Image forming apparatus

Abstract

To prevent image formation from being performed on sheets with different characteristics before and after interruption when image formation is interrupted before job completion.SOLUTION: An image forming apparatus includes: a manual feed tray where sheets are set; a feeding mechanism 1000 that feeds sheets from the manual feed tray; a media sensor 280 that detects sheet characteristics of the sheets conveyed by the feeding mechanism 1000; an image forming unit 320 that forms images on the sheets conveyed by the feeding mechanism 1000; and a control unit 300 that, when executing a job to form images on the multiple sheets, causes the image forming unit 320 to form images on the multiple sheets under operating conditions based on the sheet characteristics detected by the media sensor 280. When image formation is interrupted before job completion, the control unit 300 controls whether to re-execute detection of the sheet characteristics by the media sensor 280 in a case of recovery from the interruption depending on the cause of the interruption.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus, such as a printer, a copier, or a multifunction device, that is equipped with a media sensor that detects paper characteristics such as the surface texture and thickness of the paper being transported. [Background technology]

[0002] An electrophotographic image forming device feeds paper one sheet at a time from a paper feed section such as a paper feed cassette or manual feed tray, and prints an image on the fed paper. Each type of paper has different paper characteristics such as surface properties and thickness. The image forming device determines the operating conditions for image formation control (feeding, developing, transfer, fixing control, etc.) according to the paper characteristics, and prints on the paper. The operating conditions are, for example, the paper transport speed, bias voltage during development, transfer bias during transfer, fixing temperature, etc.

[0003] In addition to being manually set by the user, the paper characteristics can also be automatically set using a media sensor installed on the paper transport path. An image forming device equipped with a media sensor can use the media sensor to determine the paper characteristics of the paper being transported and automatically determine the operating conditions for image formation control based on the paper characteristics (Patent Document 1). Such an image forming device transports a single sheet of paper to detect the paper characteristics when replacing paper, when starting up, or when returning from a power saving mode that reduces standby power, and determines the operating conditions based on the detected paper characteristics. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2022-62122 Summary of the Invention [Problem to be solved by the invention]

[0005] When the media sensor is used to determine the characteristics of the paper, the operating conditions for image formation control are determined based on the characteristics of the first sheet of paper, for example, and are reflected in the second and subsequent sheets. Also, when a job is being executed to form images on multiple sheets of paper, the job is temporarily interrupted if, for example, the paper loaded in the paper feed section runs out. In such a case, there is a risk that paper with different characteristics will be loaded before and after the job is interrupted.

[0006] In consideration of the above-mentioned problems, the main object of the present invention is to prevent image formation from being performed on paper with different characteristics before and after the interruption when image formation is interrupted before a job is completed. [Means for solving the problem]

[0007] The image forming apparatus of the present invention comprises a paper feeding means in which paper is set, a feeding means for feeding the paper from the paper feeding means, a detection means for detecting paper characteristics of the paper transported by the feeding means, an image forming means for forming an image on the paper transported by the feeding means, and a control means for forming an image on the multiple sheets of paper by the image forming means under operating conditions based on the paper characteristics detected by the detection means when a job of forming an image on multiple sheets of paper is executed, and is characterized in that if image formation is interrupted before the job is completed, the control means controls whether or not to detect the paper characteristics again by the detection means when returning from the interruption, depending on the cause of the interruption. Effect of the Invention

[0008] According to the present invention, when image formation is interrupted before a job is completed, it is possible to prevent image formation from being performed on paper having different characteristics before and after the interruption. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram illustrating the configuration of an image forming apparatus. [Diagram 2] FIG. [Diagram 3] FIG. 4 is a configuration diagram of a media sensor. [Figure 4] FIG. 11 is an explanatory diagram of a result of paper discrimination. [Diagram 5] FIG. [Figure 6] FIG. [Figure 7] FIG. [Figure 8] FIG. 13 is a diagram showing an example of an automatic setting screen. [Figure 9] FIG. [Figure 10] 11 is a flowchart showing a process for setting paper feed stage information. [Figure 11] 11 is a flowchart showing an automatic media discrimination process. [Figure 12] FIG. 13 is a diagram showing an example of a display screen for an interruption cause. [Figure 13] 13 is a diagram illustrating an example of a notification screen. [Figure 14] 6 is a flowchart showing a paper detection process at the start of a job. [Figure 15] FIG. 13 is another configuration diagram of the media sensor. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

[0011] 1 is a configuration diagram of an image forming apparatus according to the present embodiment. The image forming apparatus 100 includes a scanner unit 101 and a UI (User Interface) 330 at its upper portion. Such an image forming apparatus 100 can be realized by, for example, a copier, a multifunction machine, or an MFP (Multi Function Peripheral).

[0012] The scanner unit 101 reads an image of an original document, for example, when copying or sending a facsimile. The scanner unit 101 transmits image data indicating the read original image to the image forming apparatus 100. When copying, the image forming apparatus 100 prints an image on paper based on the image data acquired from the scanner unit 101.

[0013] The UI 330 is an operation unit having an input interface and an output interface. The UI 330 includes various key buttons such as a numeric keypad 331, a start key 332, and a stop key 333, and a touch panel as an input interface. The UI 330 includes a display 334 and a speaker as an output interface. The user can input various instructions and settings to the image forming apparatus 100 through the UI 330. The UI 330 can display on the display 334 a screen for inputting instructions and settings to the image forming apparatus 100 and a screen showing the status of the image forming apparatus 100.

[0014] The image forming apparatus 100 includes a laser scanner unit 110, a process unit 120, a primary transfer section 121, a transfer belt 130, a secondary transfer section 140, a fixing section 170, paper feed cassettes 150 and 220 for storing paper, and a feed mechanism 1000 for feeding paper. The image forming apparatus 100 transfers an image (toner image) formed by the process unit 120 and the laser scanner unit 110 to paper fed by the feed mechanism 1000 through the primary transfer section 121, the transfer belt 130, and the secondary transfer section 140. The image forming apparatus 100 fixes the toner image to the paper through the fixing section 170. The paper on which the image has been printed in this manner is discharged to a paper discharge port A200, a paper discharge port B196, or a paper discharge port C199.

[0015] The process unit 120 includes a photosensitive drum, a developing unit, a charging roller, a photosensitive drum cleaner, etc. In the process unit 120, the surface of the photosensitive drum is charged by the charging roller, and then a latent image is formed on the photosensitive drum by a laser beam irradiated from the laser scanner unit 110. The laser scanner unit 110 irradiates the photosensitive drum with a laser beam modulated based on image data acquired from the scanner unit 101 or an external personal computer, etc. As a result, a latent image based on the image data is formed on the photosensitive drum.

[0016] The latent image formed on the photosensitive drum is developed by toner in a developing device. By developing, an image (toner image) is formed on the photosensitive drum. The process unit 120 of this embodiment has four photosensitive drums to form a color image. Toner images of different colors are formed on the four photosensitive drums. In this embodiment, toner images of yellow (Y), magenta (M), cyan (C), and black (K) are formed on the four photosensitive drums. When a monochrome image is formed, only a black toner image is formed.

[0017] A primary transfer voltage is applied to the toner images on the photosensitive drums in the primary transfer section 121, and the toner images are transferred to the transfer belt 130. The four photosensitive drums sequentially transfer the toner images onto the transfer belt 130. The toner images of each color are superimposed on the transfer belt 130. The toner images of each color transferred to the transfer belt 130 are transported to the secondary transfer section 140 by the rotation of the transfer belt 130. The photosensitive drums are used for the next image forming operation after the toner remaining on the photosensitive drums after transfer is removed by a photosensitive drum cleaner.

[0018] When the process unit 120 starts an image forming operation, the paper is set in the paper feed cassettes 150 and 220 and the manual feed tray 210, which are paper feed units, and fed. The fed paper is conveyed to the secondary transfer unit 140 via a conveyance path 40. The paper stored in the paper feed cassette 150 is fed to the conveyance path 41 by a pickup roller 151. The conveyance paths 40 and 41 from the paper feed cassette 150 to the secondary transfer unit 140 are provided with conveyance rollers A153, B154, C155, and pre-registration conveyance rollers 161 for conveying the fed paper. The paper placed on the manual feed tray 210 is fed to the conveyance path 42 by the pickup roller 211. The conveyance paths 40 and 42 from the manual feed tray 210 to the secondary transfer unit 140 are provided with conveyance rollers C155 and pre-registration conveyance rollers 161 for conveying the fed paper. The pre-registration transport rollers 161 transport the paper to the secondary transfer unit 140 in accordance with the timing at which the toner image carried by the transfer belt 130 is transported to the secondary transfer unit 140 .

[0019] A pickup sensor 152 is provided between the pickup roller 151 and the transport roller A 153. A manually-fed paper presence / absence detection sensor 214 is provided at the base end of the manual feed tray 210. A first transport sensor 160 and a media sensor 280 are provided on the transport path 40 between the transport roller C 155 and the pre-register transport roller 161.

[0020] The secondary transfer unit 140 transfers the toner images of each color to the paper all at once by applying a secondary transfer voltage to the paper and the toner images. The paper onto which the toner images have been transferred by the secondary transfer unit 140 is transported to the fixing unit 170. A transport belt 190 is provided between the secondary transfer unit 140 and the fixing unit 170, and the paper is transported to the fixing unit 170 by the transport belt 190.

[0021] The fixing unit 170 heats and presses the paper with the transferred toner image at a predetermined fixing temperature while pinching and transporting the paper, thereby melting and fixing the toner image to the paper. This fixes the image to the paper. The paper with the fixed image is transported to one of the transport paths C234, B231, and A230. For this purpose, flappers A172 and B182 are provided downstream of the fixing unit 170 in the transport direction of the paper. Transport roller D162 and second transport sensor 171 are provided between the fixing unit 170 and flappers A172 and B182.

[0022] The conveying path C234 is provided with a paper discharge roller 180. The paper discharge roller 180 discharges the paper to the paper discharge port A200. The conveying path B231 is connected to a conveying path D181. The conveying path D181 branches into a paper discharge path A193 to the paper discharge port B196 and a paper discharge path B184 to the paper discharge port C199. A flapper 183 is provided at the branch point between the paper discharge path A193 and the paper discharge path B184. The conveying path B231 and the conveying path D181 are provided with a conveying roller E232, a paper discharge roller A241, and a paper discharge roller B242.

[0023] The discharge path A193 is provided with discharge rollers C243 and a first discharge sensor 195. The paper transported to the discharge path A193 by the flapper 183 is discharged to the discharge outlet B196 by the discharge rollers C243. The discharge path B184 is provided with discharge rollers D244, E245, F246, and a second discharge sensor 197. The paper transported to the discharge path B184 by the flapper 183 is discharged to the discharge outlet C199 by the discharge rollers D244, E245, and F246.

[0024] The conveying path A230 is provided with a reversing roller 163, a double-sided conveying roller A164, a double-sided conveying roller B165, a double-sided conveying roller C166, a double-sided conveying roller D179, and a double-sided conveying roller E168. A double-sided reversing conveying path 233 is connected to the conveying path A230.

[0025] For example, when discharging a sheet of paper to the paper outlet A200 with the print side facing down during single-sided printing, the reversing roller 163 reverses its rotation direction just before the rear end of the sheet of paper guided by the flapper A172 to the transport path A230 passes through the reversing roller 163. This transports the sheet toward the paper discharge roller 180. Also, when discharging a sheet of paper after printing on its first side has been completed during double-sided printing, the reversing roller 163 transports the sheet of paper without reversing its rotation direction. The sheet of paper is transported to the double-sided reversing transport path 233 via the reversing roller 163, double-sided transport roller A164, double-sided transport roller B165, double-sided transport roller C166, double-sided transport roller D179, and double-sided transport roller E168.

[0026] A duplex conveying path 235 for conveying paper to the conveying path 41 is connected to the duplex reversing conveying path 233. After being conveyed to the duplex reversing conveying path 233, the conveying direction of the paper is reversed and the paper is conveyed to the duplex conveying path 235. For this purpose, a flapper 178 is provided at a branching point of the duplex conveying path 235. The duplex conveying path 235 is provided with duplex conveying rollers F169, G175, H176, and I177. Note that the duplex reversing conveying path 233 and the duplex conveying path 235 are also provided with a plurality of sensors for detecting paper.

[0027] When the paper is conveyed to the double-sided reversing conveyance path 233 during double-sided printing, the conveyance is temporarily stopped when the rear end passes the double-sided conveyance roller D179. The double-sided conveyance roller E168 reverses the rotation direction and conveys the paper in the opposite direction. The flapper 178 guides the paper to the double-sided conveyance path 235. The paper guided to the double-sided conveyance path 235 is conveyed to the conveyance path 41 by the double-sided conveyance roller F169, the double-sided conveyance roller G175, the double-sided conveyance roller H176, and the double-sided conveyance roller I177. Through this series of operations, the print side of the paper is reversed, and the second side opposite to the first side becomes the print side. The paper conveyed to the conveyance path 41 is conveyed to the secondary transfer unit 140, and an image is printed on the second side in the same manner as on the first side.

[0028] 2 is an explanatory diagram of a control unit that controls the operation of the image forming apparatus 100 having such a configuration. The control unit 300 is built into the image forming apparatus 100. The control unit 300 is an information processing apparatus including a central processing unit (CPU) 301, a read only memory (ROM) 302, a random access memory (RAM) 303, and a non-volatile memory 304. The control unit 300 also includes a return cause monitoring unit 305, a network interface (I / F) 314, a fax interface (I / F) 315, and an image processing unit 316. The image forming unit 320, the above-mentioned UI 330, and an I / O 307 are connected to the control unit 300. The return cause monitoring unit 305 monitors a return cause to a job, for example, when the job is interrupted before completion.

[0029] To the I / O 307, various sensors provided in the image forming apparatus 100 and various motors serving as drive sources for the feeding mechanism 1000 are connected. The various motors are, for example, a pre-fixing conveying motor 145, a fixing motor 173, a post-fixing conveying motor 146, a manual feed conveying motor 147, a first paper discharge conveying motor 148, and a second paper discharge conveying motor 149. The various sensors are, for example, the above-mentioned first conveying sensor 160, the second conveying sensor 171, the pickup sensor 152, the first paper discharge sensor 195, the second paper discharge sensor 197, the manual feed paper presence / absence detection sensor 214, and the media sensor 280. To the I / O 307, as other various sensors, a fixing motor stable rotation detection sensor 174, a first paper length detection sensor 218, a second paper length detection sensor 219, and a manual feed paper width volume sensor 217 are connected.

[0030] CPU 301 controls the operation of image forming apparatus 100 by executing a computer program stored in ROM 302. RAM 303 provides a working area when CPU 301 executes processing. CPU 301 acquires detection results from various sensors via I / O 307, and controls the operation of various motors via I / O 307 based on the acquired detection results. In this way, CPU 301 controls paper feeding and fixing unit 170.

[0031] CPU 301 of control unit 300 starts a print operation when, for example, an instruction to start a print operation (hereinafter, referred to as a "job") is input from UI 330. CPU 301 can also accept jobs via network I / F 314 and fax I / F 315. Network I / F 314 accepts jobs from an external device such as a personal computer via a network. Fax I / F 315 accepts jobs via facsimile communication.

[0032] The CPU 301 performs image processing on the image to be printed in accordance with the job using the image processing unit 316. The image processing unit 316 performs image processing such as image development and rotation. The CPU 301 performs print processing of the image on the paper by controlling the operation of each component in the image forming apparatus 100 described above using the image forming unit 320. The image forming unit 320 can control the application of high voltage to the process unit 120, the transfer belt 130, the secondary transfer unit 140, etc. in FIG. 1, drive control, and control the laser scanner unit 110. The image forming unit 320 can also control the heater of the fixing unit 170 in FIG. 1.

[0033] The CPU 301 that has acquired the job interprets the acquired job and starts a printing operation. After starting the printing operation, the CPU 301 performs a paper feed operation. When feeding paper from paper feed cassette 150, CPU 301 drives pre-fixing conveyance motor 145 via I / O 307 to rotate pickup roller 151. As pickup roller 151 rotates, paper sheets in paper feed cassette 150 are fed one by one. At this time, CPU 301 determines whether the paper feeding operation was performed normally based on the detection result of pickup sensor 152. When feeding paper from manual feed tray 210, with paper placed on manual feed tray 210, an instruction to transport paper on manual feed tray 210 is input by UI 330. CPU 301 determines whether paper is placed on the manual feed tray based on the detection result of manual feed paper presence / absence detection sensor 214. CPU 301 drives manual feed motor 147 via I / O 307 to rotate pickup roller 211. As pickup roller 211 rotates, the paper on manual feed tray 210 is fed one sheet at a time.

[0034] The fed paper has its paper characteristics, such as surface property and thickness, detected by the media sensor 280. The CPU 301 detects the paper characteristics based on the detection result of the media sensor 280, and sets the operating conditions for image formation control, such as the fixing temperature, transfer voltage, and paper conveyance speed, according to the detected paper characteristics, to perform image formation.

[0035] In parallel with the paper feeding operation, the CPU 301 starts the image forming operation by the process unit 120 so as to be in time for the paper to arrive at the secondary transfer unit 140. The image forming operation by the process unit 120 is as described above.

[0036] CPU 301 detects the position of the paper conveyed by conveyance rollers A 153, B 154, and C 155 based on the detection result of first conveyance sensor 160. CPU 301 controls the conveyance of the paper based on the timing at which first conveyance sensor 160 detects the leading edge of the paper so that the leading edge of the paper and the leading edge of the toner image on transfer belt 130 coincide with each other at secondary transfer unit 140. For example, if first conveyance sensor 160 detects the paper earlier than the toner image, CPU 301 stops the paper at the position of pre-registration conveyance rollers 161 for a predetermined time and then resumes conveyance.

[0037] CPU 301 transfers the toner image onto the paper by applying a secondary transfer voltage to the paper and toner image that have reached secondary transfer unit 140. The paper onto which the toner image has been transferred is transported to fixing unit 170 via transport belt 190. CPU 301 drives a fixing roller of fixing unit 170 using fixing motor 173 to heat and fix the toner image onto the paper. The paper onto which the image has been fixed is then transported further downstream in the paper transport direction.

[0038] When the second conveyance sensor 171 detects the leading edge of the paper after the image is fixed, the CPU 301 judges whether the paper is to be conveyed to the conveyance path A230, the conveyance path B231, or the conveyance path C234 according to the job contents specified in advance from the UI 330. The CPU 301 controls the flapper A172 and the flapper B182 according to the judgment result to switch the guide destination of the paper. Specifically, in the case of double-sided printing and when the paper is discharged to the paper discharge port A200 with the print side facing down, the CPU 301 switches the flapper A to guide the paper to the conveyance path A230. When single-sided printing or double-sided printing is completed on both sides, the CPU 301 guides the paper to either the conveyance path B231 or the conveyance path C234. When the paper is discharged to the paper discharge port B196 or the paper discharge port C199, the CPU 301 switches the flapper B182 to guide the paper to the conveyance path B231. When discharging the paper to the paper discharge port A200, the CPU 301 switches between the flapper A172 and the flapper B182 to guide the paper to the transport path C234.

[0039] The CPU 301 drives the conveying rollers D162 and E232 by the post-fixing conveying motor 146 to convey the paper conveyed to the conveying path B231 to the conveying path D181. The CPU 301 drives the paper discharge rollers A241 and B242 by the first paper discharge conveying motor 148 to convey the paper in the direction of the paper discharge outlet B196 and the paper discharge outlet C199.

[0040] When discharging the paper to paper discharge port B196, CPU 301 switches flapper 183 to guide the paper to paper discharge path A193, and drives paper discharge rollers C243 with first paper discharge conveyance motor 148 to discharge the paper to paper discharge port B196. When discharging the paper to paper discharge port C199, CPU 301 switches flapper 183 to guide the paper to paper discharge path B184, and drives paper discharge rollers D244, E245, and F246 with second paper discharge conveyance motor 149 to discharge the paper to paper discharge port C199.

[0041] When the paper is discharged to the paper outlet A200 with the print side facing down in single-sided printing, the CPU 301 switches the flapper A172 and controls the rotation of the reversing roller 163 to transport the paper as described above. When the printing on the first side is completed in double-sided printing, the CPU 301 switches the flapper A172 to guide the paper to the double-sided reversing transport path 233. To transport the paper to the double-sided reversing transport path 233, the CPU 301 controls the rotation of the reversing roller 163, the double-sided transport roller A164, the double-sided transport roller B165, the double-sided transport roller C166, the double-sided transport roller D179, and the double-sided transport roller E168. After that, the CPU 301 reverses the rotation of the double-sided transport roller E168 and controls the rotation of the double-sided transport roller G175, the double-sided transport roller H176, and the double-sided transport roller I177 as described above to transport the paper to the transport path 41.

[0042] The image specified in the job is printed on the specified number of sheets of paper. When all the sheets of paper with the printed image have been ejected, the printing operation for the job is completed. When the entire job is completed, the CPU 301 displays the completion of the job on the UI 330.

[0043] (Media Sensor) 3 is a configuration diagram of the media sensor 280. The media sensor 280 of this embodiment is used to detect the surface properties and thickness of the paper as paper characteristics. The media sensor 280 includes a media sensor unit 54, an external LED (Light Emitting Diode) 55b as an external light source, a light collecting guide 57d, and an arithmetic and control unit 58. The media sensor unit 54 includes an LED 55a as a light source, phototransistors 56a and 56b as light receiving units, and slits 57a, 57b, and 57c therein. The arithmetic and control unit 58 controls the operation of the media sensor 280 and performs arithmetic operations according to the output values ​​of the phototransistors 56a and 56b.

[0044] When detecting the surface property of the paper S, the media sensor 280 operates as follows. Light emitted from the LED 55a is irradiated via the slit 57a onto the surface of the paper S transported along the transport path 40. The phototransistor 56a receives the reflected light that is reflected by the surface of the paper S and concentrated via the slit 57b. The phototransistor 56b receives the reflected light that is reflected by the surface of the paper S and concentrated via the slit 57c.

[0045] The surface quality of the paper S is judged as follows. The phototransistor 56a receives light diffusely reflected by the paper S from the light source LED 55a and outputs a diffuse reflection output value corresponding to the amount of diffusely reflected light received. The phototransistor 56b receives light specularly reflected by the paper S from the light source LED 55a and outputs a specular reflection output value corresponding to the amount of specularly reflected light received. The surface roughness x of the paper S is expressed by the following equation based on the output values ​​of the phototransistors 56a and 56b. Surface roughness x = specular reflection output value / diffuse reflection output value ... (Equation 1)

[0046] Equation 1 utilizes the characteristic that the amount of specularly reflected light increases when the surface of the paper S is "smooth" and "fine". The calculation control unit 58 performs calculation processing of Equation 1 and transmits a numerical value (surface property x) that quantifies the surface property of the paper S to the CPU 301. The CPU 301 uses the acquired surface property x and a threshold value for determining the surface property to determine the surface property. If the surface property x is larger than the threshold value, the surface property is determined to be "smooth" and "fine". If the surface property x is smaller than the threshold value, the surface property is determined to be "rough" and "coarse". Although one threshold value is used in this embodiment, the CPU 301 may use multiple threshold values ​​to determine the surface property in more detail.

[0047] The thickness of the paper S is determined as follows: The transport path 40 is provided with an opening for irradiating the paper S with light from the external LED 55b. Light emitted from the external LED 55b as a light source passes through the light collecting guide 57d and is irradiated onto the back surface of the paper S. At least a portion of this light passes through the paper S. The transmitted light that passes through the paper S is received by the phototransistor 56a via the slit 57b. The phototransistor 56a outputs a specular transmission output value according to the amount of transmitted light received. The calculation control unit 58 detects the transmittance of the paper S from the specular transmission output value. The calculation control unit 58 sends the detected transmittance to the CPU 301. The thicker the paper S, the lower the transmittance value, and the thinner the paper S, the higher the transmittance value. The thickness of the paper S is determined by this transmittance characteristic.

[0048] The CPU 301 determines the thickness of the sheet S using the obtained transmittance and a threshold value for determining thickness. In this embodiment, the thickness of the sheet S is classified into three types: "thick," "normal," and "thin." To this end, the CPU 301 uses a thickness / thin discrimination threshold value A and a thickness / thin discrimination threshold value B as threshold values ​​for determining the thickness. Here, the thickness / thin discrimination threshold value A is a value greater than the thickness / thin discrimination threshold value B.

[0049] The CPU 301 judges the thickness of the sheet S to be "thin" if the transmittance is higher than the thickness / thin discrimination threshold A, and judges the thickness of the sheet S to be "thick" if the transmittance is lower than the thickness / thin discrimination threshold B. The CPU 301 judges the thickness of the sheet S to be "normal" if the transmittance is lower than the thickness / thin discrimination threshold A and higher than the thickness / thin discrimination threshold B. Note that, although two thickness / thin discrimination thresholds are used in this embodiment, the CPU 301 may use one thickness / thin discrimination threshold, or may use three or more thickness / thin discrimination thresholds to more finely classify the thickness of the sheet S.

[0050] Although the media sensor 280 of this embodiment has been described taking an optical sensor as an example, the sensor is not limited to this as long as it is capable of detecting paper characteristics such as the surface property and thickness of the paper S. For example, the media sensor 280 may be another type of sensor such as an ultrasonic sensor that uses reflection or transmission of ultrasonic waves. The surface property and thickness of the paper S may be manually set by the user using the UI 330 without using the media sensor 280. Furthermore, the paper characteristics detected by the media sensor 280 may be at least one of the surface property and the thickness, or a characteristic other than the surface property and the thickness.

[0051] (Media sensor discrimination result) FIG. 4 is an explanatory diagram of the results of paper discrimination by the media sensor 280. In this embodiment, the surface property 11 has three detection patterns ("fine (smooth)", "standard", and "coarse (rough)"), and the paper thickness 12 has three detection patterns ("thin", "normal", and "thick"). The paper type 13 is automatically discriminated from nine types. In this embodiment, the paper type 13 has nine types: "high-quality thin paper", "high-quality plain paper", "high-quality thick paper", "thin paper", "plain paper", "thick paper", "recycled thin paper", "recycled plain paper", and "recycled thick paper". The CPU 301 detects the paper properties based on the detection results (surface property x, transmittance) obtained from the media sensor 280, and discriminates the paper type based on the detected paper properties.

[0052] FIG. 5 is an explanatory diagram of paper feed stage information indicating the paper type placed on each paper feed stage of the paper feed section. The paper feed stages in this embodiment include paper feed cassettes 150 and 220, and manual feed tray 210. Here, paper feed cassette 150 is the first paper feed cassette, and paper feed cassette 220 is the second paper feed cassette. Paper feed stage information indicating the paper type for each paper feed stage is stored in RAM 303. In FIG. 5, the paper type of the first paper feed cassette is "high-quality thin paper," and the paper type of the second paper feed cassette is "high-quality plain paper." The paper type of paper placed on manual feed tray 210 is not set, and is automatically determined using media sensor 280 ("automatic").

[0053] The procedure for setting the paper type for manual feed tray 210 will be described. The user places paper on manual feed tray 210 and sets the paper type for manual feed tray 210. The user first operates UI 330 to display a setting screen for the paper type for manual feed tray 210 on display 334. Fig. 6 is a view showing an example of such a setting screen.

[0054] This setting screen displays a fixed mode selection button 501, a specified every time mode selection button 502, and an OK button 505. The fixed mode selection button 501 is a button for fixing and setting the paper type of paper placed on the manual feed tray 210. The specified every time mode selection button 502 is a button for setting the paper type of paper placed on the manual feed tray 210 every time the paper is placed. In the example of FIG. 6, the fixed mode selection button 501 is selected, and a paper type selection button 503 for selecting a fixed paper type and an automatic media selection button 504 for selecting "automatic" as the paper type are selectable. When the paper type selection button 503 is selected by the UI 330, a paper type selection screen is displayed on the display 334. FIG. 7 is a diagram showing an example of such a selection screen.

[0055] This selection screen displays a paper type selection button group 601, an automatic setting button 602, and an OK button 605. The user selects the paper type from the paper type selection button group 601 and the automatic setting button 602 using the UI 330, and presses the OK button 605 to select the paper type. When a selection is made from the paper type selection button group 601, the paper type of the manual feed tray 210 is set to the selected paper type. When the automatic setting button 602 is selected, the paper type of the manual feed tray 210 is set to "automatic." By setting "automatic," the paper type of the paper placed on the manual feed tray 210 is automatically determined using the media sensor 280.

[0056] When OK button 605 on the selection screen in Fig. 7 is pressed, the display on display 334 returns to the setting screen in Fig. 6. Paper type selection button 503 displays the content selected on the selection screen in Fig. 7. Here, "plain paper" is selected on the selection screen, and "plain paper" is displayed on paper type selection button 503. Note that when automatic media selection button 504 is selected on the setting screen in Fig. 6, the paper type for manual feed tray 210 is set to "automatic" without going through the selection screen in Fig. 7.

[0057] When the automatic media selection button 504 is selected on the setting screen of FIG. 6, the automatic setting screen shown in FIG. 8 is displayed on the display 334. On the automatic setting screen, the conditions for detecting paper by the media sensor 280 can be set. On the automatic setting screen, an "ON every time" button 401, an "Auto" button 402, an "OFF every time" button 403, and an OK button 404 are displayed. The user can set the conditions for detecting paper by selecting one of the "ON every time" button 401, the "Auto" button 402, or the "OFF every time" button 403 on the UI 330 and then pressing the OK button 404.

[0058] The "ON Every Time" button 401 is a button for setting the first sheet of paper to always be detected by the media sensor 280 when starting execution of a job or resuming after interruption. By selecting the "ON Every Time" button 401, the paper type is always automatically determined when starting a job or resuming after interruption. The "Auto" button 402 is a button for setting whether or not to automatically detect the first sheet of paper by the media sensor 280 when resuming a job after interruption. When the "Auto" button 402 is set as the paper detection condition to "Auto", whether or not to detect the first sheet of paper by the media sensor 280 is automatically determined when resuming a job after interruption, for example, based on the cause of the job interruption. The "OFF Every Time" button 403 is a button for setting not to detect the first sheet of paper by the media sensor 280 when starting execution of a job or resuming a job after interruption.

[0059] Fig. 9 is a view showing an example of a setting screen when each time specification mode selection button 502 is selected in Fig. 6. When each time specification mode selection button 502 is selected, the selection screen of Fig. 7 is displayed on display 334 when paper is placed on manual feed tray 210. The user selects the paper type from this selection screen every time paper is placed on manual feed tray 210. Information set on each screen of Figs. 6 to 9 is stored in RAM 303.

[0060] Fig. 10 is a flowchart showing the process of setting the paper feed stage information in Fig. 5. This process shows the flow of processing from when paper is placed on manual feed tray 210 to when paper feed stage information is stored in RAM 303.

[0061] CPU 301 waits until paper is placed on manual feed tray 210 (S201: N). CPU 301 can determine whether paper is placed on manual feed tray 210 based on the detection result of manual feed paper presence / absence detection sensor 214. When paper is placed on manual feed tray 210 (S201: Y), CPU 301 refers to RAM 303 and determines whether the designated mode is set every time (S202).

[0062] If the specified every time mode is not set (S202: N), CPU 301 updates the paper type of manual tray 210 in the paper feed stage information based on the settings made on the setting screen in Fig. 6 (S203). If the paper type is set to "automatic," the paper feed stage information is updated based on the results of automatic media discrimination processing, which will be described later.

[0063] If the every-time specification mode is set (S202: Y), CPU 301 displays the selection screen of FIG. 7 on display 334 (S204). CPU 301 waits until a paper type is selected from the selection screen and OK button 603 is pressed (S205: N). When OK button 603 is pressed (S205: Y), CPU 301 updates the paper type of manual tray 210 in the paper feed stage information with the paper type selected on the selection screen (S206). This ends the paper feed stage information setting process.

[0064] 11 is a flowchart showing the automatic media discrimination process when the paper type is set to "automatic." When the paper type is set to "automatic," the paper type is set by the media sensor 280 detecting the paper being conveyed when a job is started. The CPU 301 waits until the job is started (S101: N). When the job is started (S101: Y), the CPU 301 performs paper detection processing at the start of the job (S102). Details of the paper detection processing at the start of the job will be described later. The CPU 301 determines the paper characteristics and paper type from the paper detection result, and determines the operating conditions of the image formation control based on the paper characteristics.

[0065] After the paper detection process is completed, the CPU 301 determines whether a factor for interrupting the job has occurred before completion of the job while executing the print process (S112). The print process is performed based on the operating conditions of the image formation control set based on the paper characteristics. There are various factors for interrupting the job, such as "no paper," "paper jam," "no toner," and "full paper output section." The CPU 301 determines that a factor for interrupting the job has occurred when it becomes difficult to continue the job due to these factors. The CPU 301 can detect these factors using various sensors provided in the image forming apparatus 100. If a factor for interrupting the job has not occurred before completion of the job (S112: N), the CPU 301 determines whether the print process of the job has ended (S113). If the print process has not ended (S113: N), the CPU 301 returns to the process of S112 and continues to determine whether a factor for interrupting the job has occurred while executing the print process. If the print process has ended (S113: Y), the CPU 301 ends this process.

[0066] If an interruption factor occurs before the job is completed (S112: Y), CPU 301 displays the interruption factor of the job on display 334 and starts recovery factor monitoring to monitor for resolution of the interruption factor by recovery factor monitoring unit 305 (S103). Fig. 12 is an example of an interruption factor display screen. This display screen is displayed when the interruption factor is "no paper" indicating that there is no paper on manual feed tray 210.

[0067] CPU 301 waits until the cause of interruption is eliminated and the job can be resumed (S104: N). In the example of Fig. 12, the cause of interruption is eliminated when paper is placed on manual feed tray 210. In this case, CPU 301 can detect that paper has been placed on manual feed tray 210 as a cause of recovery from interruption based on the detection result of manual feed paper presence / absence detection sensor 214.

[0068] When the job can be resumed (S104: Y), the CPU 301 judges whether or not "OFF every time" is set as the paper detection condition on the automatic setting screen of FIG. 8 (S105). If "OFF every time" is set (S105: Y), the paper type is not identified. In this case, the CPU 301 resumes the job under the operating conditions determined in the process of S102, and then judges whether or not the print process of the job has ended (S113). If the print process has not ended (S113: N), the CPU 301 returns to the process of S112 and continues to judge whether or not a factor that interrupts the job has occurred while executing the print process. If the print process has ended (S113: Y), the CPU 301 ends this process.

[0069] If "OFF every time" is not set (S105: N), CPU 301 judges whether "Auto" is set as the paper detection condition (S106). If "Auto" is set (S106: Y), CPU 301 judges whether the interruption cause of the job is "no paper" (S107). If the interruption cause is not "no paper" (S107: N), the possibility that paper will be newly placed on manual feed tray 210 is low, and therefore the possibility that paper of a different paper type will be mistakenly placed is also low. For this reason, CPU 301 can judge not to newly identify the paper type. In this case, CPU 301 resumes the job under the operating conditions determined in the process of S102, and then judges whether the printing process of the job has ended (S113). If the printing process has not ended (S113: N), CPU 301 returns to the process of S112 and continues to judge whether a factor for interrupting the job has occurred while executing the printing process. If the printing process is completed (S113: Y), the CPU 301 ends this process.

[0070] If the paper detection condition is not set to "automatic" (S106: N), or if the cause of the job interruption is "out of paper" (S107: Y), it is necessary to determine the paper type from the first sheet of paper when the job is resumed after the interruption. To this end, in these cases, CPU 301 feeds paper, obtains the paper detection results from media sensor 280, and detects the paper type again (S108). CPU 301 also detects the paper characteristics based on the obtained detection results, and determines new operating conditions for image formation control based on these paper characteristics.

[0071] CPU 301 determines whether or not the paper has been mixed in one job based on the paper type detected in the process of S102 and the paper type detected in the process of S108 (S109). If the paper type detected in the process of S102 and the paper type detected in the process of S108 are the same, it is determined that the paper has not been mixed, and if they are different, it is determined that the paper has been mixed.

[0072] If there is no mixed paper (S109: N), CPU 301 resumes the job under the operating conditions determined in the process of S102, and then determines whether the printing process of the job has ended (S113). If the printing process has not ended (S113: N), CPU 301 returns to the process of S112, and while executing the printing process, continues to determine whether a factor that interrupts the job has occurred. If the printing process has ended (S113: Y), CPU 301 ends this process.

[0073] If there is mixed paper (S109: Y), CPU 301 notifies the user that there is mixed paper (S110). FIG. 13 is an example of a notification screen for notifying the user that there is mixed paper. CPU 301 notifies the user by displaying this notification screen on display 334. This notification alerts the user that the type of paper that was replenished without paper is incorrect. If the user wishes to continue the job in this state, he or she presses "YES" button 701 on the notification screen, or if the user wishes to interrupt the job, he or she presses "NO" button 702 on the notification screen.

[0074] If the "YES" button 701 is pressed (S111: Y), the CPU 301 resumes the job under the new operating conditions determined in the process of S108, and then determines whether the print processing of the job has ended (S113). If the print processing has not ended (S113: N), the CPU 301 returns to the process of S112, and while executing the print processing, continues to determine whether a factor that interrupts the job has occurred. If the print processing has ended (S113: Y), the CPU 301 ends this process. If the "NO" button 702 is pressed (S111: N), the CPU 301 ends the job and ends this process.

[0075] The paper detection process at the start of a job in S102 of Fig. 11 will be described below. Fig. 14 is a flowchart showing the paper detection process at the start of a job. CPU 301 determines whether the paper detection condition is set to "OFF every time" (S301). If the detection condition is set to "OFF every time" (S301: Y), CPU 301 ends the paper detection process without detecting the paper. If the detection condition is not set to "OFF every time" (S301: N), CPU 301 feeds the paper and detects the fed paper with media sensor 280 (S302). CPU 301 obtains the paper detection result from media sensor 280, and determines the paper characteristics and paper type based on this detection result. This ends the paper detection process.

[0076] As described above, the image forming apparatus 100 of this embodiment judges whether or not to re-determine the paper type depending on the cause of recovery when the job is restored from an interrupted state. For example, if a job is interrupted due to an out-of-paper condition, new paper needs to be loaded. In this case, there is a possibility that a different type of paper will be loaded by mistake. For this reason, if the cause of recovery is an out-of-paper condition, the paper type is re-determined. By re-determining the paper type, the operating conditions for image formation control are also reset.

[0077] In addition, by comparing the paper type determined at the start of a job with the paper type determined when the job resumes after being interrupted, it is possible to determine whether or not a different paper type has been set by mistake. If a different paper type has been set, the user is notified to alert them. This prevents mixed paper types from being loaded during a job.

[0078] The image forming apparatus 100 described above reduces the frequency of determining paper characteristics and paper type, and as a result, reduces the waiting time required for resetting the operating conditions after determining the paper characteristics. This reduces the decrease in printing productivity.

[0079] (Another example of a media sensor) FIG. 15 is another configuration diagram of the media sensor 280. The control unit 300 can detect the characteristics of the paper sheet using this media sensor 280. FIG. 15 is a diagram seen from the conveying direction of the paper sheet S (the conveying roller C155 side). This media sensor 280 has an ultrasonic sensor 281 and an optical sensor 282, and detects the paper characteristics (for example, the surface property and basis weight) of the paper sheet S. The ultrasonic sensor 281 is composed of an ultrasonic transmitter 2811 and an ultrasonic receiver 2812. The optical sensor 282 is configured as a CIS (Contact Image Sensor) having, for example, a light source 1501 and a line sensor 1502. For example, an LED is used as the light source 1501.

[0080] When the optical sensor 282 detects the brightness value, it is necessary to hold the paper at the optical focal position. When detecting the paper S by ultrasonic waves, it is necessary to reduce the effect of fluttering of the paper S being transported. In order to stabilize the posture of the paper S, the media sensor facing roller 260 and the paper pressing roller 261 are provided between the transport roller C155 and the pre-registration transport roller 161. The media sensor facing roller 260 is provided opposite the optical sensor 282 and is configured to press the paper S against the optical sensor 282. This reduces the variation in the position and posture of the paper S when the media sensor 280 measures the surface of the paper S. Therefore, the media sensor 280 can stably measure the surface properties and basis weight of the paper S.

[0081] 5, the ultrasonic transmitter 2811 is disposed on the upper block 4011 side, and the ultrasonic receiver 2812 is disposed on the lower block 4012 side, with the transport path 40 of the paper S sandwiched between them. The ultrasonic sensor 281 is configured to transmit and receive ultrasonic waves via the paper S, thereby outputting information (output voltage) for determining the basis weight of the paper S. The basis weight here is the mass per unit area of ​​the paper S, and is expressed in [gsm].

[0082] Both the ultrasonic transmitter 2811 and the ultrasonic receiver 2812 are composed of a piezoelectric element (also called a piezo element) which is an element for mutual conversion between mechanical displacement and an electric signal, and an electrode terminal. When a pulse voltage of a predetermined frequency is inputted from the electrode terminal of the ultrasonic transmitter 2811, the piezoelectric element of the ultrasonic transmitter 2811 oscillates to generate an ultrasonic wave. The generated ultrasonic wave propagates through the air. When the ultrasonic wave reaches the paper S, the paper S vibrates due to the ultrasonic wave. In this manner, the ultrasonic wave generated by the ultrasonic transmitter 2811 propagates to the ultrasonic receiver 2812 via the paper S. The piezoelectric element of the ultrasonic receiver 2812 receives the ultrasonic wave propagated via the paper S, and generates an output voltage according to the amplitude of the received ultrasonic wave at the electrode terminal of the ultrasonic receiver 2812. The ratio of the output voltage when there is no paper S between the ultrasonic transmitter 2811 and the ultrasonic receiver 2812 and the output voltage when there is paper S is the transmittance. Since the ultrasonic transmittance changes depending on the basis weight (area density) of the paper S, the basis weight of the paper S can be estimated using the ultrasonic transmission coefficient-paper basis weight conversion formula.

Claims

1. A paper feed means in which paper is set; a feeding means for feeding the paper from the paper feeding means; a detection means for detecting paper characteristics of the paper conveyed by the feeding means; an image forming means for forming an image on the paper conveyed by the feeding means; a control unit that, when executing a job of forming images on a plurality of sheets of paper, causes the image forming unit to form images on the plurality of sheets of paper under operating conditions based on the sheet characteristics detected by the detection unit; the control means, when the image formation is interrupted before the job is completed, controls whether or not to execute detection of the paper characteristics by the detection means again when the job is resumed depending on a cause of the interruption. Image forming device.

2. the control means, if the cause of the interruption is the absence of paper in the paper feed means, re-determines the paper type based on the paper characteristics detected by the detection means.

2. The image forming apparatus according to claim 1.

3. The control means determines whether or not a paper of a different paper type has been set in the paper feed means by comparing the paper type determined at the start of the job with the paper type determined again when the job is resumed from the interruption.

3. The image forming apparatus according to claim 2.

4. When paper of a different paper type is set in the paper feed means, the control means notifies a user that paper of a different paper type has been set.

4. The image forming apparatus according to claim 3.

5. The printer further includes a paper presence / absence detection means for detecting paper set in the paper feed means, The control means detects the cause of the interruption based on the detection result of the paper presence / absence detection means.

3. The image forming apparatus according to claim 2.

6. When the control means re-determines the paper type based on the paper characteristics, the control means determines new operating conditions based on the paper characteristics detected by the detection means, and re-determines the paper type based on the determined new operating conditions.

2. The image forming apparatus according to claim 1.

7. the control means compares the paper type determined at the start of the job with the paper type determined again when the job is resumed from the interruption, and when paper of the same paper type is set in the paper feed means, causes the image forming means to form an image under the operating conditions at the start of the job.

7. The image forming apparatus according to claim 6.

8. the control means, when a paper of a different paper type is set in the paper feed means and, upon receiving a notification from a user to continue the job in this state, causes the image forming means to form an image under the new operating conditions.

8. The image forming apparatus according to claim 7.

Images