Image forming apparatus

Abstract

To solve the problem in which: when medium detection is performed in every job after turn-on of power or return from sleep, FCOT or the start of supply of the second sheet is delayed due to waiting for the completion of the medium detection or waiting for switching of an image forming operation condition after the medium detection, which reduces the productivity of the job after turn-on of power or return from sleep.SOLUTION: An image forming apparatus stores, in a backup memory, the presence or absence of sheets on a paper feed tray before turn-off of power or transition to sleep, and the size of the sheets, determines whether to execute medium detection from a result of comparison between the presence or absence of sheets on the paper feed tray after turn-on of power or return from sleep, and the size of the sheets, and the presence or absence of sheets and the size of the sheets stored in the backup memory, and reduces the frequency of execution of the medium detection at the start of a job after turn-on of power or return from sleep to prevent a reduction in the productivity of the job.SELECTED DRAWING: Figure 11(b)

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus equipped with a media detection sensor on a recording paper transport path for determining characteristics such as the surface texture and thickness of recording paper, and in particular to a technology for suppressing declines in image formation productivity by reducing unnecessary recording paper characteristic determination operations. [Background technology]

[0002] Conventionally, in an electrophotographic image forming apparatus, a recording sheet is fed and conveyed one by one from a selected one of a plurality of paper feed trays in which a stack of recording sheets is set, such as a paper feed cassette or a manual feed tray, and an electrostatic latent image formed on a photosensitive member is developed with toner, and the toner image is transferred and fixed to the recording sheet to form an image on the recording sheet. Furthermore, in an image forming apparatus having a media sensor on a recording sheet conveying path for determining the characteristics of the recording sheet, after a stack of recording sheets is set or replaced in a paper feed tray selected during image formation, or after the power is turned on or the apparatus returns to a normal power mode from a power saving mode that reduces standby power, the characteristics of the recording sheet are unknown, so the characteristics of the recording sheet are determined using the first sheet of recording sheet fed and conveyed into the image forming apparatus, and the operating conditions of the image forming process, such as the recording sheet conveying speed, developing and transfer output, and fixing temperature, are determined according to the determined characteristics of the recording sheet, thereby forming an optimal image. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2022-62122 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, when the characteristics of the recording paper are identified by a media sensor on the recording paper transport path, and the operating conditions for image formation are switched in accordance with the characteristics of the recording paper identified for the first sheet, image formation begins after waiting for the motor speed change and fixing temperature change to be completed, so it takes time for the first sheet to be discharged outside the image forming device. Also, for feeding the second sheet, the characteristics of the recording paper are identified for the first sheet, and feeding begins after the operating conditions are switched, so the interval between feeding the first and second sheets becomes large, and it takes longer than usual to discharge the second sheet outside the device.

[0005] In particular, in image forming devices that use a timer function to switch to a power saving mode if the image forming device is not operated or used for a specified period of time or longer, the frequency of returning from the power saving mode at the start of image formation and switching to the power saving mode after image formation increases, and determining the characteristics of the recording paper each time the device switches from the power saving mode results in a decrease in the productivity of image formation.

[0006] It is estimated that the device usually switches to power saving mode with a stack of recording paper still set in the paper feed tray, and often returns from power saving mode without the stack of recording paper being replaced during power saving mode. It is therefore desirable to reduce unnecessary waiting time by not determining the characteristics of the recording paper when image formation begins after returning from power saving mode, and if it is detected that the stack of recording paper has been replaced during power saving mode, to determine the characteristics of the recording paper when image formation begins after returning from power saving mode, and to form an image that corresponds to the characteristics of the recording paper.

[0007] The present invention has been made against this background, and its object is to provide an image forming apparatus equipped with a recording paper characteristic discrimination means and a power saving mode, which reduces the need to perform recording paper characteristic discrimination when starting image formation after returning from the power saving mode, suppresses a decrease in productivity of image formation after returning from the power saving mode, and, if it detects that a stack of recording paper has been replaced during the power saving mode, discriminates the characteristics of the recording paper when forming images after returning from the power saving mode, and can form images corresponding to the characteristics of the recording paper. [Means for solving the problem]

[0008] In order to achieve the above object, an image forming apparatus according to the present invention has a display unit (330), a paper feed tray (210), a paper characteristic detection means (280) provided on a paper transport path for detecting characteristics such as the surface property and thickness of paper, a paper presence / absence detection means (214) for detecting the presence or absence of paper set in the paper feed tray, a storage means (304) for storing paper characteristic information detected by the paper characteristic detection means and a paper presence / absence detection result of the paper presence / absence detection means (FIG. 10, S806), a power saving state (S800, Table 2) in which power consumption is reduced compared to a normal state, and a control means (301) for controlling the above, When returning from a power state to a normal state, or when returning from a power OFF state to a power ON state, the control means checks the paper presence / absence detection result stored in the memory means (FIG. 11(b), S913) and the paper presence / absence detection result of the paper presence / absence detection means (FIG. 11(b), S905), and depending on the results, determines whether, at the start of image formation after returning to the normal state, the control means will perform image formation after detecting the paper characteristics by the paper characteristic detection means (FIG. 11(b), S917), or will perform image formation based on the paper characteristic information stored in the memory means without detecting the paper characteristics (FIG. 11(b), S918).

[0009] The image forming apparatus according to the present invention further comprises a first size detection means (217) for detecting the size of the paper set in the paper feed tray in a main scanning direction perpendicular to the transport direction, at least one second size detection means (218, 219) arranged in the transport direction of the paper set in the paper feed tray for detecting the length of the paper and the presence or absence of the paper, a size determination means (FIG. 4, Table 1) for determining the size of the paper set in the paper feed tray in accordance with the detection results of the first size detection means (217) and the second size detection means (218, 219), a first size determination screen (FIG. 5) for displaying the results of the size determination means on the display unit, and a paper size determined by the size determination means or the paper size determined from the first size determination screen. and the storage means (304) for storing therein the paper size (FIG. 10, S806), and when returning to the normal state from the power saving state or when returning to the power ON state from the power OFF state, the control means determines, depending on the result of comparing (FIG. 11(b), S915) the paper size stored in the storage means (FIG. 11(b)) with the paper size determined by the size determination means (FIG. 11(b), S906, S907, S908, S909, S910), at the start of image formation after returning to the normal state, whether to perform image formation after detecting the paper characteristics by the paper characteristic detection means (FIG. 11(b), S917), or to perform image formation based on the paper characteristic information stored in the storage means without detecting the paper characteristics (FIG. 11(b), S918).

[0010] Furthermore, the image forming apparatus according to the present invention is characterized in that, when the paper presence detection result stored in the memory means (FIG. 11(b), S913) indicates that there is no paper and the paper presence detection result of the paper presence detection means (FIG. 11(b), S905) indicates that there is paper, the control means assumes that paper was set in power saving mode or while the power is off, and determines to perform usage characteristic detection when image formation starts (FIG. 11(b), S917).

[0011] Furthermore, in the image forming apparatus according to the present invention, when the paper presence detection result stored in the storage means (FIG. 11(b), S913) indicates the presence of paper and the paper presence detection result of the paper presence detection means (FIG. 11(b), S905) indicates the presence of paper, the image forming apparatus further compares (FIG. 11(b), S915) the paper size stored in the storage means (FIG. 11(b), S913) with the paper size determined by the size determination means (FIG. 11(b), S906, S907, S908, S909, S910). If the paper size is different, it is assumed that the paper was replaced during the power saving mode or while the power was off, and it is decided to detect the paper characteristics when image formation starts (FIG. 11(b), S917); if the paper size is the same, it is assumed that the paper was not replaced during the power saving mode or while the power was off, and it is decided to form an image based on the paper characteristics information stored in the storage means when image formation starts (FIG. 11(b), S918).

[0012] In addition, the image forming apparatus according to claims 1 to 4 of the present invention is characterized in that it comprises a paper characteristic determination means (FIG. 12) which determines whether to use the paper characteristic detection result detected by the paper characteristic detection means (FIG. 14, S416) as paper characteristic information, or to use the paper characteristics selected by user operation (FIG. 13, S305, S306, S307, S308, S309, S310) as paper characteristic information. Effect of the Invention

[0013] As described above, according to the present invention, when returning to the normal state from a power saving state or when returning to the power ON state from a power OFF state, the control means determines, at the start of image formation after returning to the normal state, whether to perform image formation after detecting the paper characteristics by the paper characteristics detection means, or to perform image formation based on the paper characteristics information stored in the storage means without detecting the paper characteristics, depending on the results of comparing the paper presence detection result stored in the storage means with the paper presence detection result of the paper presence detection means, and the paper size stored in the storage means with the paper size determined by the size determination means.This reduces the frequency of paper characteristics determination, and as a result, reduces the wait time due to switching of image formation operating conditions after paper characteristics determination, thereby suppressing a decrease in productivity of image formation, and makes it possible to provide an image forming apparatus that can detect the replacement of a stack of paper during power saving or when the power is OFF and perform paper characteristics determination to form an image corresponding to the paper characteristics. [Brief description of the drawings]

[0014] [Figure 1] FIG. 2 is a cross-sectional view of the image forming apparatus. [Diagram 2] 1 is a block diagram showing a system configuration of an image forming apparatus. [Diagram 3] FIG. 2 is a cross-sectional view of the media sensor. [Figure 4] FIG. [Diagram 5] FIG. 11 is a diagram showing the relationship between the main scanning length and the manual feed paper width volume sensor. [Figure 6] FIG. 13 is a diagram showing an example of a setting screen for setting the surface properties of paper. [Figure 7] FIG. 11 is a diagram showing an example of a setting screen for setting a paper thickness. [Figure 8] FIG. 13 is an image diagram of a manual feed paper size display screen. [Figure 9] 13 is a flowchart showing a process for displaying a manual feed paper size notification screen. [Figure 10(a)] 13 is a flowchart showing a sleep mode transition. [Figure 10(b)] 13 is a power-off transition flowchart. [Figure 11(a)] 11 is a flowchart showing a return from a sleep mode. [Figure 11(b)] 11 is a flowchart showing a return from a sleep mode. [Figure 12] FIG. 13 shows a screen for selecting whether to use the media sensor. [Figure 13] 13 is a flowchart showing a subroutine for setting media information. [Figure 14] 10 is a flowchart showing a paper feed and transport subroutine during image formation. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the embodiment described below is an example, and the present invention is not limited to the following embodiment. EXAMPLES

[0016] Fig. 1 is a cross-sectional view of an image forming apparatus 100 and a scanner unit 101 according to an embodiment of the present invention, and Fig. 2 is a control block diagram according to the embodiment of the present invention. The basic configuration will be described with reference to Figs. 1 and 2.

[0017] The control unit 300 in FIG. 2 is composed of a CPU 301, a ROM 302, a RAM 303, an EEPROM 304, and a return factor monitoring unit 305. The return factor monitoring unit 305 will be described in detail later. When an instruction to start a print operation (hereinafter, a job) is input to the CPU 301 from the UI 330 of the operation unit, for example, the print operation is started. The CPU 301 is configured to be able to drive and control the pre-fixing conveyance motor 145, the fixing motor 173, the post-fixing conveyance motor 146, the manual feed conveyance motor 147, the discharge conveyance 1 motor 148, and the discharge conveyance 2 motor 149, which are connected via the I / O 307. Also, the CPU 301 is capable of detecting input signals from the paper conveyance sensor 171, the pre-register conveyance sensor 160, the paper feed pickup sensor 152, and the like, via the I / O 307. Furthermore, the CPU 301 is configured to be able to accept jobs input from the network I / F 314 and the fax I / F 315.

[0018] The CPU 301 also has an image processing unit 316 that processes images corresponding to jobs from the UI 330 and the like, and performs image processing such as image development and rotation. The CPU 301 is configured to be able to control an image forming unit 320. The image forming unit 320 can control high voltages and drives of the process unit 120, transfer belt 130, secondary transfer unit 140, and the like in FIG. 1, and can also control the laser scanner unit 110. The image forming unit 320 can also control the heater of the fixing unit 170 in FIG. 1. The scanner unit 101 is a unit that reads an original when making a copy.

[0019] Next, a basic image forming operation will be described with reference to Fig. 1 and Fig. 2. When a job is input from the UI 330, the CPU 301 interprets the job and starts a print operation. The CPU 301 drives the pre-fixing transport motor 145, which is the drive source of the paper feed pickup roller 151, via the I / O 307, so that the paper feed pickup roller 151 rotates and transports the paper in the paper feed cassette 150 one by one. At this time, the CPU 301 monitors using the paper feed pickup sensor 152 whether the paper feed operation has been performed normally. Similarly, the transport of paper from the manual feed tray 210 will be described. When a command is given from the UI 330 to transport the paper on the manual feed tray 210 with paper set in the manual feed tray 210, the CPU 301 drives the manual feed transport motor 147 via the I / O 307 to rotate the manual feed pickup roller 211, and the paper on the manual feed tray 210 is fed and transported one by one. As with feeding from a paper feed cassette, CPU 301 monitors pre-register conveyance sensor 160 to determine whether the paper feed operation was performed normally. Manual feed paper presence / absence detection sensor 214 is a sensor for determining whether paper is set on the manual feed tray. As an example of paper size detection, the configuration of manual feed tray 210 will be described in detail later.

[0020] Next, media detection will be described. The thickness and surface properties of the transported paper are detected by a media sensor 280 arranged on the transport path, and printing conditions such as fixing temperature and transfer voltage and image formation are performed according to the detected properties. The media sensor 280 will be described later.

[0021] Meanwhile, the CPU 301 starts the image forming operation in the process unit 120 so as to be in time for the arrival of the paper at the secondary transfer section 140. The process unit 120 is composed of a photosensitive drum, a developing device, a charging roller, a photosensitive drum cleaner, and the like. In the process unit 120, after the surface of the photosensitive drum is charged, a latent image is formed on the photosensitive drum by a laser irradiated from the laser scanner unit 110. Then, the formed latent image is developed on the photosensitive drum by the toner in the developing device. Then, a primary transfer voltage is applied to the toner image developed on the photosensitive drum in the primary transfer section 121, and the toner image is transferred to the transfer belt 130. The toner image transferred to the transfer belt 130 reaches the secondary transfer section 140 by the rotation of the transfer belt 130.

[0022] Furthermore, CPU 301 detects the position of the paper conveyed by conveyance rollers A 153, B 154, and C 155 by monitoring pre-registration conveyance sensor 160. Then, taking into consideration the timing when the leading edge of the paper reaches pre-registration conveyance sensor 160, conveyance of the paper is controlled so that the leading edge of the paper and the leading edge of the toner image on transfer belt 130 coincide at secondary transfer unit 140. For example, if the paper arrives earlier than the toner image, pre-registration conveyance rollers 161 stop the paper for a predetermined time and then resume conveyance.

[0023] By applying a secondary transfer voltage to the paper and toner image that have reached secondary transfer unit 140 in the manner described above, the toner image is transferred onto the paper.

[0024] After the secondary transfer, the paper is conveyed to a conveyor belt 190 and a fixing device 170. The toner image on the paper is heated and fixed to the paper by the fixing device 170. After that, the paper is conveyed further downstream of the apparatus.

[0025] When the leading edge of the paper after fixing reaches the paper transport sensor 171, the CPU 301 determines whether the paper is to be transported to the paper transport path A230, the paper transport path B231, or the paper transport path C234 according to the job contents specified in advance from the UI 330, and switches the transport destination of the paper by switching the transport flapper A172 and the transport flapper B182. Specifically, in the case of a double-sided print job or when the paper is to be discharged with the print side facing down to the paper discharge port A200, the transport flapper A is switched to transport the paper to the paper transport path A230, in the case of single-sided printing or double-sided printing, when the paper is to be discharged to the paper discharge port B196 or the paper discharge port C199, the transport flapper B182 is switched to transport the paper to the paper transport path B231, and in the case of a paper discharge command to the paper discharge port A200, the transport flapper A172 and the transport flapper B182 are switched to transport the paper to the paper transport path C234.

[0026] The paper conveyed to the paper conveying path B231 is conveyed further downstream by conveying rollers E232. Then, the paper is conveyed to the paper conveying path D181 and conveyed toward the paper discharge port B196 and the paper discharge port C199. The paper conveyed to the paper conveying path D181 is conveyed by paper discharge rollers F241, G242, and H243 driven by the paper discharge conveying motor 148, and in the case of a paper discharge command to the paper discharge port B196, the flapper 183 is switched to convey the paper to the conveying path 193 and output the paper to the paper discharge port B196. In the case of a paper discharge command to the paper discharge port C199, the flapper 183 is switched to the direction of the conveying path 184. Then, the paper is conveyed by paper discharge rollers I244, J245, and K246 driven by the paper discharge conveying motor 2 149 and output to the paper discharge port C199.

[0027] In addition, when printing on one side and discharging the paper with the print side facing down to the paper discharge port A200, the paper advances to the paper transport path A230, and when the rear end of the paper passes the reversing roller 163, the drive is reversed to rotate toward the paper discharge roller 180, and the paper is discharged directly to the paper discharge port A200.

[0028] During double-sided printing, the paper advances to paper transport path A230 and is transported to double-sided reversing transport path D233 by double-sided transport rollers A164, B165, C166, D179, and E168. When the rear end of the paper passes double-sided transport rollers D179, double-sided reversing flapper 178 is switched to the direction of double-sided transport rollers F169 and the drive is reversed. The paper is then transported by double-sided transport rollers F169, G175, H176, and I177, and handed over to transport rollers C155. When all jobs are completed, CPU 301 displays the completion on UI 330.

[0029] The above-described basic image forming operation is merely an example, and the present invention is not limited to the above-described configuration.

[0030] Fig. 3 is a cross-sectional view of the media sensor 280. Next, how the thickness and surface properties of the paper are detected will be described with reference to Fig. 3.

[0031] The media sensor 280 is composed of the media sensor main unit 54 and an external LED 55b as external illumination means. The media sensor main unit 54 has therein an LED 55a as illumination means, a phototransistor 56a as first reading means, and a phototransistor 56b as second reading means.

[0032] Next, detection of the surface property of the paper will be described. Light from LED 55a as a light source is irradiated through slit 57a onto the surface of sheet P, which is paper on paper transport guide 40. Also, paper transport guide 40 is provided with a window for irradiating light from the back side of sheet P. Light reflected from sheet P is collected through slits 57b and 57c and received by phototransistors 56a and 56b. For light from LED 55a as a light source, phototransistor 56a obtains a diffuse reflection output value, and phototransistor 56b obtains a regular reflection output value.

[0033] From the obtained output value, the surface roughness x is calculated by the following formula. Surface roughness x = specular reflection power / diffuse reflection power (Equation 1)

[0034] The calculation formula of Equation 1 utilizes the characteristics that a surface is "smooth" and "fine" and easily reflects specularly. An arithmetic device (not shown) disposed in the media sensor 280 performs the calculation of Equation 1 to quantify the surface property of the sheet P and notify the CPU 301 of the calculation result. The CPU 301 judges the surface property using the notified numerical value of the surface property and a threshold value for judging the surface property. If the value is higher than the threshold value, the surface property is judged to be "smooth" and "fine", and if the value is lower than the threshold value, the surface property is judged to be "rough" and "coarse". Although one threshold value is used in this embodiment, multiple threshold values ​​may be used to make further finer divisions.

[0035] Next, detection of the thickness of the paper will be described. Light emitted from the external LED 55b as a light source is irradiated onto the rear surface of the sheet P through a light collecting guide 57d that is provided to collect the light. The transmitted light from the sheet P is received by the phototransistor 56a through the slit 57b. The phototransistor 56a obtains a regular transmission output value for the light emitted from the external LED 55b as a light source. This detects the transmittance of the sheet P. The thicker the paper, the lower the transmittance, and the thinner the paper, the higher the transmittance. Taking advantage of this characteristic, the thickness of the paper is determined using the transmittance. The detected transmittance is notified to the CPU 301. The CPU 301 determines the thickness using the notified transmittance value and a threshold value for determining the thickness.

[0036] In this embodiment, a thickness / thin discrimination threshold A and a thickness / thin discrimination threshold B are used to distinguish between three types of thickness, normal, and thin. If the detected transmittance is higher than the thickness / thin discrimination threshold A, it is judged to be "thin", if the transmittance is lower than the thickness / thin discrimination threshold B, it is judged to be "thick", and if neither of these apply, it is judged to be "normal". In this embodiment, two thresholds are used, but in another embodiment, one threshold may be used, or three or more thresholds may be used for further classification. In this embodiment, an optical sensor is used, but the present invention is not limited to this, and a configuration using another type of sensor such as an ultrasonic sensor may be used as long as the sensor can detect the surface property or thickness.

[0037] In another embodiment, the detection of the surface property may be performed not by using the media sensor 280 but by inputting the surface property of the paper using a setting screen 600 for setting the surface property of the paper shown in FIG. 6, which will be described later.

[0038] As yet another embodiment, the thickness may be detected not by using the media sensor 280 but by inputting the thickness using a setting screen 700 for setting the thickness of the paper as shown in FIG.

[0039] Next, the setting of the surface property of the paper will be described with reference to Fig. 6. Fig. 6 is an example of a setting screen 600 for setting the surface property of the paper. The liquid crystal screen of the UI 330 displays 601 indicating that the surface property of the paper is fine (smooth), 602 indicating that the surface property is standard, and 603 indicating that the surface property is coarse (rough). The user inputs information corresponding to the surface property of the recording paper set for each paper feed port, and confirms the surface property by pressing 604 indicating confirmation. The input information is notified to the CPU 301. Note that, as another embodiment, a configuration may be adopted in which the surface property is detected using the media sensor 280 described in Fig. 3, without having the surface property setting means described in Fig. 6.

[0040] Next, the setting of the paper thickness will be described with reference to FIG. 7. FIG. 7 is an example of a setting screen 700 for setting the paper thickness. The liquid crystal screen of the UI 330 displays 701 indicating that the paper thickness is thin, 702 indicating that the paper thickness is medium, and 703 indicating that the paper thickness is thick. The user inputs information corresponding to the thickness of the recording paper set for each paper feed slot, and confirms the thickness by pressing 704 indicating confirmation. The input information is notified to the CPU 301. In another embodiment, the thickness of the paper may be detected using the media sensor 280 described in FIG. 3 without having the thickness setting means described in FIG. 7.

[0041] FIG. 4 is a top view of the manual feed tray 210. When a stack of sheets is set on the manual feed tray 210, the sheets are separated and transported one by one by the manual feed pickup roller 211. At this time, the manual feed paper presence / absence detection sensor 214 determines that there is paper. The set stack of sheets is narrowed by the manual feed side regulation guides 212 and 213 to prevent the sheets from being transported skewed when transported by the manual feed pickup roller 211. The manual feed side regulation guides 212 and 213 slide in the directions of the arrows 215 and 216 to prevent skew even if sheets of different main scanning lengths are set. Furthermore, the manual feed side regulation guides 212 and 213 are connected to the manual feed paper width volume sensor 217 via a link (not shown), and inputs an AD value according to the position of the manual feed side regulation guide 212 to the CPU 301. The CPU 301 detects the paper width in the main scanning direction based on the input AD value. A manual feed sub-scanning length detection 1 sensor 218 and a manual feed sub-scanning length detection 2 sensor 219 are flag-type sensors, and are sensors for detecting the sub-scanning length of the paper set on the manual feed tray 210 .

[0042] Next, a method for detecting the size of paper set in the manual feed tray 210 will be described with reference to FIG. 5 and Table 1. FIG. 4 is a diagram showing the relationship between the output of the AD value of the manual feed paper width volume sensor 217 according to the movement of the manual feed side regulation guides 212 and 213 and the main scanning length of the paper that is actually detected. The manual feed paper width volume sensor 217 is specifically a sensor that outputs 10-bit AD, and is configured to output an output value of 0 to 0x400 approximately linearly. In FIG. 4, the output value 0x320 of the manual feed paper width volume sensor 217 indicates 210 mm, which is the A4R width, and similarly, the output value 0x384 indicates 257 mm, which is the B4R width, and the output value 0x3D4 indicates 297 mm, which is the A4 width. The CPU 301 refers to Table 1 based on the output value of the manual feed paper width volume sensor 217 and the outputs of the manual feed sub-scanning length detection 1 sensor 218 and the manual feed sub-scanning length detection 2 sensor 219 to identify the paper size.

[0043] [Table 1]

[0044] According to Table 1, the A5 size is identified when the manual feed paper presence / absence detection sensor 214 is ON, the manual feed sub-scanning length detection 1 sensor 218 is OFF, the manual feed sub-scanning length detection 2 sensor 219 is OFF, and the output value of the manual feed paper width volume sensor 217 is 0x320±0x10. Similarly, the A4R size is identified when the manual feed paper presence / absence detection sensor 214 is ON, the manual feed sub-scanning length detection 1 sensor 218 is ON, the manual feed sub-scanning length detection 2 sensor 219 is OFF, and the output value of the manual feed paper width volume sensor 217 is 0x320±0x10. In this way, even if the output value of the manual feed paper width volume sensor 217 is the same, it is possible to determine that the sizes are different depending on the output of the manual feed sub-scanning length detection 1 sensor 218 or the manual feed sub-scanning length detection 2 sensor 219. Conversely, for B5 size, the output of the manual feed sub-scan length detection 1 sensor 218 and the manual feed sub-scan length detection 2 sensor 219 is the same as for A5 size, but the output value of the manual feed paper width volume sensor 217 is 0x384±0x10, and it is also possible to determine the paper size based on the difference in the output value of the manual feed paper width volume sensor 217.

[0045] In this embodiment, a volume sensor or a flag type sensor is used as a means for detecting the main scanning length and sub-scanning length of the paper, but this is not limited to this method, and other methods may be used, such as size detection by a combination output of a triple or quadruple switch whose output value changes in conjunction with a regulating guide. Also, in this embodiment, the paper size detection of the manual feed tray 210 is described, but the other paper feed tray, the paper feed cassette 150, is also configured to be capable of paper size detection in a similar manner.

[0046] Next, a screen displayed on UI 330 to allow the user to check the size of the paper set in manual feed tray 210 will be described with reference to Fig. 8. Fig. 8 shows manual feed paper size notification screen 500. Specifically, this screen displays the size of the paper set in manual feed tray 210 and prompts the user to check. The size detection method will be described later with reference to Fig. 9. If there is no problem with the size displayed on manual feed paper size notification screen 500, press manual feed paper size display OK button 503, and if display size 501 and the set size differ, press manual feed paper size display change button 502.

[0047] 9 is a basic flowchart from when paper is set in manual feed tray 210 to when manual feed paper size notification screen 500 is displayed on UI 330. CPU 301 starts processing in S700, and determines in S701 whether manual feed paper presence / absence detection sensor 214 is ON. If it is ON, proceed to S702, and turn on paper presence / absence Flg (variable in RAM 303) and media detection request Flg (variable in RAM 303). The ON / OFF state of media detection request Flg is checked at the start of image formation, and if it is ON, paper characteristics are detected, and it is turned OFF after the paper characteristics are detected. The paper presence / absence Flg will be described later. In S703, the output value of manual feed paper width volume sensor 217 is stored in AdVal (variable in RAM 303). Next, the process proceeds to S704, where the output value of the manual insertion sub-scanning length detection 1 sensor 218 is stored in L1Val (variable in RAM 303), and the output value of the manual insertion sub-scanning length detection 2 sensor 219 is stored in L2Val (variable in RAM 303) in S705. Next, the process proceeds to S706, where the obtained information is compared with Table 1 to determine whether the size is suitable. If the size is suitable, the process proceeds to S707, where the suitable size is stored in PapSize (variable in RAM 303). If the size is not suitable in S706, the process proceeds to S708, where indefinite is stored in PapSize. After storing in each PapSize, the process proceeds to S709, where the manual insertion paper size notification screen 500 is displayed on the UI 330 based on the stored size, and the process ends in S710. On the other hand, if the manual insertion paper presence / absence detection sensor 214 is OFF in S701, the process proceeds to S711, where the paper presence / absence Flg is turned OFF, and the flow returns to S701.

[0048] Next, the sleep mode of the image forming apparatus 100 will be described with reference to Table 2 and Fig. 10(a). Table 2 explains the blocks in the block diagram of Fig. 2 that are energized in the sleep mode and in other modes.

[0049] [Table 2]

[0050] In normal operation, power is supplied to all blocks except the return cause monitoring unit 305, whereas in sleep mode, power is supplied to not only the return cause monitoring unit 305 but also the UI 330, the network I / F 314, and the fax I / F 315, and power is not supplied to the other blocks. The UI 330 requires only power to accept input from the sleep button 335, and the liquid crystal portion is turned off. On the other hand, the network I / F 314 and the fax I / F 315 must be powered on because they must respond to both image formation requests even in sleep mode. The return cause monitoring unit 305 monitors whether an image formation request has occurred in the network I / F 314 and the fax I / F 315 during the sleep mode described above, and is configured with a circuit that consumes less power than the CPU 301, such as an application specific integrated circuit (ASIC) or a programmable logic device (CPLD), and is a mechanism that detects the occurrence of a return cause from the sleep mode and starts powering the CPU 301. In this manner, in this embodiment, a low power consumption sleep mode is realized by supplying power only to the minimum number of blocks necessary.

[0051] 10A is a flowchart for the image forming apparatus 100 to actually transition to the sleep mode. In S800, the CPU 301 starts processing, and in S801, it is determined whether the image forming apparatus 100 is forming an image. If it is determined that the image formation is completed, the process proceeds to S802. If it is determined that the image formation is completed, the process waits for the image formation to be completed.

[0052] In step S802, the CPU 301 clears and starts a sleep timer (not shown) provided therein. For example, the sleep timer can be set to one minute, four minutes, 30 minutes, or one hour by a user operation of the UI 330, and if there is no operation of the UI 330 or no image formation when the set time has elapsed, the device transitions to the sleep mode.

[0053] Next, in S803, it is determined whether or not the user has operated the UI 330. If there has been no user operation, the process proceeds to S804, where it is determined whether or not the sleep timer started in S802 has timed out. If it is determined in S804 that the sleep timer has not yet timed out, the process returns to S803, where it is determined whether or not the UI 330 has been operated. If it is determined in S803 that there has been a user operation, the process proceeds to S805, where it is determined whether or not the user operation was a press of the sleep button. If the user operation was not a press of the sleep button but an operation of the numeric keypad or another menu, the process is repeated from clearing and starting the sleep timer in S802.

[0054] If it is determined in S804 that the sleep timer has timed out, or in S805 that the sleep button has been pressed, the process proceeds to S806. In S806, the size information (AdVal, L1Val, L2Val, PapSize, paper presence / absence Flg, media detection request Flg, media detection Mode, media information) obtained in the flow starting from S700 is backed up to variables BupAdVal, BupL1Val, BupL2Val, BupPapSize, Bup paper presence / absence Flg, Bup media detection request Flg, Bup media detection Mode, and Bup media information in EEPROM 304, and the process proceeds to S807. In S807, the power to each block is turned off based on the power information in Table 2 in order to transition to sleep mode, and the process ends in S808.

[0055] 10B is a flowchart for the image forming apparatus 100 to transition to a power OFF state. The CPU 301 starts processing in S810, and determines in S811 whether or not a power switch (not shown) has been turned OFF. If it is determined that the power switch has been turned OFF, the process proceeds to S812. If it is determined that the power switch is still ON, the power switch OFF determination of S811 is repeated.

[0056] 10(a) of the flowchart for transitioning to sleep, in S812, the size information (AdVal, L1Val, L2Val, PapSize, paper presence / absence Flg, media detection request Flg, media detection Mode, media information) obtained in the flow starting from S700 is backed up to variables BupAdVal, BupL1Val, BupL2Val, BupPapSize, Bup paper presence / absence Flg, Bup media detection request Flg, Bup media detection Mode, and Bup media information in EEPROM 304, and the process proceeds to S813. In S813, power is turned off to all blocks in Table 2 to transition to the power OFF state, and the process ends in S814.

[0057] Next, a flow chart of a return from sleep mode, which is one of the controls that characterize the present invention, will be described with reference to FIG. 11. First, FIG. 11(a) is a flow chart showing the operation of the return cause monitor unit 305. The return cause monitor unit 305 starts processing from S930, and judges whether the sleep button 335 has been pressed in S931. If the sleep button 335 has been pressed, the process proceeds to S934, and if not, the process proceeds to S932. In S932, the network I / F 314 judges whether an image formation request via the network has been generated, and if so, the process proceeds to S934, and if not, the process proceeds to S933. In S933, the fax I / F 315 judges whether an image formation request via the wax has been generated, and if so, the process proceeds to S934, and if not, the process returns to S931. In each step, when the process proceeds to S934, that is, when it is judged that a return request from sleep mode has been generated, the process first performs a power supply process for the CPU 301, and ends the process in S935.

[0058] 11B is a flow chart showing the operation immediately after the start of energization of the CPU 301 in S934. The CPU 301 starts processing from S900 and proceeds to S904. In S904, energization of each block is started based on Table 2, and the process proceeds to S905 to determine whether the manual paper presence / absence detection sensor 214 is ON. If it is OFF, the process proceeds to S919 and ends. If it is ON, the process proceeds to S906 to store the output value of the manual paper width volume sensor 217 in AdVal (variable of RAM 303). Next, the process proceeds to S907 to store the output value of the manual paper sub-scanning length detection 1 sensor 218 in L1Val (variable of RAM 303), and in S908, the output value of the manual paper sub-scanning length detection 2 sensor 219 in L2Val (variable of RAM 303). Next, the process proceeds to S909 to compare the obtained information with Table 1 and determine whether the size is compatible. If the size matches, the process proceeds to S910, and the matched size is stored in PapSize (a variable of the RAM 303). If the size does not match in S909, the process proceeds to S911, and indefinite is stored in PapSize.

[0059] Next, the process proceeds to S912, where BupAdVal, BupL1Val, BupL2Val, BupPapSize, Bup paper presence / absence Flg, Bup media detection request Flg, Bup media detection Mode, and Bup media information are read from the EEPROM 304. In S913, the Bup paper presence / absence Flg is determined, and it is determined whether the manual paper presence / absence detection sensor 214 was ON or OFF when the mode was switched to the sleep mode. If it was OFF, it is determined that no paper was set in the manual feed tray 210 when the mode was switched to the sleep mode, and in S916, the size notification screen 500 is displayed on the UI 330. If it was ON in S913, it is determined that paper was set in the manual feed tray 210 when the mode was switched to the sleep mode, and the process proceeds to S914. In S914, it is determined whether the current paper size is undefined, and if it is undefined, the process proceeds to S916, and if it is not undefined, the process proceeds to S915.

[0060] In S915, PapSize is compared with BupPapSize, which is the paper size at the time of transition to the sleep mode, and if it is determined that a different size has been set, the process proceeds to S916. If it is determined that the sizes are the same, the process proceeds to S918. In S916, a size notification screen is displayed, and after the paper size is confirmed by a user operation, the process proceeds to S917. In S917, a media detection request Flg (variable in RAM 303) is set to ON. That is, it is assumed that paper was set during the sleep mode in the determination of the presence of paper in the manual feed tray 210 when returning from the sleep mode in S905 and the determination of the absence of paper in the manual feed tray at the time of transition to the sleep mode in S913, and after the paper size is confirmed in S916, the media detection request Flg is turned ON in S917, which determines that paper characteristics detection will be performed at the start of the next image formation.

[0061] Also, in S905 to determine whether there is paper in the manual feed tray 210 when returning from sleep mode, S913 to determine whether there is paper in the manual feed tray when transitioning to sleep mode, and S915 to determine whether the paper size at transition to sleep mode and the paper size at return from sleep mode do not match, it is assumed that paper of a different size was replaced during sleep mode, and after the paper size is determined in S916, the media detection request Flg is turned ON in S917, which determines that paper characteristics will be detected when the next image formation is started. If the sizes are determined to be the same in S915, the process proceeds to S918. In S918, the media detection request Flg and media information are overwritten with the backed up Bup media detection request Flg and Bup media information.

[0062] In other words, it is assumed that no paper change has been performed during sleep mode, and the media detection request Flg and media information at the time of transition to sleep mode are inherited. If the media detection request Flg inherited from the backup is OFF, paper characteristics detection has been completed at the time of transition to sleep mode, and it is determined that paper characteristics detection will not be performed at the start of the next image formation, and the operating conditions for image formation are set using the media information inherited from the backup. If the media detection request Flg inherited from the backup is ON, paper characteristics detection has not been completed at the time of transition to sleep mode, and it is determined that paper characteristics detection will be performed at the start of the next image formation. After each process has been performed, the process proceeds to S917, where it ends.

[0063] When the power is turned on, the same processing as that in the flow of FIG. 11(b) is performed, and therefore the description thereof is omitted.

[0064] Next, a paper media information determination method according to this embodiment will be described with reference to FIGS.

[0065] 12 shows a setting screen 800 for a media information determination method displayed on the UI 330 according to the embodiment. The setting screen 800 for a media information determination method is displayed when a setting menu for a media information determination method is selected from a user setting menu (not shown) of the UI 330.

[0066] A setting screen 800 for the media information determination method displays the following menu buttons for setting how to detect the media information: Set according to the detection result of the media sensor 801 and Set manually 802.

[0067] After selecting one of the above menu buttons, the user presses the decision button 903 to finalize the media information decision method.

[0068] FIG. 13 is a flowchart showing a subroutine for setting media information executed by CPU 301 according to the embodiment.

[0069] In step S301, the media information determination method setting screen 800 is displayed on the UI 330.

[0070] In S302, if the execution is completed, step S303 is executed.

[0071] In step S303, after the user selects either the menu button 801 for setting based on the detection result of the media sensor or the menu button 802 for manual setting, the process waits until the decision button 803 is pressed and the media information decision method is finalized.

[0072] In S303, the determined media information determination method is stored in a media detection mode (variable of the RAM 303).

[0073] In S304, it is determined whether the determined media information determination method is manual setting. If it is not manual setting in S304, the process proceeds to S311 and ends. If it is determined to be manual setting in S304, the process proceeds to S305.

[0074] In S305, the screen 700 for setting the paper thickness shown in FIG.

[0075] In S306, the process waits until the user selects one of the menu buttons, thin paper 701, normal paper 702, or thick paper 703, and then presses the decision button 702 to decide the thickness information.

[0076] In S307, the determined thickness information is stored in the thickness of the media information (variable in the RAM 303).

[0077] In S308, a screen 600 for setting the surface properties of the paper shown in FIG.

[0078] In S309, the process waits until the user selects one of the menu buttons, fine 601, standard 602, or coarse 603, and then presses the decision button 602 to decide the surface texture information.

[0079] In S310, the determined surface property information is stored in the surface property of the media information (variable in the RAM 303).

[0080] After the above steps are completed, the process ends in S311.

[0081] Note that the buttons and the settings stored in the RAM 303 are merely an example of an embodiment and are not limiting.

[0082] The paper feed and transport process with and without paper characteristic detection will be described with reference to Table 3 and FIG.

[0083] Table 3 shows the paper feed transport speeds corresponding to the surface properties and thickness of the paper as paper characteristic information.

[0084] [Table 3]

[0085] The image forming apparatus according to the present embodiment has two paper feed transport speeds, 340.0 mm / sec and 137 mm / sec, as examples. Paper with fine surface properties that tend to stick to each other is prone to double-feed jams, where multiple sheets are fed overlapping each other during feeding, so the slower speed of 137.0 mm / sec is set to ensure reliable paper feeding. Also, when the paper surface property is rough, the paper is set to be fed at the slower speed of 137.0 mm / sec because there is a risk of the paper getting caught in the paper transport path. In addition, when the paper surface property is standard, the stiffness of the paper creates high resistance at the bend in the paper transport path, which may cause a jam, so the paper is set to be fed at the slower speed of 137.0 mm / sec. When the paper surface property is standard, only thin paper and normal paper are set to be fed at the faster speed of 340.0 mm / sec.

[0086] The settings of the paper characteristic information and paper feed transport speed in Table 3 are merely an example, and are not limiting.

[0087] FIG. 14 is a flowchart showing a paper feed and transport subroutine during image formation executed by CPU 301 according to the embodiment.

[0088] In S401, it is determined whether or not there is paper in the specified paper feed tray. If there is no paper, a paper out notification is issued in S419, and the process ends in S408.

[0089] If it is determined in S401 that there is paper, it is determined in S402 whether or not the second or subsequent sheet is to be fed from the designated paper feed tray. If it is determined in S401 that there is the second or subsequent sheet, the process proceeds to S403, in which the paper feed speed corresponding to the determined paper characteristics is set according to Table 3, in order to feed and convey the second or subsequent sheets without detecting the paper characteristics. Next, one sheet is fed from the designated paper feed tray in S404, and it is confirmed in S405 whether a jam has occurred, and it is confirmed in S406 that the pre-registration conveyance sensor 160 is ON. If it is determined in S405 that no jam has occurred, it is confirmed in S406 that the pre-registration conveyance sensor 160 is ON, and if it is determined that it is OFF, it returns to the confirmation of the presence or absence of a jam in S405. If it is determined that a jam has occurred in S405, a jam occurrence notification is issued in S420, and the process ends in S408.

[0090] If it is determined in S406 that the pre-registration transport sensor 160 is ON, a pre-registration loop formation process is performed in S407 to remove any skew in the paper, and the paper feed transport process ends in S408.

[0091] If it is determined in S402 that the sheet is the first sheet from the specified sheet feed tray, the media detection mode is determined in S409. If it is determined in S409 that the media detection mode is set to manual, the process proceeds to S403, where the sheet is fed and conveyed without media detection.

[0092] If it is determined in S409 that the media detection mode is the detection result of the media sensor, the ON / OFF state of the media detection request Flg is checked in S410. If the media detection request Flg is OFF in S410, it is determined that the media information will be inherited, and the process proceeds to S403, where paper is fed and conveyed without media detection.

[0093] If the media detection request Flg is ON in S410, it is determined that media detection is necessary, and the paper feed transport speed for media detection is set in S411. Here, the slower speed of 137.0 mm / sec is set because the paper characteristics are unknown before the media is detected and the paper characteristics can be reliably detected by the media sensor.

[0094] Next, one sheet is fed from the specified paper feed tray in S412, and it is checked in S413 whether a jam has occurred, and it is checked in S414 whether the pre-registration transport sensor 160 is ON. If it is determined in S413 that no jam has occurred, it is checked in S414 whether the pre-registration transport sensor 160 is ON, and if it is determined that it is OFF, the process returns to checking whether a jam has occurred in S413. If it is determined in S413 that a jam has occurred, a jam occurrence notification is issued in S420, and the process ends in S408.

[0095] If it is determined in S414 that the pre-register transport sensor 160 is ON, in S415, the paper characteristics are detected by the media sensor as described above with reference to Fig. 3. After that, in S416, the paper characteristics detected in S415 are stored in the media information.

[0096] In S417, the media detection request Flg is turned OFF so that media detection is not performed in the subsequent paper feed transport.

[0097] Finally, in S418, a pre-registration loop forming process is performed to remove any skew in the paper, and the process ends in S408.

[0098] As described above, according to this embodiment, when returning to the normal state from the power saving state or when returning to the power ON state from the power OFF state, the control means determines, at the start of image formation after returning to the normal state, whether to perform image formation after detecting the paper characteristics by the paper characteristics detection means, or to perform image formation based on the paper characteristics information stored in the storage means without detecting the paper characteristics, depending on the results of comparing the paper presence detection result stored in the storage means with the paper presence detection result of the paper presence detection means, and the paper size stored in the storage means with the paper size determined by the size determination means.This reduces the frequency of paper characteristics determination, and as a result, reduces the waiting time due to switching of image formation operating conditions after paper characteristics determination, thereby suppressing a decrease in productivity of image formation, and makes it possible to provide an image forming apparatus that can detect the replacement of a stack of paper during power saving or when the power is OFF and perform paper characteristics determination to form an image corresponding to the paper characteristics. [Explanation of symbols]

[0099] 110 Laser Scanner 120 Process Unit 210 Manual feed tray 160 Front register transport sensor 130 Intermediate transfer belt 170 Fixing unit 100 Printers 301 CPU 302 ROM 303 RAM 330 UI 280 Media Sensor

Claims

1. a display unit, a paper feed tray, paper characteristic detection means provided on a paper transport path for detecting characteristics such as the surface texture and thickness of paper, paper presence / absence detection means for detecting the presence or absence of paper set in the paper feed tray, storage means for storing paper characteristic information detected by the paper characteristic detection means and a paper presence / absence detection result of the paper presence / absence detection means, a power saving state in which power consumption is reduced compared to a normal state, and control means for controlling the above, When returning to a normal state from the power saving state or when returning to a power ON state from the power OFF state, the control means determines, at the start of image formation after returning to the normal state, whether to perform image formation after detecting the paper characteristics by the paper characteristic detection means, or to perform image formation based on the paper characteristic information stored in the memory means without detecting the paper characteristics, depending on the results of checking the paper presence / absence detection result stored in the memory means and the state of the paper presence / absence detection result of the paper presence / absence detection means when image formation is started after returning to the normal state.

2. the device has a first size detection means for detecting a size in a main scanning direction perpendicular to a transport direction of the paper set in the paper feed tray, one or more second size detection means arranged in the transport direction of the paper set in the paper feed tray for detecting the length of the paper and the presence or absence of the paper, a size determination means for determining the size of the paper set in the paper feed tray according to the detection results of the first size detection means and the second size detection means, a first size determination screen for displaying the results of the size determination means on the display unit, and a storage means for storing the paper size determined by the size determination means or the paper size determined from the first size determination screen, The image forming device according to claim 1, characterized in that when returning from the power saving state to the normal state or when returning from the power OFF state to the power ON state, the control means determines, depending on the result of comparing the paper size stored in the memory means with the paper size determined by the size determination means, whether to perform image formation after detecting the paper characteristics by the paper characteristic detection means, or to perform image formation based on the paper characteristic information stored in the memory means without detecting the paper characteristics, when starting image formation after returning to the normal state.

3. The image forming apparatus according to claim 1 or claim 2, characterized in that, when the paper presence detection result stored in the memory means is no paper and the paper presence detection result of the paper presence detection means is paper present, the control means assumes that paper has been set in a power saving mode or while the power is off, and decides to perform usage characteristic detection when image formation starts.

4. if the paper presence / absence detection result stored in said storage means indicates that paper is present and the paper presence / absence detection result of said paper presence / absence detection means indicates that paper is present, then a comparison is made between the paper size stored in said storage means and the paper size determined by said size determination means, and if the paper sizes differ, it is assumed that paper has been replaced during a power saving mode or while the power is off, and a decision is made to perform paper characteristic detection at the start of image formation, An image forming apparatus as described in any one of claims 1 to 3, characterized in that if the paper size is the same, it is assumed that the paper has not been changed during power saving mode or when the power is off, and it is determined to perform image formation based on the paper characteristic information stored in the memory means when image formation is started.

5. 5. The image forming apparatus according to claim 1, further comprising a paper characteristic determination means for determining whether to use the paper characteristic detection result detected by the paper characteristic detection means as paper characteristic information or to use the paper characteristics selected by a user operation as paper characteristic information.

Images