JP2014056219A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus designed at a safety standard at an altitude of 2,000 m or less, which can be prevented from being used in such a state that safety performance and product performance are not satisfied by detecting that the image forming apparatus is installed at a place whose altitude is above 2,000 m.SOLUTION: The image forming apparatus includes a process part 176 including an electrifying part electrifying a photoreceptor drum, detection parts (R3 and R4) detecting the discharge voltage Vc of the electrifying part, a determination part 180 determining whether or not the detected discharge voltage Vc is a predetermined threshold value or more (a voltage V1 corresponding to the discharge voltage Vc is a reference voltage V0 or more), and a restriction part (CPU) restricting the function of the image forming apparatus, when the determination part 180 determines that the discharge voltage is the threshold value or more. The threshold value is equal to or higher than the value of the discharge voltage when the image forming apparatus is installed at an altitude of 2,000 m. Thus, the image forming apparatus can be prevented from being used in such a state that safety performance and product performance are not satisfied.

Description

  The present invention relates to an image forming apparatus designed according to safety standards of an altitude of 2000 m or less. In particular, the image forming apparatus can be prevented from being used in a state where safety performance and product performance are not satisfied because it is installed in a place where the altitude exceeds 2000 m. The present invention relates to an image forming apparatus.

  An image forming apparatus or the like is designed and manufactured based on a predetermined safety standard. As a safety standard related to information technology equipment, a domestic standard J60950 and an international standard IEC60950 corresponding thereto are known. These standards stipulate requirements for reducing the risk of fire due to equipment, as well as the risk of electric shock and injury to equipment users and maintainers.

  In order to ensure safety, for example, a minimum spatial distance (the shortest distance when measuring in space between two different conductive parts or between the conductive part and the boundary surface of the device) is defined. The minimum clearance (insulation clearance) is determined for a device used at an altitude of 2000 m or less according to the determined required withstand voltage according to a predetermined table. For devices used at an altitude of over 2000 m, the minimum spatial distance at an altitude of 2000 m or less is multiplied by a predetermined coefficient (correction coefficient) to determine a stricter (larger) minimum spatial distance.

  Designed and manufactured equipment is usually mass produced and sold after passing safety tests. For equipment used at an altitude of over 2000 m, as described above, a minimum spatial distance is required that is greater than equipment used at an altitude of 2000 m or less, so to secure distances between board patterns and power transformers. In addition, the size of the parts to be used increases and the cost increases. Therefore, in general, a safety test is performed as a device intended for use at an altitude of 2000 m or less. At the time of sale, for example, a label prohibiting use at an altitude of over 2000 m is affixed to the device so that it will not be used by mistake in places where the altitude exceeds 2000 m, and a warning to that effect is also written in the instruction manual. However, the altitude at which the equipment is actually installed and used is unknown.

  When an image forming apparatus designed for use at an altitude of 2000 m or less is used in a place where the altitude exceeds 2000 m, in addition to being unable to ensure safety, there is a problem that the performance as an image forming apparatus cannot be maintained. is there. For example, after the photosensitive drum is charged by a charger (corona discharge) charger, an electrostatic latent image is formed on the photosensitive drum, and a toner image formed according to the electrostatic latent image is formed on the recording paper. In an image forming apparatus that transfers and forms an image (hereinafter also referred to as printing), the atmospheric pressure is low at a high altitude, and the discharge of the charger cannot be controlled appropriately. Therefore, the image quality of the formed image is deteriorated. In addition, an image forming apparatus that applies a high voltage to the gap between the developing sleeve and the photosensitive drum as a developing device is also affected by atmospheric pressure, so that appropriate development is not performed, causing image quality deterioration.

  In order to improve the image quality degradation problem, Japanese Patent Application Laid-Open No. 2004-228561 controls the voltage output to the developing device in consideration of the effect of changes in atmospheric pressure on image formation without using an atmospheric pressure sensor. An image forming apparatus is disclosed. This image forming apparatus detects a leak current generated when a high voltage is applied, and controls a voltage (development bias) to be applied according to the detected leak current. The leakage current changes according to the atmospheric pressure, and the leakage current increases as the atmospheric pressure decreases. By correcting the development bias according to the leak current, an image with stable image quality can be formed.

JP 2010-48960 A

  As described above, when an image forming apparatus designed and manufactured based on a safety standard with an altitude of 2000 m or less is used in a place where the altitude exceeds 2000 m, printing is executed in a state where safety performance and product performance are not satisfied. The As a result, there is a problem that safety cannot be ensured, such as damage to the image forming apparatus and injury to the user. Depending on the invention described in the above-mentioned Patent Document 1, it is not possible to ensure safety even though it is possible to prevent a decrease in print quality.

  In Patent Document 1, it is not necessary to provide an atmospheric pressure sensor, but it is necessary to separately provide a circuit for detecting a leak current in order to detect atmospheric pressure. It is desirable to be able to detect the installation at a location exceeding an altitude of 2000 m more easily and prevent use in that state.

  Therefore, the present invention is an image forming apparatus designed with a safety standard of an altitude of 2000 m or less, and can easily detect that it is installed in a place exceeding an altitude of 2000 m, and safety performance and product performance are satisfied. It is an object of the present invention to provide an image forming apparatus that can be prevented from being used in a state where it is not used.

  The above object can be achieved by the following.

  In other words, the image forming apparatus according to the present invention is an image forming apparatus including a discharge unit that performs discharge for printing. The image forming apparatus includes a detection unit that detects a discharge voltage of the discharge unit, a determination unit that determines whether the discharge voltage detected by the detection unit is equal to or higher than a predetermined threshold, and a detection unit that detects the discharge voltage. In response to determining that the discharge voltage detected by the unit is equal to or higher than the threshold value, the discharge voltage and the threshold value are negative values. The threshold value is equal to or greater than the value of the discharge voltage of the discharge portion when the image forming apparatus is installed at an altitude of 2000 m.

  Preferably, the image forming apparatus further includes a display unit that displays a predetermined message when the determination unit determines that the discharge voltage detected by the detection unit is equal to or higher than the threshold value.

  More preferably, the restriction of the function of the image forming apparatus by the restriction unit is prohibition of the printing function.

  More preferably, the detection unit detects a discharge voltage of the discharge unit during execution of printing by the image forming apparatus.

  Preferably, the detection unit detects a discharge voltage of the discharge unit during execution of the startup process of the image forming apparatus or after receiving the print instruction after the startup process, and the limiting unit is detected by the detection unit. When it is determined that the discharge voltage is equal to or higher than the threshold value, the image forming apparatus is stopped.

  More preferably, the image forming apparatus has a color printing function using a plurality of color toners, and includes a plurality of discharge units, and each of the plurality of discharge units carries a plurality of color toners. A charging unit that charges each of the drums, the detection unit detects charging voltages of the plurality of charging units, and the determination unit outputs at least one discharge voltage among the plurality of discharge voltages detected by the detection unit. It is determined whether or not the threshold value is exceeded.

  According to the present invention, it is possible to easily detect that the image forming apparatus is installed at a place where the altitude exceeds 2000 m, and it is possible to prevent the image forming apparatus from being used in a state where safety is not ensured.

  By restricting the execution of only functions (printing functions) that are affected by changes in atmospheric pressure and enabling functions that are not affected by changes in atmospheric pressure (scanner functions, FAX transmission functions, etc.), the user is restricted more than necessary. You can avoid giving.

  Immediately after the power of the image forming apparatus is turned on, it is possible to promptly indicate that safety is not ensured by determining whether or not the image forming apparatus is installed in a place where the altitude exceeds 2000 m. In addition, the image forming apparatus can be quickly stopped without activating it.

  In an image forming apparatus capable of color printing, by detecting the discharge voltage of the charger for each color, it is possible to quickly detect that the image forming apparatus is installed at a location exceeding an altitude of 2000 m.

1 is a block diagram illustrating a configuration of an image forming apparatus according to an embodiment of the present invention. 1 is a cross-sectional view illustrating an image forming apparatus according to an embodiment of the present invention. 1 is a cross-sectional view showing a structure of a charger of an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a circuit diagram illustrating a configuration of an elevation detection unit of the image forming apparatus according to the embodiment of the present invention. FIG. 3 is a plan view showing an operation unit of the image forming apparatus according to the embodiment of the present invention. 6 is a diagram showing an example of a screen displayed on the operation unit of the image forming apparatus according to the embodiment of the present invention. FIG. It is a flowchart which shows the control structure of the program which detects the elevation performed in the image forming apparatus which concerns on embodiment of this invention. It is a block diagram which shows the structure of the experimental apparatus for obtaining the relationship between an altitude and a discharge voltage. It is experimental data which shows the relationship between an atmospheric pressure and a discharge voltage. It is experimental data which shows the relationship between an altitude and a discharge voltage. It is data showing the relationship between altitude and atmospheric pressure. It is a figure which shows the example of the warning screen displayed on an operation part. It is a flowchart which shows the control structure of the program which is performed in the image forming apparatus which concerns on embodiment of this invention, and detects the altitude different from FIG. It is a figure which shows the example of the warning screen displayed on an operation part.

  In the following embodiments, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  An image forming apparatus according to an embodiment of the present invention is a digital multifunction peripheral having a plurality of functions such as a copy function, a printer function, a scanner function, and a facsimile (hereinafter also referred to as FAX) function. Referring to FIG. 1, an image forming apparatus 100 according to an embodiment of the present invention is connected to a communication network (hereinafter simply referred to as a network) 190 and a telephone line 192, and is received from an external computer or a FAX apparatus. The image formation on the recording paper is executed according to the data.

  The image forming apparatus 100 includes a CPU (Central Processing Unit) 102 that controls the entire image forming apparatus 100, a ROM (Read Only Memory) 104 for storing programs, and a RAM (Random Access) that is a volatile storage device. Memory) 106 and HDD (Hard Disk Drive) 108, which is a non-volatile storage device that retains data even when power is turned off. The ROM 104 stores programs and data necessary for controlling the operation of the image forming apparatus 100.

  The image forming apparatus 100 further includes a NIC (Network Interface Card) 110, a modem 112, a document reading unit 120, an image forming unit 122, an altitude detecting unit 124, a power supply unit 126, a recording paper transport unit 128, an operation unit 130, and a bus. 114. The CPU 102, ROM 104, RAM 106, HDD 108, NIC 110, modem 112, document reading unit 120, image forming unit 122, power supply unit 126, recording paper transport unit 128, and operation unit 130 are connected to the bus 114. Data (including control information) is exchanged between the units via the bus 114. The CPU 102 reads a program from the ROM 104 onto the RAM 106 via the bus 114, and executes the program using a part of the RAM 106 as a work area. That is, the CPU 102 controls each part of the image forming apparatus 100 according to a program stored in the ROM 104, and realizes each function of the image forming apparatus 100.

  The document reading unit 120 reads a document with a CCD (Charge Coupled Device) and generates image data (digital signal). The image data is temporarily stored in the RAM 106. The image forming unit 122 forms an image on the recording paper conveyed by the recording paper conveying unit 128 based on the image data on the RAM 106.

  As will be described later, the operation unit 130 includes a touch panel display and an operation key unit. The touch panel display includes a display panel composed of a liquid crystal panel and the like, and a touch panel that is disposed on the display panel and detects a touched position. A screen for instructing the image forming apparatus 100 is displayed on the touch panel display (display panel) of the operation unit 130. The user selects a key displayed on the touch panel display on the touch panel overlaid on the display panel (touches a corresponding portion on the touch panel), thereby performing function setting, operation instruction, and the like of the image forming apparatus 100. Can do.

  The NIC 110 is an interface that is connected to the network 190 and allows the image forming apparatus 100 to communicate with an external device via the network 190. The modem 112 is connected to the telephone line 192 and transmits and receives FAX data.

  The altitude detection unit 124 detects the discharge voltage of the charger included in the image forming unit 122 and outputs a detection signal for determining whether or not the place where the image forming apparatus is installed is over 2000 m. . The detection signal is directly transmitted to the CPU 102. The power supply unit 126 is controlled by the CPU 102 and supplies a predetermined voltage to each unit in the image forming apparatus 100.

  With reference to FIG. 2, the conveyance of the recording paper and the image formation on the recording paper in the image forming apparatus 100 will be specifically described. The document reading unit 120 includes an image reading device 90 and an automatic document feeder (ADF: Auto Document Feeder) 150. The image reading device 90 is a reduction optical system image reading device that includes a document placing table 92 made of transparent glass on which a document is placed, and includes a light source, a mirror, a lens, a CCD, and the like. An automatic document feeder 150 is attached on the document table 92. The automatic document feeder 150 automatically conveys the document on the document table 92. The automatic document feeder 150 is configured to be rotatable around a predetermined axis, and the document can be placed by hand by opening the document table 92.

  The image forming unit 122 includes an optical scanning device 1, a developing device 2, a photosensitive drum 3, a cleaner unit 4, a charger 5, an intermediate transfer belt unit 6, a fixing unit 7, a paper feed tray 81, a manual paper feed tray 85, and A paper discharge tray 91 is provided. The manual paper feed tray 85 is a tray for manually supplying recording paper.

The image data handled in the image forming apparatus 100 is black (BLACK, hereinafter “K
Color images using cyan, CYAN (hereinafter also referred to as “C”), magenta (hereinafter also referred to as “M”) and yellow (YELLOW, hereinafter also referred to as “Y”). Data, that is, image data broken down into these four color components. Accordingly, four each of the developing device 2, the photosensitive drum 3, the charger 5, and the cleaner unit 4 are provided so as to form four types of latent images corresponding to the respective colors. Four image stations are configured to process magenta and yellow.

  The charger 5 is a device for uniformly charging the surface of the photosensitive drum 3 to a predetermined potential. Here, the charger 5 is a corona discharge type charger as shown in FIG. The charger 5 has a length substantially equal to the length of the cylindrical photosensitive drum 3 in the central axis direction (perpendicular to the paper surface in FIG. 2), and is installed along the photosensitive drum 3. The charger 5 includes a case 160, a discharge electrode 162, a grid electrode 164, a discharge electrode holding unit 168, and a grid electrode holding unit 170. The grid electrode 164 is disposed between the discharge electrode 162 and the photosensitive drum 3. Case 160, discharge electrode 162, and grid electrode 164 are formed of a conductive member. The discharge electrode holding part 168 and the grid electrode holding part 170 are formed of an electrically insulating member.

  The case 160 has a U-shaped cross section. The discharge electrode 162 is formed in a sawtooth shape, for example, and the sawtooth portion is disposed toward the open portion of the case 160. The grid electrode 164 has a mesh shape and is disposed on the open surface of the case 160.

  A negative predetermined DC voltage (hereinafter also referred to as grid bias voltage) Vg (Vg <0) is applied to the grid electrode 164 and the case 160. A negative predetermined DC voltage (hereinafter also referred to as a charge voltage or a discharge voltage) Vc is applied to the discharge electrode 162 (Vc <Vg <0). As shown in FIG. 4, the charge voltage Vc and the grid bias voltage Vg are generated by a discharge control unit 172 and a discharge voltage generation unit 174 provided in the image forming unit 122. The process unit 176 includes the photosensitive drum 3 and the charger 5. Under the control of the CPU 102, the discharge controller 172 inputs a control signal for generating the charge voltage Vc and the grid bias voltage Vg to the discharge voltage generator 174 at a predetermined timing. The discharge voltage generator 174 generates a charge voltage Vc and a grid bias voltage Vg according to the input control signal, and supplies them to the GB terminal and MC terminal of the process unit 176, respectively. The supplied charge voltage Vc and grid bias voltage Vg are supplied to the discharge electrode 162 of the charger 5, the grid electrode 164, and the case 160, respectively.

  Since the image forming apparatus 100 is an apparatus capable of color printing, the discharge control unit 172, the discharge voltage generation unit 174, and the process unit 176 shown in FIG. 4 correspond to four colors K, C, M, and Y. A total of 4 sets are equipped.

  By applying the charge voltage Vc and the grid bias voltage Vg, an electric field is formed between the case 160 and the discharge electrode 162, and air is ionized by this electric field, and negative charges (negative ions) are generated around the discharge electrode 162. Will occur. The generated negative charges are attracted and moved by the grid electrode 164, and the negative ions that have passed through the grid electrode 164 reach the surface of the photosensitive drum 3.

  The surface of the photosensitive drum 3 is formed of a member having semiconductivity when not exposed and having conductivity when exposed. The surface of the photosensitive drum 3 is charged (hereinafter referred to as initialization charging) by negative ions reaching the surface of the photosensitive drum 3, and the surface of the photosensitive drum 3 has a predetermined potential (hereinafter referred to as initialization charging potential). It becomes VO.

  The optical scanning device 1 is a laser scanning unit (LSU) provided with a laser emitting unit, a reflection mirror, and the like. The optical scanning device 1 includes a polygon mirror that scans a laser beam and optical elements such as a lens and a mirror for guiding the laser light reflected by the polygon mirror to the photosensitive drum 3. The optical scanning device 1 exposes the photosensitive drum 3 charged as described above according to the input image data, thereby forming an electrostatic latent image according to the image data on the surface thereof.

  Specifically, when the surface of the photosensitive drum 3 that has been initialized and charged is exposed by the optical scanning device 1, the portion (bright portion) becomes conductive, and the negative charge moves to the ground. The portion where the negative charge has moved changes to a positive potential and becomes a bright portion potential VE. An electrostatic latent image is formed on the photosensitive drum 3 by a portion where the negative charge exists on the surface of the photosensitive drum 3 and a portion where the negative charge does not exist, that is, the portion of the initialization charging potential VO and the portion of the bright portion potential VE. .

  The developing device 2 visualizes the electrostatic latent images formed on the respective photosensitive drums 3 with toner of four colors (YMCK). The cleaner unit 4 removes and collects toner remaining on the surface of the photosensitive drum 3 after development and image transfer.

  The intermediate transfer belt unit 6 disposed above the photosensitive drum 3 includes an intermediate transfer belt 61, an intermediate transfer belt driving roller 62, an intermediate transfer belt driven roller 63, an intermediate transfer roller 64, and an intermediate transfer belt cleaning unit 65. I have. Four intermediate transfer rollers 64 are provided corresponding to each color of YMCK.

  The intermediate transfer belt driving roller 62, the intermediate transfer belt driven roller 63, and the intermediate transfer roller 64 are driven to rotate while the intermediate transfer belt 61 is stretched. Each intermediate transfer roller 64 supplies a transfer bias described later in order to transfer the toner image on the corresponding photosensitive drum 3 onto the intermediate transfer belt 61. The intermediate transfer belt 61 is provided in contact with each photosensitive drum 3. A color toner image (multicolor toner image) is formed on the intermediate transfer belt 61 by sequentially superimposing and transferring the respective color toner images formed on the photosensitive drum 3 onto the intermediate transfer belt 61.

  The toner image is transferred from the photosensitive drum 3 to the intermediate transfer belt 61 by an intermediate transfer roller 64 that is in contact with the back side of the intermediate transfer belt 61. A high-voltage transfer bias (a high voltage having a polarity (+) opposite to the toner charging polarity (−)) is applied to the intermediate transfer roller 64 in order to transfer the toner image. The intermediate transfer roller 64 is a roller whose surface is covered with a conductive elastic material. With this conductive elastic material, a high voltage can be uniformly applied to the intermediate transfer belt 61.

  As described above, the electrostatic images visualized according to the hues on the photosensitive drums 3 are stacked on the intermediate transfer belt 61. The image information (toner density distribution) thus laminated is transferred onto the recording paper by the transfer roller 10 disposed at the contact position between the recording paper and the intermediate transfer belt 61 as the intermediate transfer belt 61 rotates. .

  At this time, the intermediate transfer belt 61 and the transfer roller 10 are pressed against each other at a predetermined nip, and a voltage for transferring the toner onto the recording paper is applied to the transfer roller 10 (what is the toner charging polarity (−))? Reverse polarity (+) high voltage).

  The toner remaining on the intermediate transfer belt 61 without being transferred onto the recording paper by the transfer roller 10 causes the toner to be mixed in the next step. Therefore, the toner is removed and collected by the intermediate transfer belt cleaning unit 65. The In the intermediate transfer belt cleaning unit 65, for example, a cleaning blade that contacts the intermediate transfer belt 61 is disposed as a cleaning member. The intermediate transfer belt 61 that contacts the cleaning blade is supported by the intermediate transfer belt driven roller 63 from the back side. Has been.

  The paper feed tray 81 is a tray for storing recording paper used for image formation, and is provided below the optical scanning device 1. In addition, recording paper used for image formation can be placed on the manual paper feed tray 85. The paper discharge tray 91 is a tray for stacking printed recording sheets face down, that is, with the print side down.

  A recording paper transport path S is formed inside the image forming unit 122 to send the recording paper in the paper feed tray 81 and the manual paper feed tray 85 to the paper discharge tray 91 via the transfer roller 10 and the fixing unit 7. Has been. In the vicinity of the recording paper transport path S from the paper feed tray 81 or the manual paper feed tray 85 to the paper discharge tray 91, pickup rollers 11a to 11b, transport rollers 12a to 12d, registration rollers 13, transfer rollers 10, and a fixing unit. 7 etc. are arranged.

  The paper feed tray 81, the manual paper feed tray 85, the pickup rollers 11a to 11b, the transport rollers 12a to 12d, and the registration roller 13 constitute the recording paper transport unit 128 shown in FIG.

  The transport rollers 12 a to 12 d are small rollers for promoting and assisting the transport of the recording paper, and a plurality of transport rollers 12 a to 12 d are provided along the recording paper transport path S. The pickup roller 11 a is disposed near the end of the paper feed tray 81, picks up recording paper from the paper feed tray 81 one by one, and supplies it to the recording paper transport path S. Similarly, the pickup roller 11 b is arranged near the end of the manual paper feed tray 85, picks up recording paper one by one from the manual paper feed tray 85, and supplies it to the recording paper transport path S.

  The registration roller 13 temporarily holds the recording paper conveyed through the recording paper conveyance path S. Then, the recording paper is conveyed to the transfer roller 10 at the timing when the leading edge of the toner image on the photosensitive drum 3 and the leading edge of the recording paper coincide.

  The fixing unit 7 includes a heat roller 71 and a pressure roller 72. The heat roller 71 and the pressure roller 72 rotate with the recording paper interposed therebetween. Further, the heat roller 71 is set to a predetermined fixing temperature by the CPU 102 based on a signal from a temperature detector (not shown), and by thermally pressing the toner together with the pressure roller 72 to the recording paper, It has a function of fusing, mixing, and pressing the multicolor toner image transferred to the recording paper and thermally fixing the recording paper. An external heating belt 73 for heating the heat roller 71 from the outside is provided.

  The functions (copy function, printer function, scanner function, and facsimile function) installed in the image forming apparatus 100 are executed when the operation unit 130 is operated by the user. Referring to FIG. 5, the operation unit 130 includes a touch panel display 132 and an operation key unit 134. The touch panel display 132 includes a display panel configured by a liquid crystal panel and the like, and a touch panel that is disposed on the display panel and detects a touched position. In FIG. 5, the home screen of the image forming apparatus 100 is displayed on the touch panel display 132 (display panel) of the operation unit 130. On the home screen, keys for instructing each function such as copying and printing are displayed.

  The operation key unit 134 includes a home key 136, a power key 138 for turning on / off the power of the image forming apparatus 100, and an LED lamp 142 that is turned on when the power is turned on, as hardware keys. . The screen displayed on the touch panel display 132 changes variously (screen transition) according to the state of the image forming apparatus 100. The home key 136 is a key for returning the screen displayed on the touch panel display 132 to the home screen. That is, when the home key 136 is pressed, the home screen is displayed on the touch panel display 132.

  The operation unit 130 receives an input of an instruction or the like from the user to the image forming apparatus 100. The user checks the state of the image forming apparatus 100 and the job processing status on the screen displayed on the touch panel display 132. By selecting a key displayed on the touch panel display 132, function setting and operation instruction of the image forming apparatus 100 can be performed.

  For example, when the copy key 144 is touched, the CPU 102 displays a copy mode basic screen on the touch panel display 132. Specifically, the CPU 102 reads predetermined graphics data from the ROM 104 or the HDD 108, and generates, for example, image data of the screen 200 shown in FIG. The generated image data is transmitted to the touch panel display 132 and displayed.

  In FIG. 6, in the system area 210 of the screen 200, a character “copy” indicating the copy mode is displayed at the left end, and a key for displaying the job execution status is displayed at the right end. The function setting area 220 displays keys for making settings related to the copy function (keys for setting a color mode, copy density, copy magnification, etc.). Some keys display the set contents. The numeric keypad area 252 is an area for setting the number of copies for image formation. When the keys “0” to “9” are touched, the numerical values continuously input are displayed as the number of copies. When the “C” key is touched, the input number of copies is canceled. Below the numeric keypad area 252, a schematic diagram of the image forming apparatus 100 is displayed, and numbers “1” to “2” are displayed to distinguish the paper feed trays. In the action panel area 240, information on operation assistance, advice, proposals, and the like is displayed. For example, when a user selects a specific function, a function related to the function is displayed. In the task trigger area 230, a trigger key that is operated by the user in order to actually operate the image forming apparatus 100 after the setting is completed is displayed. In the present embodiment, the task trigger area 230 includes a monochrome start key 232 for starting a black and white copy of a document, a color start key 234 for starting a color copy, a document once scanned, and the image forming apparatus 100 taking the image as an image. A scan-in key 236 for starting the processing to be performed and a clear all (CA) key 238 for clearing all the settings are displayed.

  Each mode for executing the functions (copy function, printer function, scanner function, and facsimile function) installed in the image forming apparatus 100 will be briefly described.

(Copy mode)
When the image forming apparatus 100 is used as a copying machine, image data of a document read by the document reading unit 120 is output from the image forming unit 122 as a printed matter.

  Image data read by the CCD of the image reading device 90 provided in the document reading unit 120 is completed as output data (printing data) on the RAM 106 and then stored in the HDD 108. When there are a plurality of documents, this reading operation and storage operation are repeated. Thereafter, based on the processing mode instructed from the operation unit 130, the image data stored in the HDD 108 is sequentially read out at an appropriate timing and sent to the RAM 106.

  In the paper supply unit (the paper supply tray 81 or the manual paper supply tray 85), the recording paper is pulled out by the pickup roller and conveyed to the image forming unit 122 by the plurality of conveyance rollers 12a to 12d. The image forming unit 122 forms an electrostatic latent image corresponding to the image data on the surface of the photoconductive drum 3 by exposing the charged photoconductive drum 3 according to the input image data. After toner is attached to the electrostatic latent image portion on the photosensitive drum 3, the toner image is transferred onto the conveyed recording paper via the intermediate transfer belt 61. Thereafter, the recording paper is heated and pressurized (this fixes the image on the recording paper), and is discharged to a paper discharge tray.

(Printer mode)
When the image forming apparatus 100 is instructed to print from a computer or the like connected to the network 190, the NIC 110 receives image data from the computer or the like. The received image data is sent to the RAM 106 in units of pages as output image data, and then stored in the HDD 108. Thereafter, the image data stored in the HDD 108 is sequentially read out at an appropriate timing and sent to the RAM 106. In the same manner as in the copy mode described above, the image data is transmitted to the image forming unit 122, image formation is performed, and the image data is discharged to a paper discharge tray.

(Scanner mode)
When the image forming apparatus 100 is used as a network scanner, for example, image data of a document read by the document reading unit 120 is transmitted from the NIC 110 to the computer or the like via the network 190. Also in this case, the original is electronically read by the CCD provided in the original reading unit 120. The read image data of the document is completed as output data on the RAM 106 and then stored in the HDD 108. Thereafter, the image data is sent again from the HDD 108 to the RAM 106, and after establishing communication with the transmission destination designated via the operation unit 130, the image data is transmitted from the NIC 110 to the designated transmission destination.

(Facsimile mode)
When the image forming apparatus 100 is used as a facsimile apparatus, data received by FAX from an external facsimile apparatus via the telephone line 192 and the modem 112 is formed on the RAM 106 as image data, and stored in the HDD 108 as described above. Printing by the image forming unit 122 can be executed. Further, the image forming apparatus 100 can read out image data from the HDD 108, convert it to a data format for FAX communication, and transmit it to an external facsimile apparatus via the modem 112 and the telephone line 192.

  Hereinafter, with reference to FIG. 7, a program executed in the image forming apparatus 100 for determining whether or not the altitude is over 2000 m and executing processing corresponding to the result will be described.

  Here, regarding the discharge control unit 172, the discharge voltage generation unit 174, and the process unit 176 constituting the image forming apparatus 100, the relationship between the charge voltage Vc supplied to the charger 5 when performing printing, the atmospheric pressure, and the altitude is shown. In advance, it is obtained by experiments, and it is determined whether or not the altitude is over 2000 m.

  In the experiment, for example, as shown in FIG. 8, the process unit 176 is disposed in the decompression tank 178, the atmospheric pressure in the decompression tank 178 is changed, and the discharge control unit 172 and the discharge voltage generation unit 174 charge the printing. Discharge (charging of the photosensitive drum) by the device 5 is executed, and the charge voltage Vc is measured. The results of measuring the charge voltage Vc with reference to the frame ground FG are shown in FIGS. The environmental temperature during the experiment was 24 to 25 ° C. The discharge voltage Vc is supplied from the MHV output terminal of the discharge voltage generator 174 with a constant current Ic. Specifically, Ic = −1403.6 μA.

  In the graph of FIG. 9, the discharge voltage Vc is plotted with the atmospheric pressure (mmHg) in the decompression tank 178 as the horizontal axis. FIG. 10 is a plot of the discharge voltage Vc with the horizontal axis representing the altitude (m) corresponding to the atmospheric pressure in the decompression tank 178 in consideration of the relationship between the atmospheric pressure and the altitude. The relationship between atmospheric pressure and altitude was as shown in FIG.

  From the graph of FIG. 10, −5.47 kV is obtained as the value of the discharge voltage Vc corresponding to the altitude of 2000 m. This value varies depending on the print performance (speed) by the discharge control unit 172, the discharge voltage generation unit 174, and the process unit 176 mounted on the image forming apparatus 100. Therefore, the discharge corresponding to the altitude of 2000 m is performed. The voltage Vc is preferably determined by experiment for each image forming apparatus.

  In the image forming apparatus 100, it is determined whether or not the image forming apparatus 100 is installed at a location exceeding an altitude of 2000 m by determining whether or not the discharge voltage Vc is equal to or higher than a predetermined threshold value Vth during printing. Can be determined. Specifically, the CPU 102 determines from the magnitude of the detection signal Vd output from the altitude detection unit 124 according to the discharge voltage Vc. The threshold value Vth is set to a value equal to or higher than −5.47 kV, which is the discharge voltage Vc corresponding to an altitude of 2000 m (the absolute value of the threshold value Vth is equal to or lower than the absolute value of the discharge voltage Vc). For example, Vth = −5.4 kV is set. The altitude corresponding to this value is over 2000 m.

  The elevation detection unit 124 is configured as shown in FIG. The altitude detection unit 124 includes a voltage comparison unit 180, a logical sum unit 182 and resistors R1 to R4. The voltage comparison unit 180 is a comparator, for example, and outputs a high level or low level signal according to the result of comparing the input voltage V1 and the reference voltage V0. Here, the input voltage V1 and the reference voltage V0 are both negative. For example, when the input voltage V1 is higher than the reference voltage V0, the voltage comparison unit 180 outputs a high level signal, and otherwise outputs a low level signal.

  The reference voltage V0 is determined by the resistors R1 and R2 and the constant voltage V2 applied to the resistor R1. The voltage V1 is determined by the resistors R3 and R4 and the discharge voltage Vc. Therefore, the values of the resistors R1 to R4 may be set so that V1 = V0 when the discharge voltage Vc is equal to the threshold value Vth = −5.4 (V). The allowable range of the input voltage of a normal comparator is several tens of volts at most. Also, the constant voltage V2 is at most several tens of volts. However, in consideration of the fact that the absolute value of the discharge voltage Vc is on the order of kV, which is 2 to 3 orders of magnitude higher than those, it is preferable to set the resistance value of the resistor R3 sufficiently larger than the resistance value of R4. Furthermore, the voltage V1 changes at the same rate as the change rate of the discharge voltage Vc due to the change in altitude, and the change (difference) in the voltage value itself (absolute value) is much greater than the change (difference) in the discharge voltage Vc. Small. Therefore, it is preferable to use a comparator that can detect the change (difference) in the voltage V <b> 1 as the comparator used in the voltage comparison unit 180.

  Since the discharge control unit 172, the discharge voltage generation unit 174, and the process unit 176 are provided in four sets, four signals corresponding to them are input to the logical sum unit 182 to calculate the logical sum of the input levels. The calculated result is output as a detection signal Vd. That is, if at least one of the four input signals to the logical sum unit 182 is high level, the detection signal Vd is high level. If all four input signals to the logical sum unit 182 are at a low level, the detection signal Vd is at a low level. Therefore, the CPU 102 can determine whether the altitude of the place where the image forming apparatus 100 is installed is more than 2000 m by determining the level of the detection signal Vd.

  The image forming apparatus 100 is in a standby state in which the altitude detecting unit 124 is configured as described above, the power is turned on, and each function can be executed. In step 400 of FIG. 7, the CPU 102 determines whether or not the operation unit 130 has been operated. That is, it is determined whether a key on the screen displayed on the touch panel display 132 is touched or a key of the operation key unit 134 is pressed (see FIG. 5). If it is determined that it has been operated, control proceeds to step 402. Otherwise, step 400 is repeated.

  In step 402, the CPU 102 determines whether or not the operation accepted in step 400 is a print instruction. For example, when it is detected that the monochrome start key 232 or the color start key 234 is touched on the basic screen 200 in the copy mode shown in FIG. 6, it is determined that the instruction is a print instruction. If it is determined that the instruction is a print instruction, control proceeds to step 404. Otherwise control passes to step 418.

  In step 418, the CPU 102 executes processing corresponding to the operation. Thereafter, control proceeds to step 416.

  In step 416, the CPU 102 determines whether an end instruction has been received. For example, when the power key 138 is pressed, it is determined that an end instruction has been received. If it is determined that an end instruction has been received, the CPU 102 ends the program. Otherwise, control returns to step 400.

  As described above, by repeating Step 400, Step 402, Step 416, and Step 418, the user sets predetermined conditions (including setting of printing conditions) to the image forming apparatus 100, and in accordance with the conditions, A predetermined function (function other than printing) can be executed. For example, when the copy key 144 is touched on the home screen shown in FIG. 5, the basic screen 200 of the copy mode shown in FIG. 6 is displayed. In accordance with the user's key operation on the basic screen 200, the copy conditions are set as described above.

  In step 404, the CPU 102 starts the printing process described above. Specifically, a program for executing printing is started.

  In step 406, the CPU 102 detects the discharge voltage Vc at a predetermined timing. The predetermined timing is when the discharge voltage generator 174 supplies the discharge voltage Vc to the charger 5 under the control of the discharge controller 172. Specifically, the CPU 102 acquires the output signal Vd from the elevation detection unit 124 of FIG.

  In step 408, the CPU 102 determines whether or not the voltage Vd acquired in step 406 is equal to or higher than a predetermined voltage. If it is determined that the value is equal to or greater than the predetermined value (high level), the control proceeds to step 410. Otherwise, control returns to step 400.

  In step 410, the CPU 102 stops printing (stops the program started in step 404) and displays a warning screen on the operation unit 130. Specifically, the CPU 102 displays a warning screen 300 as shown in FIG. 12 on the touch panel display 132, for example. The warning screen 300 displays that the image forming apparatus 100 is installed at a location that exceeds an altitude that is assumed to be used, and that safety and print quality cannot be guaranteed. It is also displayed that when the OK key 302 is touched, functions (such as document scanning and FAX transmission) other than image formation (copying, printing, and FAX reception) can be executed.

  In step 412, the CPU 102 determines whether or not the OK key 302 on the warning screen 300 has been touched. If it is determined that the touch has been made, the control proceeds to step 414. Otherwise, step 412 is repeated.

  In step 414, the CPU 102 performs a setting for prohibiting the print function. Specifically, the CPU 102 sets a flag secured in a predetermined area of the RAM 106 to a value (for example, “1”) different from the initial value (for example, “0”). When the CPU 102 receives a user instruction and starts a program for executing a predetermined function of the image forming apparatus 100, the CPU 102 first checks the value of the flag and uses a value indicating prohibition (for example, “0”). If not, the corresponding program is started. If the value represents prohibition (for example, “1”), the corresponding program is not started and a warning screen or the like is displayed.

  As described above, if the image forming apparatus 100 is installed in a place exceeding an altitude of 2000 m, a warning can be displayed on the operation unit and printing can be prohibited. Therefore, it is possible to prevent the image forming apparatus 100 assumed to be installed at an altitude of 2000 m or less from being used without guaranteeing safety and print quality. If the image forming apparatus 100 is installed at an altitude of 2000 m or less, the user can use the image forming apparatus 100 as usual without being restricted.

  As described above, the detection voltage Vd becomes a high level if at least one of the discharge voltages Vc of the four chargers 5 corresponding to the four colors is equal to or higher than the threshold value Vth. Accordingly, in any printing based on image data including any color, immediately after the printing is started, it is determined whether or not the altitude of the place where the image forming apparatus 100 is installed is more than 2000 m. Can do.

  Since the flag set in step 414 is secured in the volatile RAM 106, when the image forming apparatus 100 installed at a place where the altitude exceeds 2000 m is moved to a place where the altitude is 2000 m or less and the power is turned on. All functions of the image forming apparatus 100 can be executed.

  In the above description, a case has been described in which it is determined in step 400 and step 402 whether or not an operation unit has been operated to receive a print instruction, but the present invention is not limited to this. In step 400, it may be determined whether or not a print job or FAX data is received. If a print job or FAX data is received, it is determined in step 402 that a print instruction has been received, and step 404 is executed. Subsequent processes in steps 406 to 416 are the same as described above.

  In the above description, the case where the discharge voltage of all the chargers corresponding to the toner of each color used by the image forming apparatus 100 is detected has been described, but the present invention is not limited to this. What is necessary is just to detect the discharge voltage of at least one charger. For example, the discharge voltage of only one of the chargers (for example, a charger corresponding to a frequently used toner) may be detected. In that case, when the printing is performed for the first time after the image forming apparatus 100 is turned on, there is a possibility that the charger is not used, and at that time, it cannot be determined whether or not the altitude is over 2000 m. However, since the charger is used in any case, it is possible to determine whether or not the altitude is over 2000 m although it is slightly delayed in time.

  In the above step 406, the case where the CPU 102 detects the discharge voltage Vd at the discharge timing of the charger 5 has been described, but the present invention is not limited to this. For example, if a latch circuit is provided on the output side of the logical sum unit 182 shown in FIG. 4 so that the high-level output signal Vd is latched, the CPU 102 does not consider the discharge timing of the charger 5. The discharge voltage Vd can be detected. Since the latch circuit maintains the corresponding high level output signal once the input signal (output signal Vd) becomes high level, the CPU 102 outputs the output of the latch circuit at any timing after the charger is discharged. What is necessary is just to acquire the level of a signal. Note that the CPU 102 appropriately resets the latch circuit and returns the output signal to a low level.

  In the above description, a case is described in which a comparator is used for the voltage comparison unit 180, and the input voltage V1 to the comparator is generated by distributing the discharge voltage Vc with a resistor. However, the present invention is not limited to this. Any circuit that can compare the discharge voltage Vc with a predetermined threshold value Vth and output a signal corresponding to the result may be used.

  In the above description, a case has been described in which it is determined whether or not the altitude is over 2000 m when printing is actually performed. However, the present invention is not limited to this. For example, as shown in FIG. 13, the determination may be made at the time of warming up that is executed when the power of the image forming apparatus 100 is turned on.

  Specifically, when power key 138 is pressed, in step 500, CPU 102 executes a normal startup process. After the start-up process is completed, in step 502, the CPU 102 causes the charger 5 to perform discharge in the same manner as in the above step 406, and detects the discharge voltage Vc at that time. Specifically, the CPU 102 acquires the value of the output signal Vd from the elevation detection unit 124 in FIG.

  In step 504, the CPU 102 determines whether or not the voltage Vd acquired in step 502 is equal to or higher than a predetermined voltage. If it is determined that the value is equal to or greater than the predetermined value (high level), the control proceeds to step 506. Otherwise, the CPU 102 ends this program and the image forming apparatus 100 enters a standby state.

  In step 506, the CPU 102 displays a warning screen on the operation unit 130. Specifically, the CPU 102 displays a warning screen 320 as shown in FIG. 14 on the touch panel display 132, for example.

  In step 508, the CPU 102 determines whether or not the end key 322 of the warning screen 320 has been touched. If it is determined that the touch has been made, the control proceeds to step 510. Otherwise, step 508 is repeated.

  In step 510, the CPU 102 activates a program for turning off the power of the image forming apparatus 100 and ends this program.

  As described above, if the image forming apparatus 100 is installed in a place where the altitude exceeds 2000 m, a warning is displayed on the operation unit, and the power can be forcibly turned off without putting the image forming apparatus 100 in a standby state. it can. Therefore, it is possible to prevent the image forming apparatus 100 assumed to be installed at an altitude of 2000 m or less from being used without guaranteeing safety and print quality. If the image forming apparatus 100 is installed at an altitude of 2000 m or less, the image forming apparatus 100 enters a standby state and can be used as usual.

  Since the discharge voltage of the charger 5 is detected before receiving a print instruction from the user, even in a color image forming apparatus, the altitude detecting unit 124 detects only the discharge voltage of any one of the chargers. do it. That is, the elevation detection unit 124 only needs to include one voltage comparison unit 180. In that case, in step 502, the CPU 102 operates only the charger that supplies the discharge voltage Vc to the discharge line input to the voltage comparison unit 180 to detect the discharge voltage Vc.

  Step 502 may be executed without waiting until the start-up process is completed when the charger 5 can be operated. If it is determined in step 504 that the altitude is more than 2000 m, the image forming apparatus 100 is forcibly terminated, and there is no problem even if the activation is not completed. If it is determined in step 504 that the altitude is not more than 2000 m, if the activation of the image forming apparatus 100 is not completed, the activation process is continued. Since the image forming apparatus 100 is in a standby state after the start-up process is completed, there is no problem.

  Although the case where the screen 320 shown in FIG. 14 is displayed in step 506 has been described above, the present invention is not limited to this. For example, the screen 300 shown in FIG. 12 may be displayed. In that case, step 412 and step 414 in FIG. 7 may be executed instead of step 508 and step 510.

  Although the case where the charger 5 is a scorotron charger having the grid electrode 164 has been described above, the present invention is not limited to this. It may be a corotron type charger not having a grid electrode.

  In the above description, the discharge electrode 162 has a sawtooth shape, but is not limited thereto. It may be a discharge electrode having other shapes, for example, a wire-like discharge electrode. Since the discharge voltage Vc corresponding to an altitude of 2000 m varies depending on the shape of the discharge electrode, it is preferable to appropriately determine the determination threshold value Vth by experiment.

  In the above description, the case where the discharge voltage Vc of the charger 5 is detected and it is determined whether or not the altitude is over 2000 m has been described. However, the present invention is not limited to this. If the image forming apparatus 100 employs a discharge type for the transfer unit, the discharge voltage applied to the transfer unit, specifically, the transfer roller 10 or the intermediate transfer roller 64 is detected in the same manner as described above. Compared with the threshold value, it can be determined whether the altitude is over 2000 m. The threshold value is determined in advance for each model of the image forming apparatus through experiments.

  The present invention has been described above by describing the embodiment. However, the above-described embodiment is an exemplification, and the present invention is not limited to the above-described embodiment, and is implemented with various modifications. be able to.

100 Image forming apparatus 102 CPU
104 ROM
106 RAM
108 HDD
110 NIC
112 modem 114 bus 120 document reading unit 122 image forming unit 124 altitude detecting unit 126 power supply unit 128 recording paper transport unit 130 operation unit 150 automatic document feeder 172 discharge control unit 174 discharge voltage generation unit 176 process unit 180 voltage comparison unit 182 OR unit 190 Network 192 Telephone line

Claims (6)

An image forming apparatus including a discharge unit that performs discharge for printing,
Detecting means for detecting a discharge voltage of the discharge unit;
Determination means for determining whether or not the discharge voltage detected by the detection means is greater than or equal to a predetermined threshold;
A limiting unit that limits the function of the image forming apparatus when the determination unit determines that the discharge voltage detected by the detection unit is greater than or equal to the threshold value;
The discharge voltage and the threshold are negative values,
The image forming apparatus, wherein the threshold value is equal to or greater than a value of a discharge voltage of the discharge portion when the image forming apparatus is installed at an altitude of 2000 m.   2. The display device according to claim 1, further comprising a display unit configured to display a predetermined message when the determination unit determines that the discharge voltage detected by the detection unit is greater than or equal to the threshold value. The image forming apparatus described in 1.   The image forming apparatus according to claim 1, wherein the restriction of the function of the image forming apparatus by the restricting unit is prohibition of a printing function.   The image forming apparatus according to claim 1, wherein the detection unit detects a discharge voltage of the discharge unit during execution of printing by the image forming apparatus. The detection unit detects a discharge voltage of the discharge unit during execution of the start-up process of the image forming apparatus or after receiving the print instruction after the start-up process.
4. The image forming apparatus according to claim 1, wherein the limiting unit stops the image forming apparatus when it is determined that the discharge voltage detected by the detecting unit is equal to or higher than the threshold value. 5. The image forming apparatus according to claim 1. Has a color printing function using multiple color toners,
Comprising a plurality of the discharge parts;
Each of the plurality of discharging units is a charging unit that charges each of a plurality of photosensitive drums each carrying a plurality of colors of toner,
The detecting means detects charging voltages of the plurality of charging units,
6. The determination unit according to claim 1, wherein the determination unit determines whether or not at least one of the plurality of discharge voltages detected by the detection unit is greater than or equal to the threshold value. The image forming apparatus according to claim 1.

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