JP2013174929A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that facilitates a recovery process for the apparatus even if conveyance abnormality of a recording sheet occurs, and can achieve a series of printing operations in a short period of time as a whole.SOLUTION: An image forming apparatus comprises: recording medium feeding means for feeding a recording medium to a prescribed conveyance path; conveyance means for conveying the recording medium, fed from the recording medium feeding means, on the conveyance path; conveyance status detection means, disposed on the conveyance path, for detecting a conveyance status of the recording medium; control means for controlling operations of the recording medium feeding means, the conveyance means, and the conveyance status detection means; and storage means for storing the recording medium. The control means controls feeding of the recording medium with the recording medium feeding means and conveyance of the recording medium with the conveyance means on the basis of detection result by the conveyance status detection means, thereby discharges the recording medium existing in the image forming apparatus to the storage means.

Description

  According to the present invention, even when a recording paper conveyance abnormality occurs, the printing paper can be transported in a short time by continuing the conveyance of the recording paper without stopping the apparatus and discharging the recording paper remaining in the apparatus. The present invention relates to an image forming apparatus.

  Conventionally, for example, a copying machine having an annular paper conveyance path for double-sided recording has been known. In such a copying machine, when a conveyance abnormality occurs on the paper conveyance path, it is necessary to temporarily stop the apparatus and remove all the recording sheets circulating in the image forming apparatus.

  In the copying machine described in Patent Document 1, a recording sheet on which double-side recording has been performed is specified from among the recording sheets remaining in the apparatus when a jam occurs, and paper is discharged when the recording sheet is not jammed paper. ing. That is, in the copying machine described in Patent Document 1, in a copying machine that performs double-sided recording while circulating a plurality of recording papers on a transport path, when a paper jam occurs in the transport path, the recording paper discharge destination information The recording paper to be discharged is determined on the basis of (information indicating whether it should be discharged out of the apparatus or transported to the reverse path) and the positional information on the conveyance path of the recording paper, and the paper jam information of the recording paper If it is determined that no paper jam has occurred, the paper is discharged out of the apparatus. This prevents the use of printed effective recording paper.

  In the recording apparatus described in Patent Document 2, the posture of the recording paper, such as bending or skew, is detected on the conveyance path, and when it is out of the specified range, the direction is different from the original paper supply / discharge direction. By guiding and removing it from the conveyance path, the occurrence of jam is reduced.

  However, Patent Document 1 discloses an effective recording that is not an object of jamming even when a jam occurs for the purpose of preventing the use of a valid recording sheet that has been recorded normally. It only describes discharging paper.

  Further, Patent Document 2 merely describes that a recording sheet that has been bent or skewed is immediately removed from the conveyance path for the purpose of preventing the occurrence of a jam in the conveyance path of the recording sheet.

  On the other hand, for example, a large-scale user requesting printing of about 90 sheets per minute is not limited to a high printing speed, but can also perform a recovery process in the case where the recording paper is transported abnormally and the apparatus is stopped. There is a demand to do in a short time.

  Therefore, even if a recording paper conveyance abnormality is detected, the present invention continues the conveyance as if the recording paper was normally conveyed without stopping the apparatus if it is a minor conveyance abnormality. An object of the present invention is to provide an image forming apparatus that discharges the recording paper remaining in the apparatus to facilitate the recovery process of the apparatus and realize a series of printing operations in a short time as a whole.

  In order to solve the above-described problems, an image forming apparatus according to the present invention includes a recording medium supply unit that supplies a recording medium to a predetermined conveyance path, and a recording medium supplied from the recording medium supply unit on the conveyance path. Conveying means, conveying state detecting means for detecting the conveying state of the recording medium disposed in the conveying path, control means for controlling the operation of the recording medium supply means, the conveying means, and the conveying state detecting means, A storage unit configured to store a recording medium, and the control unit stops the supply of the recording medium by the recording medium supply unit and detects the delay of conveyance of the recording medium by the conveyance state detection unit; Control is performed so as to continue the conveyance of the recording medium for a predetermined period, and the recording medium existing in the image forming apparatus is discharged to the storage unit.

  According to the present invention, when a slight conveyance delay occurs, the recording medium in the image forming apparatus is discharged to the predetermined storage unit without stopping the conveyance unit. It is possible to easily recover from an abnormal state, and a series of printing operations can be realized in a short time as a whole.

1 is an image forming apparatus (laser printer) as an example to which the present invention is applied. 1 is an image forming apparatus to which the present invention is applied. FIG. 3 is a functional block diagram illustrating a relationship among each unit of the image forming apparatus according to the exemplary embodiment. It is the figure which cut out and showed a part of conveyance path in order to explain unreasonableness. It is a timing chart for demonstrating the mode of detection of the recording paper by sensor S1, S2. 6 is a flowchart illustrating processing based on a recording sheet conveyance state when failure has occurred. It is the figure which cut out and showed typically a part of conveyance path in order to demonstrate retention. It is a timing chart for demonstrating the mode of detection of the recording paper by sensor S3. It is a flowchart which shows the process based on the conveyance condition of the recording paper at the time of stagnating. It is a flowchart for demonstrating operation | movement after detecting conveyance abnormality. It is a timing chart for demonstrating operation | movement after detecting conveyance abnormality.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows an image forming apparatus (laser printer) as an example to which the present invention is applied, in which an image forming apparatus main body (1) and a duplex printing apparatus (2) are integrally configured. In FIG. 1, 1A to 1C are paper feed trays, 2A to 2C are paper feed rollers, 3 is a registration roller, 4 is a photosensitive member, 5 is a charging charger, 6 is an optical unit, 7 is a developing unit, 8 is a transfer charger, 9 is a fixing device, 10 is a paper discharge tray, 11 is a paper discharge roller, 12 is a switching claw, 13 is a reverse roller, 14 is a reverse claw, 15 is a paper feed roller, and 16 is a main motor.

  In the image forming apparatus shown in FIG. 1, image formation is performed by a normal electrophotographic process. That is, the recording paper fed from the paper feed trays 1A, 1B, and 1C is conveyed to the photoconductor 4 by the paper feed rollers 2A, 2B, and 2C and the registration roller 3, and is charged with the charging charger 5, the optical unit 6, and the developing unit. 7. Each image forming process such as charging, exposure, development, transfer, and fixing is performed by the transfer charger 8, the fixing device 9, and the like, and image formation is performed. Each means of the above image forming process is driven by the main motor 16. The recording paper printed on one side after exiting the fixing device 9 is discharged as it is to the paper discharge tray 10 or is conveyed to the double-sided printing device (2) for backside printing. Whether the paper is discharged to the paper discharge tray 10 or conveyed to the double-sided printing apparatus (2) is selected by switching control of the paper discharge roller 11 and the switching claw 12 based on a printing instruction by the user. When transported to the duplex printing apparatus (2), the recording paper is transported to the transport path a on the reversing roller 13 side by the control of the switching claw 12, and then the reversing roller 13 and reversing claw 14 are controlled to control the transport path b side. The recording papers are switched back and conveyed one by one. That is, the side printed on one side of the recording paper is reversed, and the recording paper is conveyed to the registration roller 3 by the paper feed roller 15 in a state where the other side to be printed next becomes the recording side.

  In this image forming apparatus, when a large number of sheets are printed at a time, recording sheets are sequentially supplied from the large-capacity paper feed tray 1C. For example, a plurality of recording sheets (3 to 4 sheets) are circulated through the entire conveyance path at the same time. Will be transported. In this case, the first, second, and third recording sheets are sequentially supplied from the sheet feeding tray 1C into the image forming apparatus main body (1) for surface printing, and image formation is performed. After the front surface of the eye is printed, the first back side of the sheet that has been re-feeded via the duplex printing device (2) is printed, and then the newly fed fourth recording sheet Surface printing is performed. That is, as the printing order in this case, the first sheet, the second sheet, the third sheet, the first sheet, the fourth sheet, the second sheet, and so on are sequentially printed. Become.

  Incidentally, in such an image forming apparatus, it is inevitable that a recording paper conveyance abnormality occurs. In addition to the so-called jam, in which the recording paper is bent in a bellows shape or wound around a roller, the recording paper does not reach the predetermined transport position in the image forming apparatus at a predetermined timing, or is not transported. There is a so-called stay in which the recording paper stays at a predetermined transport position in the image forming apparatus even when the predetermined timing is reached. When a jam occurs, the device must be stopped immediately. However, in the case of unreached or staying, as long as the period of unreached or staying is within a predetermined range ( In other words, if the recording paper is transported and detected within a predetermined period of time after reaching the unachieved state or staying state, and the unachieved state or staying state is resolved), the device immediately fails at that point. Since it does not occur, it is not always necessary to stop the apparatus immediately and remove the recording paper manually. Such a situation can be regarded as a minor conveyance abnormality.

  FIG. 2 shows an image forming apparatus to which the present invention is applied. In FIG. 2, 101 and 102 are paper feed trays, 103 and 104 are paper feed rollers, 105 is a reverse roller, 106 is a transport roller, 107 is a transfer roller, 108 is a fixing roller, 109 is a transport roller, 110 is a flip roller, 111 is a transfer roller, 112 is a transfer belt, 113 to 117 are sensors, 118 is a paper discharge tray, 119 is a switching claw, 120 is a paper discharge roller, 121 is a paper discharge tray, 122 and 123 are switching claws, and 124 and 125 are It is a sensor. As a path for transporting the recording paper, A is a transport path, B is a single-sided print path, C is a double-sided print path, D is a reverse path, and E is a paper discharge path. Furthermore, in order to clarify the characteristics of the present invention, the present embodiment shows a state in which a large number of recording sheets are circulated inside the image forming apparatus. That is, FIG. 2 shows a state where seven recording papers are circulated in the paths A to E. For example, F or G is the recording paper.

  In FIG. 2, the recording paper is supplied from the paper feed tray 101 or 102. The fed recording paper is conveyed in the counterclockwise direction on the conveyance path A through the paper supply roller 103 or 104 or the like. Here, the conveyance path A is an annular path that is subjected to front surface printing in the image forming process after the recording paper is supplied and then reversed by the reversing roller 105 to reach the image forming apparatus again for back side printing. Shall point to. That is, it is an annular path that reaches the conveyance roller 106 again through the respective rollers such as the conveyance roller 106, the transfer roller 107, the fixing roller 108, the conveyance roller 109, the flip roller 110, the reverse roller 105, and the conveyance roller 111. An image is formed on the recording paper on the conveyance path A. The image forming system is equivalent to the image forming apparatus described with reference to FIG. 1, for example, and the image forming apparatus described with reference to FIG. Similarly, a general process such as charging, exposure, development, transfer, and fixing is performed. In FIG. 2, illustration of charging, exposure, and development devices is omitted. In FIG. 2, a transfer roller 107 constitutes a part of the transfer device, and transfers a visible image formed on the transfer belt 112 to a recording sheet by a developing device (not shown). Further, the fixing roller 108 constitutes a part of the fixing device.

  On the conveyance path A, a plurality of sensors 113 to 117 are provided for detecting the conveyance state of the recording paper. By these sensors, it is detected that the recording paper has not reached or stayed. That is, for example, the transfer timing sensor 116 is used to measure the transfer timing with the transfer device in the next process, but the leading edge of the recording paper to be transferred is not detected by the sensor 116 at a predetermined timing. It is determined that the recording paper has not been reached. This determination includes, for example, the timing at which the other sensor 115 detects the leading edge of the recording paper, the timing at which the recording paper is fed from the paper feed roller 103, and the timing at which the transfer timing sensor 116 detects the leading edge of the recording paper. Is performed by managing the period. Further, after the leading edge of the recording paper is detected, if the trailing edge of the recording paper is not detected even at a predetermined timing (that is, the recording paper normally passes through the sensor 116 and the sensor 116 is If it should be detected that the presence of recording paper is still detected at that timing), it is determined that the recording paper stays.

  In this embodiment, when it is determined that the recording paper has not reached or stayed, the supply of the recording paper from the paper feed trays 101 and 102 is stopped, and the conveyance system rollers (for example, rollers 105 to 111) are stopped. Etc.) is controlled so as to continue for a predetermined period, and all the recording sheets on the transport path A are discharged to the discharge tray 118. Details of unreached and stayed and details of the operation of the device when unreached and stayed occur will be described later. Note that the installation location, shape, and the like of the tray 118 for discharging the recording paper are not limited to those described using this embodiment, and can be appropriately configured without departing from the spirit of the present invention.

  The recording paper that has been fixed by the fixing device 108 can then take two paths, a single-sided printing path B and a double-sided printing path C. Here, the single-sided printing path B indicates a path from the conveying roller 109 to the paper discharge roller 120, and the double-sided printing path C is switched back by the reversing roller 105 from the conveying roller 109 through the flip roller 110 and the reversing roller 105. The path to the conveyance roller 111 is indicated. Switching between the single-sided printing path B and the double-sided printing path C is performed by controlling the switching claw 119. When single-sided printing is instructed, the recording paper is discharged to the paper discharge tray 121 by the paper discharge roller 120 via the single-sided printing path B. Even in the case of single-sided printing, in the case of reverse discharge for the convenience of the user who takes out the discharged paper, the reverse path D (from the transport roller 109 to the reverse roller 105 via the flip roller 110) Is routed back by the reversing roller 105, and is again discharged to the paper discharge tray 121 via the flip roller 110. On the other hand, when double-sided printing is instructed, the recording paper is transported in the reverse path D → paper switchback by the reverse roller 105 → double-sided print path C, and is directed toward the image forming apparatus for backside printing. Will be fed again. Whether the sheet switched back by the reversing roller 105 returns to the flip roller 110 side or is guided to the duplex printing path C side is switched by controlling the switching claw 122.

  A paper discharge tray 118 provided below the reverse roller 105 is opened so as to cover at least a discharge port from the paper discharge path E and a discharge port from the reverse path D passing through the reverse roller 105. The paper discharge path E is a path from the flip roller 110 to the paper discharge tray 118 formed by controlling the switching claw 123. With this configuration, it is possible to discharge from the discharge path E or to discharge from the reverse path D. When paper is discharged from the paper discharge path E, the recording paper guided to the paper discharge path E by the switching claw 123 is naturally dropped and stored in the paper discharge tray 118. Further, without providing the switching claw 123 and the paper discharge path E, the recording paper may be passed through the reversing roller 105 and guided from the reverse path D to the paper discharge tray 118 as it is. In this case, the reverse path D can also be used as the paper discharge path, and the reverse roller 105 is controlled so that the recording paper is stored in the paper discharge tray 118 by the driving force of the reverse roller 105.

  Note that a recording paper detection sensor 124 is provided in the paper discharge tray 118. This is for detecting whether or not recording paper is present in the paper discharge tray 118. That is, the recording paper detection sensor 124 monitors whether there is recording paper, and if it detects the presence of recording paper, notifies the user of that fact. As a notification method, for example, a warning lamp may be turned on, or a message to that effect may be displayed on the display panel of the image forming apparatus. For example, when the recording paper is not removed and remains on the paper discharge tray 118, the error state of the image forming apparatus may not be released and the usable state may not be restored.

  FIG. 3 is a functional block diagram showing the relationship between the units of the image forming apparatus according to the present embodiment. Specifically, the detection unit 201 is, for example, sensors 113 to 117, and detects the conveyance state of the recording paper. Specifically, the control unit 202 is, for example, a CPU (not shown), and controls the operation of the detection unit 201, and controls the operation of the paper feeding unit 203, the conveyance unit 204, and the image forming unit 205 described below. Specifically, the paper supply unit 203 is, for example, a paper supply tray 101 or a paper supply roller 103, and supplies recording paper for image formation. Specifically, the transport unit 204 is, for example, a transport roller 106, a transfer roller 107, and the like, and transports the recording paper in order to execute an image forming process on the recording paper in the image forming apparatus to perform printing and discharge. Specifically, the image forming unit 205 is, for example, the transfer belt 112, the fixing roller 108, and the like, and executes an image forming process on the recording paper.

  With the above configuration, the recording paper supplied from the paper feed trays 101 and 102 is subjected to the image forming process while being transported on the transport path A by the transport roller 106, the transfer roller 107, and the like, and the printed recording paper is discharged. The paper is discharged to the paper tray 121. When double-sided printing is instructed, the recording paper is circulated through the conveyance path A via the double-sided printing path C by controlling the switching claws 119, 122, etc., and is discharged after the reverse side printing is performed. Is done.

  Next, what kind of situation is unachieved and the operation when unachieved will be described in detail with reference to FIGS.

  FIG. 4 is a diagram schematically showing a part of the transport path A, in which sensors S1 and S2 are arranged on the transport path X, and the recording paper transported along the transport path X is the sensor S1, Assume that the detection is sequentially performed in S2. In contrast to FIG. 2, the transport path X corresponds to the transport path A, and the sensors S1 and S2 correspond to, for example, the sensors 115 and 116, respectively.

  When the distance between the sensor S1 and the sensor S2 is L (mm) and the conveyance speed of the recording paper is V (mm / second), the leading edge of the recording paper passes through the sensor S1 and then passes through the sensor S2. Time required (the time from when the sensor S1 detects the leading edge of the recording paper to when the sensor S2 detects the leading edge of the recording paper, and after the sensor S1 detects the presence of the recording paper, the sensor S2 detects the presence of the recording paper. Time) is L / V (seconds). In the apparatus, a time T1 = L / V (seconds) from the time when the leading edge of the recording paper passes the sensor S1 to the time when the leading edge of the recording paper passes the sensor S2 is set in advance (in the following description, this is defined as a predetermined transport timing). Therefore, by comparing this time T1 with the timing t1 when the recording paper is actually conveyed and detected by the sensor S2, (1) during normal conveyance, (2) when a slight conveyance delay occurs, ( 3) There are three modes when a large conveyance delay occurs.

  FIG. 5 is a timing chart for explaining the state of detection of the recording paper by the sensors S1 and S2, where (0) a normal conveyance timing, (1) normal conveyance, and (2) a slight conveyance delay occurred. In this case, (3) a case where a large conveyance delay occurs is shown in comparison. FIG. 6 is a flowchart showing subsequent processing for each of the three modes (1) to (3). With reference to FIG. 5 and FIG. 6, a method of controlling the apparatus when the failure has occurred will be described. Note that the detection of the recording paper and the control of the apparatus based thereon are realized by a central processing unit (CPU) mounted on the image forming apparatus.

(0) Specified transport timing When the recording paper reaches the sensor S1 and the sensor S1 detects the leading edge of the recording paper, the detection signal S1 is changed from S1 = 0 (no paper) to S1 = 1 as shown in FIG. It changes to (with paper). Similarly, when the recording paper reaches the sensor S2 after passing through the sensor S1, the detection signal S2 changes from S2 = 0 (no paper) to S2 = 1 (paper exists). In both S1 and S2, when the trailing edge of the recording paper passes through each sensor, the detection signal changes to 0 (no paper). As described above, the time from the rise of the signal S1 to the rise of the signal S2 is T1 = L / V. FIG. 5 also shows delay times α and β from the rise of the signal S2.

(1) During normal conveyance As shown in FIG. 5, when the detection timing t1 of the recording paper leading edge by the sensor S2 is delayed within α hours from T1 (when T1 <t1 ≦ T1 + α), the CPU It is determined that the recording paper is normally conveyed, and the apparatus is controlled to execute a predetermined function (Yes in S11 in FIG. 6 → S12). Specifically, α is, for example, 60 ms (milliseconds), and when T1 <t1 ≦ T1 + 60 ms, the CPU determines that the recording paper is normally conveyed, and executes the transfer function, for example. Control. Since the recording paper is transported by friction, when it deviates from the above timing T1, it is normally in the direction of transport delay. However, in actuality, when T1−α ≦ t1 ≦ T1 + α, normal transport is performed. It is good to judge that it is done.

(2) When a slight conveyance delay occurs As shown in FIG. 5, when the detection timing t1 of the leading edge of the recording sheet by the sensor S2 is a delay greater than α hours and within β hours (T1 + α <t1 ≦ In the case of T1 + β), the CPU determines that a slight conveyance delay has occurred in the recording paper, stops supplying the recording paper from the paper feed tray 101 or 102, and executes the predetermined function described above. In step S13 in FIG. 6, the conveyance operation for discharging the recording paper is performed. Such a transport operation for discharging the recording paper inside the apparatus is referred to as jam clear transport. Specifically, β is, for example, 120 ms, and when T1 + 60 ms <t1 ≦ T1 + 120 ms, the CPU determines that a recording paper conveyance abnormality (a slight conveyance delay) has occurred, and the subsequent transfer function is Without carrying out, the conveying operation is continued so as to discharge all recording paper remaining in the apparatus. The reason for operating in this way is that even if a conveyance abnormality occurs inside the device, if it is a slight conveyance abnormality, it is unlikely that a jam will occur later, so recording without stopping the device This is to shorten the time until the apparatus is recovered by discharging the paper.

(3) When a large transport delay occurs As shown in FIG. 5, when the detection timing t1 of the recording paper leading edge by the sensor S2 is delayed more than β time from T1 (when T1 + β <t1), the CPU It is determined that a large conveyance delay has occurred in the recording paper, and control is performed to immediately stop the apparatus (No in S13 in FIG. 6, S15). Specifically, for example, β is 120 ms, and if T1 + 120 ms <t1, the CPU determines that a recording paper conveyance abnormality (large conveyance delay) has occurred and does not execute the subsequent transfer function. Of course, the transport system also stops. The reason for this operation is that when a large conveyance abnormality occurs inside the apparatus, the recording sheet collides with the subsequent recording sheet, and the conveyance itself cannot be performed (such a situation). If this happens, there is a very high possibility of jamming if you continue to carry it). Therefore, although β = 120 ms is exemplified here, the setting method for the β time is based on whether or not the recording paper causing the conveyance abnormality collides with the recording paper to be conveyed next, and the collision It is sufficient to set within the range not to be. The case where β is infinitely large, that is, the case where the sensor S2 cannot detect the leading edge of the recording paper is also included.
When such a large conveyance delay occurs, the apparatus is stopped, but it is also possible to construct a system that returns to a state where a slight conveyance delay occurs. Normally, when the detection timing t1 is delayed more than β time from T1, it is determined that a large conveyance delay has occurred. However, when the delay time is close to β time, control to increase the rotation speed of the conveyance roller is performed. If it carries out, it will become possible to return to the state of “(2) When a slight conveyance delay occurs” in the sensors after the sensor that has detected that a large conveyance delay has occurred. That is, if the sensor S2 detects a conveyance delay of (β + Δβ) time with respect to the specified detection timing T1, the delay is eliminated to less than β time by controlling the rotation speed of the conveyance roller that conveys the recording paper. Then, it is possible to return to the state of “(2) When a slight conveyance delay occurs”, so that it is possible to execute the jam clear conveyance operation without stopping the apparatus. The Δβ time can be set as appropriate depending on the characteristics of the transport roller, but if the transport delay exceeds the (β + Δβ) time, it cannot be returned to the jam clear transport operation. In this case, a large transport delay occurs. Judgment is made and the apparatus is stopped.

  By the way, whether or not the recording papers sequentially and sequentially conveyed collide with each other depends on the relative positional relationship between the recording paper conveyed first and the recording paper conveyed next. In other words, for example, even if the previously transported recording paper is delayed by 130 ms with respect to the preset detection timing, the next transported recording paper is also delayed by 100 ms. In this case, the recording paper conveyed first is only delayed by 30 ms relative to the recording paper conveyed next, and in this case, the two do not collide. Therefore, assuming such a situation, correction of detection timing or conveyance control according to the detection situation of each recording sheet by each sensor is performed, and when it is determined that the preceding and following recording sheets do not collide, “(2) It is more preferable to perform the control as described in “When a slight conveyance delay occurs”.

  If it is allowed to reduce the productivity, a method of reducing the printing speed can be considered as a method for preventing the apparatus from being stopped. For example, when using special recording paper that is difficult to transport, such as coated paper, abnormal conveyance is more likely to occur than when recording paper that is easy to transport is handled. For this reason, by changing the setting of the rotation speed of the paper feed roller and the conveyance roller to set the print speed to be reduced from 90 sheets to 80 sheets per minute, for example, the number of recording sheets circulating in the apparatus is reduced, thereby reducing the recording speed. It is possible to widen the range in which the jam clear conveyance where the paper is hard to collide can be executed. In this case, specifically, the values of the α time and β time described above are adjusted.

  As described above, the unachieved state has been described, but the retention can be considered similarly. The unachieved state is determined based on the detection timing of the leading edge of the recording paper, but in the case of staying, it may be determined based on the detection timing of the leading edge of the recording paper and the trailing edge of the recording paper. Hereinafter, what kind of situation is staying and the operation when staying occurs will be described.

  FIG. 7 is a diagram schematically showing a part of the transport path A, in which a sensor S3 is arranged on the transport path Y, and the recording paper transported along the transport path Y is sequentially detected by the sensor S3. Shall be. In contrast to FIG. 2, the transport path Y corresponds to the transport path A, and the sensor S3 corresponds to the sensor 116, for example. Here, when the size of the recording paper in the conveyance direction is D (mm) and the conveyance speed of the recording paper is V (mm / second), the trailing edge of the recording paper after the leading edge of the recording paper passes the sensor S3. Required for the sensor to pass through the sensor S3 (the time from when the sensor S3 detects the leading edge of the recording paper until the trailing edge is detected. The sensor S3 detects the presence of the recording paper and then the sensor S3 detects the recording paper. The time until the absence is detected is D / V (seconds). Since the time T2 = D / V (seconds) from the time when the leading edge of the recording paper passes the sensor S3 to the time when the trailing edge passes the sensor S3 is set in the apparatus in advance, this time T2 and the recording paper are actually set. Is compared with the timing t2 when the trailing edge of the recording paper is detected by the sensor S3, and (1) normal conveyance and (2) a slight conveyance delay occur as in the case of non-delivery detection. 3) There are three modes when a large conveyance delay occurs.

  FIG. 8 is a timing chart for explaining the state of detection of the recording paper by the sensor S3, where (0) a normal conveyance timing, (1) normal conveyance, and (2) a slight conveyance delay occurs. (3) A case where a large conveyance delay occurs is shown in comparison. FIG. 9 is a flowchart showing subsequent processing for each of the three modes described above. With reference to FIGS. 8 and 9, a description will be given of how to control the apparatus when a stay based on the detection result of the recording paper occurs.

(0) Specified transport timing When the recording paper reaches the sensor S3 and the sensor S3 detects the leading edge of the recording paper, the detection signal S3 is changed from S3 = 0 (no paper) to S3 = 1 as shown in FIG. It changes to (with paper). When the recording paper is conveyed and its trailing edge passes the sensor S3, the detection signal S3 changes to S3 = 0 (no paper). As described above, the time from the rising edge to the falling edge of the signal S3 is T2 = D / V. FIG. 8 also shows delay times γ and δ from the falling edge of the signal S3.

(1) During normal conveyance As shown in FIG. 8, when the detection timing t2 of the trailing edge of the recording sheet by the sensor S3 is delayed within γ hours from T2 (when T2 <t2 ≦ T2 + γ), the CPU Determines that the recording paper is normally conveyed, and controls the apparatus to execute a predetermined function (Yes in S21 in FIG. 9 → S22). Specifically, γ is, for example, 60 ms (milliseconds), and when T2 <t2 ≦ T2 + 60 ms, the CPU determines that the recording sheet is normally conveyed, and executes the transfer function, for example. Control. FIG. 8 shows a state in which the sensor S3 detects the trailing edge of the recording paper with a delay within γ time from T2.

(2) When a slight conveyance delay occurs As shown in FIG. 8, when the detection timing t2 of the trailing edge of the recording sheet by the sensor S3 is a delay greater than γ time and within δ time from T2 (T2 + γ < In the case of t2 ≦ T2 + δ), the CPU determines that a slight conveyance delay has occurred in the recording paper, stops supplying the recording paper from the paper feed tray 101 or 102, and performs the predetermined function described above. Without the execution, a jam clear conveying operation for discharging the recording paper is executed (Yes in S23 in FIG. 9 → S24). Specifically, for example, δ is 120 ms, and if T2 + 60 ms <t2 ≦ T2 + 120 ms, the CPU determines that a recording paper conveyance abnormality (slight conveyance delay) has occurred, and the subsequent transfer function is Without carrying out, the conveying operation is continued so as to discharge all recording paper remaining in the apparatus. The reason for operating in this way is the same as that described for unachieved.
FIG. 8 shows a state in which the sensor S3 detects the trailing edge of the recording paper with a delay greater than γ time and within δ time from T2.

(3) When a large conveyance delay occurs As shown in FIG. 8, when the detection timing t2 of the trailing edge of the recording sheet by the sensor S3 is delayed more than δ time from T2 (when T2 + δ <t2), the CPU Determines that a large conveyance delay has occurred in the recording paper, and immediately controls to stop the apparatus (No in step S23 in FIG. 9 → S25). Specifically, for example, δ is 120 ms, and when T2 + 120 ms <t2, the CPU determines that a recording paper conveyance abnormality (large conveyance delay) has occurred, and does not execute the subsequent transfer function. Of course, the operation of the transport system is also stopped. The reason for operating in this way is the same as that described for unachieved. The δ time may be set as appropriate within a range where no collision occurs, based on whether or not the recording sheet causing the conveyance abnormality collides with the subsequent recording sheet.
FIG. 8 shows how the sensor S3 detects the trailing edge of the recording paper with a delay greater than δ time from T2. The case where δ is infinitely large, that is, the case where the sensor S3 cannot detect the trailing edge of the recording paper is also included.
When a large conveyance delay occurs, it is possible to return to a state where a slight conveyance delay has occurred by controlling the rotation speed of the conveyance roller, as described above. Further, whether or not the recording papers that are sequentially conveyed before and after collide with each other is used as a criterion, that is, based on the relative positional relationship between the recording paper that is conveyed first and the recording paper that is conveyed next. As described above, it is more suitable to correct the detection timing and carry control, and to make it difficult to cause a conveyance abnormality by adjusting the γ time and δ time. .

  As described above, the detection of unachieved and staying and the operation corresponding thereto are executed, and the subject of the present invention is particularly “(2) When a slight conveyance delay occurs” described above. As described above, when it is determined that a slight transport delay has occurred, a jam clear transport operation is executed, and all the recording sheets in the image forming apparatus are accommodated in the paper discharge tray by the jam clear transport operation. Therefore, the conveying system rollers are driven for the time required for this purpose. For example, when an LCT (Large Scale External Paper Feed Tray) is connected to the image forming apparatus as an option, there is a “slight conveyance delay” on the recording paper in the image forming apparatus immediately after feeding from the LCT. Assuming the case where it occurs, it is only necessary to drive the rollers of the transport system for a period of time until the recording paper fed from the LCT is discharged to the paper discharge tray (until it reaches). In this case, in the current technical level, for example, it is only necessary to drive the rollers of the transport system for 4 to 5 seconds.

  Next, the overall operation of the image forming apparatus to which the jam clear conveyance operation is applied will be described with reference to FIGS.

  FIGS. 10 and 11 show the operations from when the transfer timing sensor 116 detects a conveyance error such as recording paper not reaching or staying until the remaining recording paper in the image forming apparatus is stored in the paper discharge tray 118. It is the flowchart and timing chart for demonstrating. Here, the case where the transfer timing sensor 116 detects unsatisfied or staying will be described, but other sensors 113 to 115, 117, etc. other than the transfer timing sensor 116 have a function of detecting unsatisfied and staying of the recording paper, The arrangement, the number of sensors, and the like can be selected as appropriate, and the present invention is not limited thereby.

  In FIG. 10, it is assumed that, for example, the transfer timing sensor 116 detects a slight conveyance abnormality (not reached) from the state of normal operation (S31 in FIG. 10) (Yes in S32, FIG. 11A). That is, it is assumed that the conveyance of the recording paper is delayed for some reason, the leading edge of the recording paper does not reach the transfer timing sensor 116 at a timing that should originally arrive, and the failure has occurred. At this time, based on a signal from the transfer timing sensor 116 serving as the detection unit 201, if the apparatus is a conventional apparatus, it is determined that a conveyance abnormality has occurred, and the apparatus is immediately stopped. On the other hand, in the image forming apparatus of the present invention, the control unit 202 stops the paper feeding unit 203 and prohibits new recording paper from being supplied to the transport path A (S33, FIG. 11). (C)) On the other hand, control to continue driving the conveying means 204 is performed (S34, FIG. 11B).

  By the way, when the transfer timing sensor 116 detects non-achievement, there may be a case where one of a plurality of recording sheets remaining in the apparatus is passing near the switching claw 123. In such a case, it is only necessary to wait for the recording paper to pass through the switching claw 123 using the sensor 125 and to control the switching claw 123 so as to switch the conveyance direction of the recording paper to the discharge path E side. . That is, the control unit 202 monitors the signal from the sensor 125 due to the signal indicating the conveyance abnormality from the transfer timing sensor 116, and when the sensor 125 detects the absence of paper (Y in S35, FIG. 11 (d)). The control means 202 controls to switch the switching claw 123 (S36), and switches the recording paper conveyance direction from the reverse path D side to the paper discharge path E side when the image forming apparatus is operating normally. By performing such control, the recording paper that has passed through the flip roller 110 is sequentially sent to the conveyance path E side, and then naturally falls on the paper discharge tray 118 and stored. Then, by monitoring the various sensors 113 to 117, 125, etc. on the transport path A and determining that there is no recording paper on the transport path A (Y in S37), the control unit 202 transports the switching claw 123 again. Switching control is performed so that the direction is on the reverse path D side (S38, FIG. 11E), and the driving of the conveying unit 204 is stopped (S39, FIG. 11B). Here, instead of determining whether or not there is no recording paper on the transport path A by various sensors, it may be controlled to stop driving the transport unit 204 after a certain time has elapsed after the start of the jam clear transport operation. Absent.

  Further, the user is notified that the recording paper is stored in the paper discharge tray 118 by a lamp (not shown) or the like. This notification may be made visually using a warning lamp (not shown) or an operation display panel of the image forming apparatus, or may be made audible, for example, by making a warning sound. This is performed based on a detection signal from the installed recording paper detection sensor 124.

  If no conveyance abnormality has occurred (N in S32), naturally, the driving of the conveying unit 204 is continued (S40), and after the print job is completed (Y in S41), the conveying unit 204 is driven. Is stopped (S39).

  By the way, in the above control, even when a slight conveyance delay occurs, that is, when there is a possibility of causing a jam after that, the recording paper is discharged immediately without stopping the apparatus. On the other hand, the conveyance system is continuously driven without judging whether or not an accordion-like jam has actually occurred. Therefore, for example, in the example in which the upper LCT is connected, there is a possibility that damage will be magnified by continuing to drive the rollers of the conveyance system for 4 to 5 seconds even after the non-achievement is detected (the conveyance system for 4 to 5 seconds). Could cause a bellows-like jam).

  Therefore, as a countermeasure against such a problem, the detection of the recording paper conveyance state is continuously performed by each sensor even during the jam clear conveyance operation. This will be described below.

  For the sake of convenience, a slight conveyance delay that may cause a jam is referred to as a first conveyance abnormality detection. Then, when the first conveyance abnormality is detected, the process shifts to a jam clear conveyance operation. After the transition, each sensor continues to detect the conveyance status of the recording paper, and further, has not reached or stayed? Let me monitor. This is called the second conveyance abnormality detection. The second conveyance abnormality detection can also be detected in the same manner as the above-described failure to reach or stay. And if a second conveyance abnormality is detected, it is considered that there is a high possibility (or actually occurs) of a large bellows-shaped jam, so do not spread the damage further. Stop the device immediately to do so.

  When the above control is performed, an error code relating to the first conveyance abnormality detection (a code indicating what kind of conveyance abnormality has occurred) is displayed on the display panel, while an error code relating to the second conveyance abnormality is not displayed. . This is because the recording paper that is subject to the second conveyance abnormality detection is not normally the recording paper that is normally conveyed, so this is not important information for the user, and the first conveyance abnormality has occurred for the user. This is because it is important information. Even in such a case, if the warning lamp displays where the recording paper remains as the remaining paper in the image forming apparatus, there is no problem for the user, but the first conveyance abnormality Since the type is known, it becomes reference information when, for example, repairing the apparatus.

  As described above, when a conveyance abnormality occurs, all the recording sheets on the conveyance path A are stored in the discharge tray 118, so that the user can immediately take out the recording sheets stored in the discharge tray 118. The image forming apparatus can be recovered to operate normally.

  In this embodiment, all the recording sheets on the transport path A are accommodated in the paper discharge tray 118. However, in addition to the paper discharge tray 118, the paper discharge path E is placed on the middle path of the transport path A. A paper discharge path that performs the same function as that of the paper discharge tray 118 may be formed so as to be divided into a plurality of storage means together with the paper discharge tray 118. Alternatively, a configuration may be adopted in which a recording paper retracting portion is provided on the transport path A in place of the accommodating means, and the paper is retracted to a plurality of positions together with the paper discharge tray 118. However, even in these cases, it is desirable that the arrangement be made in consideration of the convenience of the user so that the user can easily recover the apparatus.

  Although the above description has been made on the case where it has not been reached, the remaining recording paper in the image forming apparatus can be accommodated in the paper discharge tray 118 by the same method even when the stagnation occurs.

  As described above, in the present invention, even when a conveyance abnormality such as failure to reach or stay occurs, if the recording sheet is conveyed within a predetermined period, there is no remaining recording sheet on the conveyance path A. Continue to drive the transport means. Therefore, even when unachieved or stagnated, the user can recover the image forming apparatus easily and quickly simply by removing the recording paper from the paper discharge tray 118, and a series of printing operations can be performed in a short time as a whole. Can be realized.

101, 102 Paper feed tray 103, 104 Paper feed roller 105 Reversing roller 106 Carrying roller 107 Transfer roller 109 Carrying roller 110 Flip roller 111 Carrying roller 113 to 117 Sensor 118 Paper discharge tray 201 Detection means 202 Control means 203 Paper feeding means 204 Carrying Means 205 Image forming means A Conveyance path B Single-sided printing path C Double-sided printing path D Reversing path E Discharge path F, G Recording paper X, Y Conveyance path S1, S2, S3 Sensor

JP 2002-268304 A JP 56-8163 A

In order to solve the above-described problems, an image forming apparatus according to the present invention includes a recording medium supply unit that supplies a recording medium to a predetermined conveyance path, and a recording medium supplied from the recording medium supply unit on the conveyance path. Conveying means , upstream and downstream conveying state detection means arranged on the upstream side and downstream side of the conveying path for detecting the conveying state of the recording medium, the recording medium supply means, the conveying means, and the Control means for controlling the operation of the conveyance state detection means, first discharge means for discharging the recording medium recorded in a normal conveyance state by controlling the conveyance means by the control means, and the control means by comprising a second discharge means for discharging the recording medium caused the transport delay by controlling the transport means, the control means, the predetermined conveyance of said conveying state detecting means recording medium When detecting the Les, characterized by discharging a recording medium in which the transport delay is detected by the second exhaust means.

Claims (7)

Recording medium supply means for supplying a recording medium to a predetermined transport path;
Conveying means for conveying the recording medium supplied from the recording medium supply means on the conveying path;
A conveyance state detecting means disposed in the conveyance path for detecting a conveyance state of the recording medium;
Control means for controlling the operation of the recording medium supply means, the transport means, and the transport state detection means;
A storage means for storing the recording medium;
When the conveyance state detection unit detects a delay in conveyance of the recording medium, the control unit stops supplying the recording medium by the recording medium supply unit and continues conveyance of the recording medium by the conveyance unit for a predetermined period. The image forming apparatus is controlled to discharge the recording medium existing in the image forming apparatus to the storage unit.   The control means, when the conveyance state detection means detects that the recording medium conveyance delay and the distance between the recording medium causing the conveyance delay and the subsequent recording medium are larger than a predetermined distance, The supply of the recording medium by the recording medium supply unit is stopped and the conveyance of the recording medium by the conveyance unit is controlled to continue for a predetermined period, and the recording medium existing in the image forming apparatus is discharged to the storage unit. The image forming apparatus according to claim 1.   3. The image forming apparatus according to claim 1, further comprising: a display unit configured to display a detection result by the conveyance state detection unit on the display unit.   The image forming apparatus according to claim 3, wherein a detection result of the conveyance state detection unit is a type of conveyance abnormality.   The control unit performs control so as to stop the conveyance unit when the conveyance state detection unit detects again a delay in conveyance of the recording medium during a predetermined period during which the conveyance is continued. Item 5. The image forming apparatus according to any one of Items 1 to 4.   6. The image formation according to claim 1, wherein the predetermined period is set to a period during which all the recording media existing on the conveyance path can be discharged to the storage unit. apparatus.   2. The printing apparatus according to claim 1, wherein the conveyance path is configured in an annular shape, and further includes a recording medium reversing unit in the conveyance path, and the recording medium is reversed and conveyed by the recording medium reversing unit to perform duplex printing. The image forming apparatus according to any one of claims 6 to 6.

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