JPH0473134B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Technical Field> The present invention relates to a detection device for detecting document size.

<Prior Art> In an electrophotographic copying machine or the like, when copying an original to be copied, it is possible to detect the original size and automatically select and feed the copy paper size. In addition to automatically selecting the paper size and feeding the paper, the document size is also detected prior to copying in order to automatically set the magnification.

Conventional document size detection devices arrange light-emitting and light-receiving elements according to the size of each document placed on a document table, and detect reflected light or transmitted light from the document at the light-receiving element. It receives light and performs size detection according to the light receiving state of this light receiving element. In this case, all the light-emitting elements and the light-receiving elements are driven simultaneously, and each output of the light-receiving element is applied to a comparator via a respective amplifier and converted into an original presence/absence signal. The outputs of these comparators are temporarily stored in a latch circuit or the like, and the size of the original is determined according to the state thereof, and it is sent to the copy control circuit. This naturally requires an individual amplifier and comparator for each light-receiving element, which not only complicates the circuit but also increases cost.

<Objective> An object of the present invention is to enable document size detection using a simple circuit.

Further, the present invention provides a document size detection device that is inexpensive in terms of cost.

Particularly, the present invention provides a device for detecting the document size using one comparator.

<Example> FIG. 1 is a diagram showing a circuit configuration for detecting the document size in the present invention, and in the figure, LD ₀ ,
LD ₁ ...LD _N is a light emitting diode, PD ₀ , PD ₁ ...
PD _N is a photodiode. light emitting diode
LD ₀ and photodiode PD ₀ form a pair and are provided specifically to detect the open/closed state of the document cover for pressing the document. Light emitting diode LD ₁
~LD _N and its corresponding photodiode PD ₁
~PD _N is arranged according to the size of the original placed at a specified position, and serves to detect the original size.

Examples of the actual arrangement positions of each of the light emitting diodes LD and photodiodes PD are shown in FIGS. 2 and 3. In the figure, reference numeral 1 is an original platen made of a transparent glass plate, which is installed on the top of the copying machine body, and 2 is an original platen plate 1, which is pivotally supported at one end of the copying machine main body.
A document cover 3 is provided to be openable and closable, a document 3 is placed at a prescribed position on the document table 1, and a sensor 4 is arranged according to the size of the document and detects the presence or absence of the document. As explained above, this sensor 4 is composed of light emitting and photodiodes LD and PD.

The document cover 2 is provided with a reflection plate 5 that is interlocked with opening and closing operations. Reflector plate 5 is provided separately from document cover 2, reflects light from light emitting diode LD of sensor 4, and is formed in a size that does not cover document table 1.
Further, although the reflector 5 is configured to open and close following the opening and closing of the document cover 2, if it is opened and closed by more than the angle θ, it will remain at the angle θ even if the document cover 2 is opened by an angle greater than that. It is configured to be When the document cover 2 is closed, the reflector 5 maintains the angle θ until the document cover 2 reaches a certain angle, and thereafter closes as the document cover 2 closes.

With respect to the reflector 5 configured as described above, the sensors 4 are arranged at positions unrelated to optical scanning during image exposure, corresponding to the size of each document placed on the document table 1. In particular, the arrangement is such that the light from the light emitting diode LD of the sensor 4 is reflected by the reflecting plate 5 when the reflecting plate 5 is opened and is received by the photodiode PD. That is, by opening the reflection plate 5 at a predetermined angle θ, the light from the light emitting diode LD is reflected by the reflection plate 5 via the document table 1, and an optical path is set to be guided to the photodiode PD.
Therefore, the reflecting plate 5 constitutes an optical path setting means for setting the optical path of the sensor 4 by being opened at a predetermined angle θ as described above. In particular, the light emitting diode LD ₀ detects the opening and closing of the document cover 2 and is provided at a position unrelated to the document placed on the document table 1, and a photodiode PD ₀ for light reception is placed correspondingly. has been done. Furthermore, the light emitting diode LD ₁ is used to detect, for example, a B5 size document on the document table 1, LD ₂ is used to detect an A4 size document, LD ₃ is used to detect a B4 size document, and LD ₄ is placed to detect A3 size documents. Photodiodes PD ₁ -PD _N for receiving light are arranged corresponding to each of these light emitting diodes LD ₁ -LD _N with a reflecting plate 5 interposed therebetween.

The sensor 4 that detects the placed original 3 includes a light emitting diode LD and a photodiode as shown in FIG.
The PD is connected to a control element 6 which is a one-chip microcomputer. Each of the cathode terminals of the light emitting diodes LD ₀ to LD _N is connected to each output terminal D of the control element 6 via a driving inverter 7, and the cathode terminal is grounded via a resistor. Further, each cathode terminal of the photodiodes PD ₀ to PD _N is connected to the output terminal A of the control element 6, respectively. The anode terminals of the photodiodes PD ₀ to PD _N are commonly connected and connected to one terminal of a comparator 9 via a filter circuit 8 . The other input terminal of the comparator 9 is a variable resistor 1 for level adjustment to supply the reference signal.
0 _-0 to 10 _-N are connected. This variable resistor 10 _-1 to 10 _-N is connected to each photodiode PD ₀ to
A photodiode is provided corresponding to PD _N.
The signal supplied to the input terminal of the comparator 9 is adjusted so that when the PD receives light from the light emitting diode LD, the output of the comparator 9 is inverted from "L" to "H". One ends of the variable resistors 10 _-1 to 10 _-N are commonly connected to the input terminal of the comparator 9, and the other ends are connected to the output terminal B of the control element 6.

The output of the comparator 9 is the output of the control element 6.
S Applied to the _1N input terminal. When the control element 6 inputs, for example, a signal when a document is placed to the _S1N input terminal, it specifies a specific area of the memory section (RAM) and sets that area. That is, the control element 6 is
Drives the light emitting diodes PD ₀ to PD _N in a time division manner,
It is determined via the comparator 9 according to the output state of the photodiode LD, which is a light receiving element corresponding to the light emitting diode being driven, and the state is stored in the storage area corresponding to each photodiode LD. The control element 6 is a light emitting diode PD ₀ ~
When all drive scanning of PD _N is completed, the output status of each photodiode LD ₀ to LD _N is stored in the corresponding storage area, so the document size is determined based on the stored information and the output terminal C outputs a size signal. Here, if the original is placed in the specified position, the light from one of the light emitting diodes LD will illuminate the original 3.
Since the light is blocked by the photodiode PD, the output from the photodiode PD becomes an "L" signal via the comparator 9, and this signal causes the photodiode PD to
A storage area corresponding to the size will be set. Therefore, the document size can be determined according to the information stored in the size storage area.

FIG. 4 is a flowchart showing an example of the control procedure of FIG. 1 according to the present invention, and the control procedure of the present invention will be explained in detail below according to this flowchart. After the copying machine is powered on or in a standby state after all copying operations have been completed, a control operation by the control element 6 for detecting the size of the document starts as shown in the flowchart of FIG. 4. First, in step S1, all the light emitting diodes are turned off, that is, in a non-emitting state. Then, in step S2, the control element 6
The size output of output terminal C stops, and in S3, j indicating the buffer (hereinafter referred to as memory) number, which will be described later, is set to "0", and all from memory o to memory m corresponding to this memory number are cleared. do.
This memory has a storage section corresponding to each photodiode PD ₁ to PD _N. For example, if the photodiode PD ₁ is not irradiated with light because it is shielded from light by an original, the photodiode PD ₁ is not irradiated with light. Corresponding storage units are set, and in particular, m memories are prepared.

Next, the process advances to step S4, and the timer means T is set to "0".
By setting the timer means T, time counting is started. and,
If timer T counts the time corresponding to Ta, then
Proceed from S5 to S6. This time Ta is set to, for example, a time during which the detection operation by the control element 6 becomes stable. Therefore, timer T becomes “0” after Ta time.
is reset, and the counting operation starts again, and at the same time, a signal for causing the light emitting diode _PD0 to emit light is output from the output terminal D of the control element 6. That is, the output of _D0 of the output terminal D becomes, for example, "H", and only the light emitting diode _PD0 is driven. Further, A ₀ and B ₀ of output terminals A and B are set in order to drive a photodiode LD ₀ and a level adjustment resistor 10 _-N corresponding to this light emitting diode.

As mentioned above, the light emitting diode LD ₀ is driven,
If the document cover 2 is open, the light from the LD ₀ is received by the photodiode PD ₀ via the reflection plate 5, so the input terminal S _1N of the control element 6 is set in step S8. Then, proceed to step S9. That is, when the light from the light emitting diode LD _{0 reaches the photodiode PD 0 ,} the output of the comparator 9 becomes "H", and by inputting that signal to the input terminal S _1N , the control element 6 performs the step as S _1N set. Move on to S9. However, when the document cover 2 is closed, the light emitting diode LD ₀
The light is not received by the photodiode PD ₀ , and the input terminal S _1N receives an “L” signal from the comparator 9.
Since the signal is input, the process advances from step S8 to step S23. In this step S23, it is determined whether or not the α flip-flop, which is reset when all the reading operations of the detected information on the document are completed, is in the reset state. In this case, since the α flip-flop has not been reset, step S4
Return to and repeat the operations described above. In other words, the above-described operation is repeated until the document cover 2 is opened. In addition, in step S7, it _is determined whether or not _the timer T has counted the time Tb.
It counts the number of times when a stable state is reached.

Next, when opening of the document cover 2 is detected as described above, control for detecting the size of the document 3 placed on the document table 1 is executed. First, in step S9, the signal output C indicating the document size is set to "0", that is, the output of the document size signal is stopped.
Then, the light emitting diode LD ₀ is turned off, and i indicating the number of the next light emitting diode LD ₁ is set to "1". Then, the process advances to step S11, where the timer T is set to "0" and starts counting time again.
The light emitting diode LD _i or LD ₁ is driven. Also, a photodiode PDi (PD ₁ here) and a variable resistor 1 corresponding to this light emitting diode LD _i
To put 0 _-i , 10 _-1 into operation, Ai, A ₁ and Bi, B ₁ of output terminals A and B are set.

After driving the light emitting diode LD ₁ , it is determined in S12 whether or not the timer T has finished counting the time Tc, and after counting the time Tc, the process proceeds to step S13, where it is determined whether a signal is input to the input terminal _S1N . be exposed.
In this step S12 as well, as in S7, it is determined whether the light emitting diode _LD1 and the photodiode _PD1 are in a stable state, and then the input state of _S1N in S13 is determined. Therefore, in S13, if the output of the comparator 9 is "H", it is assumed that the input terminal _S1N is set, and the step
Proceed to S14 and reset the size i. In other words, if document 3 is not placed, the light emitting diode
The light from LD ₁ passes through the reflector 5 to the photodiode.
The light is received by PD ₁ , and the output of comparator 9 is “H”
and is input to input terminal S _1N . This results in
A predetermined area i in the RAM of the control element 6 is reset to indicate "no document". If there is a document, the photodiode PD ₁ does not receive the light, and an "L" signal is input to the input terminal S _1N , and the process moves to step S15, where the photodiode PD 1 does not receive the light.
The size area i corresponding to the diode PD ₁ is set as document "present".

After setting or resetting the specific size area corresponding to the photodiode PDi, the currently operating light emitting diode LD _i is turned off, and the next light emitting diode is turned off.
In order to drive LD _i , the number i is set to i+1. Then, in S17, it is determined that i>n, but
Here, if all the driving scans up to the light emitting diode LD _o have been completed, i will be larger than N, but
Otherwise, the process returns to S11 and the operation for detecting the presence or absence of the document 3 described above is performed using the next light emitting diode LD _i+1.
and is repeated. When all the operations for detecting the document 3 are completed, the process moves from S17 to S18, and each photodiode PD ₁ is stored in the j-th memory j.
All the data of the size area in which document detection information in scanning up to PD _N is temporarily stored is transferred.
Therefore, memory j consists of photodiodes PD ₁ ~ _{PD N}
It has N storage sections up to N, and stores document detection information corresponding to each photodiode.

After transferring the data to the above memory j, in S19
=m is determined. This is to determine whether all the information has been transferred to the m memories since the document cover 3 was opened. If the information has not been transferred to all the memories, the process moves to S21 and specifies the next memory. Therefore, j+1 is executed and the α flip-flop is reset. After this reset, the process returns to step S4, and after confirming that the document cover 3 is open, the process proceeds to step S9, where each photodiode PD 1 checks whether there is a document 3 placed on the document table ₁ . ~ PD _N is detected, and each detection information is temporarily stored in a corresponding size area. Then, the process moves to S18, and the data of the temporarily stored size area is transferred to the jth memory. Repeat this operation each time, and once the information has been transferred to all m memories, set j indicating the memory number to "0" in S20, and move to the 0th (or 1st) memory number. memory will be specified. Information has already been transferred to this 0th (wait for 1st) memory, but new information will be transferred after the presence or absence of the document 3 is detected.

When the document cover 2 is closed during the above operation,
Proceed from S8 to S23. However, even if the document cover 2 is closed, while the operations from step S9 onwards are being executed, the scanning up to the light emitting diode LD _N is completed, and all the detection information of the corresponding photodiode PD _N is stored in the memory j. After being transferred, the step
The process moves to S8, and detection of opening/closing of the document cover 2 is performed.
At this time, the j-th memory is designated as having stored the information transferred m times before. Then, the process moves from S8 to S23, and after the reset state of the α flip-flop is confirmed, the α flip-flop is set. Subsequently, in step S25, the set state of the area storing the detection state of the photodiode _PD1 in the j-th memory is confirmed. Here, if the information that the document 3 was detected is stored, that area has been set, and the process advances to the next step S26, where the stored information corresponding to the photodiode PD ₂ is confirmed.

Now, if the sequence progresses from S25 to S26 to S27 to S28 and all of the j-th memory are in the set state, the incident light from PD ₁ to _{PD 4} will be blocked by the original 3 as shown in Figure 2. In this state, it is assumed that the document size is A3, and the process proceeds to step S31, where a signal indicating the A3 size is sent from the output terminal C to the control circuit of the main body of the copying machine. Or S25→S26→S27→S28
→, and if it is in the reset state at step S28, it means that only photodiode PD ₄ has received light, and all others are in the set state, so the process proceeds to step S32 with the size of document 3 set as B4, and output. Terminal C
A signal indicating B4 is output.

Further, the process proceeds in the order of S25→S26→S27, and if in step S27 the area corresponding to the photodiode PD ₃ of the j-th memory is in the reset state, the process moves to S29 and similarly to step S28, the area corresponding to the photodiode PD ₄ is in the reset state. A storage state is determined. in this case,
If the set state is confirmed in S25→S26 and the reset state is confirmed in S27, it is assumed that the document is in the reset state in S29 as well, and the process proceeds to S33. That signal is output. However, for some reason,
If the area corresponding to phototransistor PD ₄ in the memory is set, it is determined that the original is placed incorrectly or that there are multiple originals placed, and the process returns to step S2, and the output terminal is C
Therefore, the document size signal is not output.

Furthermore, when proceeding to S25 → S26 → S30, if the original is B5 size, only the area corresponding to photo diode PD ₁ is set, and all others are in the reset state, so proceed to S34. A signal indicating the B5 size will be output from the output terminal C. However, in S30, if the areas corresponding to the photodiodes PD ₃ and PD ₄ of the memory are in the set state, the process returns to step S2 as a defective state as in S29. Further, in step S25, if the area corresponding to the photodiode _PD1 of the j-th memory is in the reset state, it is determined that there is no original 3 or the original is not placed in the normal position, and the process returns to S2.
No size signal is output from output terminal C. As described above, the area surrounded by the broken line is the flow for determining the document size based on information on detecting the presence or absence of a document.

The original size signal from the output terminal C of the control element 6 is sent to the control circuit on the copying machine main body side, as described above. Based on the original size signal, the control circuit automatically selects and feeds paper that matches the original size in the same-size copy mode. Here, in the present invention, the photodiodes PD ₁ to
Once all of the PD _N document detection information has been memorized, that information is transferred to memory. A plurality of memories are prepared, and information from the latest information to the previous m pieces of information is stored in the memory. Furthermore, the information stored in the memory m pieces before is used for checking the document size. In particular, when document detection information is stored in a single memory in one memory, it is possible that the document detection information may be captured during unstable opening/closing operations of the document cover 2. By importing new data each time, storing new data each time, and determining the document size based on the m previous information, the above-mentioned unstable factors can be eliminated and accurate document size information can be provided.

As shown in the time chart of FIG. 5, while the document cover 2 is open, even with the period Tα,
The presence or absence of a document is repeatedly detected by the light emitting transistors LD ₁ to LD _N and the like, and the detection information is stored or updated each time. Even when the document cover 2 is closed, the size signal is not output from the output terminal C in that state, and the size signal is not output from the output terminal C after confirming the closed state of the document cover 3 during drive scanning of the light emitting diode LD ₀ . ,
Outputs the original size signal. Therefore, it can be seen that accurate document size information can be output.

According to this embodiment, m memories are prepared and the document size is determined based on the document detection information stored m times ago. However, the document size is determined using all m memories. may be determined. For example, if the status of the same area in each memory is all the same, it is possible to output a more accurate document size by outputting that information as correct, or by using the information with a certain probability that has more information. can.

<Effects> According to the document size detection device of the present invention, sensors consisting of light-emitting and light-receiving elements are provided corresponding to the size of the placed document, and these sensors are scanned and driven in a time-division manner to detect the light-receiving elements. Since the detection information based on all scans is temporarily stored and the document size is determined based on this stored information, only one comparator is required to compare the signals from the light receiving element, making the entire circuit extremely simple. Not only that, but also significant cost reductions can be expected.

Since it is sufficient that the document cover is opened by a predetermined angle or more, the document size can be accurately detected without being affected by the opening/closing operation of the document cover.

[Brief explanation of the drawing]

FIG. 1 is a circuit configuration diagram for detecting the size of a document according to the present invention, FIG. 2 is an external perspective view of a copying machine showing an arrangement example of a sensor for detecting a document according to the present invention, and FIG. 3 is a sectional view of FIG. 2. , FIG. 4 is a flowchart showing the control procedure of FIG. 1, and FIG. 5 is a time chart. 1... Original table, 2... Original cover, 3... Original, 5... Reflector, 6... Control element, 9... Comparator, LD, LD ₀ ~ _{LD N} ... Light emitting diode,
PD, PD ₀ ~ PD _N ... photo diode.

Claims (1)

[Scope of Claims] 1. A document cover that can be opened and closed to cover a document placed on a document table provided at the top of the copying machine body, and a plurality of sensors consisting of light emitting and light receiving means arranged according to the size of the document. and is provided separately from the document cover so as to be openable and closable, and when the document cover is opened at a predetermined angle or more in conjunction with the opening/closing operation of the document cover, the document cover is maintained at a predetermined angle, and this angular state is maintained at a predetermined angle. so that the original placed on the original platen is detected via the original platen,
an optical path setting means configured to set an optical path for guiding light from the light emitting means to the light receiving means; and scanning the plurality of sensors in a time-divisional manner while the optical path setting means is opened at the predetermined angle. a driving means; and 1 for determining document detection information from the light receiving means of each sensor, which is driven and scanned in a time-division manner.
a memory means for storing document detection information obtained by the comparison means in association with each sensor; and a storage means storing information related to the fact that the document cover is closed below the predetermined angle. A document size detection device comprising: a determining means for determining the document size based on document detection information obtained by time-division drive scanning of all sensors.