JPH0729060Y2 - Cassette size detector - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an image forming apparatus such as an electrophotographic copying machine and various printers, and more particularly, to a size detecting device for a paper cassette that stores paper used in the image forming apparatus. It is about.

[Prior art]

In image forming apparatuses such as electrophotographic copying machines and various printers,
For example, sheets of various sizes are used to transfer the toner image formed on the photosensitive drum. For example, A3 size, B4 size, A4 size, B5 size, legal size,
Various types of paper such as letter size and postcard size are used,
These sheets are stored in a sheet feeding cassette having protrusions at different positions depending on the sheet size, and are used one by one.

For detecting the size of a conventional paper feed cassette, when the paper feed cassette is mounted on the image forming apparatus, a push switch is provided at a position where the protrusion provided on the above-mentioned paper feed cassette abuts, and the paper feed cassette is mounted. When the protrusion turns on the push switch, the detection unit detects the cassette size based on the on / off signals from the push switch.

[Problems of conventional technology]

Since the push switch used in the conventional paper cassette size detecting device as described above has a short switching stroke for switching on / off, the dimensional accuracy of the protrusion or the mounting position accuracy of the paper cassette is high. Otherwise, false detection of the cassette size will occur.

For example, although the push switch must be turned off, on, and on due to the protrusion provided at the predetermined position, the central push switch cannot be turned on due to the dimensional error of the protrusion and so on. If detected, the wrong cassette size will be detected.

In order to prevent such an erroneous detection of the cassette size, it is necessary to raise the mounting position accuracy of the paper feed cassette more than necessary, or to adjust the positions of the protrusion and the push switch individually. . However, doing so also causes an increase in the cost of the device.

[Purpose of device]

In view of the above-mentioned conventional drawbacks, the present invention makes it possible to surely detect the cassette size to be used even if the mounting position of the paper feed cassette is slightly displaced, and provides a very inexpensive multi-stage cassette size detection device. The purpose is to do.

[Key points of device]

In order to achieve the above-mentioned object, the present invention provides a cassette size detecting device for detecting the size of a paper cassette mounted in an image forming apparatus, wherein a first light emitting element group provided in the first paper cassette and having a plurality of light emitting elements. A plurality of second light emitting element groups provided in the second paper cassette, and a first light receiving element provided in the apparatus main body and facing the first light emitting element group when the first paper cassette is mounted. Group, a second light receiving element group provided in the apparatus body and facing the second light emitting element group when the second sheet cassette is mounted, and a first sheet cassette mounted in the apparatus body By attaching the first power supply terminal for supplying power to the first light emitting element group provided in the first paper cassette and the second paper cassette provided in the apparatus main body to the second power supply terminal.
Second power supply terminal for supplying power to the second light emitting element group provided in the paper cassette, and control means for supplying a signal to one terminal of the first light receiving terminal group by switching between high and low. Inversion means for inverting and supplying the signal to one terminal of the second light receiving element group, and the one of the predetermined light receiving elements of the first light receiving element group and the second light receiving element group. A plurality of input lines for connecting the other terminals to the terminals to input to the control means, the control means,
It is possible to detect the sizes of the first paper cassette and the second paper cassette based on signals output by switching the signal to a high signal and a low signal and outputting the signals according to the switching timing. Characterize.

[Example of device]

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

FIG. 1 is a cross-sectional view of a cassette size detecting device according to the first embodiment in a state in which a paper feed cassette is mounted, and this cassette size detecting device is provided in a paper cassette mounting portion. In the figure, the paper cassette loading section is provided in two upper and lower stages, and the upper paper cassette loading section 1 has a paper feed roller 1
a, a paper sensor 1b, and a power supply terminal 1c are provided, and the lower paper cassette mounting portion 2 is provided with a paper feed roller 2a, a paper sensor 2b, and a power supply terminal 2c.

The paper cassettes 3 and 4 mounted in the upper and lower paper cassette mounting portions 1 and 2 have the cross-sectional shapes shown in FIG. That is, the front side plates 3a and 4a of the paper cassettes 3 and 4, respectively.
Holes 3a 'and 4a' are formed in the lower part of the LED, and LEDs (light emitting diodes) 5 and 6 are formed inside the holes 3a 'and 4a'.
Is provided. Further, as shown in FIG. 2 which is a perspective view of the paper cassettes 3 and 4 from below, the LED 5 or 6 is used.
Are selectively provided in the three holes 3a 'provided in a row. Further, the positional relationship between the LEDs 5 and 6 and the paper sensors 1b and 2b is set such that the light emitted from the LEDs 5 and 6 respectively enters the phototransistors described later in the corresponding paper sensors 1b and 2b. There is. The power supply terminal and the ground terminal of the LED 5 are connected to the lands 9a and 9b through wiring of a pattern (not shown) provided on the substrate 7. Further, when the paper cassette 3 is mounted on the upper paper feed cassette mounting portion 1, the above-mentioned power supply terminals 1c come into contact with the lands 9a and 9b. Similarly, the power supply and ground terminal of LED6 are the substrate 8
Is connected to the lands 9a 'and 9b' through pattern wiring provided on the lower side paper cassette mounting portion 2 and the above-mentioned power supply terminal 2c is connected to the lands 9a 'and 9b'. It is the structure which abuts.

The paper in the paper cassette 3 is sent to the transport roller 14 via the carry-out guide plate 1d by the rotation of the paper feed roller 1a, and the paper in the paper cassette 4 is carried out by the rotation of the paper feed roller 2a.
It is configured so that the toner image is sent to the carrying roller 14 via the sheet and is then used for transfer of the toner image and the like.

On the other hand, each of the above-mentioned paper sensors 1b and 2b is provided with three phototransistors as described later, and each phototransistor is a CPU (central processing unit) in the image forming apparatus.
It is connected to the.

FIG. 3A is a diagram showing this circuit diagram. A to C shown in the figure are phototransistors provided in the paper sensor 1b, and A'to C'are phototransistors provided in the paper sensor 2b. Phototransistors A to C, A '
˜C ′ are signal lines l ₄ and l ₅ to which a signal output from the output terminal O ₀ of the CPU 10 is inverted by the inverter 11 or a signal inverted by the inverter 12 and the input terminal I _{1 of the} CPU 10. is a matrix disposed between the signal line l ₁ to l ₃ connected to ~I _3. The other end of the signal line l ₁ to l ₃ via a resistor R ₁ to R ₃ each corresponding is grounded. Since the pull-up resistor R ₀ and the dip switch 13 are connected to the input terminal I _{0 of the} CPU 10 and the other end of the pull-up resistor R ₀ is connected to the power supply (V _cc ), the normal input terminal I ₀ is High signal ( _Vcc )
However, when the dip switch 13 is turned on, the input terminal I ₀ is connected to the ground and a low signal is supplied. As will be described later, the dip switch 13 is selected depending on the destination of the image forming apparatus using the cassette size detecting device. It is a specification.

On the other hand, as an example of this embodiment, the paper cassette 3 is a cassette for vertically storing letter size paper, and the circuit configuration of the substrate 7 in the paper cassette 3 is three as shown in FIG. 3 (b). LEDs 5a to 5c and LEDs provided in all holes 3a '
Is a resistor R ₄ to R ₆ which are connected to the bodies 5a to 5c, LED 5a via the feed terminal 1c to the aforementioned lands 9a, abuts on 9b (connection)
~ 5c is connected to power and ground.

The paper cassette 4 is a cassette for storing B4 size paper, and the circuit configuration of the substrate 8 in the paper cassette 4 is provided in two holes 3a 'on the left and right as shown in FIG. 3 (c).
LEDs 6a, 6c and respective LEDs 6a, is a resistor R _7, R ₈ connected to 6c, LEDs 6a via the feed terminal 2c to be connected to the above-described land 9a ', 9b', 6c is connected to the power supply and ground There is.

In the paper size detection device configured as above, CP
The paper size detection operation by U10 will be described below. However, in this embodiment, the dip switch 13 is turned off and the case of Japanese specifications is shown. First, the paper cassette 3 in which letter-size paper is stored is mounted in the upper paper cassette mounting portion 1 as described above. When the paper cassette 3 is mounted at a predetermined position, the power supply terminal 1c contacts the lands 9a and 9b of the board 7, and the current from the power supply _Vcc causes the power supply terminal 1c → land 9a → resistance as shown in FIG. 3 (b). through R ₄ ~R _6, LED5a~5
It is supplied to c, and LEDs 5a to 5c light up. This light has 3 holes
The light is emitted from 3a ', enters the phototransistors A to C arranged at the position facing the hole 3a', and turns on the phototransistors A to C. From the output terminal O ₀ of CPU 10 are output the high signal / low signal at a predetermined cycle, CPU 10 at the timing when the low signal is outputted, a high signal through the inverter 11 is signal line l ₄ → phototransistor A~ C → Check if the signal is output to the input terminals I _{1 to} I ₃ via the signal lines l _{1 to} l ₃ . At this time, since the phototransistors A to C are all in the ON state, the light emitted from the LEDs 5a to 5c surely turns on the phototransistors A to C, and a high signal is input to all the input terminals I _{1 to} I ₃ , and the CPU 10 in the state of the dip switch 13, based on an input signal of the input terminal I ₁ ~I _3, to determine the paper size in the mounted paper cassette 3 in accordance with a first table shown below.

That is, in this case, a high signal is input to all of the input terminals I _{1 to} I ₃ (however, in Table 1, the high signal is indicated by “1”,
Since the low signal is indicated by "0"), it is determined that the paper cassette 3 for storing the letter size paper is installed. Moreover, as described above, in the state of the input terminal I ₀ , since the dip switch 13 is off, the input signal to the input terminal I ₀ is a high signal, and the cassette in which letter size paper is vertically loaded is loaded. Can be confirmed.

After that, the CPU 10 outputs data indicating that the paper cassette 3 used for vertically using letter size paper is mounted in the upper paper cassette mounting unit 1 to a display unit (not shown), and the paper cassette loaded by the operator is displayed. Tell the kind.

Next, as described above, the paper cassette 4 accommodating the B4 size paper is loaded into the lower paper cassette loading portion 2. When the paper cassette 4 is mounted at a predetermined position, the power supply terminal 2c abuts on the lands 9a 'and 9b' of the substrate 8, and as shown in FIG. 3 (c), the current from the power supply _Vcc is transferred to the power supply terminal 2c → land. 9a '→
Through a resistor R _7, R _8, and supplies LEDs 6a, to 6c, lit LEDs 6a, the 6c. This light is emitted from the left and right holes 3a 'except the hole 3a' in the center and enters the phototransistors A'and C'arranged at the positions facing the holes 3a ', turning on the phototransistors A'and C'. To do.

The high signal / low signal is output from the output terminal O _{0 of the} CPU 10 at a predetermined cycle as described above, and at the timing when the high signal is output, the high signal via the inverters 11 and 12 is transferred to the phototransistors A ′ to C. 'Is output to the collector.
At this time, since the phototransistors A ′ and C ′ are in the ON state due to the incidence of the light, the high signal is output to the input terminals I ₁ and I _{3 of} the CPU 10 and the low signal is output to the input terminal I ₂ .
In the CPU 10, the state of the DIP switch 13 as described above,
Based on the input signals from the input terminals I _{1 to} I ₃ , the size of the loaded paper cassette 4 is determined according to Table 1. In this case, it can be accurately determined from Table 1 that the paper cassette 4 for storing B4 size paper is installed.

In this case, since the DIP switch 13 is on in the US and European specifications, the input signal is input to the input terminal I ₀ as a low signal, and it is determined that the letter size paper is used in the horizontal specification.

By operating the circuit as described above, the CPU 10 can accurately detect the size of the paper cassette without causing erroneous detection, as in the conventional case.

FIGS. 4 (a) and 4 (b) are circuit diagrams showing a second embodiment of the present invention. The difference from the above-mentioned embodiment is that two or three lands of the paper cassette are provided and the land for grounding is provided. 15 is a predetermined position, and the other one or two lands 18 are connected to the feeding terminals 16a to 16d.
Is provided at a proper position where the LED contacts, and a signal of 10 KHz or 20 KHz is supplied from the oscillation circuit 17 to the LEDs 19 and 20. In this case, by changing the connection configuration of the land 18 and the power supply terminals 16a to 16d as shown in FIGS.
Different kinds of states can be created for the LEDs 19,20. For example, in the state of FIG.
The LED19 emits light with the frequency of
Emits light with a frequency of 20 KHz, and the LED 20 is not lit. In addition, 9 kinds of states can be created including non-lighting of LED19,20. Therefore, 10KHz light emission from LED19,20, 20K
Phototransistor detects the state of Hz light emission and non-lighting, and CP
By judging with U, it is possible to detect the cassette size with two LEDs and phototransistors for each paper cassette mounting portion.

Further, FIG. 5 is a circuit diagram showing a third embodiment of the present invention. In this case, in addition to the LED 22 connected to the resistor R ₉ , an oscillation circuit 21 is built in the paper cassette 23. .
Then, by using the paper cassette 23 in which the capacity of the capacitor 21a is different for each paper size to be stored and supplying the power _Vcc through the lands 24a and 24b, the frequency from the LED 22 for each paper cassette 23 is supplied from the oscillation circuit 21 to each paper cassette 23. The phototransistor emits light of different frequencies, and the CPU uses the detection signals of different frequencies from the phototransistor to detect the paper cassette.
It is to judge the size of 23.

Note that the present invention is not limited to the above embodiment, and a cassette size detecting device may be configured by providing one photosensor having a different sensitivity depending on the wavelength for each paper cassette mounting portion and using LEDs having different emission wavelengths for each size. good. Also, in the first embodiment, the lighting of the LED may be modulated. In particular, if the LED lighting is modulated, malfunction due to ambient light can be further prevented.

[Effect of device]

As described in detail above, according to the present invention, even if the mounting position of the paper cassette is slightly deviated, the accurate cassette size can be detected, and the mounting position accuracy of the paper cassette can be rough.

In addition, unlike the push switch, the present invention can detect the cassette size without any mechanical operation, so that it is not necessary to consider damage to the switch.

Further, since the single output terminal of the CPU can be used as the upper and lower cassette detection signals, the detection circuit can be constructed at extremely low cost.

[Brief description of drawings]

FIG. 1 is a sectional view of a cassette size detecting device according to the first embodiment, FIG. 2 is a perspective view of a paper cassette used in the cassette size detecting device according to the first embodiment, and FIGS. 3 (a) to 3 (c). Is a circuit diagram of the cassette size detecting device of the first embodiment, FIGS. 4 (a) and 4 (b) are circuit diagrams of the cassette size detecting device of the second embodiment, and FIG. 5 is the third embodiment. 2 is a circuit diagram of the cassette size detection device of FIG. 1,2 …… Paper cassette mounting part, 1c, 2c, 16a to 16e …… Power supply terminal, 3,4,23 …… Paper cassette, 5,6,19,20,22 …… LE
D, 7,8 ... substrate, 9a, 9b, 9a ', 9b', 15,18, ... land,
17,21 …… Oscillation circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kenzo Itoh Kenzo Ito 2-229 Sakuragaoka, Higashiyamato-shi, Tokyo Casio Electronics Co., Ltd. (56) References JP-A-60-67337 (JP, A) JP-A-SHO 62-180827 (JP, A)

Claims (1)

[Scope of utility model registration request] 1. A cassette size detection device for detecting the size of a paper cassette mounted in an image forming apparatus, comprising: a first paper cassette, a plurality of first light emitting element groups, and a second paper cassette. A plurality of second light emitting element groups provided in the apparatus main body, a first light receiving element group provided in the apparatus main body and facing the first light emitting element group when the first paper cassette is mounted, and the apparatus main body A second light receiving element group that is provided in the apparatus main body and faces the second light emitting element group when the second sheet cassette is mounted, and the first sheet cassette that is provided in the apparatus main body by mounting the first sheet cassette. A first power supply terminal for supplying power to the first light emitting element group provided in the cassette, and a second power supply terminal provided in the second paper cassette by mounting the second paper cassette provided in the apparatus main body. A second power supply terminal for supplying power to the light emitting element group, a control unit for supplying a signal to one terminal of the first light receiving element group by switching between high and low, and one terminal of the second light receiving element group Inverting means for inverting and supplying the signal to the first light receiving element group and the second light receiving element group, and connecting the other terminal to the one terminal of each predetermined light receiving element of the second light receiving element group. A plurality of input lines for inputting to the control means, wherein the control means switches the signal to a high signal and a low signal and outputs the signal, and based on a signal input from the plurality of input lines according to the switching timing. A cassette size detecting device for detecting the sizes of the first paper cassette and the second paper cassette.