JPH0326637A - Paper detecting device for discharge paper stacker of large quantity - Google Patents

Abstract

PURPOSE:To accurately detect whether paper is left or not on a paper tray by providing constitution in such a way as projecting light from a light emitting element through a through hole, provided in the paper tray, into a residual paper-detecting light receiving element so as to detect the paper not present, when it is not left on the paper tray. CONSTITUTION:In a condition that paper 70 is not present on a paper tray 54, light from a light emitting element 60 is transmitted to pass through a through hole in the paper tray 54 and projected into a residual paper-detecting light receiving element 65. However, when the paper 70 is left present on the paper tray 54, the light from the light emitting element 60 is intercepted by the paper 70 and not projected into the residual paper-detecting light receiving element 65. As a result, presence/absence the paper can be accurately detected with no influence by dispersion of a set position of the paper tray 54.

Description

[Detailed Description of the Invention] The present invention is a method for stacking paper in a large quantity discharge stacker that sequentially stacks a large quantity of paper discharged from an image forming device such as a laser printer or a copying machine. This paper relates to a paper detection device. Figure 5 shows a conventional large-volume stacker. This stacker consists of three units: a carry-in unit 1, a feed unit 2, and a tray unit 3. The carry-in unit 1 has a gate 4 that opens depending on the paper size, a drive roller 5, and a guide plate 6, and conveys the paper 7 discharged from the image forming apparatus to the feed unit 2. The feed unit 2 includes a crank arm 9 that rotates around a shaft 8, and a feed roller 10 that is pivotally supported at the free end of the crank arm 9. Drive pulley 11 rotating around shaft 8
, a feed motor 12 that rotates the feed roller 10 via the drive pulley 11, a spring 13 that presses the feed roller 10 against the sheet 7, and an electromagnet 14 that retracts the feed roller 10 from the sheet 7 loading surface.
Then, the paper 7 carried in by the carrying unit 1 is conveyed by the feed roller 10 until its leading edge collides with a paper stopper 16 that is a part of the frame 15 of the tray unit 3. The tray unit 3 has a vapor tray 19 installed horizontally between a pair of lifting wires 17 and 18 attached to a frame 15, and the paper tray 1 is moved by driving these lifting wires 17 and 18 simultaneously by an lifting motor 20.
Go up and down 9. The entire tray unit 3 can be pulled out of the housing 22 along a rail 21. The feed unit 2 further includes a paper tray 19.
a remaining paper detection mechanism 23 that detects that there is no paper 7 on top;
Paper detection mechanisms are attached to two of the stacking height detection mechanisms 24 that detect the stacking height of the paper 7 on the paper tray 19. The remaining paper detection mechanism 23 includes a detection lever 26 that rotates around a shaft 25, a photo sensor 27, and an electromagnet 28 that retracts the detection lever 26. As shown in FIG. 6, when there is paper 7 on the paper tray 19, the detection lever 2
The lower end of the paper 7 is connected to the recess 19 of the vapor tray 19.
Since the detection lever 26 is removed from the photosensor 27, the photosensor 27 is turned on.
When the paper 7 on the vapor tray 19 runs out, the lower end of the detection lever 26 falls into the recess 19a, so the detection lever 2
6 blocks the light of the photosensor 27 and the photosensor 2
7 is turned off.

The loading height detection mechanism 24 includes a photosensor 29 whose light is blocked by the upper end 9a of the crank arm 9. When the number of sheets stacked on the paver tray 19 increases, the feed roller 10 is lifted and the crank arm 9 is rotated in the eight directions of arrows as shown by the solid line in FIG. blocks the light from the photosensor 29, turning the photosensor 29 off. Then, the paper tray l9 is lowered. Along with this, the crank arm 9 rotates in the opposite direction to the eight directions as shown by the chain line in FIG. .

However, in this type of large-volume stacker, the paper tray 19 is removable and the entire tray unit 3 can be pulled out as described above.
There are many variations in the set position of the recess 19a, and the recess 19a is often misaligned with the detection lever 26. Therefore, the seventh
As shown in the figure, the lower end of the detection lever 26 is connected to the paper tray 1.
Even if the paper has come off the recess 19a of the paver tray 19 and is no longer on the paver tray 19, the conventional remaining paper detection mechanism 23 has the problem of incorrectly detecting the presence of remaining paper. In addition, in the conventional stacking height detection mechanism 29, the feed roller 10 collides with the paper stacking surface and vibrates as shown in FIG. However, there was a problem that caused paper jams. The present invention aims to eliminate both the conventional erroneous detection of the presence or absence of remaining paper and the erroneous detection of the stacking height. A method for solving the problem In the present invention, in order to detect the presence or absence of remaining paper on the paver tray, a light emitting element is arranged at a predetermined position above the paper tray, while a remaining paper detection element is arranged at a predetermined position below the paper tray opposite to the light emitting element. A through hole is provided in the paper tray to transmit light from the light emitting element to the light receiving element for remaining paper detection. Further, in order to detect the stacking height, the light emitting element has a focal point at a predetermined height above the paper tray, and the loading height is such that the light receiving optical axis intersects the light emitting optical axis of the light emitting element at a predetermined angle at the focal point. Equipped with a light-receiving element for detection. When there is no paper on the paper tray, the light from the light emitting element passes through the transparent light of the paver tray and enters the light receiving element 12 for detecting remaining paper, but when there is paper on the paper tray, the light from the light emitting element passes through the transparent light of the paver tray and enters the light receiving element 12. The light is blocked by the paper and does not enter the light receiving element for detecting remaining paper.1. When paper is stacked on the paver tray to the height of the focal point of the light emitting element, the amount of reflected light that enters the photodetector for stacking height detection increases, so the output of the photodetector increases; When the height is lower than the height of the focal point of the light emitting element, the amount of reflected light that enters the light receiving element for detecting the loading height decreases, so the output of the light receiving element decreases. Embodiment Next, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 4 is an internal mechanism diagram of a large-volume paper stacker equipped with a paper detection device according to the present invention. This large-volume stacker includes a carry-in unit 30, a feed unit 31, and a tray unit 3.
2 and the paper detection device I! according to the present invention.
It consists of 33. The carry-in unit 30 has a gate 3 that opens depending on the paper size.
4, a drive roller 35, and a guide plate 36, and conveys the paper discharged from the image forming device to the feed unit 31. The feed unit 31 includes a crank arm 38 rotating around a shaft 37, a feed roller 39 pivotally supported at the free end of the crank arm 38, and a driven pulley 40 coaxial with the feed roller 39.
, a drive pulley 41 that rotates around a shaft 37, a round belt 42 stretched between these pulleys 40 and 41, a drive gear 43 that rotates integrally with the drive pulley 41, a motor gear 44 that meshes with the drive gear 43, A feed motor 45, a spring 46 that presses the feed roller 39 against the paper, and an electromagnet 4 that retracts the feed roller 39 from the paper stacking surface.
7. Then, the paper carried in by the carry-in unit 30 is placed so that its leading edge is connected to the frame 4 of the tray unit 32.
The paper is conveyed by the feed roller 39 until it collides with the paper stopper 49, which is a part of the paper. The tray unit 32 has a pair of lifting wires 50 and 51 stretched between upper and lower pulleys 52 and 53 mounted on both sides of the frame 48, respectively.
A vapor tray 54 is installed horizontally between them, and the vapor tray 54 is raised and lowered by simultaneously driving these lifting wires 50 and 51 by a lifting motor 55. The entire tray unit 32 is attached to the housing 5 along the rails 56.
7 It is now possible to pull it out. Figure 1 specifically shows the paper detection device 1i33. A light emitting element 60, a light receiving element 61 for detecting loading height, and control ICs 62 and 63 are attached to a printed circuit board 59 disposed inside the cover 58, and on the bottom of the frame 48, light emitted from the light emitting element 60 is mounted. A light receiving element 6 for detecting remaining paper is mounted on the shaft 64.
5 is installed.

The light from the light emitting element 60 is projected through a lens 66, and its focal point 67 is at a predetermined position above the paper tray 54. The vapor tray 54 has a through hole 6 large enough to transmit the light from the light emitting element 60 to the light receiving element 65 for detecting remaining paper.
8 are provided. When there is no paper on the vapor tray 54, the light from the light emitting element 60 passes through the through hole 68 and enters the light receiving element 65 for detecting remaining paper.
4. If there is paper above it, it will be blocked by the paper. With this, it is possible to detect whether there is any remaining paper on the paver tray 54. In this case, the light from the light emitting element 60 is emitted from the paper tray 5.
Since the focal point 67 is focused at a predetermined position above the paper 4, the light is magnified and then enters the light receiving element 65 for detecting remaining paper, so even if the position of the light receiving element 65 for detecting remaining paper is slightly shifted, it can be sufficiently detected. The light receiving element 61 for detecting the loading height is oriented so that its light receiving optical axis 69 forms a predetermined angle e with the light emitting optical axis 64 of the light emitting element 60 and intersects at a focal point 67, as shown in FIG. Loading of paper 70 stacked on 54 ゛Top surface 7
The reflected light from the lens 1 enters through the lens 72. The amount of incident light becomes maximum when the height of the loading top surface 71 matches the height of the focal point 67. Therefore, at this time, the output of the light receiving element 61 for detecting the loading height is at a maximum of v6 as shown in FIG.
As the number of loaded sheets of paper 70 increases from this state, the output decreases, and the position of the maximum changes from the solid line waveform A to the broken line waveform B8 in the figure. Now, the number of sheets loaded is ΔY
The output of the light receiving element 61 increases to V. Suppose that the output of the light receiving element 61 decreases from V. to v1. When the vapor tray 54 is lowered until it matches again (by ΔY),
The height of the loading top surface 71 again matches the height of the focal point 67.
As explained above, according to the present invention, when there is no paper on the paper tray, light from the light emitting element is made to enter the light receiving element for detecting remaining paper through the through hole provided in the paver tray. Since the system detects when there is no remaining paper, there is no possibility of incorrectly detecting the presence or absence of remaining paper due to variations in the set position of the paver tray or tray unit, and accurate detection is possible even if there are variations. Furthermore, according to the second aspect of the invention, it is possible to eliminate erroneous detection of the loading height due to vibration of the feed roller.

[Brief explanation of drawings]

1yA is a side view of the paper detection device according to the present invention, FIG. 2 is a side view of the stack height detection state thereof, and FIG. 3 is the output of the light receiving element for stack height detection and paper stacking in the detection state. Fig. 4 is a side view of the internal mechanism of a large-volume paper stacker equipped with this paper detection device. Fig. 5 is a side view of the internal mechanism of a conventional large-volume stacker, Fig. 6 is a front view of the remaining paper detection mechanism and stacking height detection mechanism thereof, and Fig. 7 is an erroneous detection state of the remaining paper detection mechanism. Figure 8 is a side view of the loading height detection mechanism.
FIG. 9 is an explanatory diagram illustrating the vibration of the feed roller that causes erroneous detection by the loading height detection mechanism.

Claims (1)

[Scope of Claims] 1. A large-volume paper stacker that transports sheets of paper until their leading edges collide with a paper stopper and stacks them on a paper tray, detects the stacking height, and lowers the paper tray according to the detected height. A light emitting element is disposed at a predetermined position above the paper tray, and a light receiving element for detecting remaining paper is disposed at a predetermined position below the paper tray.
A sheet detection device for a large-volume sheet discharge stacker, characterized in that a through hole is provided for transmitting light from the light emitting element to the light receiving element for detecting remaining sheets. 2. The light emitting element has a focal point at a predetermined height above the paper tray, and is equipped with a light receiving element for detecting loading height, the light receiving optical axis of which intersects the light emitting optical axis of the light emitting element at a predetermined angle at the focal point. A paper detection device for a large quantity discharge stacker according to claim 1, characterized in that: