Image forming apparatus

Abstract

To provide an image forming apparatus that can detect occurrence of an abnormality causing noise.SOLUTION: An image forming apparatus of the present disclosure comprises: a control unit that is provided to output first control information; a first control information conversion unit that has a first output channel; a second control information conversion unit that has a second output channel; a high voltage output generation unit that is connected with the first output channel; and a comparison unit. The first control information conversion unit is provided to, upon receiving input of first control data, output second control information to the first output channel. The second control information conversion unit is provided to, upon receiving input of the first control data, output the second control information to the second output channel. The second output channel is an empty channel. The comparison unit is provided to compare the second control information in the first output channel with the second control information in the second output channel. The control unit is provided to detect an abnormality in the image forming apparatus on the basis of output from the comparison unit.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] This disclosure relates to an image forming apparatus.

Background Art

[0002] A plurality of high voltage outputs such as charging / developing / transferring / peeling and discharging are required for an image forming apparatus. In particular, a color image forming apparatus may have more than 10 types of high voltage outputs, such as high voltage outputs for charging / developing for four colors and high voltage outputs for primary and secondary transfers. The high voltage output generation unit that generates the high voltage output required for image formation may be concentrated in one location inside the image forming apparatus or may be dispersed in multiple locations. When the high voltage output generation unit is concentrated in one location, it is necessary to generate more than 10 types of high voltage outputs with the concentrated high voltage output generation unit. On the other hand, when performing a plurality of controls on the concentrated high voltage output generation unit (such as a substrate), it is known to use a DA converter (digital-to-analog converter) for reasons such as suppressing control lines (signal lines).

[0003] [[ID=E19]] It is also known that a DA converter is a control method that is relatively vulnerable to external noise, and the output of the DA converter may change when noise is received on the DATA (DI) / CLK / LD lines (see, for example, Patent Document 1).

[0004] For example, suppose a 10-bit DA converter with output channels A01 to A08 (when the maximum voltage of an output channel is set to 5.0V, the output voltage of the corresponding output channel is 0V when the input data signal is 0 (decimal), and the output voltage of the corresponding output channel is 5.0V when the input data signal is 1023 (decimal)) has set the output voltage of channel A02 of the DA converter to 4.5V based on a control signal. The control unit sends a signal (binary) to the DA converter using the DATA(DI) / CLK / LD line to "set the output voltage of channel A05 to 2.0V," but the DATA(DI) / CLK / LD line is affected by noise and loaded with a 1-shift (D4 becomes "1"). The digital data when there is no noise will have the address and data (binary) as shown in the upper part of Figure 2. When "1" is loaded into D4 due to noise, the digital signal (binary) will be shifted by one, as shown in the lower part of Figure 2. Therefore, the DA converter receives an incorrect signal that "sets the output voltage of channel A02 to 4.0V," and the DA converter changes the output voltage of channel A02 from 4.5V to 4.0V. In this case, if channel A02 is the DA converter output for GB-K output control, the GB-K output (as described later, for example, if channel A02 voltage = 1.0V and GB-K output = -150V, and channel A02 voltage = 5.0V and GB-K output = -850V) changes from -761V to -675V, resulting in an image with a black cast.

[0005] Possible sources of external noise include electrostatic discharge strikes from operators, contact leaks in the high-voltage output path, and leaks caused by foreign objects. However, it is considered difficult to completely eliminate these noise sources. Therefore, various countermeasures have been considered to ensure that the output of the DA converter does not change even when subjected to external noise, or that if the output of the DA converter changes, it quickly returns to its original state. One such countermeasure is to continuously rewrite the same signal (specified channel information + output information for that channel) to the DA converter (rewrite control).

[0006] By continuously rewriting the same signal to the DA converter, even if the DA converter's output temporarily changes due to external noise, it will recover to its original output in a short time (at most the length of the rewrite cycle). This type of control limits the image impact to a minor one due to momentary output changes. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2013-238753 [Overview of the project] [Problems that the invention aims to solve]

[0008] However, a problem with this noise countermeasure using rewriting is that if the external noise is due to contact leaks in the high-voltage output path, the noise source will not fundamentally disappear from inside the image forming apparatus (except in cases where foreign matter burns out due to leakage), and there is a possibility of intermittent exposure to external noise. Furthermore, while the noise countermeasure using rewriting addresses changes in the output of the DA converter, it does not improve the situation where minor image effects occur due to noise such as contact leaks. In addition to minor high-voltage output failures, there is also the possibility of false detections by paper feed sensors, and depending on the extent of the leak, in the worst case, it may even lead to an unpleasant odor due to the leak. This disclosure has been made in view of these circumstances and provides an image forming apparatus capable of detecting the occurrence of an anomaly that generates noise. [Means for solving the problem]

[0009] This disclosure provides a control unit configured to output first control information including an address and data; a first control information conversion unit having a first output channel and connected to the control unit; a second control information conversion unit having a second output channel and connected to the control unit; a high-voltage output generation unit connected to the first output channel; and comparison units connected to the first and second output channels. The first control information conversion unit is configured to receive first control data from the control unit, including an address corresponding to the first output channel and data corresponding to the high-voltage output of the high-voltage output generation unit, to convert the data corresponding to the high-voltage output into second control information and output the second control information to the first output channel. The present invention provides an image forming apparatus characterized in that, when the second control information conversion unit receives first control data from the control unit, which includes an address corresponding to the second output channel and data corresponding to the high voltage output of the high voltage output generation unit, it converts the data corresponding to the high voltage output into second control information and outputs the second control information to the second output channel, the second output channel is an empty channel not connected to the high voltage output generation unit, the comparison unit is provided to compare the second control information of the first output channel with the second control information of the second output channel, and the control unit is provided to detect an abnormality in the image forming apparatus based on the output of the comparison unit. [Effects of the Invention]

[0010] The second control information conversion unit converts data corresponding to the high voltage output of the high voltage output generation unit connected to the first output channel of the first control information conversion unit into second control information and outputs the second control information to the second output channel, which is an empty channel. Therefore, the second control information corresponding to the high voltage output of the high voltage output generation unit instructed by the control unit can be stored in the second output channel. Consequently, if the second control information of the first output channel becomes erroneous due to noise, the control unit can use the comparison unit to compare the second control information of the first output channel with the second control information stored in the second output channel to detect the occurrence of noise, and can detect that an abnormality causing noise has occurred in the image forming apparatus. Furthermore, if the second control information of the second output channel becomes erroneous due to noise, the control unit can detect the occurrence of noise by comparing the second control information of the second output channel with the second control information of the first output channel using the comparison unit, thereby detecting that an abnormality causing noise has occurred in the image forming apparatus. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic diagram showing the configuration of an image forming apparatus according to one embodiment of the present disclosure. [Figure 2] This diagram illustrates how the control signals change when the DATA (DI) / CLK / LD lines are subjected to noise. [Figure 3] This is a time chart of the first control information sent from the control unit to the first and second control information conversion units using the DATA(DI) / CLK / LD line. [Figure 4] This is a time chart of the first and second control information when output glitches occur in the second control information of the output channels of the first and second control information conversion units due to a leak. [Modes for carrying out the invention]

[0012] The image forming apparatus disclosed herein comprises a control unit provided to output first control information including an address and data; a first control information conversion unit having a first output channel and connected to the control unit; a second control information conversion unit having a second output channel and connected to the control unit; a high-voltage output generation unit connected to the first output channel; and comparison units connected to the first and second output channels. When the first control information conversion unit receives first control data from the control unit, including an address corresponding to the first output channel and data corresponding to the high-voltage output of the high-voltage output generation unit, it converts the data corresponding to the high-voltage output into second control information and outputs the second control information to the first output channel. The second control information conversion unit is configured to output a second output channel, and when it receives first control data from the control unit, which includes an address corresponding to the second output channel and data corresponding to the high voltage output of the high voltage output generation unit, it converts the data corresponding to the high voltage output into second control information and outputs the second control information to the second output channel, the second output channel being an empty channel not connected to the high voltage output generation unit, the comparison unit is configured to compare the second control information of the first output channel with the second control information of the second output channel, and the control unit is configured to detect an abnormality in the image forming apparatus based on the output of the comparison unit.

[0013] Preferably, the control unit is configured to repeatedly output first control information, including an address corresponding to the first output channel and data corresponding to the high voltage output of the high voltage output generation unit, to the first control information conversion unit, and is configured to output first control information, including an address of the second output channel and data corresponding to the high voltage output of the high voltage output generation unit, to the second control information conversion unit when there is a change in the high voltage output of the high voltage output generation unit. Preferably, the address of the first output channel is the same as the address of the second output channel. Preferably, the control unit is connected to the first and second control information conversion units via data signal lines, connected to the first and second control information conversion units via clock signal lines, connected to the first control information conversion unit via a first load signal line, and connected to the second control information conversion unit via a second load signal line.

[0014] Preferably, the image forming apparatus further comprises a notification unit, and the control unit is configured to notify a user or a remote management system of an abnormality using the notification unit based on the output of the comparison unit. Preferably, the control unit is provided to store information regarding the output of the comparison unit, to determine whether or not to notify of an abnormality based on the stored information regarding the output, and to be able to change the criteria for determining whether or not to notify.

[0015] An embodiment of this disclosure will be described below with reference to the drawings. The configurations shown in the drawings and the following description are illustrative, and the scope of this disclosure is not limited to those shown in the drawings and the following description.

[0016] Figure 1 is a schematic diagram showing the configuration of the image forming apparatus according to this embodiment. The image forming apparatus 50 of this embodiment includes a control unit 2 provided to output first control information including an address and data, a first control information conversion unit 3 having a first output channel and connected to the control unit 2, a second control information conversion unit 4 having a second output channel and connected to the control unit 2, a high voltage output generation unit 5c connected to the first output channel, and a comparison unit 6 connected to the first and second output channels. When the first control information conversion unit 3 receives first control data from the control unit 2, which includes an address corresponding to the first output channel and data corresponding to the high voltage output of the high voltage output generation unit 5c, it converts the data corresponding to the high voltage output into second control information and outputs the second control information to the first output channel. The second control information conversion unit 4 is configured to output to a channel, and when it receives first control data from the control unit 2, which includes an address corresponding to the second output channel and data corresponding to the high voltage output of the high voltage output generation unit 5c, it converts the data corresponding to the high voltage output into second control information and outputs the second control information to the second output channel, the second output channel being an empty channel not connected to the high voltage output generation unit 5c, the comparison unit 6 is configured to compare the second control information of the first output channel with the second control information of the second output channel, and the control unit 2 is configured to detect an abnormality in the image forming apparatus 50 based on the output of the comparison unit 6.

[0017] The image forming apparatus 50 is an electrophotographic image forming apparatus that forms images using electrophotographic technology. The image forming apparatus 50 may be a monochrome image forming apparatus capable of forming monochrome images, or it may be an intermediate transfer type color image forming apparatus capable of forming color images as shown in Figure 1. The image forming apparatus 50 is, for example, a so-called tandem type full-color image forming apparatus having a configuration in which a toner image forming unit 18a for forming a toner image of black toner, a toner image forming unit 18b for forming a toner image of cyan toner, a toner image forming unit 18c for forming a toner image of magenta toner, and a toner image forming unit 18d for forming a toner image of yellow toner are arranged side by side in a predetermined direction (for example, horizontal or vertical). The image forming apparatus 50 may also be other color image forming apparatuses, copiers, multifunction printers, or facsimile machines.

[0018] The control unit 2 is a part that controls the image forming apparatus 50. The control unit 2 can include, for example, an arithmetic processing unit (e.g., CPU), RAM, a storage device (e.g., HDD), a network controller, a video controller, etc. Also, the control unit 2 is connected to the first control information conversion unit 3 and the second control information conversion unit 4 via a data signal line DATA(DI) for transmitting a data signal, a clock signal line CLK for transmitting a clock signal, load signal lines LD1 and LD2 for transmitting load signals. For example, like the image forming apparatus 50 shown in FIG. 1, the control unit 2 can be connected to the first control information conversion unit 3 and the second control information conversion unit 4 via a data signal line, can be connected to the first control information conversion unit 3 and the second control information conversion unit 4 via a clock signal line, can be connected to the first control information conversion unit 3 via the load signal line LD1, and can be connected to the second control information conversion unit 4 via the load signal line LD2. The control unit 2 can transmit the first control information to the first control information conversion unit 3 and the second control information conversion unit 4 using a data signal, a clock signal, and a load signal.

[0019] The first control information is control information for controlling a high voltage necessary for image formation in the image forming apparatus 50 and is a digital signal. The first control information includes an address of an output channel of the first or second control information conversion unit corresponding to the voltage application location and data corresponding to the voltage value applied to the voltage application location. The first control information is, for example, control information regarding high voltage application to the charging rollers 21a to 21d, control information regarding high voltage application to the developing unit, information regarding high voltage application for transferring the toner image, etc.

[0020] The control unit 2 can repeatedly output (rewrite) the first control information to the first control information conversion unit 3 and the second control information conversion unit 4. By doing this, even if the output of the first control information conversion unit 3 or the second control information conversion unit 4 temporarily changes due to external noise, it can recover to the original output in a short time (at most the time of the rewrite cycle). When such control is performed, only a minor image influence due to an instantaneous output change is sufficient.

[0021] The first control information conversion unit 3 and the second control information conversion unit 4 are the parts that convert the first control information input from the control unit 2 into second control information and output it to the output channel. The second control information can be a voltage (analog signal). The first control information conversion unit 3 or the second control information conversion unit 4 can have multiple output channels. The first control information conversion unit 3 or the second control information conversion unit 4 is, for example, a multi-channel voltage output digital-to-analog converter. The number of channels of the first control information conversion unit 3 or the second control information conversion unit 4 is, for example, 3, 8, or 10. For example, the first control information conversion unit 3 included in the image forming apparatus 50 shown in Figure 1 has three output channels chX, chY, and chZ, and the second control information conversion unit 4 has three output channels chX, chY, and chZ. When the second control information is a voltage, each output channel of the first control information conversion unit 3 or each output channel of the second control information conversion unit 4 can output a voltage in the range of 1.0V to 5.0V with a resolution of, for example, 10 bits.

[0022] A digital-to-analog converter (DA converter) can perform multiple control operations using data signals (DATA (DI)), clock signals (CLK), and load signals (LD). The DA converter reads the data signal input via the data signal line DATA (DI) one bit at a time at the timing of the clock signal input via the clock signal line CLK, and inputs the read data (a predetermined number of bits) at the timing of the load signals on the load signal lines LD1 and LD2. For example, 14 data points D0 to D13 as shown in Figure 2 are input. The four data points D0 to D3 are data indicating the address of the output channel of the DA converter, and the ten data points D4 to D13 are data (in binary) corresponding to the output (second control information) of this output channel. While there are various classifications of DA converters, such as their conversion method, here we will focus on resolution and the number of channels.

[0023] First, the resolution is determined by the required precision of the controlled high-voltage output. For example, if the grid bias black (GB-K) output of the charging roller 21a needs to be controlled between -150V and -850V in 1V intervals, a resolution of 700 or higher is required, necessitating the use of a 10-bit (resolution: 1023) DA converter. In this case, for example, the high-voltage output generation unit 5d operates so that the GB output is -150V when the DA converter output is 1.0V, and the GB output is -850V when the DA converter output is 5.0V. Generally, an 8-bit or 10-bit DA converter is considered necessary when controlling the high-voltage output required for image formation.

[0024] Next, regarding the number of channels, it is inevitable that the number of channels required will be greater than the number of high-voltage outputs to be controlled. For example, in the case of 10-bit DA converters, 4-channel, 8-channel, and 10-channel products are common.

[0025] Each output channel of the first control information conversion unit 3 or each output channel of the second control information conversion unit 4 can be connected to the high-voltage output generation units 5a to 5e via circuit board patterns or wires. In addition, the first control information conversion unit 3 or the second control information conversion unit 4 may have output channels (empty channels) that are not connected to the high-voltage output generation units 5a to 5e. The high-voltage output generation units 5a to 5e are the parts that generate the high voltage to be applied to the voltage application point based on the second control information of each output channel of the first control information conversion unit 3 or each output channel of the second control information conversion unit 4. The outputs of the high-voltage output generation units 5a to 5e are connected to the voltage application point via circuit board patterns or wires. With this configuration, the control unit 2 can control the voltage applied to the voltage application point using the first control information, thereby appropriately controlling the potential of the voltage application point.

[0026] For example, the output channel chX of the first control information conversion unit 3 included in the image forming apparatus 50 shown in Figure 1 is connected to the input of the high-voltage output generation unit 5a via a substrate pattern and wires, and the output of the high-voltage output generation unit 5a is connected to the charging roller 21d of the toner image forming unit 18d that forms the toner image of the yellow toner via a substrate pattern and wires. Therefore, the output channel chX of the first control information conversion unit 3 corresponds to the charging roller 21d. The output channel chY of the first control information conversion unit 3 is connected to the input of the high-voltage output generation unit 5b via a substrate pattern and wires, and the output of the high-voltage output generation unit 5b is connected to the charging roller 21c of the toner image forming unit 18c, which forms the toner image of magenta toner, via a substrate pattern and wires. Therefore, the output channel chY of the first control information conversion unit 3 corresponds to the charging roller 21c.

[0027] The output channel chZ of the first control information conversion unit 3 is connected to the input of the high voltage output generation unit 5c via a substrate pattern and wires, and the output of the high voltage output generation unit 5c is connected to the charging roller 21b of the toner image forming unit 18b, which forms the toner image of the cyan toner, via a substrate pattern and wires. Therefore, the output channel chZ of the first control information conversion unit 3 corresponds to the charging roller 21b. The output channel chX of the second control information conversion unit 4 is connected to the input of the high-voltage output generation unit 5d via a substrate pattern and wires, and the output of the high-voltage output generation unit 5d is connected to the charging roller 21a of the toner image forming unit 18a, which forms the toner image of the black toner, via a substrate pattern and wires. Therefore, the output channel chX of the second control information conversion unit 4 corresponds to the charging roller 21a.

[0028] The output channel chY of the second control information conversion unit 4 is connected to the input of the high-voltage output generation unit 5e via a circuit board pattern and wires. The output of the high-voltage output generation unit 5e is connected via a circuit board pattern and wires to the transfer unit 24, which transfers the toner image on the intermediate transfer belt 20 to the paper being transported along the paper transport path 25. Therefore, the output channel chY of the second control information conversion unit 4 corresponds to the transfer unit 24. The output channel chZ of the second control information conversion unit 4 is an unused channel that is not connected to the high-voltage output generation unit.

[0029] The control unit 2 can repeatedly output (rewrite) first control information, which includes the address of the output channel chZ of the first control information conversion unit 3 and data corresponding to the high voltage output of the high voltage output generation unit 5c, to the first control information conversion unit 3. Furthermore, if there is a change in the high voltage output of the high voltage output generation unit 5c, the control unit 2 can output first control information, which includes the address of the output channel chZ (empty channel) of the second control information conversion unit 4 and data corresponding to the high voltage output of the high voltage output generation unit 5c, to the second control information conversion unit 4. In this way, the data corresponding to the high voltage output of the high voltage output generation unit 5c can be stored as second control information in the output channel chZ of the second control information conversion unit 4.

[0030] The comparison unit 6 is configured to compare the second control information of the output channel chZ of the first control information conversion unit 3, which is connected to the high-voltage output generation unit 5c, with the second control information of the output channel chZ (empty channel) of the second control information conversion unit 4, and to output the comparison result to the control unit 2. The comparison unit 6 can also be configured to amplify the difference between the second control information (voltage) of the output channel chZ of the first control information conversion unit 3 and the second control information (voltage) of the output channel chZ (empty channel) of the second control information conversion unit 4, and output this difference to the control unit 2. The comparison unit 6 is, for example, an operational amplifier. The comparison unit 6 may have an input connected to the output channel chZ of the first control information conversion unit 3 via a circuit board pattern or wires, an input connected to the output channel chZ of the second control information conversion unit 4 via a circuit board pattern or wires, and an output connected to the control unit 2 via a circuit board pattern or wires.

[0031] The second control information of the output channel chZ of the first control information conversion unit 3 is repeatedly rewritten, and the second control information of the output channel chZ of the second control information conversion unit 4 is updated when there is a change in the high voltage output of the high voltage output generation unit 5c. For this reason, the second control information of the output channel chZ of the first control information conversion unit 3 and the second control information of the output channel chZ of the second control information conversion unit 4 basically match. However, if noise causes the first control information input to the first control information conversion unit 3 from the control unit 2 to become incorrect, and the second control information of the output channel chZ of the first control information conversion unit 3 becomes an incorrect value, the second control information of the output channel chZ of the first control information conversion unit 3 will be a different value from the second control information of the output channel chZ of the second control information conversion unit 4. As a result, the output of the comparison unit 6 increases, and the control unit 2 can detect that noise has occurred that causes the first control information to become an incorrect value, and can detect abnormalities such as the presence of a noise source in the image forming apparatus 50.

[0032] The address corresponding to the output channel chZ of the first control information conversion unit 3 (the address included in the first control information) may be the same as the address corresponding to the output channel chZ of the second control information conversion unit 4 (the address included in the first control information). By outputting the first control information containing this address to the first and second control information conversion units, the control unit 2 can simultaneously write both the second control information for the output channel chZ of the first control information conversion unit 3 and the second control information for the output channel chZ of the second control information conversion unit 4. Furthermore, by outputting a load signal to either the first control information conversion unit 3 or the second control information conversion unit 4, the control unit 2 can output the first control information containing this address to either the first control information conversion unit 3 or the second control information conversion unit 4.

[0033] The notification unit 7 is a part provided to notify the user or a remote management system of information. The notification unit 7 may be, for example, the operation panel of the image forming apparatus 50 or a communication unit for connecting to a server. The control unit 2 is configured to notify the user or remote management system of any abnormality in the image forming apparatus 50 using the notification unit 7 based on the output of the comparison unit 6.

[0034] The control unit 2 is configured to store information regarding the output of the comparison unit 6, and to determine whether or not to notify the image forming apparatus 50 of an abnormality based on the stored output information. For example, the control unit 2 can be configured to count the number of times the output of the comparison unit 6 increases and calculate the frequency. If this detection frequency is high, there is a high possibility that a leakage current that frequently causes noise is occurring inside the image forming apparatus 50. For this reason, if the detection frequency exceeds a predetermined value, the control unit 2 notifies the user or remote management system of the abnormality of the image forming apparatus 50 via the notification unit 7. This allows a service technician or user to perform appropriate machine maintenance.

[0035] The control unit 2 is provided so that the notification criteria can be changed. For example, the control unit 2 is provided so that a user can change the threshold for whether or not to notify (for example, the threshold for the detection frequency).

[0036] Here, we will describe the control / output generation operation for high-voltage output generation of an image forming apparatus 50 in which noise countermeasures are taken by rewriting using a specific set of multiple DA converters (first control information conversion unit 3 and second control information conversion unit 4). In the image forming apparatus 50 shown in Figure 1, the first DA converter is designated as DAC1 (first control information conversion unit 3), and the second DA converter as DAC2 (second control information conversion unit 4). We will explain by focusing only on the output channels chX, chY, and chZ of DAC1 and the output channels chX, chY, and chZ of DAC2.

[0037] Output channel chX of DAC1 is output A, output channel chY of DAC1 is output B, output channel chZ of DAC1 is output C, output channel chX of DAC2 is output D, output channel chY of DAC2 is output E, and output channel chZ of DAC2 is left as an empty channel.

[0038] As an example, Figure 3 shows a time chart (rewrite control) in which 1C7h is rewritten to output A, 23Ah to output B, 0E8h to output C, 1A1h to output D, and 197h to output E. Here, outputs A to E are shown in hexadecimal (a 10-digit binary number is represented by a 3-digit hexadecimal number; 'h' is taken from hexadecimal, meaning hexadecimal). In the time chart of Figure 3, DAC1 inputs data from the DATA signal line at the timing of the load signal on load signal line LD1, and DAC2 inputs data from the DATA signal line at the timing of the load signal on load signal line LD2. The data on the DATA signal line includes addresses (D0 to D3) and output data (D4 to D13). DAC1 or DAC2 that has input data from the DATA signal line writes the output to the address specified by the input data based on the output data contained in the input data. At this time, the same output (0E8h) as output C is written once to DAC2's output channel chZ (empty channel).

[0039] After the same output (0E8h) as output C is written to output channel Z of DAC2 only once, no output is written to output channel Z of DAC2 until output C is changed again. Instead, the rewriting of the five outputs (repeated writing of the same value to each output channel) continues in the order of output A → output D → output B → output E → output C → output A → ...

[0040] Furthermore, even if any of outputs A, B, D, or E are changed, only one of outputs A, B, D, or E in the sequence ...→Output A→Output D→Output B→Output E→Output C→Output A→... will be changed from a certain point in time, and no output will be written to DAC2's output channel chZ until output C is changed.

[0041] Figure 4 shows a time chart of the state when a leak occurs during the rewrite control described above, resulting in output glitches. In reality, it is unlikely (basically impossible) for output glitches to occur simultaneously in all six outputs (output channels chX~chZ of DAC1 and output channels chX~chZ of DAC2) as shown in Figure 4, but for ease of visualization, Figure 4 shows a case where all six outputs glitch simultaneously due to a single leak (a single block).

[0042] Five of the six outputs (DAC1 output channels chX~chZ and DAC2 output channels chX and chY) can recover their output in a short time (= a time when there may be a minor impact on image quality / at most the time of the rewrite cycle), but the unused DAC2 output channel chZ is not rewritten and therefore its output will not recover.

[0043] In this state, by comparing the output voltages of DAC1's output channel chZ (output C) and DAC2's output channel chZ using the comparison unit 6, the control unit 2 can detect that output distortion has occurred in the DA converter due to external noise or some other reason.

[0044] In reality, it's rare for a single leak (a single block of leakage) to cause output glitches at multiple outputs simultaneously. In fact, if a leak were large enough to cause simultaneous output glitches, it's likely that other problems (besides high-voltage output generation) would also occur. Therefore, let's consider the cases of one output glitch and two output glitches. (We believe the same basic reasoning applies to three or more outputs.)

[0045] First, let's consider the case where one output malfunctions. If output C malfunctions, it will recover in a short time (at most the time of the rewrite cycle). By comparing the output voltage of output C and the output channel chZ of DAC2 using the comparison unit 6 during the time it takes for the output to recover, it is possible to detect that the DA converter malfunction occurred due to external noise or some other reason.

[0046] Conversely, there remains doubt about the reliability of determining the occurrence of output glitches in such a short time. In the first place, the reliability of determining that output glitches were detected in a short time when the high-voltage output generation means were affected by external noise or some other reason—that is, the "possibility of external noise"—is likely low. Therefore, it is considered better for the control unit 2 to ignore this short-time anomaly detection or treat it as a "suspicion of output glitches."

[0047] Regarding the handling of "suspected output glitches," it is preferable that the control unit 2 has a selection (operation) means to select whether to allow / prohibit notification (warning) to the operator using the notification unit 7, etc., in the case of "suspected output glitches," the control unit 2 can select options such as prohibiting notification, notifying if multiple detections occur within a certain period of time, or notifying on a single occurrence, so that the operator can choose how to respond, such as canceling the notification.

[0048] Secondly, even if any one of outputs A, B, D, or E malfunctions, the output will recover in a short time (at most the time of the rewrite cycle), and there is no means to compare it with the output voltage of an available channel, so the control unit 2 cannot detect that a malfunction has occurred in the DA converter's output.

[0049] Thirdly, if the output channel chZ of DAC2 experiences output corruption, there is no output recovery through rewriting. Therefore, the control unit 2 can detect that the DA converter's output corruption has occurred due to external noise or some other reason by comparing the output voltage of the DAC2's output channel chZ with output C using the comparison unit 6. Since this output corruption persists until the next output change of output C, the reliability can be increased by detecting it multiple times. If the abnormality detection result is highly reliable, it would seem better to always enable notification (warning) to the operator using the notification unit 7, but there are cases where notification (warning) is not necessarily the best course of action.

[0050] In cases of DAC output glitches caused by leakage within the high-voltage output path, notifying (warning) the operator is effective in removing the leak source. However, if the DAC output glitch is caused by static electricity, lightning strikes, or other external noise from the operator, notifying (warning) the operator is largely meaningless and only causes inconvenience. Even with highly reliable anomaly detection results, it is better to allow the operator to choose how to respond, such as deactivating the notification. At the very least, even without notifying (warning) the operator, recording this anomaly detection information (keeping it as a detection history and making it displayable) can be expected to enable service personnel / operators to perform appropriate machine maintenance (reducing work time).

[0051] Next, let's consider the case where the two outputs are output-faulty. In the case of output failure in this (two-output failure), if output C and one of outputs A, B, D, or E fail, output C will recover in a short time (at most the time of the rewrite cycle). Therefore, by comparing the output voltage of output C and the output channel chZ of DAC2 using the comparison unit 6 during the time until output recovery, it is possible to detect that output failure in the DA converter has occurred for some reason, such as external noise. In this respect, it is the same as the first case of "when one output fails," and for one of outputs A, B, D, or E, it is the same as the second case of "when one output fails."

[0052] Secondly, even if two of the outputs A, B, D, or E malfunction, these two outputs will recover within a short time (at most the time of the rewrite cycle), and there is no way to compare them with the output voltage of an available channel, so it is impossible to detect that the DA converter has malfunctioned.

[0053] Thirdly, if the output channels chZ and C of DAC2 experience output glitches, the output channel chZ of DAC2 will not recover after rewriting, but after output C is rewritten, the comparison unit 6 can be used to compare the output voltages of the output channels chZ and C of DAC2, allowing detection that the output glitch in the DA converter occurred due to external noise or some other reason. Since this output glitch persists until the next output change of output C, the reliability can be increased by detecting it multiple times.

[0054] However, until output C is rewritten, it is unclear whether the two outputs changed to the same voltage (same output set) or to different voltages (different outputs set), as this is due to external noise, etc. Furthermore, since this detection occurred for a short period of time and at a time when the high-voltage output control system was affected by noise for some reason, it is better to ignore this detection or treat it as a "suspicion of output glitch."

[0055] The fourth point is that if either output channel chZ of DAC2 or any one of outputs A, B, D, or E experiences output corruption, output channel chZ of DAC2 will not recover through rewriting. However, after output C is rewritten, it is possible to detect that output corruption has occurred in the DA converter due to external noise or some other reason by comparing the output voltages of output channel chZ and output C of DAC2. This is the same as the third point in "When one output experiences output corruption," and the situation for any one of outputs A, B, D, or E is the same as the second point in "When one output experiences output corruption." [Explanation of symbols]

[0056] 2: Control unit 3: First control information conversion unit 4: Second control information conversion unit 5a~5e: High voltage output generation unit 6: Comparison unit 7: Notification unit 18a, 18b, 18c, 18d: Toner image forming unit 19a, 19b, 19c, 19d: Photoreceptor 20: Intermediate transfer belt 21a, 21b, 21c, 21d: Charging roller 24: Transfer unit 25: Paper transport path 33: Exposure unit 50: Image forming apparatus

Claims

1. The system comprises a control unit provided to output first control information including an address and data, a first control information conversion unit having a first output channel and connected to the control unit, a second control information conversion unit having a second output channel and connected to the control unit, a high-voltage output generation unit connected to the first output channel, and comparison units connected to the first and second output channels. The first control information conversion unit is configured to receive first control data from the control unit, which includes an address corresponding to the first output channel and data corresponding to the high voltage output of the high voltage output generation unit, to convert the data corresponding to the high voltage output into second control information and output the second control information to the first output channel. The second control information conversion unit is configured to receive first control data from the control unit, which includes an address corresponding to the second output channel and data corresponding to the high voltage output of the high voltage output generation unit, to convert the data corresponding to the high voltage output into second control information and output the second control information to the second output channel. The second output channel is an empty channel that is not connected to the high-voltage output generation unit. The comparison unit is provided to compare the second control information of the first output channel with the second control information of the second output channel. The image forming apparatus is characterized in that the control unit is provided to detect an abnormality in the image forming apparatus based on the output of the comparison unit.

2. The image forming apparatus according to claim 1, wherein the control unit is configured to repeatedly output first control information, including an address corresponding to a first output channel and data corresponding to the high voltage output of the high voltage output generation unit, to a first control information conversion unit, and is configured to output first control information, including an address of a second output channel and data corresponding to the high voltage output of the high voltage output generation unit, to a second control information conversion unit when there is a change in the high voltage output of the high voltage output generation unit.

3. The image forming apparatus according to claim 1, wherein the address of the first output channel is the same as the address of the second output channel.

4. The image forming apparatus according to claim 1, wherein the control unit is connected to the first and second control information conversion units via a data signal line, connected to the first and second control information conversion units via a clock signal line, connected to the first control information conversion unit via a first load signal line, and connected to the second control information conversion unit via a second load signal line.

5. Furthermore, with the addition of a news department, The image forming apparatus according to any one of claims 1 to 4, wherein the control unit is provided to notify a user or a remote management system of an abnormality using the notification unit based on the output of the comparison unit.

6. The control unit is provided to store information relating to the output of the comparison unit, and is provided to determine whether or not to report an abnormality based on the stored information relating to the output and the notification criteria. The aforementioned notification criteria include a threshold for determining whether or not to provide notification. The image forming apparatus according to claim 5, wherein the control unit is provided to change the threshold.

Images