JPH10236724A - Paper discharge condition control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent misoperation due to that detection similar to a full condition is even performed temporarily such as in the case that paper is discharged to a discharge tray in a curled condition, surely control a full condition of the paper, and attain reduction of the number of write times relating to a memory for this control. SOLUTION: Paper 14 passing through a photosensitive body drum 21, detecting its rear end by a discharge sensor 26 and by a full stack sensor 31, is discharged onto a discharge tray 15. The full stack sensor 31 is turned on when the paper 14 passes and in a condition stacking the paper 14 in a prescribed height or more. In the point of time this on-condition is continued, a full stack counter starts a count for control, in the point of time leading to a prescribed count value, the paper 14 is discriminated in a full condition. Even when the curled paper 14 is temporarily discharged, before leading to this value, by resetting the count, the full condition is prevented from being discriminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for performing predetermined processing on sheets and discharging the sheets one after another, such as an image forming apparatus such as a copying machine, a facsimile apparatus, and a printer, and a printing apparatus. The present invention relates to a sheet discharge state management device for managing the state of sheet discharge to a discharge tray for discharging sheets.

[0002]

2. Description of the Related Art In an apparatus such as an image forming apparatus such as a printer or a copying machine, which performs predetermined processing on sheets and discharges the sheets one by one to a discharge tray, the amount of sheets stacked in the discharge tray is limited. In some cases, it may be necessary to monitor for reaching this limit.

[0003] As a paper discharge state management device for performing the management for this purpose, there is, for example, one described in Japanese Patent Application Laid-Open No. 63-127981. In this apparatus, the paper is discharged to a discharge tray provided in an upper part of the apparatus, and an actuator is provided so as to protrude to a discharge port. Then, when the sheets are sequentially discharged to a discharge tray and the height of the uppermost sheet reaches a predetermined height, the actuator is turned on, and the fullness of the sheet is detected.

[0004]

However, in such a paper ejection state management device, if one ejected paper happens to be curled, the actuator is turned on, and at that time, the paper becomes full. False detection. Therefore, there are many cases where sheets cannot be stored in the discharge tray until they are full. Therefore, for example, an operator who sets a large number of recording sheets so that the output tray does not become full must be called by the apparatus before the completion of the recording and must remove the sheet on the output tray once and restart printing. A situation such as leprosy has occurred.

In such a curled sheet, an actuator or a sensor is temporarily turned on at that time, but when the next sheet is discharged to a discharge tray, the curl is often corrected by its weight.

Accordingly, an object of the present invention is to ensure that the paper is fully filled without malfunction even if the same detection is performed as when the paper is temporarily discharged to the discharge tray in a curled state. The object of the present invention is to provide a paper discharge state management device which can manage the paper discharge state.

Another object of the present invention is to manage the paper discharge state in which the number of times of writing to the memory required for the control can be sufficiently reduced when managing the fullness of the paper discharged to the discharge tray. It is to provide a device.

[0008]

According to the present invention, (a) a discharge tray for discharging sheets, and (b)
The paper tray is located on the paper transport path near this discharge tray. When the paper is discharged to the discharge tray, this paper is detected and turned on, and the paper is discharged on the discharge tray in a state where the paper is stacked below the specified height. (C) a first sheet detection sensor whose detection state is released and turned off when the detection is performed, and (c) a sheet conveyance path which is away from the first sheet detection sensor by a predetermined distance on a side opposite to the discharge tray. A second sheet detection sensor that detects the passage of the trailing edge of the sheet conveyed toward the discharge tray, and (d) detects the trailing edge of the sheet after the second sheet detection sensor detects the trailing edge of the sheet. When the period until the trailing edge of the paper conveyed in the cycle is detected is T, the first paper detection sensor is continuously turned on for a time obtained by multiplying this period T by a predetermined numerical value N of 2 or more. The output tray is full when the status is maintained. A full stack determining means for determining that the tack is provided in the paper discharge state machine.

That is, according to the first aspect of the present invention, the first sheet detection sensor is provided on the sheet conveyance path near the discharge tray.
A second paper detection sensor is arranged at a slight distance from the second paper detection sensor, and the first paper detection sensor detects that the paper on the discharge tray is full (full stack), and the second paper detection sensor is maintained in that state. When the detection sensor detects the passage of the sheet more than a predetermined number of times, it is determined that the stack is full. When the same detection as the full state is temporarily performed, such as when the paper is discharged to the discharge tray in a curled state, the first paper detection sensor is turned off from the on state by discharging the next paper or the like. Since the state can be changed, if the state is shifted to the off state before the time period obtained by multiplying the period T by a predetermined number N equal to or more than two, the full stack is detected without malfunction. Note that the second paper detection sensor is disposed on the paper transport path at a predetermined distance from the first paper detection sensor on the opposite side of the discharge tray because the second paper detection sensor detects the trailing edge of the paper. This is because it is assumed that the sheet is detected by the first sheet detection sensor and the leading end of the sheet is discharged onto the discharge tray.

According to the second aspect of the present invention, (a) a discharge tray for discharging the paper, and (b) a paper tray disposed on the paper conveyance path near the discharge tray, when the paper is discharged to the discharge tray. A first sheet detection sensor which is turned on upon detecting this sheet, and which is released when the sheet is discharged in a state where the sheet is stacked on the discharge tray at a height equal to or less than a specified value and which is turned off; (C) a second sensor which is disposed on a sheet conveyance path at a predetermined distance from the first sheet detection sensor on the side opposite to the discharge tray and detects the passage of the rear end of the sheet conveyed toward the discharge tray. Paper detection sensor,
(D) Assuming that a period from when the second sheet detection sensor detects the trailing edge of the sheet to when the second sheet detecting sensor detects the trailing edge of the next sheet is T, the first sheet detecting sensor detects the trailing edge of the period T or more. Counting means for starting counting the number of sheets passing through the second sheet detection sensor when the ON state is maintained for a continuous time; and (e) discharging when the counting means counts a predetermined numerical value of 2 or more. A full stack discriminating unit for discriminating that the tray is full stack, and (f) a counting unit when the detection state of the first sheet detection sensor changes to off before the counting unit counts the predetermined numerical value. The sheet discharge state management device includes a count value reset unit that resets the count value to an initial value.

That is, according to the second aspect of the present invention, the first sheet detecting sensor is provided on the sheet conveying path near the discharge tray.
A second paper detection sensor is arranged at a slight distance from this, and the first paper detection sensor passes through the second paper detection sensor when the on state is continuously maintained for the period T or more. Start counting the number of sheets.
When the detection state of the paper detection sensor changes to OFF and reaches a predetermined value before the count value is reset, it is determined that the discharge tray is full stack. As described above, since the count start condition is limited, the number of accesses to the memory holding the count value is sufficiently reduced. The period T is the second
However, it is also possible to use a timer circuit.

According to the third aspect of the present invention, (a) a discharge tray for discharging the paper, and (b) a paper tray disposed on the paper conveyance path near the discharge tray, when the paper is discharged to the discharge tray. A first sheet detection sensor which is turned on upon detecting this sheet, and which is released when the sheet is discharged in a state where the sheet is stacked on the discharge tray at a height equal to or less than a specified value and which is turned off; (C) on the sheet conveyance path separated by a predetermined distance shorter than the length obtained by adding the gap between the sheets at the time of conveyance to the shortest length in the sheet conveyance direction on the side opposite to the discharge tray with respect to the first sheet detection sensor. A second detecting unit that detects the passage of the rear end of the sheet that is disposed and conveyed toward the discharge tray
And (d) the detection state of the second paper detection sensor is changed from ON to OFF, and is changed from ON to OFF again by the detection of the paper in the next cycle.
The counting of the number of sheets passing through the second sheet detection sensor is started each time the detection state of the second sheet detection sensor changes from ON to OFF from the time when the detection state of the sheet detection sensor is held ON. (E) full stack discriminating means for discriminating that the discharge tray is full stack when the counting means has counted a predetermined numerical value of 2 or more; When the detection state of the first paper detection sensor changes to off before counting the numerical value, the paper discharge state management device is provided with count value resetting means for resetting the count value of the counting means to an initial value.

That is, the invention according to claim 3 is an invention directly based on the embodiment described below, wherein the first and second paper detection sensors are arranged at a predetermined interval in a predetermined order. The detection state of the first paper detection sensor is turned on until the detection state of the second paper detection sensor changes from on to off and then changes from on to off again by the detection of paper in the next cycle. From the time of holding, the counting of the number of sheets passing through the second sheet detection sensor is started each time the detection state of the second sheet detection sensor changes from ON to OFF. When the counting means counts a predetermined numerical value of 2 or more, it is determined that the discharge tray is full stack. On the other hand, in case the curled paper is discharged, the counting means sets the predetermined numerical value. When the detection state of the first sheet detection sensor changes to off before counting the count, the count value of the counting means is reset to an initial value. Note that the expression "the length obtained by adding the gap between the sheets at the time of conveyance to the shortest length in the sheet conveyance direction" is based on counting at the next on-to-off edge of the next sheet.

According to a fourth aspect of the present invention, the count value of the counting means is written into the non-volatile memory in the sheet discharge state management device according to the third aspect, and the count value is decremented by one from an initial value consisting of a positive integer. When the output tray becomes "0", the full stack determination means determines that the discharge tray is full stack.

Of course, the counting need not be performed in descending order, but may be performed in ascending order. Further, the reset numerical value need not be “0”, but may be a predetermined positive or negative numerical value.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to embodiments.

FIG. 1 shows the appearance of a printer using a paper discharge state management device according to an embodiment of the present invention. The printer 11 can set a paper feed tray 13 below the apparatus main body 12. The paper 14 in the paper feed tray 13 is sent out one sheet at a time to the back side of the apparatus main body 12, the image information is printed by a recording unit (not shown) inside the main body, and after the image is fixed, The paper is discharged from a discharge port 16 on a discharge tray 15 provided on the upper side toward the near side.

FIG. 2 shows a main portion of a transport path leading to a discharge tray of the printer. The paper 14 on which the toner image has been transferred by passing between the photoreceptor drum 21 of the apparatus main body 12 and the transfer roll 22 arranged opposite thereto is conveyed to the upper part of the apparatus and
The toner image passes through a fixing device composed of a pressure roller 3 and a pressure roll 24, and at this time, the toner image is fixed. A discharge sensor (second paper detection sensor) 26 for detecting the passage of the rear end of the paper is disposed slightly above the heat roll 23 and the pressure roll 24. The sheet 14 on which the fixing has been completed is conveyed upward as shown by an arrow 27 ₁ in the figure, passes through two pairs of conveyance rolls 28 and 29 arranged at the top of the apparatus main body 12 in order, and is discharged onto the discharge tray 15. Is to be discharged.

The transport roll pair 29 is disposed immediately inside the discharge port 16, and a full stack sensor 31 for detecting the fullness (full stack) of the sheets on the discharge tray 15 is disposed in the discharge port 16. I have. In the case of a sheet to be discharged to the discharge tray 15 as it is, after passing between the heat roll 23 and the pressure roll 24, the sheet is conveyed in the direction of the arrow 27 ₁ and detected by the discharge sensor 26, and further two pairs of conveyance rolls 28 and 29. Sequentially through the full stack sensor 3
After being detected 1, and is discharged onto the discharge tray 15 as indicated by arrow 27 _2.

On the other hand, when double-sided recording is performed, two sets
Through the transport roll pairs 28 and 29 of the discharge tray 1
The paper 14 which is about to be discharged onto the paper 5
When the sheet is conveyed to the position of the printer pair 28, it stops once. So
And the arrow 27 from the rear end side of the paper 14_ThreeAs shown in
The conveyance is started in the downward direction in FIG.
Two pairs of transport rolls 3 vertically arranged on the far side
3, 34 with arrow 27_Four, 27_FiveConveyed sequentially in the direction.
The paper 14 is then marked with an arrow 27₆Transported in the direction
Arranged on the exit side of paper feed tray 13 arranged in main body 12
Feed roll 35₁Form 14 sent from
Passes through a pair of transport rolls 36 for transporting
It is transported to the roll pair 37, where it is temporarily stopped.
Is stopped. Then, the toner image on the photosensitive drum 21 is
Arrow 27 after the recording position is matched between₇In the direction
The conveyance is started, and the transfer of the photosensitive drum 21 and the transfer roll 22 is started.
And the toner image is transferred to the second surface.
Will be. Then, pudding is applied to both the first and second surfaces.
The sheet 14 on which the printing has been performed is indicated by the arrow 27 as described above. ₁
In the direction indicated by arrow 27_TwoAs shown in
The paper is discharged onto the output tray 15.

Slightly below the resist roll pair 37,
Other feed roll 35 ₂ is disposed. The feed roller 35 ₂ is used to convey a manual feed by the sheet from the front of the device (right side portion not shown in FIG. 2).

In the case of single-sided recording or double-sided recording and recording of the first side, the paper 14 accommodated in the paper feed tray 13 is
5 ₁ or from the feed roll 35 ₂ one by one at a predetermined timing is sent to the arrow 27 the _eight directions, the arrow 27 ₉
As shown in the figure, the sheet is conveyed to the position of the registration roll pair 37 via the conveyance roll pair 36, and thereafter, the photosensitive drum 21
Then, recording on the first surface of the sheet 14 is performed after passing between the transfer roller 22 and the transfer roller 22. Of course, the printer according to the present embodiment can have an optional additional paper feed tray. When a paper feed tray is added, a paper feed tray (not shown) is provided below and parallel to the paper feed tray 13 shown in the figure.
The paper fed from the additional paper feed tray moves upward, and the transport roll pair 36
, And thereafter receives the same control as the paper 14 transported from the paper feed tray 13.

As described above, in the printer according to the present embodiment, the discharge tray 15 switches between the function as a tray for originally discharging the paper and the recording surface of the paper on which the recording of the first surface has been completed in double-sided recording. Function as a space for switchback. Incidentally, the loop-shaped transport path indicated by the arrow 27 _{1-27 7} in this embodiment can convey paper 14 two simultaneously. Therefore,
At the time of double-sided recording, two sheets can be present in this loop-shaped conveyance path to achieve high-speed recording.

FIG. 3 shows a state in which the full stack sensor is attached to the outlet of the printer. The full stack sensor 31 includes the transport roll pair 2 shown in FIG.
An actuator unit 31A rotatably attached to a support plate 41 that supports the pinch roll 29A among the pinch rolls 29B that constitute the upper side of 9 is provided. Actuator section 31A is given the habit of rotating in the direction of arrow 42 by coil spring 31B. In a state where the sheet has not passed between the pinch roll 29A and the discharge roll 29B constituting the transport roll pair 29, as shown in a frame 43 in FIG.
Is in contact with the end 41A. In this state, the full stack sensor 31 is off.

On the other hand, when a sheet (not shown) is transported in the direction of arrow 44 between the pinch roll 29A and the discharge roll 29B, the tip of the actuator 31A is pushed upward. At this time, the full stack sensor 31
Is turned on.

FIG. 4 shows a detection state of the full stack sensor in a state where the paper is fully stored on the discharge tray. In this state, the height of the sheets 14 stacked on the discharge tray 15 becomes equal to or higher than a predetermined height, and as a result, the actuator unit 31A of the full stack sensor maintains the ON state. When the height of the uppermost layer of the paper 14 that has been released from the discharge tray 15 is lower than this,
While the sheet 14 is being discharged onto the discharge tray 15, the full stack sensor 31 is temporarily turned on, and then turned off.

FIG. 5 shows a change in the detection output of the full stack sensor when the sheets are successively discharged to the discharge tray. In this figure, the horizontal axis indicates the passage of time. The full stack sensor 31 is turned on for approximately a fixed time each time the actuator unit 31A (see FIG. 3) is pressed when the paper is discharged, and as a result, the discharge tray 15
The ON state and the OFF state are repeated in a state where the amount of paper 14 deposited is small (see FIG. 4). Then, a time t ₁ subsequent to the height of the paper 14 which has been deposited onto the discharge tray 15 as it reaches a predetermined or more shown in FIG. 4 will be held in the ON state. The time t ₁ and later, the arrow 46 _1, 46 _2, ...
In each section indicated by..., The paper 14 is discharged onto the discharge tray 15 one after another. At time t ₂ the discharge has been performed of the paper 14 by repeating a predetermined plurality of times, the printer detects that the full stack state, the control such as the paper 14 is not discharged any more to the discharge tray 15 rows Will be

As described above, the condition that the full stack state is detected a plurality of times consecutively is based on the condition that the actuator unit 31A is temporarily turned on when the sheet 14 is discharged in a curled state. This is to prevent an erroneous detection that the discharge tray 15 has become full in the case where is held. In this embodiment, the number of continuations is set to "5", but it is needless to say that the number is not limited to this value. The state in which the paper 14 is discharged can be grasped by using the detection output of the discharge sensor 26 shown in FIG.

The ejection sensor 26 detects the sheet 14 by the preceding sensor, similarly to another sheet detection sensor (not shown) which is scattered and arranged at other portions of the transport path of the printer. Nevertheless, this is a sensor for detecting the occurrence of a jam when the paper detection sensor disposed next to this does not detect the paper 14 within the specified time. However,
In FIG. 2, the discharge sensor 26 of this embodiment, which is disposed immediately downstream of the heat roll 23 and the pressure roll 24, is disposed relatively close to the discharge port 16.
When the trailing edge of the sheet is detected,
5 is ensured. Therefore, the full stack sensor 31 further disposed on the exit side is not provided for detecting a paper jam, but is used merely for detecting the full stack of the paper 14.

As described above, in the paper discharge state management device of the present embodiment, as described with reference to FIG.
There monitor the plurality by paper 14 a predetermined time t ₁ after holding the ON state is discharged, so that to reliably detect full stack discharge tray 15. However, the paper discharge state management device of the present embodiment further includes an additional circuit, so that the detection and management of the full stack in an actual use situation where the power of the printer is turned off at night or the like is more practical and high. It can be done with high accuracy. Therefore, first, the inconvenience that occurs when the power supply is managed only by the detection control described in FIG. 5 will be described.

Strictly controlling the height of the uppermost layer of the paper 14 discharged to the discharge tray 15 is particularly required by using the discharge tray 15 as a switchback mechanism for double-sided recording of the paper 14 as in the printer of this embodiment. Important when used.
That is, if the number of sheets 14 to be accommodated is roughly managed, a completely filled discharge tray
This is because a situation may occur in which control is performed such that the leading end portion of the paper 14 is temporarily fed upward, which may cause inconvenience such as paper folding.

Therefore, in the paper discharge state management device of the present embodiment, the full stack sensor 3 is activated after time t ₁ shown in FIG.
When the detection output of the discharge sensor 26 changes from on to off for the second time while the 1 remains in the on state, the full stack counter starts counting operation, and thereafter the full stack sensor 31 is turned on for five consecutive sheets. That is, it detects the full stack. The count value of the full stack counter is written in the non-volatile memory in consideration of the case where the print job is completed before the number of sheets reaches five and the power supply of the printer is turned off.

For example, the case where the full stack sensor 31 is continuously turned on at the time of printing the last few sheets of the last print job of the day, and the number has not yet reached “5”. Think. In such a case, the printer has not detected a full stack (full stack status) at the time when the print job is completed. In this state, it is assumed that the operator forgets to remove the paper 14 from the discharge tray 15 and turns off the power. Even when the administrator turns off the printer by remote control or when the printer is automatically turned off because the printer has not been used for a predetermined time at night, the paper 14 May be left as it is. After the power is once turned off, when the printer is turned on again in the next morning or the like, the discharge tray 15 must be treated without any treatment.
History information for monitoring the full stack above is lost.
Therefore, when the full stack sensor 31 is turned on after this, and the full stack is discriminated after detecting the on state of five more sheets continuously from now on, the extra number is counted by the value cleared by turning off the power. In this state, a full stack is detected, and extra paper 1
5 is discharged, and the above-described trouble may occur.

In order to prevent such an inconvenience from occurring, in this embodiment, the full stack sensor 3 is used after time t _1.
From the second time when the detection output of the discharge sensor 26 changes from on to off while maintaining the on state, the number of sheets discharged one by one each time the detection output of the discharge sensor 26 changes from on to off. The value is subtracted from the numerical value “4”. When the power is turned off, the count value is held, and when the full stack sensor 31 is turned on the next time the printer is turned on,
Each time the ejection sensor 26 detects ejection of the sheet 14, the count value is decremented by one, and when the value becomes "0", a full stack is determined. Of course, depending on the device, the numerical value may be sequentially counted up, and when a predetermined value is reached, the full stack may be determined.

FIG. 6 shows the relationship between the discharge sensor and the full stack sensor in detecting the full stack state. FIG. 7A shows a change in the on / off state of the discharge sensor 26 (see FIG. 2). The discharge sensor 26 detects this when the paper 14 passes, turns it on when it is detected, and turns off when it is not detected, thereby generating a detection pulse 51 corresponding to the passage of the paper 14. At the falling point 52 of each detection pulse 51, the full stack flag is turned on, and the count value of the full stack counter described later is a numerical value “4”.
Is set. FIG. 3B shows the full stack sensor 31.
(See FIG. 2). Due to the displacement of the ejection sensor 26 and the full stack sensor 31 on the conveyance path, the detection pulse 52 of the ejection sensor 26 is generated first on the same sheet 14, and the detection pulse 53 of the full stack sensor 31 is subsequently generated. Become. The full stack flag is cleared at the falling edge 54 of the detection pulse 53 by utilizing such a time lag of the detection. That is, if the detection of the full stack sensor 31 changes from ON to OFF after the discharge sensor 26 detects the trailing end of the paper 14, the discharge tray 15 has a sufficient capacity for storing the paper 14, and the full stack flag Is always cleared. Therefore, the count value "4" of the full stack counter is held as it is without performing the subtraction processing.

[0037] a certain time t ₁ detection output of full stack sensor 31 after turned on, when the ON state is maintained, is not performed is cleared full stack flag. The detection pulse 51 at time t ₁ after the state count value N of the full stack counter each time that falls after the second time is subtracted by one. Then, the count value of the full stack counter at time t ₂ is the detection of the full stack is performed when it becomes "0". Since the count value of the full stack counter is stored in a non-volatile memory (not shown), the value is retained even if the power is turned off while the printer is turned off.

FIG. 7 shows a main part of a circuit configuration of a printer including a paper discharge state management device. This printer includes an image recording unit 61 for outputting an image, and a microcomputer (MC) for controlling the image recording unit 61.
U) 62 is built-in. In the MCU 62, a central processing unit (CPU) 63 and a non-volatile memory (NVM) 64 such as an EEPROM that can be written a predetermined number of times are provided.
Is arranged. The MCU 62 includes a laser scanning unit 65 for irradiating the photosensitive drum 21 shown in FIG. 2 with a laser beam corresponding to image information, a fixing control circuit 66 for heating and controlling the heat roll 23 at a predetermined temperature, An input / output circuit 67 for inputting detection outputs of various sensors such as the discharge sensor 26 or the full stack sensor 31 and for rotating a motor (not shown); a control panel 68 for recording; 69, a high voltage supply circuit 70 and a controller MCU 71.

Here, the low voltage supply circuit (LVPS) 69
Is a circuit for supplying a voltage to a relatively low voltage circuit component such as a semiconductor circuit, and a high voltage supply circuit (HVPS)
Reference numeral 70 denotes a circuit for supplying a voltage to a circuit component requiring high voltage application, such as the transfer roll 22 (see FIG. 2). The controller MCU 71 performs necessary input for operations from a control panel 75 for performing operations such as image editing, and outputs necessary information using a display or a lamp built in the control panel 75. Has become. The nonvolatile memory 64 constitutes a full stack counter described later in cooperation with the control of the CPU 63.

FIG. 8 shows an outline of a processing flow of the sheet discharge state management device of this embodiment. When the power of the printer is turned on, first, the status of the apparatus is checked and initial processing is performed (step S101). After the completion of the initial processing, printing is executed after a print command is received from a host (not shown). At this time, the CPU 63 shown in FIG. 7 monitors the discharge sensor 26 and the full stack sensor 31 via the input / output circuit 67. Then, the discharge sensor 26
When the detection output of the sheet 14 is turned off from on, that is, when the rear end of the sheet 14 is detected (step S102;
Y), a full stack (FS) counting process is executed as a predetermined process when the detection output of the discharge sensor 26 is turned on (step S103). When the full stack sensor 31 is turned off from on (step S104; Y), a full stack sensor process is performed as a predetermined process when the full stack sensor 31 is turned on (step S105).
The full stack count process and the full stack sensor process will be described in detail together with the initial process in order.

In the state where the discharge sensor 26 does not switch from ON to OFF (step S102; N) and the state where the full stack sensor 31 does not switch from ON to OFF (step S104; N), the next processing is performed without performing any processing. The process waits until the discharge sensor 26 switches from on to off or the full stack sensor 31 switches from on to off. Such processing for managing the paper discharge state after the initial processing is performed will be continued until the power of the printer is turned off.

FIG. 9 shows the contents of the initial processing in step S101 of FIG. In the initial processing, first, the on / off state of the full stack sensor 31 is checked (step S201). If the full stack sensor 31 is off in the initial state when the power is turned on (N), there is no problem in storing the paper 14 in the discharge tray 15 shown in FIG. Then, the value of the full stack counter for controlling the state of the discharge tray 15 while subtracting the count value is set to "4" as the maximum value, and the initial processing is ended (END).

On the other hand, if the full stack sensor 31 is turned on in the initial state when the power is turned on (step S201; Y), there is a possibility that the paper 14 is full or nearly full. Therefore, in this case, the full stack flag is set (step S203).
Then, it is checked whether or not the value of the full stack counter written in the nonvolatile memory 64 shown in FIG. 7 is "0" (step S204). This is because the nonvolatile memory 64 stores the value of the full stack counter at the time when the power of the printer is turned off. If this value is not "0" (N), the discharge tray 15 is not full, so that the printer can perform printing for the time being. Therefore, in this case, the processing is terminated as it is (end).

On the other hand, if it is determined in step S204 that the count value of the full stack counter is "0" (Y), the full stack status is set. When the full stack status is set, an instruction to remove the paper 14 from the discharge tray 15 is displayed on the control panel 75, and an alarm sound is output. The operator cannot perform printing until the sheet 14 is removed from the discharge tray 15 and the detection output of the full stack sensor 31 is turned off.

FIG. 10 shows the contents of the full stack count process in step S103 of FIG. In the full stack counting process as a process when the detection output of the discharge sensor 26 changes from on to off, first, it is checked whether or not the full stack flag is set by the initial process shown in FIG. 9 (step S301). If it has not been set (N), the full stack flag is set as described in FIG. 6 (step S302), and the process ends (END).

On the other hand, if the full stack flag is set (step S301; Y),
This means that the full stack sensor processing in step S105 was not performed between the time when the detection output of the discharge sensor 26 changed from on to off and the next time the detection output of the discharge sensor 26 changed from on to off. . Therefore,
There is a possibility that the discharge tray 15 is almost full, and the CPU
63 decrements the count value of the full stack counter by "1" (step S303). Then, in the next step S304, it is checked whether or not the resulting count value has become “0”. If the count value of the full stack counter is not yet "0" (N), the current process is terminated in this state where the count value has been subtracted (END).

On the other hand, when the count value of the full stack counter becomes "0", it is checked whether or not it is the one at the time of the discharge processing of the first batch of two batches (step S305). As described above, the printer according to the present embodiment can perform double-sided recording. At this time, when a part of the paper 14 is discharged to the discharge tray 15 by printing two sheets at a time, the The second surface is recorded by being drawn into the apparatus main body 12. Therefore, if the first batch of two batches is to be discharged (Y), the sheet 14 is not finally discharged to the discharge tray 15. Therefore, in this case, the count value of the full stack counter is set to "1" (step S306). Then, when the recording on the second surface is completed, the discharge to the discharge tray 15 is ensured. Therefore, when it is determined in step S305 that it is not the first of the two batches (N), the full stack status is set and the process ends (step S307). In this case, as described above, the operator operates the discharge tray 1
Printing cannot be performed until the sheet 14 is removed from the sheet No. 5 and the detection output of the full stack sensor 31 is turned off.

FIG. 11 shows the contents of the full stack sensor processing shown in step S105 of FIG. If the full stack sensor 31 is off (step S401; Y), the full stack flag set by the operation of the discharge sensor 26 is cleared (step S402). Then, the full stack counter is set to "4" so that the operation of monitoring the sheets on the discharge tray 15 can be started again (step S403). If the full stack status has been set, it is cleared (step S404). For example, when the discharge tray 15 is full and the full stack status is set, and the operator removes the sheet 15, the full stack sensor 31 is turned off and the full stack status is cleared. Is ready for recording.

When the sheet 14 is discharged to the discharge tray 15 in a curled state, the count value of the full stack counter is sequentially subtracted from "4" in the full stack counting process shown in FIG. However, the curl is corrected by the weight of the sheet 14 discharged later before the count value reaches “0”, and the full stack sensor 3
The detection output of No. 1 changes from on to off. In such a case, the count value of the full stack counter is set to "4" again at this point (step S403), and the process shifts to the status 102 of FIG.

In the embodiment described above, the writing of the count value to the nonvolatile memory 64 constituting the full stack counter is controlled by the discharge sensor 26 after time t ₁ (FIG. 6) when the full stack sensor 31 is kept on. Is limited to the time after the second detection output changes from on to off. By writing all the changes in the count value into the non-volatile memory 64 without performing such control, it is also possible to store the state of the discharge tray when the power of the apparatus such as the printer is turned off. However, in this case, the number of times of writing data to the nonvolatile memory 64 becomes enormous, and a memory element having an upper limit in the number of times of writing may exceed this limit. With a configuration that can save the number of times of writing the count value to the non-volatile memory 64 as in this embodiment, it is unlikely that the number of times of writing exceeds these limits even if the life of the device such as a printer is sufficiently long. This makes it easy to select a memory element. In this embodiment,
By using an EEPROM as the nonvolatile memory 64, sufficient reliability in writing the count value could be obtained.

In the embodiment, the full stack sensor 31 having the actuator section 31A for mechanically detecting the paper 41 is used. However, the height of the paper at the time of discharging is detected by another detection principle such as optical. The change in the level (corresponding to the on / off state of the detection output in this embodiment) can naturally manage the paper discharge state, and the present invention can be applied to such a detection unit. It is.

In the embodiment, the management of the discharge mechanism of the printer has been described. However, the present invention can be similarly applied to other image forming apparatuses or general paper discharge mechanisms.

[0053]

As described above, according to the first aspect of the present invention, in addition to the first paper detection sensor for detecting the height of the paper at the time of discharging to the tray near the discharge tray, the passage of the paper. Since the second paper detection sensor that performs the detection is arranged, the second paper detection sensor can also be used for paper jam detection, and the number of sensors can monitor the paper in the discharge tray and monitor the paper conveyance status. It is possible to realize both monitoring functions of monitoring.

According to the second aspect of the present invention, the second
Can detect the passing cycle of the sheet, it is possible to monitor the holding state of the ON state of the first sheet detection sensor without using a special timer circuit. It is possible to prevent a situation in which the discharge tray is erroneously detected as being full due to a temporary malfunction of the sheet detection sensor or curl of the sheet.

Further, according to the third aspect of the present invention, the arrangement of the first paper detection sensor and the second paper detection sensor is characterized, so that the number of times of counting by the counting means can be reduced by simple circuit control. The counter can be configured using a memory element having a limited number of times of writing, thereby increasing the degree of freedom in selecting a circuit element.

According to the fourth aspect of the present invention, since the counter is formed using the nonvolatile memory, the state of the discharge tray can be reliably stored even when the power supply of the apparatus is temporarily cut off. It is possible to surely monitor the full state.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating an appearance of a printer using a sheet discharge state management device according to an embodiment.

FIG. 2 is a schematic configuration diagram illustrating an outline of a paper transport path of a printer used in the embodiment.

FIG. 3 is a perspective view illustrating a state in which a full stack sensor is attached to a discharge port of the printer.

FIG. 4 is a schematic configuration diagram illustrating a detection state of a full stack sensor in a state where sheets are fully stored on a discharge tray.

FIG. 5 is a timing chart showing a change in a detection output of a full stack sensor when sheets are successively discharged to a discharge tray.

FIG. 6 is a timing chart showing a relationship between a discharge sensor and a full stack sensor in detecting a full stack state.

FIG. 7 is a block diagram illustrating a main part of a circuit configuration of a printer including a sheet discharge state management device.

FIG. 8 is a block diagram illustrating an outline of a processing flow of the sheet discharge state management device of the present embodiment.

FIG. 9 is a flowchart showing the contents of an initial process in step S101 of FIG. 8;

FIG. 10 is a flowchart showing the contents of a full stack count process in step S103 of FIG. 8;

FIG. 11 is a flowchart showing the contents of a full stack sensor process shown in step S105 of FIG.

[Explanation of symbols]

11 printer, 13 paper feed tray, 14 paper, 15
... discharge tray, 16 ... discharge port, 26 ... discharge sensor, 31
... Full stack sensor, 63 ... Central processing unit (CP
U), 64: Non-volatile memory

Claims (4)

[Claims] A discharge tray for discharging paper; a discharge tray disposed on a paper conveyance path near the discharge tray, detecting the paper when the paper is discharged to the discharge tray; A first sheet detection sensor that is released when the sheet is discharged in a state where the sheets are stacked at a height equal to or less than a specified value and is turned off; A second sheet detection sensor that is disposed on a sheet conveyance path that is away from the tray by a predetermined distance and that detects the passage of the rear end of the sheet conveyed toward the discharge tray; and Assuming that a period from when the trailing edge of the sheet is detected to when the trailing edge of the sheet conveyed in the next cycle is detected is T, the first sheet detecting sensor takes a predetermined numerical value of 2 or more during this period T. Continuous for more than N times A sheet discharge state management device, comprising: a full stack determination unit that determines that the discharge tray is full stack when the on state is maintained. 2. A discharge tray for discharging paper, and a discharge tray disposed on a paper conveyance path near the discharge tray. When the paper is discharged to the discharge tray, the paper is detected and turned on. A first sheet detection sensor that is released when the sheet is discharged in a state where the sheets are stacked at a height equal to or less than a specified value and is turned off; A second sheet detection sensor that is disposed on a sheet conveyance path that is away from the tray by a predetermined distance and that detects the passage of the rear end of the sheet conveyed toward the discharge tray; and Assuming that a period from when the trailing edge of the sheet is detected to when the trailing edge of the next sheet is detected is T,
Counting means for starting counting the number of sheets passing through the second sheet detection sensor when the first sheet detection sensor keeps the ON state continuously for the period T or more; Full stack determination means for determining that the discharge tray is full stack when a predetermined numerical value is counted; and a detection state of a first sheet detection sensor being turned off before the counting means counts the predetermined numerical value. And a count value resetting means for resetting the count value of the counting means to an initial value when the count value has changed to. 3. A discharge tray for discharging paper, and a discharge tray disposed on a paper conveyance path near the discharge tray. When the paper is discharged to the discharge tray, the paper is detected and turned on. A first sheet detection sensor that is released when the sheet is discharged in a state where the sheets are stacked at a height equal to or less than a specified value and is turned off; After the sheet conveyed toward the discharge tray, it is placed on the sheet conveyance path at a predetermined distance shorter than the shortest length in the sheet conveyance direction plus the gap between the sheets during conveyance on the opposite side of the tray. A second paper detection sensor for detecting the passage of the edge, and a first paper detection sensor that changes from on to off when the detection state of the second paper detection sensor changes from on to off again by the detection of paper in the next cycle. Paper inspection A count that starts counting the number of sheets that have passed through the second paper detection sensor each time the detection state of the second paper detection sensor changes from on to off from when the detection state of the intellectual sensor is held on Means for determining that the discharge tray is full stack when the counting means has counted a predetermined numerical value of 2 or more; and And a count value resetting means for resetting the count value of said counting means to an initial value when the detection state of the first sheet detection sensor changes to off. 4. The count value of said counting means is written into a non-volatile memory, and when the count value is decremented by one from an initial value consisting of a positive integer and becomes "0", said full stack discriminating means outputs said discharge value. 4. The sheet discharge state management device according to claim 3, wherein it is determined that the tray is full stack.