JP2006243498A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress degradation in image formation efficiency while preventing melt-sticking of a toner. <P>SOLUTION: A delivery roller 38 conveys the recording media subjected to heat fixing and ejects the media to an ejection tray. A CPU 40 computes data indicating the amount of the toner used of the toner image based on the image data. An image forming engine controller 54 controls the ejection means in such a manner that the ejection time intervals of the recording media to the ejection tray are longer as the amount of the toner used which is indicated by the data on the computed amount of the toner used is greater. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus that transfers a toner image formed on an image carrier based on image data to a recording medium, and heat-fixes the toner image onto the recording medium.

  In recent years, image forming apparatuses such as laser printers and electrophotographic copying machines that form an image by irradiating a photosensitive member as an image carrier with a light beam have become widespread. In this type of image forming apparatus, a toner image formed on a photoreceptor by an electrophotographic method is transferred to a sheet as a recording medium, and the toner image is heated and fixed on a recording sheet. Some are conveyed by a conveyance roller or the like and discharged to a discharge tray.

By the way, in this type of image forming apparatus, for example, when image forming processing on a plurality of sheets is continuously performed, and a plurality of sheets are overlapped on the discharge tray, the toner fixed on the sheets is fixed. However, there are cases where toner is peeled off or image unevenness is caused by fusing to other paper by heat due to heat fixing. This toner fusion is particularly likely to occur in a recording medium such as an OHP (overhead projector) sheet, and the applicant of the present invention has disclosed a recording medium as a technique for preventing the toner fusion. A technique has been disclosed in which the discharge speed of the recording medium after the heat fixing is performed in accordance with the sheet type, job conditions, and the like is slowed, and the recording medium is discharged to the discharge tray after the toner has cooled. According to this technique, since the recording medium overlaps on the discharge tray with the toner cooled, it is possible to prevent toner fusion.
JP 2003-248349 A

  However, when the density of the formed toner image is low, the amount of toner adhering to the recording medium is small, so that toner fusion hardly occurs, and when the temperature near the discharge tray is low, the toner is quickly cooled. Therefore, although the toner is not fused, the technique disclosed in Patent Document 1 slows the discharge speed of the recording medium to the discharge tray according to the sheet type, job conditions, and the like, and the image forming efficiency is high. There was a problem that it might be lowered.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus capable of suppressing a decrease in image forming efficiency while preventing toner fusion.

  In order to achieve the above object, according to the first aspect of the present invention, a toner image formed on an image carrier is transferred to a recording medium based on image data, and the toner image is heated and fixed to the recording medium. An image forming apparatus that calculates a usage amount data that indicates a toner usage amount of the toner image based on the image data, and a discharge unit that conveys the heat-fixed recording medium and discharges the recording medium to a discharge tray. A control means for controlling the discharge means so that the discharge time interval of the recording medium to the discharge tray becomes longer as the toner usage amount indicated by the usage amount data calculated by the calculation means increases; It has.

  The image forming apparatus according to claim 1, wherein the toner image formed on the image carrier is transferred to a recording medium based on the image data, and the recording medium on which the toner image is heat-fixed is conveyed by a discharge unit. It is configured to discharge to a discharge tray. Here, in the present invention, usage data indicating the toner usage of the toner image is calculated based on the image data by the calculation means, and is indicated by the usage data calculated by the calculation means by the control means. The discharging means is controlled so that the discharge time interval of the recording medium to the discharge tray becomes longer as the amount of toner used increases. The control means may control the discharging means so that the discharging time interval becomes longer as the amount of toner used increases, and controls the discharging means so as to increase the discharging time interval stepwise. Also good.

  As described above, according to the first aspect of the present invention, the usage amount data indicating the toner usage amount of the toner image is calculated based on the image data, and as the toner usage amount indicated by the calculated usage amount data increases, the recording medium of the recording medium increases. Since the discharge unit is controlled so that the discharge time interval to the discharge tray becomes longer, it is possible to prevent a decrease in image formation efficiency while preventing toner fusion.

  According to the first aspect of the present invention, as in the second aspect of the present invention, the toner usage amount is set to an image density of an image indicated by the image data, and the control means is configured to make the image density higher than a predetermined density. If it is larger, the discharge speed of the recording medium to the discharge tray is slowed, or the discharge means is controlled so as to temporarily stop discharge of the recording medium to the discharge tray. Good.

  Further, according to the first aspect of the present invention, as in the third aspect of the present invention, the apparatus further comprises temperature detecting means for detecting the temperature in the vicinity of the discharge tray, and the control means uses the toner usage indicated by the usage amount data. The discharge time interval of the recording medium to the discharge tray increases as the amount increases, and the discharge time interval of the recording medium to the discharge tray increases as the temperature detected by the temperature detection means increases. The discharging means may be controlled.

  Further, according to a third aspect of the present invention, as in the fourth aspect of the present invention, the toner usage amount is set to an image density of an image indicated by the image data, and the control means is configured such that the image density is higher than a predetermined density. When the temperature is higher or the temperature is higher than a predetermined temperature, the discharge speed of the recording medium to the discharge tray is decreased, and the recording density is higher when the image density is higher than the predetermined density and the temperature is higher than the predetermined temperature. The discharging unit may be controlled so as to temporarily stop discharging the medium to the discharge tray.

  On the other hand, in order to achieve the above object, the invention described in claim 5 transfers the toner image formed on the image carrier to the recording medium based on the image data, and heat-fixes the toner image on the recording medium. An image forming apparatus that performs the above-described heat-fixed recording medium that transports and discharges the recording medium to a discharge tray, a temperature detection unit that detects a temperature in the vicinity of the discharge tray, and a detection by the temperature detection unit Control means for controlling the discharge means so that the discharge time interval of the recording medium to the discharge tray becomes longer as the measured temperature becomes higher.

  According to the fifth aspect of the present invention, the toner image formed on the image carrier is transferred to the recording medium based on the image data, and the recording medium on which the toner image is heated and fixed is conveyed by the discharging means and discharged. It is configured to discharge to a tray. Here, in the present invention, the temperature detection means detects the temperature in the vicinity of the discharge tray, and the control means discharges the recording medium to the discharge tray as the temperature detected by the temperature detection means increases. The discharging means is controlled so as to be longer.

  Thus, according to the fifth aspect of the present invention, the temperature in the vicinity of the discharge tray is detected, and the discharge means is controlled so that the discharge time interval of the recording medium to the discharge tray becomes longer as the detected temperature becomes higher. Therefore, it is possible to suppress a decrease in image forming efficiency while preventing toner fusion.

  According to a fifth aspect of the present invention, as in the sixth aspect of the present invention, the control means supplies the recording medium to the discharge tray when the temperature detected by the temperature detection means is higher than a predetermined temperature. The discharge means may be controlled to slow down the discharge speed of the recording medium or to temporarily stop the discharge of the recording medium to the discharge tray.

  As described above, according to the present invention, the usage amount data indicating the toner usage amount of the toner image is calculated based on the image data, and the discharge amount of the recording medium increases as the toner usage amount indicated by the calculated usage amount data increases. Since the discharging means is controlled so that the time interval for discharging to the tray becomes longer, it has an excellent effect that the decrease in image forming efficiency can be suppressed while preventing toner fusion.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[First Embodiment]
FIG. 1 shows a schematic configuration of an image forming apparatus 10 according to the present embodiment.

  As shown in FIG. 1, the image forming apparatus 10 reads an image from a document placed at a predetermined reading position, acquires image data indicating the image, image data acquired by the scanner 11, and An apparatus main body 12 that performs image forming processing using various image data such as image data acquired from the outside, and a touch panel display that displays an operation menu, a message, and the like, and a transmissive touch panel is integrally provided on the surface ( Hereinafter, it is referred to as a “display”) 14 and a discharge tray 39 for holding a sheet 31 (see also FIG. 2) as a recording medium on which an image is formed and discharged from the apparatus main body 12.

  Note that in the image forming apparatus 10 according to the present embodiment, a pressure-sensitive touch panel is used as the touch panel, and image formation is performed when the user touches the display surface of the display 14 with a fingertip (touch operation). Various operations can be instructed to the apparatus 10.

  Next, a schematic configuration inside the apparatus main body 12 will be described with reference to FIG.

  As shown in the figure, the apparatus main body 12 according to the present embodiment includes an image forming engine unit 15 that performs an image forming process on a paper 31 by an electrophotographic method, and a paper supply in which the paper 31 before image formation is stored. A paper tray 30.

  The image forming engine unit 15 according to the present embodiment is of a full color type and includes four image forming units 20Y, 20M, 20C, and 20K. These image forming units 20 are arranged at predetermined intervals along the longitudinal direction of the intermediate transfer belt 18. The intermediate transfer belt 18 is stretched around a plurality of winding rollers 19 and has an endless belt shape that is conveyed at a predetermined speed in the direction of arrow E in FIG.

  The image forming unit 20Y corresponds to yellow (Y), the image forming unit 20M corresponds to magenta (M), the image forming unit 20C corresponds to cyan (C), and the image forming unit 20K corresponds to black (K). An image of each corresponding color is formed. In FIG. 2, an alphabet (Y / M / C / K) indicating a color corresponding to the end of the code is given, but in the following, this alphabet at the end of the code is omitted unless the color is particularly distinguished. I will explain.

  The image forming unit 20 is provided with a cylindrical photosensitive drum 22 as an image carrier that is rotationally driven at a predetermined rotational speed in the direction of arrow F in FIG. Further, a charger 24 for uniformly charging the surface of the photosensitive drum 22 is disposed around each photosensitive drum 22. Charging of the photosensitive drum 22 by the charger 24 is the first stage of a series of image forming processes. Further, a light beam based on a desired image is irradiated in the axial direction of the photosensitive drum 22 uniformly charged by the charger 24 on the downstream side of the charger 24 along the rotation direction of each photosensitive drum 22. A ROS (Raster Output Scanner) 26 for forming an electrostatic latent image is disposed on the photosensitive drum 22.

  Further, around each photosensitive drum 22, a color (yellow / yellow) formed on the photosensitive drum 22 on the downstream side of the ROS 26 along the rotation direction of the photosensitive drum 22. A developing device 28 is provided for developing with magenta / cyan / black toner to form a toner image. A contact point with the intermediate transfer belt 18 is located downstream of the developing device 28, and a first transfer device 29 is disposed so as to sandwich the intermediate transfer belt 18 with the photosensitive drum 22. Yes. The first transfer device 29 has a role of transferring a toner image on the photosensitive drum 22 to the intermediate transfer belt 18 by applying a predetermined voltage.

  The toner images of different colors formed on the respective photosensitive drums 22 are respectively transferred to the intermediate transfer belt 18 so as to overlap (in the same area) on the belt surface of the intermediate transfer belt 18. As a result, a full-color toner image is formed on the intermediate transfer belt 18. In this embodiment, the toner image in which the four color toner images are transferred in a superimposed manner is referred to as a final toner image.

  A second transfer unit 34 including a pair of rollers 34A and 34B is disposed on the downstream side in the transport direction (in the direction of arrow E in FIG. 2) from the toner image transfer position from the photosensitive drum 22 of the intermediate transfer belt 18. Has been. Between the rollers 34A and 34B in the second transfer unit 34, the paper 31 taken out by the pickup roll 32 from the paper feed tray 30 and conveyed by the three sets of conveying rollers 33 is sandwiched. The final toner image is transferred from the intermediate transfer belt 18 to the paper 31 by this nipping and conveying.

  The paper 31 to which the final toner image has been transferred is conveyed to a nip portion between the rollers 36A and 36B of the fixing device 36 composed of a pressure roller 36A and a heating roller 36B that are arranged to face each other, and is subjected to heat fixing. As a result, the final toner image is fixed on the paper 31 and a desired image (color image) is formed on the paper 31. The sheet 31 on which the image is formed is discharged to a discharge tray 39 by a pair of discharge rollers 38 disposed on the downstream side of the fixing device 36 in the sheet conveyance direction.

  In the image forming apparatus 10 according to the present embodiment, the conveyance speed of the paper 31 from the paper feed tray 30 to the discharge tray 39 is set by the image forming engine control unit 54 (see FIG. 3), which will be described later, By controlling the rotation speed of a motor (not shown) that drives the conveyance roller 33, the second transfer device 34, the fixing device 36, and the paper discharge roller 38, the discharge speed of the paper 31 to the discharge tray 39 can be changed. Yes.

  Next, with reference to FIG. 3, the main configuration of the electrical system of the image forming apparatus 10 according to the present embodiment will be described.

  The image forming apparatus 10 temporarily stores a CPU (central processing unit) 40 that controls the operation of the entire apparatus, a ROM 42 that stores various programs including a discharge speed setting processing program described later, and various data. A RAM 48; a display driver 44 that controls display of various types of information on the display 14; an operation input detector 46 that detects a touch operation on the display 14; a scanner driver 50 that controls reading of an optical image by the scanner 11; And an image forming engine control unit 54 for controlling the image forming engine unit 15 described above.

  The CPU 40, RAM 48, ROM 42, display driver 44, operation input detection unit 46, scanner driver 50, and image forming engine control unit 54 are connected to each other via a system bus BUS. Therefore, the CPU 40 accesses the RAM 48 and the ROM 42, displays various information on the display 14 via the display driver 44, grasps the instruction content by the user's touch operation on the operation input detection unit 46, and scans the scanner driver 50. The control of the operation of the scanner 11 via the control and the control of the operation of the image formation engine 15 via the image formation engine control unit 54 can be respectively performed.

  Next, the overall operation flow when the image (final toner image) is formed on the paper 31 in the image forming apparatus 10 according to the present embodiment will be briefly described. Here, a case will be described in which an image is read and copied from a document placed at a predetermined reading position by the scanner 11.

  When the user places a document at a predetermined reading position of the scanner 11 and designates the number of copies via the display 14 and performs an operation to instruct the start of copying, the image forming apparatus 10 causes the scanner 11 to scan the image from the document. , The image data indicating the image is acquired and stored in the RAM 48. Then, the image forming apparatus 10 executes a discharge speed setting processing program, which will be described later, by the CPU 40, obtains the image density P of the image indicated by the image data stored in the RAM 48, and uses the image data based on the image density P. The information indicating the condition for changing the ejection speed when the paper 31 is ejected by the paper ejection roller 38 during image formation is stored in a predetermined area of the RAM 48.

  In the image forming apparatus 10, each device of the image forming engine unit 15 is controlled based on the image data stored in the RAM 48, and the paper 31 is conveyed at a predetermined conveying speed to perform image forming processing. When information indicating the discharge speed change condition is stored in the RAM 48 by the discharge speed setting processing program, a motor (not shown) is controlled so that the paper 31 is discharged under the discharge speed change condition indicated by the information, and the discharge tray 39, the discharge time interval until the paper 31 is discharged is adjusted.

  Next, with reference to FIG. 4, an operation when the discharge speed setting processing program according to the present embodiment is executed will be described. FIG. 4 is a flowchart showing the flow of the discharge speed setting processing program. The program is stored in a predetermined area of the ROM 42 in advance.

  In step 100 in the figure, the number of pixels in the region where toner is attached to the paper 31 of the image indicated by the image data (hereinafter referred to as processing target image data) for which image formation is being performed at this time is counted. The image density P is calculated from the ratio of the number of pixels in the toner adhesion area to the total number of pixels. In the next step 102, it is determined whether or not the calculated image density P is larger than a predetermined first threshold value P1 (15% in the present embodiment). If the determination is affirmative, the process proceeds to step 104. If the determination is negative, the routine proceeds to step 106.

  In step 104, as information indicating a condition for changing the discharge speed when the paper 31 is discharged by the paper discharge roller 38, a predetermined time (during the time when the paper 31 is conveyed by the paper discharge roller 38 after the fixing device 36 performs heat fixing. For example, the discharge is set in the RAM 48 so that the discharge of the paper 31 is stopped only for 2 seconds, and the discharge speed setting processing program is terminated.

  On the other hand, in step 106, it is determined whether or not the image density P calculated in step 100 is greater than a predetermined second threshold value P2 (8% in the present embodiment), and an affirmative determination is made. Shifts to step 108, and if a negative determination is made, the discharge speed setting processing program is terminated without setting information indicating the discharge speed change condition. For the first threshold value P1 and the second threshold value P2, values obtained by experiments or the like according to the type of the paper 31 and the toner characteristics can be appropriately applied.

  In step 108, as information indicating a condition for changing the discharge speed when the paper 31 is discharged by the paper discharge roller 38, after the heat fixing is performed by the fixing device 36, the discharge speed of the paper 31 by the paper discharge roller 38 is set to a predetermined value at normal time. Is set in the RAM 48 so as to be reduced by a predetermined rate (30% in the present embodiment) from the conveyance speed of the sheet, and the discharge speed setting processing program is terminated.

  In the image forming apparatus 10 according to the present embodiment, each device of the image forming engine unit 15 is controlled to transport the paper 31 at a predetermined transport speed to perform image forming processing. When the information indicating the discharge speed change condition is set in the RAM 48, the driving of a motor (not shown) is controlled via the image forming engine control unit 54 according to the information. At this time, the user has instructed the copying of a plurality of sheets of the document, and the RAM 48 has been set as information indicating the discharge speed change condition, the discharge speed slower than the normal normal speed or the stop of driving for a predetermined time. In this case, the start timing of the image forming process on the next sheet 31 is delayed so that the sheet 31 continuously formed by the next image forming process does not overlap between the fixing device 36 and the paper discharge roller 38.

  As described above, according to the ejection speed setting processing program according to the first embodiment, when the image density P of the image indicated by the image data is equal to or less than the second threshold value P2, it is difficult for the toner to be fused. By keeping the discharge speed of the paper 31 of the paper discharge roller 38 at a normal transport speed, it is possible to prevent a decrease in image forming efficiency. When the image density P is greater than the second threshold value P2 and less than or equal to the first threshold value P1, the discharge speed of the paper 31 of the paper discharge roller 38 is decreased, and the image density P is set to the first threshold value P1. If it is larger than P1, the conveyance of the paper 31 is temporarily stopped for a predetermined time to cool the toner and then discharged to the discharge tray, thereby fusing the toner when the paper 31 overlaps on the discharge tray. It is possible to prevent the deterioration of the image forming efficiency.

  As described above, in the image forming apparatus 10 according to the first embodiment, the discharge unit (here, the discharge roller 38) conveys the heat-fixed recording medium (paper 31) to the discharge tray. The discharge means and the calculation means (here, CPU 40) calculate the usage amount data indicating the toner usage amount of the toner image based on the image data, and the control means (here, the image forming engine control unit 54) is the calculation means. The discharge unit is controlled so that the discharge time interval of the recording medium to the discharge tray becomes longer as the amount of toner used indicated by the use amount data calculated by the above is increased. A reduction in formation efficiency can be suppressed.

  Further, the toner usage amount is an image density of an image indicated by the image data, and the control unit slows down the discharge speed of the recording medium to the discharge tray when the image density is higher than a predetermined density. Alternatively, since the discharge unit is controlled so as to temporarily stop discharge of the recording medium to the discharge tray, the higher the image density, the longer the discharge time interval, thereby preventing toner fusion. be able to. Further, when the image density is low, the discharge time interval does not become long, so that it is possible to suppress a decrease in image formation efficiency on the recording medium.

  In the first embodiment, the case has been described in which the discharge speed is set by comparing the image density P with a predetermined density (in the present embodiment, the first threshold value P1 and the second threshold value P2). The present invention is not limited to this. For example, a discharge speed changing condition obtained by calculating in advance a function having the image density P as an input value and a discharge speed as an output value is determined in advance. It is good also as a structure which sets the information which shows. Also in this case, the same effects as in the present embodiment can be obtained.

  In the first embodiment, the case where the discharge speed is set based on the image density P for the entire image indicated by the image data has been described. However, the present invention is not limited to this, and for example, the image The whole may be divided into a plurality of areas, and the discharge speed changing condition may be set based on the image density for each divided area. That is, when toner adheres to a partial area of the image and the image density is low in the entire image but the image density is high in the partial area, toner fusion is performed in the partial area. Therefore, when the image density is calculated by dividing into a plurality of areas, and the image density is equal to or higher than the threshold value in any of the areas, the discharge interval of the paper 31 may be increased. Also in this case, the same effects as in the present embodiment can be obtained.

  In the first embodiment, the case has been described in which the image density P is calculated from the number of pixels of the entire image and the number of pixels in the toner adhesion region to set the discharge speed of the paper 31, but the present invention is not limited to this. For example, the average density value of the entire image may be calculated from the density value for each pixel of the image indicated by the image data, and the discharge speed change condition may be set based on the average density value. . That is, when the density value is high, the amount of toner attached to the corresponding portion of the pixel of the recording medium increases. Therefore, when the average density value of the entire image is high, the discharge speed of the paper 31 is reduced or discharged. You may make it stop only for predetermined time. Further, the entire image may be divided into a plurality of areas, and the discharge speed changing condition may be set based on the average density value for each divided area. Furthermore, the density value for each pixel of the entire image may be accumulated, and the discharge interval of the paper 31 may be changed when the accumulated density value is equal to or greater than a predetermined value. Also in this case, the same effects as in the present embodiment can be obtained.

  Furthermore, in the first embodiment, the case where the discharge speed of the paper 31 is set based on the image density P has been described. However, the present invention is not limited to this, and for example, a plurality of continuous paper sheets. When the image forming process to 31 is performed, the discharge interval of the sheet 31 to the discharge tray 39 may be lengthened by delaying the timing of starting the conveyance of the sheet 31 based on the image density P. Also in this case, the same effects as in the present embodiment can be obtained.

[Second Embodiment]
In the second embodiment, an example in which a temperature sensor is provided in the vicinity of the discharge tray 39 and the discharge speed is set based on the temperature detected by the temperature sensor will be described.

  FIG. 5 shows a schematic configuration inside the apparatus main body 12 according to the second embodiment. Note that the same components in FIG. 2 as those in FIG. 2 of the first embodiment are denoted by the same reference numerals as those in FIG.

  As shown in the figure, the image forming apparatus 10 according to the second embodiment is provided with a temperature sensor 70 that outputs a signal corresponding to the temperature in the vicinity of the discharge port through which the paper 31 is discharged by the paper discharge roller 38. The only difference from the first embodiment is that the temperature in the vicinity of the discharge tray 39 can be detected.

  FIG. 6 shows the main components of the electrical system of the image forming apparatus 10 according to the second embodiment. Note that the same components in FIG. 3 as those in FIG. 3 of the first embodiment are denoted by the same reference numerals as those in FIG. 3, and description thereof is omitted.

  As shown in the figure, the image forming apparatus 10 includes an external signal input unit 72 to which a signal detected by the temperature sensor 70 is input, and the external signal input unit 72 is connected to the system bus BUS. Only the point differs from the first embodiment. Therefore, the CPU 40 can always grasp the temperature in the vicinity of the discharge tray 39 detected by the temperature sensor 70.

  Next, referring to FIG. 7, an operation when executing the discharge speed setting process according to the second embodiment will be described. Note that the same processing as in FIG. 4 of the second embodiment in FIG.

  In step 200 of the figure, the temperature T is detected in the vicinity of the discharge tray 39 by the temperature sensor 70. In the next step 202, it is determined whether or not the detected temperature T is higher than a predetermined first temperature T1 (23 ° C. in the present embodiment). If the determination is affirmative, the process proceeds to step 104. If the determination is negative, the routine proceeds to step 206.

  In step 206, it is determined whether or not the detected temperature T is higher than a predetermined second temperature T2 (15 ° C. in the present embodiment). If it is determined, the discharge speed setting processing program is terminated without setting information indicating the discharge speed change condition. For the first temperature T1 and the second temperature T2, values obtained by experiments or the like according to the type of the paper 31 and the characteristics of the toner can be appropriately applied.

  As described above, according to the discharge speed setting processing program according to the second embodiment, when the detected temperature T in the vicinity of the discharge tray 39 is low, the heat-fixed toner is immediately cooled and fused. Therefore, it is possible to prevent a decrease in image forming efficiency by keeping the discharge speed of the paper 31 of the paper discharge roller 38 at a normal transport speed. Further, when the temperature T is high, it is possible to secure a time until the heat-fixed toner is cooled by lowering the discharge speed, so that the melting of the toner when the paper 31 overlaps on the discharge tray can be secured. It is possible to prevent wearing and to suppress a decrease in image forming efficiency.

  As described above, in the image forming apparatus 10 according to the second embodiment, the discharge unit (here, the discharge roller 38) conveys the heat-fixed recording medium and discharges it to the discharge tray. The detection means (here, the temperature sensor 70) detects the temperature in the vicinity of the discharge tray, and the control means (here, the image forming engine control unit 54) detects the temperature as the temperature detected by the temperature detection means increases. Since the discharge unit is controlled so that the discharge time interval of the recording medium to the discharge tray becomes long, it is possible to prevent a decrease in image formation efficiency while preventing toner fusion.

  The control means slows down the discharge speed of the recording medium to the discharge tray when the temperature detected by the temperature detection means is higher than a predetermined temperature, or transfers the recording medium to the discharge tray. Since the discharge means is controlled so as to temporarily stop the discharge of the toner, the discharge time interval becomes longer as the temperature becomes higher, and toner fusion can be prevented. Further, when the temperature is low, the discharge time interval does not become long, so that it is possible to suppress a decrease in image forming efficiency on the recording medium.

  In the second embodiment, the case where the discharge speed changing condition is set by comparing the temperature T with a predetermined temperature (in this embodiment, the first temperature T1 and the second temperature T2) has been described. However, the present invention is not limited to this. For example, a function that uses the temperature T as an input value and a discharge speed output value is determined in advance, and the discharge speed change condition is obtained by calculation using the function. It is good also as a structure which sets the information to show. Also in this case, the same effects as in the present embodiment can be obtained.

[Third Embodiment]
In the third embodiment, an example in which the discharge speed is set based on the image density P of the image indicated by the image data and the temperature T detected by the temperature sensor provided in the vicinity of the discharge tray 39 will be described. To do. Since the configuration of the image forming apparatus 10 according to the third embodiment is the same as that of the second embodiment, description thereof is omitted here.

  Next, with reference to FIG. 8, an operation when executing the discharge speed setting processing according to the third embodiment will be described. Note that the same reference numerals as those in FIG. 4 are attached to the same processes as those in FIG. 4 of the first embodiment in FIG.

  In step 300 in the figure, the number of pixels in the region to which the toner of the image indicated by the image data is attached is counted, and the image density P is calculated from the number of pixels in the toner attachment region with respect to the total number of pixels in the image. In the next step 302, the temperature T near the discharge tray 39 is detected by the temperature sensor 70.

  In the next step 304, it is determined whether or not the detected temperature T is higher than a predetermined first temperature T1 (23 ° C. in the present embodiment). If the determination is affirmative, the process proceeds to step 306. If the determination is negative, the process proceeds to step 308.

  In the next step 306, it is determined whether or not the calculated image density P is larger than a predetermined first threshold value P1 (15% in the present embodiment). If the determination is affirmative, the process proceeds to step 104. If the determination is negative, the routine proceeds to step 108.

  On the other hand, in step 308, it is determined whether or not the calculated image density P is greater than a predetermined first threshold value P1 (15% in the present embodiment). If the determination is affirmative, the process proceeds to step 108. If the determination is negative, the discharge speed setting processing program is terminated without setting information indicating the discharge speed change condition.

  As described above, according to the discharge speed setting processing program according to the third embodiment, the discharge speed is changed according to the image density P of the image indicated by the image data and the temperature T in the vicinity of the discharge tray 39. Therefore, it is possible to secure an appropriate time until the toner on which heat fixing has been performed is cooled based on the image density P and the temperature T, and to further suppress a decrease in image forming efficiency.

  As described above, in the image forming apparatus 10 according to the third embodiment, the discharge unit (here, the discharge roller 38) conveys the recording medium on which heat fixing has been performed, and discharges it to the discharge tray. The calculating means (here, the CPU 40) calculates the usage amount data indicating the toner usage amount of the toner image based on the image data, and the temperature detecting means (here, the temperature sensor 70) is the discharge tray. The temperature of the vicinity is detected, and the control means (here, the image forming engine control unit 54) increases the discharge time interval of the recording medium to the discharge tray as the toner use amount indicated by the use amount data increases. At the same time, the discharge means is controlled so that the discharge time interval of the recording medium to the discharge tray becomes longer as the temperature detected by the temperature detection means becomes higher. While preventing toner fusion, a reduction in image formation efficiency can be suppressed.

  Further, the toner usage amount is an image density of an image indicated by the image data, and the control unit is configured to discharge the recording medium when the image density is higher than a predetermined density or when the temperature is higher than a predetermined temperature. The discharge rate to the tray is slowed, and the discharge of the recording medium to the discharge tray is temporarily stopped when the image density is higher than the predetermined density and the temperature is higher than the predetermined temperature. Since the means is controlled, the discharge speed of the recording medium is adjusted according to the image density and temperature, and the discharge time interval becomes longer, so that the image formation efficiency on the recording medium is reduced while preventing toner fusion. Can be suppressed.

  In the discharge speed setting process according to the third embodiment, after the determination based on the temperature T in the vicinity of the discharge tray 39 is performed, the determination based on the image density P of the image indicated by the image data is performed. However, the present invention is not limited to this, and the determination based on the temperature T may be performed after the determination based on the image density P is performed. Further, in the third embodiment, the case where the threshold values of the image density and the temperature are set to one is described. However, as in the first embodiment and the second embodiment, a configuration using a plurality of threshold values is used. Also good.

  In addition, the configuration of the image forming apparatus 10 described in the present embodiment (see FIGS. 1 to 3, 5, and 6) is an example, and can be appropriately changed without departing from the gist of the present invention. Needless to say.

  Further, the flow of the discharge speed setting process described in the present embodiment (see FIGS. 4, 7, and 8) is also an example, and can be changed as appropriate without departing from the gist of the present invention. Needless to say.

1 is a configuration diagram of an image forming apparatus according to a first embodiment. It is a block diagram which shows the principal part structure inside the apparatus main body which concerns on 1st Embodiment. 1 is a block diagram illustrating a main configuration of an electric system of an image forming apparatus according to a first embodiment. It is a flow which shows the flow of a process of the discharge speed setting process program which concerns on 1st Embodiment. It is a block diagram which shows the principal part structure inside the apparatus main body which concerns on 2nd Embodiment. FIG. 5 is a block diagram illustrating a main configuration of an electrical system of an image forming apparatus according to a second embodiment. It is a flow which shows the flow of a process of the discharge speed setting process program which concerns on 2nd Embodiment. It is a flow which shows the flow of a process of the discharge speed setting process program which concerns on 3rd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 38 Paper discharge roller 40 CPU
54 Image forming engine control unit 70 Temperature sensor

Claims (6)

An image forming apparatus that transfers a toner image formed on an image carrier based on image data to a recording medium and heat-fixes the toner image onto the recording medium.
A discharge means for transporting the recording medium subjected to heat fixing and discharging it to a discharge tray;
A calculation means for calculating usage amount data indicating a toner usage amount of the toner image based on the image data;
Control means for controlling the discharge means so that the discharge time interval of the recording medium to the discharge tray becomes longer as the toner use amount indicated by the use amount data calculated by the calculation means increases;
An image forming apparatus. The toner usage amount is the image density of the image indicated by the image data,
The control means slows the discharge speed of the recording medium to the discharge tray or temporarily stops discharging the recording medium to the discharge tray when the image density is higher than a predetermined density. The image forming apparatus according to claim 1, wherein the discharge unit is controlled as follows. Temperature detecting means for detecting the temperature in the vicinity of the discharge tray,
The control means has a longer discharge time interval for the recording medium to the discharge tray as the toner usage amount indicated by the usage data increases, and the higher the temperature detected by the temperature detection means, the higher the temperature of the recording medium. The image forming apparatus according to claim 1, wherein the discharge unit is controlled so that a discharge time interval of the discharge to the discharge tray becomes longer. The toner usage amount is the image density of the image indicated by the image data,
The control means slows the discharge speed of the recording medium to the discharge tray when the image density is higher than a predetermined density or the temperature is higher than a predetermined temperature, and the image density is higher than the predetermined density and the The image forming apparatus according to claim 3, wherein when the temperature is higher than the predetermined temperature, the discharge unit is controlled to temporarily stop discharge of the recording medium to the discharge tray. An image forming apparatus that transfers a toner image formed on an image carrier based on image data to a recording medium and heat-fixes the toner image onto the recording medium.
A discharge means for transporting the recording medium subjected to heat fixing and discharging it to a discharge tray;
Temperature detecting means for detecting the temperature in the vicinity of the discharge tray;
Control means for controlling the discharge means so that the discharge time interval of the recording medium to the discharge tray becomes longer as the temperature detected by the temperature detection means becomes higher;
An image forming apparatus. The control means slows the discharge speed of the recording medium to the discharge tray or discharges the recording medium to the discharge tray when the temperature detected by the temperature detection means is higher than a predetermined temperature. The image forming apparatus according to claim 5, wherein the discharge unit is controlled to temporarily stop the operation.

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