JPH0736932Y2 - Paper remaining amount detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an image forming apparatus such as a liquid crystal printer, a laser beam printer, and a copying machine to which an electrophotographic technique is applied. The present invention relates to a sheet remaining amount detection device that detects the remaining amount of sheets stacked in a cassette.

[Conventional technology]

Conventionally, in the paper detection in the paper feed cassette mounted on the image forming apparatus, the paper presence / absence detection device for detecting whether or not there is paper, and the remaining paper amount for detecting how much paper remains A sensing device is used.

FIG. 6 is a schematic view showing a conventional remaining paper amount detecting device,
In the figure, the sheets P stacked in the sheet feeding cassette 1 are sequentially sent to an image forming unit (not shown) by a sheet feeding roller 1 '. Then, for detection of the remaining amount of paper, a contact is brought into contact with the uppermost paper P in the paper feed cassette 1, and the contact is made.
The other contact also moves in conjunction with the movement to the lower side in accordance with the decrease of the electric current, and the movement of the other contact is detected by the detection circuit 2 as a change in the resistance value of the resistor R, and the output signal from the detection circuit 2 is detected. This is a device for roughly knowing the remaining amount of the paper P.
Such a device is conventionally used in a large-sized machine which has a relatively large amount of sheets to be loaded.

On the other hand, FIG. 7 shows a conventional device for detecting the presence or absence of paper. In the figure, a sheet (not shown) placed on the bottom plate 4 which is biased upward by the spring 4'in the sheet cassette 3 is conveyed by the sheet feeding roller 5 to an image forming unit (not shown) and stored therein. When all of the above-mentioned sheet has been carried out, the lever 6 that is in contact with the sheet enters into the notch 4a formed in the bottom plate 4. For this reason, the light of the photosensor 7 blocked by the lever 6 because it is present at the position indicated by the chain double-dashed line is incident on the light receiving portion from the light emitting portion (not shown), and the photosensor 7 is turned on. Is a device for detecting the presence or absence of the paper.

[Problems of conventional technology]

 The above-described paper detection device has the following problems.

First, in the sheet remaining amount detecting device shown in FIG. 6, the device itself is expensive, and since it is for roughly understanding the remaining amount of the sheet, it is not possible to accurately know the absence of the sheet (the remaining amount of the sheet is 1 The structure is more complicated and expensive to detect in units of one sheet).

On the other hand, since the sheet presence / absence detecting device shown in FIG. 7 cannot know the remaining amount of the sheet, for example, a large number of sheets are continuously printed even when the remaining number of sheets is small, and the sheet runs out in the middle. There was a problem. Therefore, conventionally, in order to accurately detect the sheet, for example, the sheet presence detecting device shown in FIG. 7 and the sheet remaining amount detecting device shown in FIG. However, there is a problem in that it also leads to a cost increase.

[Purpose of device]

The present invention has been made in view of the above-mentioned conventional problems, and enables detection of the paper in the paper feed cassette with one detection device having the functions of the paper presence detection device and the paper remaining amount detection device. It is also an object of the present invention to realize the device with a simple configuration.

[Key points of device]

According to the present invention, the above object is to provide a first displacing member that engages with a displaceable sheet stacking means and is displaced in association with the displacement of the sheet stacking means, and a sheet stacked on the sheet stacking means. A second displacing member that comes into contact with the uppermost sheet of paper and is displaced in conjunction with the displacement of the stacked sheets, a pair of a light emitting section and a light receiving section, and a single light between the light emitting section and the light receiving section. A detection member that outputs a binary signal based on whether or not the shaft is cut off, the relative displacement between one of the first and second displacement members and between the first and second displacement members. A detection member that is arranged to block the optical axis by the other displacement member according to the amount and outputs the binary signal according to the time of blocking and non-blocking; and the binary signal of the detecting member. Data processing means for calculating the remaining amount of the stacked sheets from the output time corresponding to the interruption, and the data processing means. It is achieved by providing a paper remaining amount detection apparatus characterized by comprising a notification means for notifying the paper remaining amount calculation result by the data processing means.

〔Example〕

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

FIG. 1 is an overall configuration diagram showing the sheet feeding device of this embodiment.

In the figure, the paper feed cassette 8 is housed in an image forming apparatus (not shown). The paper P is placed on the bottom plate 9 in the paper feed cassette 8.
Is placed. An end portion 10b of a lever 10 formed of, for example, metal or plastic in a V shape is brought into contact with the bottom plate 9 by a spring bias (not shown), and the other end portion 10 of the lever 10 is contacted.
A casing 11 having a photosensor inside is attached to c by, for example, welding, screwing, or the like. The lever 10
There is provided a hole 10a into which a spindle from a device body (not shown) is fitted. One end 12c of a lever 12 positioned substantially parallel to the lever 10 is inserted into the casing 11, and the other end 12b of the lever 12 is in contact with the uppermost sheet P. Like the lever 10, for example, the lever 12 is formed in a V shape with a metal or plastic, and is provided with a hole 12a into which a support shaft laterally installed in the apparatus main body (not shown) is fitted.

The end portion 12b of the lever 12 that comes into contact with the paper P is inserted into the rectangular cutout lever hole 13 formed in the bottom plate 9 when all the paper P in the paper feed cassette 8 has been conveyed and is lost. It is configured.

FIG. 2 is a cross-sectional view of essential parts showing the paper feeding device of this embodiment.
In the figure, the paper P accommodated in the paper feed cassette 8 is placed on the bottom plate 9, and the bottom plate 9 is biased upward by the spring 14 from the back surface. Above the sheet feeding port side of the sheet feeding cassette 8, there is provided a sheet feeding roller 15 which is axially supported by a device body (not shown).

FIG. 3 is a diagram showing a remaining paper amount detection circuit of the paper feeding device.
In the figure, a voltage (+ V _D ) is applied from the power source to the LED (light emitting diode) 17 via the resistor R ₁ and similarly to the phototransistor 18 via the resistor R ₂ , and when the LED 17 emits light, The light outputs the received light signal i received by the phototransistor 18 to the input I of the CPU 19.

That is, if the light from the LED 17 is blocked by the lever 12 described above, the CPU
Specifically, the received light signal i input to the input I of 19 is from 0 V to V _D
In the opposite case, 0V continues to be supplied to the input I, so that it is possible to detect whether or not the phototransistor 18 receives light.

A CPU 19 is a central processing unit that controls the operation of the entire image forming apparatus used in this embodiment, and is a ROM (Read Only Memory) 20 for storing a system program, a RAM (Random Access Memory) 21 and a display unit 22. Is connected to another. However, in the present embodiment, the connection configuration shown in the figure is shown only for the configuration necessary for controlling the sheet feeding device.

The RAM 21 stores the remaining paper amount data corresponding to the voltage V _D (high level) time included in the signal i. Then, this data is output from the output O ₁ or O ₂ of the CPU 19 to the display unit 27.

The operation of the sheet feeding device having the above configuration is shown in FIGS. First, when the paper P is fully loaded in the paper feed cassette 8 as shown in FIG. 9A, the paper feed roller 15 rotates in the direction of arrow A and contacts the uppermost paper P to feed the paper. Then, when this paper feeding is performed, the paper feeding roller 15 slightly pushes down the paper P and the bottom plate 9 against the urging force of the spring 14. As a result, the bottom plate 9
The lever 10 that comes into contact with moves slightly in the direction of the arrow around a spindle (not shown) provided in the hole 10a. At the same time, paper P
The end portion 12b of the lever 12 that abuts with moves slightly in the direction of the arrow around a spindle (not shown) provided in the hole 12a.

In this case, the positional relationship between the casing 11 and the lever 12 remains almost unchanged due to the relationship between the lengths of the levers 10 and 12 and the support shafts. Therefore, the optical axis formed by the LED 17 and the phototransistor 18 in the casing 11 is not blocked by the tip 12c of the lever 12 even if the lever 12 moves.

Therefore, at this time, the signal i input to the input I of the CPU 19 is the fifth signal
As shown in (A) of the figure, the voltage remains at 0V, and the CPU 19 judges from this signal that the paper P is sufficiently present in the paper feed cassette 8.

Next, the sheets P are successively loaded into the apparatus, and when the stacking amount of the sheets P in the sheet feeding cassette 8 decreases, the bottom plate 9 gradually moves upward, and the bottom plate 9 is placed on the bottom plate 9 as shown in FIG. 4 (b). The end portion 10b of the lever 10 that is in contact with the bottom plate 9 moves upward, and the casing 11 moves downward, conversely.

On the other hand, the end portion 12b of the lever 12 is in contact with the uppermost sheet P, so that it is kept in a fixed position. Therefore, the end 12 of the lever 12
c is close to the sensor point in the casing 11. Then, as shown in FIG. 7C, the paper feed roller 15 rotates in the direction of arrow A, and when the paper feed operation is performed, the levers 10 and 12 move as described above in FIG. The end 12c of the lever 12 that has been used is the LED 17 and the phototransistor 18 in the casing 11.
Block the optical axis created in. Therefore, the signal i at the input I of the CPU 19 becomes the voltage V _D (high level) as shown in FIG. 5C for a very short time t ₁ . CPU19 takes this time t
₁ is compared with the data stored in RAM 21, and the remaining paper amount data corresponding to the detected time t ₁ is output from O ₂
It is output to 22, and the display unit 22 displays the number of remaining sheets in the paper feed cassette 8.

Further, when the sheet feeding process is sequentially performed for each sheet, the bottom plate 9 gradually rises and the optical axis is moved to the tip of the lever 12 by the movement of the lever 12 in the arrow direction from the pressing by the sheet feeding roller 15 during the sheet feeding operation. The time during which 12c shuts off increases, and as shown in the time chart of FIG. 5, the time during which the signal i becomes the voltage V _D (high level) during the paper feeding operation gradually increases as t ₂ → t ₃ → t _4. . During this time, the display unit 22 displays the number of remaining sheets in the sheet feeding cassette 8 according to the remaining sheet data. Further, as shown in FIG. 4 (d), when all the paper P in the paper feed cassette 8 is exhausted, the lever 12 falls into the lever hole 13 of the bottom plate 9 and completely shuts off the optical axis.

For this reason, the voltage V _D (high level) continues to be input to the input I of the CPU 19, and the CPU 19 judges that the paper has run out as compared with the data in the RAM 21, and outputs the paper-out symbol from the output O ₁ to the display unit.
The data is output to 22 and the display unit 22 displays that the paper is out.

As described above, in the present embodiment, the remaining paper amount data and the no-paper data are stored in the RAM 21 in advance, and the lever 12 and the bottom plate 9 that move with the movement of the paper P when the paper feed roller 15 rotates.
The lever 10 that moves according to the position change is provided, and the remaining amount of paper and the presence / absence of the paper are detected from the time when the optical axis formed by the LED 17 and the phototransistor 18 is blocked based on the relative position of the lever 10 and the lever 12.

It should be noted that the one end portion 10b of the lever 10 may not be biased by the spring.
In that case, the lever 10 comes into contact by its own weight.

Further, instead of the casing 11 being integrated with the lever 10 to control the interruption of the optical axis by the lever 12, the casing 11 is provided on the lever 12 side and the distances from the spindles of the levers 10 and 12 are appropriately set. The optical axis may be controlled to be shut off by the lever 10.

Further, although the sensor LED 17 and the phototransistor 18 are used in this embodiment, it is needless to say that a contact switch, a reflection type switch or the like may be used.

[Effect of device]

As described above in detail, according to the present invention, it is possible to detect the remaining amount of paper and the presence / absence of paper with one device, which is advantageous in terms of cost, and the remaining or presence / absence of paper can be displayed. It is possible to provide an easy image forming apparatus.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing a sheet feeding device of the present embodiment, FIG. 2 is a sectional view of a main part of the sheet feeding device of the present embodiment, and FIG. 3 is a sheet remaining amount detecting circuit of the sheet feeding device. FIGS. 4 (a) to 4 (d) are diagrams showing the operation of the sheet feeding device of this embodiment, FIG. 5 is a time chart showing changes in sensor signals, and FIG. 6 is a conventional sheet remaining amount detecting device. FIG. 7 is a schematic view showing a sheet, and FIG. 7 is a view showing a conventional device for detecting the presence or absence of paper. 8 ... Paper feed cassette, 9 ... Bottom plate, 10, 12 ... Lever, 1
0a, 12a ... hole, 10b, 10c, 12b, 12c ... end, 11 ... casing, 13 ... lever hole, P ... paper.

Claims (1)

[Scope of utility model registration request] 1. A first displacing member which engages with a displaceable sheet stacking means and is displaced in association with the displacement of the sheet stacking means, and the uppermost position of the sheets stacked on the sheet stacking means. Second displacing member that comes into contact with the sheet of paper and is displaced in association with the displacement of the stacked sheets of paper, and a pair of a light emitting portion and a light receiving portion, and a single optical axis between the light emitting portion and the light receiving portion is blocked. A detection member that outputs a binary signal based on whether or not the first or second displacement member is present and the relative displacement amount between the first and second displacement members is determined. A detecting member that is arranged to block the optical axis by the other displacing member and outputs the binary signal according to the time of blocking and non-blocking, and the blocking of the binary signal of the detecting member Data processing means for calculating the remaining amount of the stacked sheets from the output time, and the data processing means And a notifying unit for notifying a result of sheet remaining amount calculation by the sheet remaining amount detecting apparatus.