JP4143428B2 - Sheet material type detection device, image forming apparatus, and sheet material type detection method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sheet material type detection apparatus that detects the type of a sheet material.
[0002]
[Prior art]
Recently, there has been a tendency to increase the types of paper used in image forming apparatuses such as copiers, printers, and fax machines. Along with this, sheet material type detection devices for detecting the type of sheet material have attracted attention. ing.
[0003]
Also, a method for discriminating the type of sheet material is disclosed (for example, see Patent Documents 1 and 2).
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 11-314443 [Patent Document 2]
US Pat. No. 6,097,497
In the technologies described in these patent documents, some numerical code or symbol is attached to the sheet material in advance (hereinafter referred to as “marking method”), and the number is detected by a sensor provided in a printer or a copying machine. This is a technology that reads information such as a code, and the printer uses this information to optimize the print mode.
[0006]
[Problems to be solved by the invention]
However, in the above marking method, the type of a sheet material that is not attached with a numeric code or the like cannot be determined.
[0007]
Therefore, an object of the present invention is to provide a sheet material type detection device that can output information on the type of sheet material even when information such as a numeric code is not attached to the sheet material in advance. is there.
[0008]
[Means for Solving the Problems]
The present invention has been made based on the finding that when an impact is applied to a sheet material by an impact application member, the degree of rebound varies depending on the sheet material.
[0009]
And the sheet material type detection device according to the present invention is the sheet material type detection device for detecting the type of the sheet material, an impact applying member bound by the sheet material, and a sensor that outputs a signal by the impact, A pulse generating means for generating a pulse when an output signal of the sensor becomes a predetermined threshold or more in accordance with the impact of the impact applying member on the sheet material; and one pulse generated by the pulse generating means; A period calculation means for obtaining an interval with other pulses, a determination means for detecting the type of the sheet material based on a detection result of the period calculation means, and a threshold value changing means for changing the threshold value to an appropriate value, and The threshold value changing means sets the second threshold value, which is a threshold value at the time of the m-th collision, to be lower than the first threshold value, which is a threshold value at the time of the n-th collision, for the second and subsequent collisions of the impact applying member. And changes the threshold value.
[0010]
When the impact applying member is bounced on the sheet material, the output signal from the sensor is attenuated, so that a pulse may not be generated from the pulse generating means despite the collision. Since the sheet material type detection device is provided with a threshold value changing means, it is possible to generate a pulse corresponding to a desired number of collisions. Since information regarding the type of sheet material is included in the time interval between the pulses (n-th and m (> n) -th), it is possible to determine the type of the sheet material by comparing with information stored in advance. it can. Note that the type here includes discrimination regarding the presence or absence of a sheet material.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 4.
[0013]
The sheet material type detection device according to the present invention is a device for detecting the type of a sheet material, and as shown in FIG. 1, an impact applying member 1 bound by the sheet material P, and the impact applying member Sensor 2 for detecting the position of 1. The sensor 2 outputs a signal corresponding to the position of the impact applying member 1 (see reference numeral 201 in FIG. 3 and reference numeral 101 in FIG. 4), and the output signal is sent to the sheet material P of the impact applying member 1. Take the local maximum at the time of collision. A pulse generating means (see reference numeral 3 in FIG. 2) generates a pulse when the output signals 101 and 201 of the sensor 2 become a predetermined threshold or more due to the impact applying member 1 colliding with the sheet material P. (See FIG. 3 (b) and FIG. 4 (b)). Then, the period calculating means (see reference numeral 5 in FIG. 2) obtains an interval (recoil period) between one pulse generated by the pulse generating means 3 and another pulse, and determines means (reference numeral 6 in FIG. 2). Reference) detects the type of the sheet material based on the detection result of the period calculation means 5.
[0014]
The above-described threshold value (threshold value for the second and subsequent collisions of the impact applying member 1) is changed to an appropriate value by the threshold value changing means (see reference numeral 4 in FIG. 2). As a change method,
-A method of lowering the threshold over time (see Example 1),
A method of lowering the threshold according to the number of collisions of the impact applying member 1,
A method of lowering the threshold value when a maximum or minimum value change occurs. A threshold value is calculated from the maximum value and the minimum value (for example, the average value) of signals output from the sensor 2 at the time of the collision. A method of using the calculated threshold as a threshold for the next collision (see Example 2);
Can be mentioned.
[0015]
In addition, as a threshold value (initial threshold value) regarding the first collision of the impact applying member 1,
・ Pre-set items before sheet material detection,
The initial threshold setting means (see reference numerals 901, 902, and 903 in FIG. 8) bounces the impact applying member 1 with the sheet material before sheet material detection (not sheet material detection but sheet material detection). And a threshold value (see Example 3) calculated from the output of the sensor 2 at the time of the collision.
[0016]
The sheet material type detection device having the above-described configuration may be arranged in the image forming apparatus, and the image forming unit may form an image according to the conditions detected by the sheet material type detection device. In such an image forming apparatus, the threshold value is calculated by the initial threshold value setting unit when the image forming apparatus is activated or reset (see the fourth embodiment), or when a change in sheet material is expected (for example, a paper feed tray). (Refer to Example 5).
[0017]
On the other hand, an elastic member (see symbol A in FIG. 1) is disposed so as to be distorted by the impact of the impact applying member 1, and a piezoelectric element as a sensor is attached to the elastic member A. Thereby, when the impact applying member 1 collides with the sheet material P, the elastic member A is distorted, and as a result, the piezoelectric element 2 outputs a signal.
[0018]
By the way, as the recoil period (interval between one pulse and another pulse) obtained by the period calculating means 5 described above,
A period in which the impact applying member 1 is hung after the collision with the sheet material P,
A period from when the impact applying member 1 collides with the sheet material P to when it collides again,
A period from one collision of the impact applying member 1 to the sheet material P to another collision (that is, a period from the n-th collision to the m-th collision, where n is an integer of 1 or more) And m is an integer greater than or equal to 2 and m> n).
Can be mentioned. For measuring the time at this time, a clock pulse and a time count circuit for measuring the number of clock pulses may be used.
[0019]
Next, the effect of this embodiment will be described.
[0020]
According to the present embodiment, it is possible to accurately detect the collision of the impact applying member with the sheet material and accurately determine the sheet material (for example, discrimination between plain paper, coated paper, and glossy paper).
[0021]
When the impact applying member is bounced by the sheet material and the type of the sheet material is detected by the behavior of the impact applying member, the position of the impact applying member is detected by the piezoelectric element and denoted by reference numeral 101 in FIG. The output signal 101 shown in the figure is obtained, the output signal 101 is compared with the threshold value Vs by a comparator (not shown), the peak portion of the output signal waveform is binarized (see FIG. 5B), and the pulse interval is set to the time. Measurement can be performed with a counter circuit (see (c) in the figure), and the sheet material can be determined using the measurement result.
[0022]
However, it is assumed that the piezoelectric element output cannot be binarized with a fixed threshold. For example, the output signal of the piezoelectric element is greatly attenuated as indicated by reference numeral 201 in FIG. 13 and becomes lower than the threshold value. On the other hand, if the threshold is set too low in advance, even noise will be picked up. Therefore, in the present embodiment, the above-mentioned concern is solved by changing the threshold value during the bounding of the impact applying member.
[0023]
Therefore, when the impact applying member bounces, if it is a damped vibration, the threshold value (second threshold value) in the m (> n) th collision is higher than the threshold value (first threshold value) in the nth collision. Will be lowered.
[0024]
Note that a sensor that outputs a signal by an impact may be referred to as a position sensor of an impact applying member in the text.
[0025]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples.
[0026]
(Example 1)
In the present embodiment, the sheet material type detection device shown in FIGS. 1 and 2 was manufactured, and the threshold value was switched to two stages with the passage of time (see reference symbol Vv in FIG. 3A).
[0027]
1 and 2A, reference numeral 1 denotes an impact applying member bound by the sheet material P, reference numeral 2 denotes a piezoelectric element (sensor) attached to the impact applying member 1, and reference numeral 3 denotes The comparator circuit block (pulse) that compares the output signal 201 of the piezoelectric element 2 with the threshold value Vv and generates an output High when the output signal 201 exceeds the threshold value Vv, and generates an output Low (binarized output) when the output signal 201 falls below the threshold value Vv. Reference numeral 4 denotes a variable comparison value generating block (threshold changing means) for supplying a comparison threshold voltage to the comparator circuit block 3. As shown in detail in FIG. 2B, the variable comparison value generation block 4 includes a power source 40, a resistor 41 for determining the high threshold Vk and the low threshold Vt, a switch 43 for switching the threshold, A circuit 44 for operating the switch 43 is provided. On the other hand, reference numeral 50 in FIG. 2 (a) denotes a circuit for counting the number of high outputs of the comparator circuit block, and reference numeral 51 denotes a time counting circuit for measuring the time (recoil period) from the predetermined number to the predetermined number. Indicates a block. Reference numeral 60 denotes a data table from a predetermined number of times set in advance according to the sheet material type to a predetermined number of times (that is, a data table in which recoil periods for various sheet materials are stored). Reference numeral 61 denotes a counter value comparison circuit block that compares the measurement time of the time count circuit block with the sheet type data of the data table 60. Reference numeral 62 denotes a circuit block that determines the type of sheet material based on the result of the data comparison circuit block 61.
[0028]
Next, the sheet material type detection method will be described.
[0029]
Now, when the impact applying member 1 is dropped and bound by the sheet material P, the output signal of the piezoelectric element 2 (see reference numeral 201 in FIG. 3) is sent to the comparator circuit block 3. On the other hand, a threshold value (fixed value) determined in advance at the initial stage is input from the threshold variable circuit block 4 to the comparator circuit block 3, and the output signal of the piezoelectric element is a threshold value from the comparator circuit block 3 to the peak counter circuit block 50. A pulse is output only when Vv is exceeded (see FIG. 3 (b)). As shown in FIG. 3A, the threshold value Vv is initially set to a high threshold value Vk and switched to a low threshold value Vt after a certain time. Therefore, the first and second peaks are compared with the high threshold value Vk, and the third and subsequent peaks are compared with the low threshold value Vt. A pulse is output each time the impact applying member 1 collides with the sheet material P. A pulse is output even if the output signal of the piezoelectric element 2 has a waveform as indicated by reference numeral 101 in FIG.
[0030]
The binarized pulses of the comparator thus obtained are counted by the peak counter circuit block 50, and the count number is output (see FIGS. 3 (c) and 4 (c)). The time counter circuit block 51 starts and stops at a predetermined count number, measures the time, and sets it as the recoil time. The type of the sheet material is determined by comparing the measurement time with data predetermined for the sheet material type in the counter value comparison block.
[0031]
The threshold generation may be performed by a microcomputer processing circuit using an A / D converter.
[0032]
(Example 2)
The present embodiment is characterized in that a threshold value for comparing waveforms at the time of the second and subsequent collisions is calculated from the maximum voltage and the minimum voltage at the time of the previous collision, and the threshold value is changed step by step.
[0033]
In this embodiment, the sheet material type detection device shown in FIG. 5 was produced. In the figure, reference numeral 80 denotes a maximum value detection circuit block that obtains the maximum value of the output signal of the piezoelectric element 2, and reference numeral 81 denotes a minimum value detection circuit block that obtains the minimum value of the output signal of the piezoelectric element 2. Reference numeral 82 denotes an adding circuit block that adds the maximum value and the minimum value, and reference numeral 83 denotes an average value that calculates the average value of the maximum value and the minimum value by dividing the output of the adding circuit block 82 by 2. / 2 indicates a circuit block, and reference numeral 84 indicates a hold circuit block that holds an average value obtained from the maximum value and the minimum value. Reference numeral 9 denotes a threshold value change timing timer circuit block for setting detection timings to the maximum value detection circuit block 80 and the minimum value detection circuit block 81, and a hold value change timing to the hold circuit block 84. Reference numeral 7 denotes an initial threshold value block that gives a threshold value at the time of the first collision to the comparator circuit block 3. The threshold is selected only at the first collision.
[0034]
As shown in FIG. 6 (a), the output signal 201 of the piezoelectric element 2 input to the comparator circuit block 3 is compared with the initial threshold value siki (1) at the first collision, and the binarized pulse is output. Output (see Fig. 6 (b)).
[0035]
By the way, at the time of the first collision, the maximum value max (1) and the minimum value min (1) of the output signal of the piezoelectric element are detected by the maximum value detection circuit block 80 and the minimum value detection block 81, and the addition circuit block 82 and The half circuit block 83 makes an average value (this value is referred to as siki (2)) and inputs it to the hold circuit block 84. Thereafter, the output of the hold circuit block 84 is switched to the average value siki (2) of the maximum value max (1) and the minimum value min (1) at the timing by the threshold value change timing timer circuit block 9, and at the time of the second collision Siki (2) is supplied to the comparator circuit block 3 as a threshold value of.
[0036]
Further, the threshold sikii (3) at the time of the third collision is an average value of the maximum value max (2) and the minimum value min (2) at the time of the second collision.
[0037]
That is, in the present embodiment, the threshold siki (n) used at the n-th collision is sukii (n) = (max (I) + min (I)) / 2.
However, I = n−1, and n is an integer of 2 or more.
It will be expressed as In the first collision, the initial threshold is used, and in the second and subsequent collisions, “the average value of the maximum value and the minimum value of the output signal at the previous collision” is used as the threshold based on the above equation. Used.
[0038]
Even if the output signal of the piezoelectric element 2 has a shape as indicated by reference numeral 101 in FIG. 7A, it is possible to accurately detect the collision of the impact applying member 1 and discriminate the sheet material.
[0039]
The maximum voltage and the minimum voltage may be A / D converted and the threshold value may be A / D converted by microcomputer processing.
[0040]
(Example 3)
In the first embodiment described above, the initial threshold value (threshold value of the comparator at the time of the first collision) is a preset threshold value, but in this embodiment, “actual paper type detection (hereinafter referred to as“ main measurement ”). "Preliminary paper type detection (paper type detection performed only for obtaining the threshold value, hereinafter referred to as" trial ")" is attempted, and the threshold value determined by the trial is set to "actual paper type It is used as an “initial threshold value at the time of the first collision of detection”. That is, in this embodiment, the maximum value at the time of the first collision at the time of the trial is detected by the trial of the preliminary paper type detection measurement, and ½ of the value (maximum value) at the time of the actual measurement (actual This is used as an initial threshold value (at the time of paper type detection).
[0041]
In this example, the apparatus shown in FIG. 8 was produced. Reference numeral 901 in the figure denotes a trial maximum value detection circuit that detects the maximum value of the piezoelectric element output at the time of trial, and reference numeral 902 holds the maximum value at trial obtained by the trial maximum value detection circuit 901 until the actual measurement. The reference numeral 903 indicates a trial peak value ½ circuit block that halves the held maximum value. Other configurations were the same as those shown in FIG.
[0042]
<At trial>
First, as a trial, the impact applying member 1 is caused to collide with the sheet material P (see S1 and S2 in FIG. 9). At that time, the maximum value of the piezoelectric element output at the time of the first collision is detected by the trial maximum value detection circuit block 901, which is held by the trial peak hold circuit 902, and the value is halved by the trial peak ½ circuit 903. (See S3 in FIG. 9) and supplied to the comparator circuit 3 as a threshold value.
[0043]
<During actual measurement>
For this measurement, the impact applying member 1 was made to collide with the sheet material P (see S4 in FIG. 9), and the sheet material was determined in the same manner as in Example 1 (see S5 and S6 in FIG. 9). However, the initial threshold value obtained by trial was used.
[0044]
The maximum value at the time of trial may be A / D converted, and the threshold value may be D / A converted by microcomputer processing and given to the comparator circuit.
[0045]
Example 4
In this embodiment, the sheet material type detection apparatus having the configuration shown in FIG. 10 is mounted on a device such as a copying machine (hereinafter referred to as “paper type detection mounting device”), and the trial of Embodiment 3 (only for obtaining a threshold value). Paper type detection performed at the time of power-on and reset of the paper type detection-equipped device.
[0046]
In FIG. 10, reference numeral 1001 indicates a trial permission circuit block for sending a signal to cause the impact applying member 1 to bounce with the sheet material P and to give an operation permission to the trial maximum value detection circuit block 901 at the time of trial. Indicates a reset detection circuit block for detecting a reset signal of the paper type detection device.
[0047]
A reset signal from the paper type detection device is detected by the reset detection circuit block 1002 and transmitted to the trial permission circuit 1001. The trial permission circuit 1001 gives an impact application operation instruction and sends an operation permission signal of the trial maximum value detection circuit block 901 to perform a trial operation.
[0048]
(Example 5)
In the present embodiment, the sheet type detection device having the configuration shown in FIG. 11 is mounted on a device such as a copying machine (hereinafter referred to as “paper type detection mounting device”), and the paper type of the paper type detection mounting device is changed. When expected, the trial of the third embodiment (paper type detection performed only for obtaining the threshold value) is performed.
[0049]
Reference numeral 1101 denotes a circuit block for detecting a change in the paper feed tray of the device equipped with the paper type detection device.
[0050]
The device paper feed tray replacement detection circuit block 1101 that has detected the paper feed tray change of the paper type detection-equipped device sends a paper feed tray change signal to the trial permission circuit 1001. The trial permission circuit 1001 operates in response to a paper feed tray change signal, and instructs the shock application driver circuit 301 and the trial maximum value detection circuit block 901 to perform a trial operation. Others are the same as the said Example.
[0051]
【The invention's effect】
As described above, according to the present invention, it is possible to accurately detect the collision of the impact applying member with the sheet material and accurately determine the sheet material.
[Brief description of the drawings]
FIG. 1 is a schematic diagram for explaining an example of a configuration of a sheet material type detection device according to the present invention.
FIG. 2 is a block diagram for explaining an example of a configuration of a sheet material type detection apparatus according to the present invention.
FIG. 3A is a waveform diagram showing how the output signal of a piezoelectric element is compared with a threshold value, FIG. 3B is a waveform diagram showing pulses output based on the comparison, and FIG. The figure which shows the mode of a pulse interval detection.
FIG. 4A is a waveform diagram showing how the output signal of a piezoelectric element is compared with a threshold value, FIG. 4B is a waveform diagram showing pulses output based on the comparison, and FIG. The figure which shows the mode of a pulse interval detection.
FIG. 5 is a block diagram for explaining an example of a configuration of a sheet material type detection apparatus according to the present invention.
6A is a waveform diagram showing how the output signal of a piezoelectric element is compared with a threshold value, FIG. 6B is a waveform diagram showing pulses output based on the comparison, and FIG. The figure which shows the mode of a pulse interval detection.
FIG. 7A is a waveform diagram showing how the output signal of a piezoelectric element is compared with a threshold value, FIG. 7B is a waveform diagram showing a pulse output based on the comparison, and FIG. The figure which shows the mode of a pulse interval detection.
FIG. 8 is a block diagram for explaining an example of a configuration of a sheet material type detection device according to the present invention.
FIG. 9 is a flowchart for explaining a state of sheet material discrimination.
FIG. 10 is a block diagram for explaining an example of a configuration of a sheet material type detection apparatus according to the present invention.
FIG. 11 is a block diagram for explaining an example of the configuration of a sheet material type detection apparatus according to the present invention.
FIGS. 12A and 12B are diagrams for explaining conventional problems, wherein FIG. 12A is a waveform diagram showing a state in which an output signal of a piezoelectric element is compared with a threshold value, and FIG. 12B is an output based on the comparison; FIG. 4C is a waveform diagram showing a pulse, and FIG.
FIGS. 13A and 13B are diagrams for explaining conventional problems, wherein FIG. 13A is a waveform diagram showing a state in which an output signal of a piezoelectric element is compared with a threshold value, and FIG. 13B is an output based on the comparison; FIG. 4C is a waveform diagram showing a pulse, and FIG.
[Explanation of symbols]
1 Impact applying member 2 Piezoelectric element (sensor)
3 Comparator circuit (pulse generation means)
4 Variable comparison value generation circuit (threshold changing means)
5 Period calculation means 6 Discrimination means

Claims (4)

In the sheet material type detection device for detecting the type of sheet material,
An impact applying member to be bound by the sheet material, and a sensor that outputs a signal by the impact, when the output signal of the sensor with the impact to the sheet material of the impact applying member is equal to or greater than a predetermined threshold value A pulse generating means for generating a pulse; a period calculating means for obtaining an interval between one pulse generated by the pulse generating means and another pulse; and a type of the sheet material is detected based on a detection result of the period calculating means. Discriminating means, and threshold value changing means for changing the threshold value to an appropriate value, and
The threshold value changing means sets a second threshold value, which is a threshold value at the time of the m-th collision, to be lower than a first threshold value, which is a threshold value at the time of the n-th collision, for the second and subsequent collisions of the impact applying member. Change the threshold,
A sheet material type detection device. (N <m, n, m are natural numbers) The sheet material type detection device according to claim 1 ,
An image forming unit that forms an image according to conditions detected by the sheet material type detection device;
An image forming apparatus. A sheet material type detection method for detecting the type of sheet material,
An impact applying step of applying an impact to the sheet material; a step of detecting the impact by a sensor; a step of outputting the detected impact as an output signal; a step of comparing the output signal with a predetermined threshold; and the sensor A pulse generating step for generating a pulse when the output signal from the signal exceeds a predetermined threshold , a period calculating step for obtaining an interval between one pulse generated in the pulse generating step and another pulse, and the period A determination step of detecting the type of the sheet material based on the detection result obtained in the calculation step, and a threshold value changing step of changing the predetermined threshold value ,
In the threshold value changing step, the second threshold value that is the threshold value at the time of the m-th collision is set lower than the first threshold value that is the threshold value at the time of the n-th collision for the second and subsequent collisions of the impact applying member. Including changing the threshold,
A sheet material type detection method characterized by the above. (N <m, n, m are natural numbers) The initial threshold value of the threshold value, at the start of the image forming apparatus, reset, or sheet type detecting method according to claim 3, characterized in that to change when the sheet material is changed.

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