JPH0684217B2 - Sheet material remaining amount detector - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a sheet material remaining amount detection device applicable to a laser beam printer, a copying machine, or the like.

[Prior Art] Conventionally, as a detection device for detecting the remaining amount of the sheet material, for example, a reflection type or a transmission type photosensor is used, and only the presence or absence of the sheet material is detected by the photosensor. It is common.

Therefore, when this detection device is applied to a laser beam printer used as a printer unit for a facsimile, for example, the user knows the state of the remaining amount of sheet material until the sheet material disappears from the sheet material stacking unit. I couldn't do that, and I had to replenish the sheet material for the first time after the sheet material was exhausted. Therefore, when the facsimile runs out of the sheet material during reception printing, there is a possibility that accurate information transmission may not be performed, which is very inconvenient.

[Object] Therefore, in view of the above point, an object of the present invention is to provide a sheet material remaining amount detecting device capable of accurately detecting the remaining amount of the sheet material before the sheet material runs out. .

[Examples] Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a schematic configuration example of a laser beam printer to which the present invention is applied.

In the figure, reference numeral 1 denotes a cassette which is a sheet material stacking means, and the sheet material P stored in the cassette 1 is fed by a feeding roller 2 toward the inside of the apparatus. At this time, the feeding roller 2 pushes the sheet material P in the arrow B direction against the elastic force of the spring 3 while rotating in the arrow A direction in order to feed only one sheet material P. Therefore, the sheet material P is moved by the displacement of the spring 3. The sheet material P displaced in this way is sent out toward the feeding roller 4 as the feeding roller 2 rotates, and the sheet material P is fed.
Feed roller 2 returns to its original position when the arrow B
The sheet material P is not pushed in the direction. At this time, the sheet material P returns to its original position by the spring 3.

On the other hand, the remaining paper amount detecting device 5 is configured as shown in FIG.

That is, the rotatable arm shaft 51 supported by the side plates 5a and 5b of the substrate 52 is arranged. An arm 5A capable of contacting the sheet material P in the cassette 1 is attached to the tip of the arm shaft 51. Furthermore, the shading plate 5B fixed on the arm shaft 51 is
The transparent photo sensor 54 for paperless notice mounted on the substrate 52 via the mounting base 53 is engaged.

As described above, since the remaining paper amount detecting device 5 is configured, when the sheet material P is sufficiently stored in the cassette 1, the arm 5A is rotated in the direction shown in FIG. Since the upper light shielding plate 5B does not engage with the sensor 54 for notifying that there is no paper and does not block the sense window, the output signal of the sensor 54 becomes "H" level. On the other hand, by continuing the printing (recording) operation, the sheet material P in the cassette 1 is
Gradually decreases, and accordingly, the arm 5A rotates in the direction of (b) shown in the figure, and the light shielding plate 5B on the arm shaft 51 eventually engages with the sensor 54 for notifying that there is no paper and interrupts the sense window.
The output of 54 changes to "L" level.

In such a configuration, it is considered that the change in the remaining amount detection amount of the sheet material when the sheet material P is fed by the feeding roller 2 toward the inside of the apparatus one by one is as shown in FIG. .

That is, as shown in FIG. 3, the sheet material P is pushed downward by the feeding roller 2 in the predetermined period T1 immediately after the sheet material is started to be fed. Changes to. Then, when the feeding roller 2 makes one rotation, the sheet material returns to the original position by the spring 3. Further, during the period T2 during which the sheet feeding is continued, the remaining amount detection amount of the sheet material changes as illustrated due to the unevenness of the sheet material. Therefore, the object of the present invention cannot be sufficiently achieved.

Therefore, in the present invention, in order to accurately detect the remaining amount detection amount that changes with the movement of the sheet material, in the period T1 of FIG. 3, the detection amount obtained in the previous period is held, T1
Do not detect the remaining amount of sheet material inside. Then, the output signal from the sensor 54 is detected only in the period T2, and the detection is performed a plurality of times to reduce the influence of the unevenness of the sheet material. Further, when it is detected that the remaining amount of the sheet material is insufficient, the state is maintained until the sheet material is replenished to eliminate chattering when the insufficient amount of the sheet material P is detected.

Next, in consideration of such a point, FIG. 4 shows a control circuit for accurately detecting the remaining amount of the sheet material P by using the output of the sensor 54 for notifying that there is no paper.

In FIG. 4, reference numeral 201 denotes a microprocessor, which controls each constituent element in accordance with each signal described later, for example, a sixth
Each control process shown in FIGS. When the feeding signal S0 is output from the microprocessor 201, the signal S0 is supplied to the transistor 203A via the buffer 203. The transistor 203A drives the feeding clutch 204 in response to the signal S0, so that the feeding roller 2 starts feeding the sheet material P in the cassette 1. At the same time, the feed signal S0 is a one-shot multivibrator.
202 is triggered, and the output signal S3 of the one-shot multivibrator 202 is set to "H" level for a certain time during the feeding operation. This "H" level period corresponds to the period T1 shown in FIG. 3, and the remaining amount of sheet material is not detected as described later.

205 is a micro switch for detecting the attachment / detachment state of the cassette 1, and when the cassette 1 is detached from the apparatus main body,
When turned off, the input signal S1 to the microprocessor 201 becomes "H" level. On the other hand, when the cassette 1 is set in the main body of the apparatus, the micro switch 205 is turned on and the input signal S1 to the microprocessor 201 becomes "L" level.

FIG. 5 shows the feed signal S0 from the microprocessor 201, the output signal S3 from the one-shot multivibrator 202, and the output signal S2 from the sensor 54 for notifying that there is no paper.
3 is an example of each timing chart of FIG.

Output signal S0 and input signals S1 to S3 obtained as described above
The control processing steps according to the present invention performed in the microprocessor 201 according to the above will be described with reference to the flowcharts of FIGS.

FIG. 6 shows a control process for detecting a plurality of times in the remaining amount detection period T2 shown in FIG.

That is, when it is determined in step S61 that the output signal S3 from the one-shot multivibrator 202 is at "L" level, that is, the remaining amount detection period T2 shown in FIG. 3, the output of the sensor 54 is output in the next step S62. It is determined whether or not the content of the register N that counts the number of times of sensing of the signal S2 (the number of times of sensing) is a predetermined odd number of times.

If the specified number of times has not been performed in step S62, the output signal S
It is determined whether or not 2 is at the "H" level, that is, whether or not the sheet material P has a predetermined amount or more. Here, at the "H" level, "1" is added to the content of the register N _H that stores the "H" level at step S64. On the other hand, when it is at the "L" level, "1" is added to the contents of the register N _L that stores the "L" level at step S65. And
In step S66, "1" is added to the content of the register N and the following processing is performed.

If these operations have been performed the specified number (odd number), step S62
If it is determined in step S67, the contents of register N _H and register N _L are compared in the next step S67, and if the value of register N _H is larger than the value of register N _L , in step S69 The output signal S2 of the sensor 54 is determined to be the "H" level, and when the output signal S2 is opposite to that, the output signal S2 is output in step S68.
Determine 2 as the “L” level. This makes it possible to know whether or not the remaining amount of sheet material is equal to or less than the predetermined amount. Then, step S70
Clears the contents of each register and performs the following process.

On the other hand, in step S61, when the output signal S3 of the one-shot multivibrator 202 is at "H" level, that is, the period T1 shown in FIG. The state of the output signal S2 of the sensor 54 for advance notice is held.

Similar to FIG. 6, FIG. 7 shows that when the output signal S3 of the one-shot multivibrator 202 is judged to be “L” level,
That is, there is a method of sensing the output signal S2 of the sensor 54 for notifying that there is no paper a plurality of times during the period T2 shown in FIG. However, in this case, when the number of continuous "H" level or "L" level obtained as the output signal S2 from the sensor 54 reaches the specified number, the state of the output signal S2 is changed to "H" level or " This is the method of determining L "level.

That is, in step S7, when the output signal S3 of the one-shot multivibrator 202 is determined to be the “L” level, the output signal S2 of the sensor 54 for the paper-out warning is detected and determined to be the “H” level. Then, in step S73, the content of the register N _L for counting the “L” level is cleared, and then in step S74, “1” is added to the content of the register N _H for counting the “H” level. On the other hand, in step S72, the output signal S
When it is determined that 2 is at the "L" level, the contents of the register N _H are cleared in step S75, and then "1" is added to the contents of the register N _{L in} step S76.

Next, in step S77, it is determined whether or not the value of the register N _H is the specified number N, and if it is the specified number N, the output signal S2 of the sensor 54 for notifying that there is no paper is set to "S" in step S79. Determined as H "level. Next, in step S80, the registers N _L and N _H are cleared and the next process is performed.

Similarly, in step S78, the value of the register N _L is set to the specified number N
If it is the prescribed number N, the output signal S of the sensor 54 for notifying that there is no paper is output in step S81.
Determine 2 as the “L” level. Next, in step S82, the registers N _L and N _H are each cleared and the next process is performed.

When neither the value of the register N _H nor the value of the register N _L has reached the specified number N, the following processing is performed with the output signal S2 of the sensor 54 for the paper-out warning previously determined.

On the other hand, in step S71, when the output signal S3 of the one-shot multivibrator 202 is at the "H" level, during that time, the microprocessor 201 sets the state determined by the output signal S2 of the sensor 54 for the immediately preceding paper-out warning. Hold.

FIG. 8 shows a state in which when the remaining amount of the sheet material is found to be insufficient, the state where the remaining amount of the sheet material is insufficient is maintained until the sheet material is replenished.

That is, if it is determined in step S81 that the output signal S3 of the one-shot multivibrator 202 is at "L" level, the determination of the current output signal S2 of the sensor 54 for the paper-out warning is "L" in the next step S82. Determine whether it is a level or "H" level. Here, if the "H" level is determined, the output signal S2 of the sensor 54 for notifying that there is no paper is detected, and if it is determined to be the "L" level in step S83, the register is registered in the next step S84. Add "1" to the contents of N _L.

Next, in step S85, it is determined whether or not the content of the register N _L is the specified number N, and when it reaches the specified number, the output signal S2 of the sensor 54 for notifying that there is no paper is set to "L" in the next step S86.
Determined as a level. Further, in step S87, the contents of the register N _L are cleared and the following processing is performed.

On the other hand, if it is determined that the level is “L” in step S82,
In order to determine whether or not the cassette 1 is once removed from the apparatus main body, in the next step S88, it is determined whether or not the output signal S1 of the micro switch 205 is at "H" level, and the cassette 1 is the apparatus main body. When the flag FLAG1 is removed and is at the "H" level, the flag FLAG1 is set in step S96. On the other hand,
In step S88, when the cassette 1 is set in the apparatus main body and the level is "L", the next step S8
At 9, the flag FLAG1 is checked to see if the cassette 1 has been removed once.

In step S89, if the flag FLAG1 has been reset without the cassette 1 being removed once, the next process is performed as it is. On the other hand, if the flag FLAG1 is set in step S89, the sensor 5 for notifying that there is no paper in the next step S90.
When the output signal S2 of 4 is detected and it is determined to be "L" level, "1" is added to the content of the register _NH .

Next, in step S92, it is determined whether or not the content of the register N _H is the prescribed number N, and if it is the prescribed number N, step S9
In step 3, the output signal S2 of the sensor 54 for notifying that there is no paper is determined to be "H" level. Further, in the next steps S94 and S95, the flag FLAG1 is reset and the contents of the register N _H are cleared to perform the following processing.

As described above, according to the present embodiment, as shown in FIG. 3, during the period T1 in which the sheet material is pushed downward by the feeding roller 2 and the remaining amount of the sheet material changes in the direction shown in FIG. Output signal S3 of one-shot multi-vibrator 202 to "H"
By setting the level, the microprocessor 201 can detect the remaining amount of the sheet material very accurately by holding the state of the remaining amount detection obtained immediately before the period T1 without detecting the remaining amount of the sheet material. You can

Further, according to this embodiment, in the period T2 shown in FIG. 3, the change in the remaining amount detection amount is detected a plurality of times, and the remaining amount is determined by using the large number of pieces of information. False detections due to unevenness can be reduced.

Further, according to the present embodiment, as shown in the flowchart of FIG. 8, when the shortage of the sheet material remaining amount is detected, the detection state is maintained until the sheet material is replenished to detect the shortage of the sheet material remaining amount. You can eliminate chattering.

[Effects] As described above, according to the present invention, the period during which the sheet material is fed while the upper surface of the sheet material is being pushed down by the rotational driving of the feeding roller, that is, the position of the upper surface of the sheet material is not stable. During the period, the detection result of the position of the upper surface of the sheet material is invalidated, and the position of the upper surface of the sheet material is detected while the feeding roller is not pushing down the upper surface of the sheet material, that is, the position of the upper surface of the sheet material is stable. Since the remaining amount of the sheet material is determined based on, the remaining amount of the sheet material on the stacking unit can be accurately determined.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing an example of an image forming apparatus to which the present invention is applied, FIG. 2 is a perspective view showing an example of a cassette unit and a sheet remaining amount detecting apparatus of the apparatus shown in FIG. 1, and FIG. Is an explanatory diagram showing an example of a change in the remaining amount of sheet material detection according to the present invention, FIG. 4 is a circuit diagram showing an example of a control circuit for detecting the remaining amount of sheet material according to the present invention, and FIG. A timing chart showing an example of each signal at the time of feeding in the circuit of FIG. 4, FIG. 6 is a flowchart for detecting the output signal of the sensor a plurality of times during the remaining amount detection period, and FIG. 7 is a remaining amount detection period. Is a flow chart in the case of detecting only when the output signal of the sensor detected multiple times in succession has not changed, FIG. 8 shows the state of insufficient remaining amount of sheet material when it is found that the remaining amount of sheet material is insufficient. Control process to hold the sheet until the sheet material is replenished It is a flowchart in the case. 1 ... Cassette, 2, 4 ... Feed roller, 3 ... Spring, 5 ... Paper remaining amount detecting device, 54 ... Sensor, 201 ... Microprocessor, 202 ... One-shot multivibrator, 205 ... Microswitch, P ... Sheet material.

Continuation of the front page (56) References JP-A-59-203032 (JP, A) JP-A-59-64446 (JP, A) Actual development: S55-43729 (JP, U)

Claims (4)

[Claims] 1. A stacking device for stacking a sheet material in a pushed-up state, a feeding roller for pushing down and not pushing down an upper surface of the sheet material according to rotation, and the feeding roller in response to a feeding signal. Driving means for rotating the feeding roller to feed the sheet material while pushing down the upper surface of the sheet material, detecting means for detecting the position of the upper surface of the sheet material on the stacking means, and a detection result of the detecting means. A sheet for determining the remaining amount of sheet material on the stacking means based on the sheet, and for invalidating the detection result of the detecting means for a predetermined time from the generation of the feeding signal; Material remaining amount detection device. 2. The method according to claim 1, wherein during the period in which the discrimination means invalidates the detection result of the detection means, the state obtained by the detection means is held immediately before the period. Sheet material remaining amount detection device. 3. The detection stage detects the remaining amount of sheet material a plurality of times during the remaining period excluding the period in which the determination means invalidates the detection result of the detection means. The sheet material remaining amount detection device according to claim 1. 4. The invention according to claim 1, wherein when the determining means determines that the remaining amount of the sheet material is insufficient, the state of the insufficient remaining amount of the sheet material is held until the sheet material is replenished. The remaining amount detection device for the sheet material according to the item.