Apparatus and optional unit

Abstract

To shorten the time required for the startup of the entire apparatus, including the optional units, compared to a case where the apparatus body outputs a signal for level number detection to an optional unit.SOLUTION: An apparatus includes a plurality of optional units attached to an apparatus body, and is configured to identify the plurality of optional units. The apparatus body includes an output section that outputs a power supply voltage generated by the apparatus body. The optional units each include: a power receiving section that receives a first direct-current (DC) voltage; a step-down circuit that steps down the first DC voltage received; a power output section that outputs a second DC voltage obtained by stepping down by the step-down circuit; and a controller that detects the first DC voltage or the second DC voltage and determines a level number of the optional units on the basis of the detected voltage. Therein: the power receiving section of the optional unit at the first level connected to the apparatus body is connected to the output section of the apparatus body; and the power receiving section of the optional unit provided at a succeeding level of the optional unit at the first level is connected to the power output section of the optional unit at a preceding level.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a device and an optional device. [Background technology]

[0002] Patent Document 1 describes a method for identifying an optional device in which a main control means of a main device sends a pulse signal for identification to a sub-control means of an optional device at the next stage. Patent document 2 describes an image forming device in which the main body control means of the device main body outputs a predetermined signal during initial communication, and each option control means of each optional device determines the installation position of the device based on the voltage value of the input predetermined signal. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-287121 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-193546 Summary of the Invention [Problem to be solved by the invention]

[0004] In a device that has a main unit and multiple optional devices for expanding or adding functions, starting up the entire device requires a so-called level detection process, in which an identification number is assigned to each optional device with the same configuration. Conventionally, this level detection process was performed by starting up the main unit and then outputting a level detection signal to the optional device. It was necessary to wait for the main unit to start up in order to perform the level detection process, and it took time for the optional devices to be assigned an identification number and for the entire device, including the optional devices, to start up. An object of the present invention is to shorten the time required to start up the entire apparatus including the optional device, compared to when the main apparatus outputs a signal for detecting the number of stages to the optional device. [Means for solving the problem]

[0005] The invention described in claim 1 is a device that includes a plurality of optional devices that are attached to a main device and that identifies the plurality of optional devices, wherein the main device includes an output unit that outputs a power supply voltage generated by the main device, and the optional devices include a power receiving unit that receives a first DC voltage, a step-down circuit that steps down the received first DC voltage, a power output unit that outputs a second DC voltage stepped down by the step-down circuit, and a control unit that detects the first DC voltage or the second DC voltage and detects the stage number of the optional device based on the detected voltage, and the power receiving unit of the first stage optional device connected to the main device is connected to the output unit of the main device, and the power receiving units of the optional devices provided after the first stage optional device are connected to the power output unit of the optional device of the previous stage. The invention described in claim 2 is the device described in claim 1, characterized in that the step-down circuit includes a diode and steps down the voltage using a forward voltage. The invention described in claim 3 is the device described in claim 2, characterized in that the step-down circuit includes a series circuit of the diode, one end of which is connected to the receiving unit, and a resistor, one end of which is connected to ground, and the connection point between the diode and the resistor is connected to the output unit. The invention described in claim 4 is the device described in claim 1, characterized in that the control unit of the optional device detects the stage number of the optional device by comparing the detected voltage with a predetermined voltage range. The invention described in claim 5 is an optional device that is attached in multiple numbers to a main device, and includes a receiving unit that receives a first DC voltage, a step-down circuit that steps down the received first DC voltage, an output unit that outputs a second DC voltage that is step-down by the step-down circuit, and a control unit that detects the first DC voltage or the second DC voltage and detects the number of stages of the optional device based on the detected voltage. [Effects of the Invention]

[0006] According to the inventions of claims 1 and 5, the time required to start up the entire device including the optional device can be shortened compared to when the main device outputs a signal for detecting the number of stages to the optional device. According to the invention of claim 2, a configuration can be achieved in which no termination components are required on the board of the optional device. According to the invention of claim 3, the step-down value and the variation in the step-down value can be controlled by the type of diode and the constant of the resistor. According to the invention of claim 4, it is possible to provide a range for the voltage value detected by the optional device. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a diagram illustrating an example of the configuration of an image forming apparatus to which the present embodiment is applied. [Figure 2] FIG. 2 is a diagram illustrating a connection state between the main body device and the paper feed device. [Figure 3] FIG. 10 is a diagram illustrating an example of a step-down circuit provided on an option board. [Figure 4] 10 is a diagram showing an example of the relationship between the number of stages on which the paper feeder is installed and the range of voltage input to a computer provided in the paper feeder. FIG. [Figure 5] 10A and 10B are diagrams showing examples of voltage states on a main board and multiple option boards. [Figure 6] 10 is an arrow diagram showing the flow of stage number detection processing in an image forming apparatus, where (a) shows a comparative example to which the present embodiment is not applied, and (b) shows an example to which the present embodiment is applied. [Figure 7] FIG. 10 is a diagram illustrating an example of a step-down circuit that steps down a voltage by voltage division using resistors. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. In the following, an example in which the present invention is applied to an image forming apparatus will be described as an example of an apparatus that has multiple optional devices attached to a main apparatus and that identifies the multiple optional devices. Note that the image forming apparatus is just one example, and the present invention may also be applied to other apparatuses that have multiple optional devices with the same configuration and that require the optional devices to be identified when starting the apparatus.

[0009] <Configuration of image forming device> FIG. 1 is a diagram showing an example of the configuration of an image forming apparatus 1 to which this embodiment is applied. The image forming apparatus 1 is an apparatus that forms an image using an electrophotographic method or the like on a recording medium such as paper P. The image forming apparatus 1 according to the present embodiment is an example of an apparatus. The image forming apparatus 1 includes a main body device 10 and a paper feeder 20, which is an example of an optional device that can be attached to the main body device 10. The image forming apparatus 1 shown in Fig. 1 includes, as an example, three paper feeders 20. Each of the multiple attached paper feeders 20 has the same configuration.

[0010] The main body device 10 forms an image on a sheet P. The main body device 10 includes an image forming unit 11 that forms an image on the sheet P, and an ejection roll 12 that ejects the sheet P on which the image has been formed. The main body device 10 also includes a main body control unit 15 that controls the operation of the image forming device 1. The image forming unit 11 forms an image on the paper P conveyed from the paper feeder 20. The image forming unit 11 forms an image, for example, by transferring toner attached to a photosensitive member onto the paper P using an electrophotographic method. Alternatively, the image may be formed by ejecting ink onto the paper P using an inkjet method.

[0011] The main body control unit 15 controls the operation of the image forming apparatus 1. The main body control unit 15 controls the operation of the main body device 10, such as the image forming process. Furthermore, the main body control unit 15 transmits a control signal relating to the control of the operation of the paper feeder 20 to the option control unit 25. The option control unit 25 controls the operation of the paper feeder 20, and the paper feeder 20 is provided with the option control unit 25. The functions of the main body control unit 15 are realized by, for example, a computer.

[0012] The paper feeder 20 stores paper P and feeds the paper P to the main device 10. A plurality of paper feeders 20 are attached to the main device 10. In the example shown in Fig. 1, the image forming apparatus 1 is provided with three tiers of paper feeders 20 at its bottom. The paper feeder 20 can be added one tier at a time. The paper feed device 20 includes a paper feed cassette 21 that stores paper sheets P, and a paper feed roll 22 that feeds paper sheets P one by one from the paper feed cassette 21. The paper feed device 20 also includes a transport roll 23 that transports the fed paper sheets P to the main device 10.

[0013] The paper feed cassettes 21 contain paper P of different sizes and types, for example, for each of the plurality of paper feed devices 20. The paper P fed from the paper feed cassettes 21 of the plurality of paper feed devices 20 is transported to the image forming unit 11 of the main body device 10 via the transport path 24. The option control unit 25 controls the operation of the sheet feeding device 20. The option control unit 25 also detects the installation position of the sheet feeding device 20 itself among the multiple sheet feeding devices 20 installed in the main body device 10. Hereinafter, the installation position may be referred to as the "tier number." The tier numbers of the multiple sheet feeding devices 20 installed in the main body device 10 may be referred to as the "first tier, second tier, ..." in order from the topmost tier, the first tier. In FIG. 1, the sheet feeding device 20 in the first tier is denoted as 20(1), the sheet feeding device 20 in the second tier is denoted as 20(2), and the sheet feeding device 20 in the third tier is denoted as 20(3). The function of the option control unit 25 is realized by, for example, a computer.

[0014] <Connection status between the main unit and paper feeder> The connection state between the main device and the paper feeder will be described with reference to FIGS. 2 and 3. FIG. FIG. 2 is a diagram showing the connection state between main body device 10 and paper feeder device 20. FIG. 2 shows the connection state between main body board 50 and option board 60. Main body board 50 is provided in main body control unit 15 (see FIG. 1) of main body device 10. Option board 60 is provided in option control unit 25 (see FIG. 1) of paper feeder 20. Main body board 50 and option board 60 are connected by connector 70. Like image forming apparatus 1 in FIG. 1, image forming apparatus 10 in FIG. 2 includes main body device 10 and three paper feeders 20. FIG. 3 is a diagram showing an example of a step-down circuit 62 provided on the option board 60 (see FIG. 2).

[0015] The main body board 50 includes a computer 30 that realizes the functions of the main body control unit 15, a power supply unit 51 that generates a power supply voltage, and an output terminal 52 that outputs the power supply voltage. The output terminal 52 is an example of an output unit.

[0016] The computer 30 includes a processor 31, a ROM (Read Only Memory) 32, a RAM (Random Access Memory) 33, and a communication interface 34 (referred to as communication I / F 34 in FIG. 2, and the same applies below). The processor 31 is, for example, a CPU (Central Processing Unit). The ROM 32 is a non-volatile memory that stores programs executed by the processor 31 and other data. The RAM 33 is a volatile memory that is used as a working area when the processor 31 executes a program. The processor 31 uses the RAM 33 as a working area and executes a program read from the ROM 32.

[0017] Communication interface 34 is connected to communication interface 44 of computer 40 provided on option board 60, for example, via a signal line. Processor 31 transmits control signals related to the control of the operation of sheet feeder 20, for example, to option control unit 25 via communication interface 34. Note that, as will be described in detail below, in this embodiment, detection of the number of stages is not based on a control signal transmitted via communication interface 34.

[0018] The power supply unit 51 generates a power supply voltage. When the image forming apparatus 1 is switched on, the power supply unit 51 generates a power supply voltage and outputs it via the power output terminal 52 to the power receiving terminal 61 of the option board 60, which will be described later. The power output terminal 52 outputs the power supply voltage generated by the power supply unit 51. The power output terminal 52 of the main board 50 is connected to the power receiving terminal 61 of the option board 60 by a connector 70.

[0019] Option board 60 includes computer 40 that realizes the functions of option control unit 25. Option board 60 also includes a power receiving terminal 61 that receives a DC voltage, a step-down circuit 62 that steps down the DC voltage received by power receiving terminal 61, and a power output terminal 63 that outputs the DC voltage stepped down by step-down circuit 62. Power receiving terminal 61 is an example of a power receiving unit, and power output terminal 63 is an example of a power output unit.

[0020] The computer 40 includes a processor 41, a ROM (Read Only Memory) 42, a RAM (Random Access Memory) 43, a communication interface 44, and an input terminal 45. The processor 41 is, for example, a CPU (Central Processing Unit). The processor 41 uses the RAM 43 as a working area and executes a program read from the ROM 42. The processor 41 detects the voltage, for example, and executes a stage number detection process to detect the stage number of the device itself. The stage number detection process will be described in detail later.

[0021] The communication interface 44 is connected to the communication interface 34 of the computer 30 provided on the main body board 50, for example, via a signal line. The processor 41 acquires a control signal from the main body control unit 15 via the communication interface 44. The processor 41 controls the operation of its own device in accordance with the acquired control signal. The input terminal 45 receives a DC voltage to be input to the computer 40 .

[0022] The power receiving terminal 61 is connected to another board via the connector 70 and receives DC voltage. When the paper feeder 20 on which the option board 60 is provided is the first stage, the power receiving terminal 61 is connected to the power output terminal 52 of the main board 50 and receives the power supply voltage output from the power output terminal 52. When the paper feeder 20 on which the option board 60 is provided is the second stage or later, the power receiving terminal 61 is connected to the power output terminal 63 of the option board 60 of the paper feeder 20 one stage before and receives the DC voltage output from the power output terminal 63.

[0023] The step-down circuit 62 is a circuit that steps down the DC voltage received by the power receiving terminal 61 . 3 is a diagram showing an example of a step-down circuit 62 provided on the option board 60 (see FIG. 2). The step-down circuit 62 includes a diode 64, and steps down the voltage by the forward voltage of the diode 64. The step-down circuit 62 shown in FIG. 3 includes a diode 64, a first resistor 65, a second resistor 66, and a capacitor 67.

[0024] The diode 64 is, for example, a pn junction diode formed by joining a p-type semiconductor and an n-type semiconductor. A pn ​​junction diode has rectification characteristics that allow current to pass in the forward direction from a p-type anode (A) to an n-type cathode (K) and block current in the reverse direction. When a forward current flows through the diode 64, a forward voltage is generated between the anode (A) and the cathode (K). In other words, the voltage is reduced by passing current through the diode 64. In the following explanation, the diode 64 is assumed to be a silicon pn junction diode with a forward voltage of approximately 0.6 V to 0.7 V. Note that the forward voltage varies depending on the current flowing through the diode 64. The anode (A) of the diode 64 is connected to the power receiving terminal 61, and the cathode (K) is connected to the power output terminal 63.

[0025] One end of the first resistor 65 is connected to ground, and the other end is connected to the cathode (K) of the diode 64. A forward current flows from the power receiving terminal 61 to the ground via the diode 64 and the first resistor 65. This forward current generates a forward voltage in the diode 64. The first resistor 65 has a predetermined electrical resistance, which adjusts the value of the current flowing through the diode 64. The diode 64 and the first resistor 65 are connected in series.

[0026] The second resistor 66 is connected between the diode 64 and the computer 40. The cathode (K) of the diode 64 is connected to the computer 40 via the second resistor 66. The voltage at the cathode (K) of the diode 64, that is, the voltage stepped down by the forward voltage of the diode 64, is supplied to the input terminal 45 of the computer 40. The second resistor 66 prevents excessive current from flowing through the voltage step-down circuit 62. The capacitor 67 has one end connected to ground and the other end connected between the diode 64 and the computer 40. The capacitor 67 suppresses fluctuations in the voltage supplied to the computer 40. The step-down circuit 62 may be configured without either or both of the second resistor 66 and the capacitor 67.

[0027] In the example shown in FIG. 3, step-down circuit 62 includes diode 64, and the voltage is stepped down by the forward voltage of diode 64. Diode 64 blocks reverse current. Therefore, since step-down circuit 62 includes diode 64, the step-down circuits 62 provided on each of the multiple option boards 60 (see FIG. 2) are electrically isolated without causing reverse current flow. As a result, option board 60 does not require a termination component, reducing the cost of option board 60. Furthermore, the size of sheet feeding device 20 equipped with option board 60 is prevented from increasing.

[0028] In the example shown in FIG. 3, the DC voltage (first DC voltage) received by the power receiving terminal 61 is supplied to the anode (A) of the diode 64. The cathode (K) of the diode 64 becomes a DC voltage (second DC voltage) obtained by stepping down the DC voltage received by the power receiving terminal 61 by the forward voltage of the diode 64. The output terminal 63 outputs a DC voltage (second DC voltage) obtained by stepping down the DC voltage received by the power receiving terminal 61 by the forward voltage of the diode. The DC voltage (second DC voltage) obtained by stepping down the DC voltage received by the power receiving terminal 61 by the forward voltage of the diode 64 is supplied to the input terminal 45 of the computer 40 via a second resistor 66.

[0029] 2, output terminal 63 of option board 60 outputs a DC voltage stepped down by step-down circuit 62. Output terminal 63 of option board 60 is connected by connector 70 to power receiving terminal 61 of option board 60 in the next stage. As shown in FIG. 2, the power receiving terminal 61 of the first-stage option board 60 connected to the main device 10 is connected to the power output terminal 52 of the main board 50. The power receiving terminal 61 of the option boards 60 provided in the second stage and beyond is connected to the power output terminal 63 of the option board 60 in the previous stage. In this embodiment, the main board 50 and multiple option boards 60 are connected in a chain. Only one path is required for the stage number detection process. In other words, the option board 60 is miniaturized.

[0030] <Step detection process> 2 to 5, the stage number detection process in the image forming apparatus 1 will be described. Here, an example will be described in which the forward voltage of the diode 64 is about 0.6 V to 0.7 V, and a power supply voltage of 3.3 V is generated in the power supply unit 51.

[0031] 4 is a diagram showing an example of the relationship between the stage number at which paper feeder 20 is installed and the range of voltage input to computer 40 provided in paper feeder 20. For example, if the voltage input to input terminal 45 of computer 40 is within the range of 2.3V to 3.3V, computer 40 detects that its own device is in the first stage. The data of the relationship values ​​shown in FIG. 4 is stored, for example, in ROM 42 of computer 40.

[0032] FIG. 5 is a diagram showing an example of the voltage state on the main board 50 and the multiple option boards 60 provided. A DC voltage of 2.3V to 3.3V is supplied to input terminal 45 of computer 40 provided on first-stage option board 60. A DC voltage of 1.6V to 2.3V is supplied to input terminal 45 of computer 40 provided on second-stage option board 60. A DC voltage of 0V to 1.6V is supplied to input terminal 45 of computer 40 provided on third-stage option board 60.

[0033] The power supply voltage generated in power supply unit 51 of main board 50 is output as a DC voltage from output terminal 52. The output DC voltage is received by power receiving terminal 61 of first-stage option board 60, and the received DC voltage is stepped down by step-down circuit 62. The DC voltage stepped down by step-down circuit 62 is input to input terminal 45 of computer 40 provided on first-stage option board 60. Computer 40 detects the input DC voltage and compares it with the voltage range stored in ROM 42 to detect the stage number of its own device.

[0034] For example, if the step-down value by step-down circuit 62 is 0.7 V, a DC voltage of 2.6 V is input to input terminal 45 of computer 40 provided on first-stage option board 60. In this case, computer 40 detects that its own device is the first stage by comparing the input DC voltage with the voltage range shown in FIG. Thus, in this embodiment, the computer 40 detects the stage number of the device itself by comparing the detected voltage with a predetermined voltage range.

[0035] Furthermore, the DC voltage stepped down by step-down circuit 62 of first-stage option board 60 is output by output terminal 63. The DC voltage output by output terminal 63 is received by receiving terminal 61 of second-stage option board 60. The received DC voltage is stepped down by step-down circuit 62 and input to input terminal 45 of computer 40 provided on second-stage option board 60. Computer 40 detects the input DC voltage and compares it with the voltage range stored in ROM 42 to detect the stage number of its own device.

[0036] For example, if the DC voltage at power receiving terminal 61 is 2.6 V and the step-down value by step-down circuit 62 is 0.68 V, a DC voltage of 1.92 V is input to input terminal 45 of computer 40. In this case, computer 40 detects that its own device is in the second stage by comparing the input DC voltage with the voltage range shown in FIG. The DC voltage stepped down by step-down circuit 62 of second-stage option board 60 is output from power output terminal 63 and received by power receiving terminal 61 of third-stage option board 60. A similar stage number detection process is also performed in third-stage option board 60.

[0037] 4, when four or more sheet feeders 20 are attached to the main device 10, it is not possible to detect the number of layers. However, by adjusting the step-down value by the step-down circuit 62 or by adjusting the DC voltage output from the main device 10 to the first sheet feeder 20, it is possible to detect the number of layers even when four or more sheet feeders 20 are attached. For example, consider a case where the step-down circuit 62 includes a diode 64 as shown in Fig. 3. In this case, by changing the type of diode 64 or the resistance value of the first resistor 65, the step-down value of the diode 64 can be adjusted to be smaller.

[0038] In the above description, the computer 40 detects the DC voltage after it has been stepped down by the step-down circuit 62, but this is not limiting. The computer 40 may also detect the DC voltage before it has been stepped down by the step-down circuit 62. For example, computer 40 may be connected between power receiving terminal 61 and diode 64. In this case, a DC voltage (first DC voltage) before being stepped down by step-down circuit 62 is input to input terminal 45 of computer 40. The DC voltage output from output terminal 52 of main board 50 is input as is to computer 40 of first-stage option board 60. The DC voltage stepped down by step-down circuit 62 of the preceding-stage option board 60 is input to computers 40 of second-stage and subsequent option boards 60.

[0039] FIG. 6 is an arrow diagram showing the flow of the stage number detection process in the image forming apparatus 1, where (a) shows a comparative example to which this embodiment is not applied, and (b) shows an example to which this embodiment is applied. The arrow diagram shown in FIG. 6(a) shows an example of the flow of the step number detection process when the computer 30 of the main device 10 outputs a signal for step number detection.

[0040] 6(a), first, power is supplied to the image forming apparatus 1 (step 1, which is indicated by a number in a circle in FIG. 6, and the same applies below). When the switch of the image forming apparatus 1 is turned on, a power supply voltage is generated in the power supply unit 51. Next, the main device 10 starts up (step 2). Power is supplied to the computer 30 of the main device 10, and the software starts up to start the initial process. Then, the main device 10 outputs a signal for detecting the number of stages (step 4). In the example shown in FIG. 6(a), the computer 30 of the main device 10 outputs a signal for detecting the number of stages to the first sheet feeder 20.

[0041] When power is supplied to image forming apparatus 1 in step 1, sheet feeding device 20 begins to start up (step 3). Power is supplied to computer 40 of sheet feeding device 20, software starts up, and initial processing begins. The initial processing in computer 40 involves fewer processes than computer 30 of main device 10, so the initial processing is completed earlier than in main device 10.

[0042] Next, the sheet feeding device 20 detects the number of stages in its own device (step 5). The computer 40 of the sheet feeding device 20 attached to the first stage receives the signal output by the main device 10 in step 4 and detects that its own device is the first stage. The computer 40 then stores the number of stages in its own device, for example, in ROM 42. Thereafter, the computer 40 outputs a signal for detecting the number of stages to the sheet feeding device 20 attached to the second stage. This processing process is repeated for the number of stages of the sheet feeding devices 20 attached to the main device 10.

[0043] Next, the main device 10 starts communication with the paper feed devices 20 (step 6). The main device 10 starts communication after all paper feed devices 20 attached to the main device 10 have detected the number of stages of their own device. Then, the configuration of the image forming device 1 is determined (step 7). The main device 10 can then start image formation processing, etc.

[0044] Conventionally, the number of stacks detection process has been performed, for example, by the process shown in Fig. 6(a). Conventionally, after the computer 30 of the main body device 10 is started, the computer 30 is required to output a signal for detecting the number of stacks to the sheet feeding device 20. In this case, the number of stacks detection process cannot start unless the computer 30 is started. Also, since the number of stacks must be detected for each sheet feeding device 20 in turn when multiple sheets are installed, it takes a long time for the entire device to start up.

[0045] On the other hand, when this embodiment is applied, the step number detection process is executed without the computer 30 of the main device 10 outputting a signal for step number detection. Therefore, in this embodiment, the step number detection process can be executed without waiting for the startup of the computer 30. An example of the flow of the step number detection process when this embodiment is applied will be described with reference to FIG. 6(b).

[0046] 6(b), first, power is supplied to the image forming apparatus 1 (step 1). When the switch of the image forming apparatus 1 is turned on, a power supply voltage is generated in the power supply unit 51. Then, the power supply voltage is output from the power output terminal 52 to the option board 60. Then, main body device 10 starts to start up (step 2). When power is supplied to image forming apparatus 1 in step 1, sheet feeding device 20 starts to start up (step 3). In this embodiment, computer 40 of sheet feeding device 20, which is started up in step 3, detects the number of stages of its own device.

[0047] Next, the main device 10 starts communication with the paper feed devices 20 (step 6). The main device 10 starts communication after all paper feed devices 20 attached to the main device 10 have detected the number of stages of their own device. Then, the configuration of the image forming device 1 is determined (step 7). The main device 10 can then start image formation processing, etc.

[0048] In this embodiment, computer 40 of sheet feeder 20 detects the number of sheets in its own device using the power supply voltage generated by power supply unit 51 of main device 10. Therefore, as shown in FIG. 6(b), the processes of steps 4 and 5 can be omitted. The number of sheets detection process can be executed without waiting for computer 30 of main device 10 to start up. This shortens the time it takes for the entire image forming apparatus 1 to start up.

[0049] The step-down circuit 62 is not limited to one including the diode 64 as shown in Fig. 3. The step-down circuit 62 may step down the voltage by voltage division using resistors, for example. FIG. 7 is a diagram showing an example of a step-down circuit 62 that steps down the voltage by voltage division using resistors. 7, the step-down circuit 62 has a first resistor 68 and a second resistor 69. The first resistor 68 and the second resistor 69 are examples of a first resistor and a second resistor, respectively.

[0050] In the step-down circuit 62, the power receiving terminal 61 is connected to the input terminal 45 of the computer 40. One end of a first resistor 68 is connected to the power receiving terminal 61, and the other end is connected to the power output terminal 63. One end of a second resistor 69 is connected to ground, and the other end is connected to the power receiving terminal 61. In other words, the connection point between the first resistor 68 and the second resistor 69 is connected to the computer 40. When the sheet feeding device 20 provided with the option board 60 (see FIG. 2) is at the first stage, the DC voltage output from the power output terminal 52 of the main body board 50 is input to the computer 40 as is.

[0051] If the sheet feeder 20 equipped with option board 60 is the second or subsequent stage, the stepped-down voltage is input to computer 40. In this case, the voltage divided by second resistor 69 and first resistor 68 of option board 60 in the immediately preceding sheet feeder 20 is input to computer 40. In this way, in step-down circuit 62 in the example shown in FIG. 7 , the voltage received at power receiving terminal 61 is stepped down by voltage division by first resistor 68 and second resistor 69. A first resistor 68 may be connected between the power receiving terminal 61 and the computer 40.

[0052] (Addendum) (((1))) A device for identifying a plurality of optional devices that are attached to a main device, the device comprising: the main body device includes an output unit that outputs a power supply voltage generated by the main body device; the optional device comprises a power receiving unit that receives a first DC voltage, a step-down circuit that steps down the received first DC voltage, a power output unit that outputs a second DC voltage stepped down by the step-down circuit, and a control unit that detects the first DC voltage or the second DC voltage and detects the stage number of the optional device based on the detected voltage; The power receiving unit of the first stage optional device connected to the main device is connected to the output unit of the main device, and the power receiving units of the optional devices provided after the first stage optional device are connected to the power output unit of the preceding stage optional device. Device. (((2))) The step-down circuit includes a diode and steps down the voltage by the forward voltage. The device according to (((1))) characterized in that (((3))) The step-down circuit includes a series circuit including the diode, one end of which is connected to the power receiving unit, and a resistor, one end of which is connected to ground, and a connection point between the diode and the resistor is connected to the power output unit. The device according to (((2))) characterized in that (((4))) The control unit of the optional device detects the stage number of the optional device by comparing the detected voltage with a predetermined voltage range. The device according to (((1))) characterized in that (((5))) A plurality of optional devices are attached to the main device, The power receiving unit includes a power receiving section that receives a first DC voltage, a step-down circuit that steps down the received first DC voltage, a power output section that outputs a second DC voltage that is stepped down by the step-down circuit, and a control section that detects the first DC voltage or the second DC voltage and detects the number of stages of the optional device based on the detected voltage. Optional equipment.

[0053] According to the inventions (((1))) and (((5))), the time required to start up the entire device including the optional device can be shortened compared to when the main device outputs a signal to the optional device to detect the number of stages. According to the invention (((2))), a configuration can be achieved in which no termination components are required on the board of the optional device. According to the invention of (((3))), the step-down value and the variation in the step-down value can be controlled by the type of diode and the constant of the resistor. According to the invention (((4))), it is possible to provide a range for the voltage value detected by the optional device. [Explanation of symbols]

[0054] 1...image forming apparatus, 10...main body device, 15...main body control unit, 20...paper feeding device, 25...option control unit, 30, 40...computer, 50...main body board, 51...power supply unit, 60...option board, 62...step-down circuit, 64...diode, 70...connector

Claims

1. A device for identifying a plurality of optional devices that are attached to a main device, the device comprising: the main body device includes an output unit that outputs a power supply voltage generated by the main body device; the optional device comprises a power receiving unit that receives a first DC voltage, a step-down circuit that steps down the received first DC voltage, a power output unit that outputs a second DC voltage stepped down by the step-down circuit, and a control unit that detects the first DC voltage or the second DC voltage and detects the stage number of the optional device based on the detected voltage; The power receiving unit of the first stage optional device connected to the main device is connected to the output unit of the main device, and the power receiving units of the optional devices provided after the first stage optional device are connected to the power output unit of the preceding stage optional device. Device.

2. The step-down circuit includes a diode and steps down the voltage by the forward voltage.

2. The device of claim 1 .

3. The step-down circuit includes a series circuit including the diode, one end of which is connected to the power receiving unit, and a resistor, one end of which is connected to ground, and a connection point between the diode and the resistor is connected to the power output unit.

3. The device according to claim 2.

4. The control unit of the optional device detects the stage number of the optional device by comparing the detected voltage with a predetermined voltage range.

2. The device of claim 1 .

5. A plurality of optional devices are attached to the main device, The power receiving unit receives a first DC voltage, a step-down circuit steps down the received first DC voltage, a power output unit outputs a second DC voltage stepped down by the step-down circuit, and a control unit detects the first DC voltage or the second DC voltage and detects the number of stages of the optional device based on the detected voltage. Optional equipment.

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