A-th connection unit and outputs the converted serial signal to the A-th switch unit; Equipped with the A switching unit outputs the serial signal input to the A switching unit to the processor, out of the serial signal input from the relay device and the serial signal input from the first external device via the A parallel-to-serial conversion unit; Imaging system.

2. the image forming apparatus, an A-th serial-parallel conversion unit that converts a serial signal input from the processor into a parallel signal when the first external device is connected to the A-th connection unit, and outputs the converted parallel signal to the first external device via the A-th connection unit; a B-switching unit that outputs a serial signal input from the processor to the relay device via the A-connection unit when the A-connection unit is connected to the O-connection unit of the relay device; Further comprising: The image forming system according to claim 1 .

3. when the 0 connection unit of the relay device is connected to the A connection unit, the B switching unit continues to input a connection signal from the relay device via the A connection unit; the connection signal is an enable signal for the B switching unit, when the first external device is connected to the A connection unit, the A serial-parallel conversion unit continues to receive an A serial signal from the first external device via the A connection unit; The A serial signal is an enable signal for the A serial-parallel conversion unit. The image forming system according to claim 2 .

4. The zero connection portion is a 0th serial signal input unit having a plurality of 01st terminals to which serial signals are input; a 0th serial signal output unit having a 0th terminal from which a serial signal is output; Including, the first serial-parallel conversion unit receives serial signals via the plurality of first terminals, the first parallel-serial conversion unit outputs a serial signal via the one second terminal; The image forming system according to claim 1 .

5. the 0th connection unit is a connector including the 0th serial signal input unit and the 0th serial signal output unit, the image forming apparatus includes a connector connectable to the zero connection portion; The image forming system according to claim 4 .

6. the relay device includes a connection signal generating unit that generates, when the zero connection unit is connected to the image forming device, a connection signal indicating that the relay device is connected to the image forming device based on power supplied from the image forming device; the 0th connection unit includes a connection signal output unit having one 03rd terminal to which the connection signal generated by the connection signal generation unit is output; The image forming system according to claim 1 .

7. The first connection portion is a first parallel signal input unit having a plurality of eleventh terminals to which parallel signals are input; a first parallel signal output unit having a plurality of twelfth terminals from which parallel signals are output; Including, the first parallel-serial conversion unit receives parallel signals via the plurality of eleventh terminals, the first serial-parallel conversion unit outputs parallel signals via the plurality of twelfth terminals. The image forming system according to claim 1 .

8. the first connection unit is a first connector including the first parallel signal input unit and the first parallel signal output unit, the first external device includes a connector connectable to the first connection portion; The image forming system according to claim 7 .

9. The relay device a second connection unit connectable to a second external device among the one or more external devices; a second serial-parallel conversion unit that converts a serial signal input from the zero connection unit into a parallel signal and outputs the converted parallel signal to the second connection unit; a second parallel-to-serial conversion unit that converts the parallel signal input from the second connection unit into a serial signal and outputs the converted serial signal to the first parallel-to-serial conversion unit; Further provided with when a serial signal is input from the second parallel-serial conversion unit, the first parallel-serial conversion unit outputs the serial signal input from the second parallel-serial conversion unit to the 0 connection unit; the second serial-parallel conversion unit converts the serial signal input from the zero connection unit into a parallel signal and outputs the converted parallel signal to the second connection unit; The image forming system according to claim 1 .

10. The second connection portion is a second parallel signal input unit having a plurality of 21 terminals to which parallel signals are input; a second parallel signal output unit having a plurality of 22nd terminals from which parallel signals are output; Including, the second parallel-serial conversion unit receives parallel signals via the plurality of 21 terminals, the second serial-parallel conversion unit outputs parallel signals via the plurality of 22 terminals. The image forming system according to claim 9 .

11. the second connection unit is a connector including the second parallel signal input unit and the second parallel signal output unit; The image forming system according to claim 10.

Images