JP4724516B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus capable of discriminating the type of recording material.

  Image forming apparatuses such as copying machines and laser printers include a latent image carrier that carries a latent image, a developing device, a transfer device, and a fixing device. The developing device visualizes the latent image as a developer image by applying a developer to the latent image carrier. The transfer device transfers a developer image by the developing device onto a recording material conveyed in a predetermined direction. The fixing device fixes the developer image transferred onto the recording material by the transfer device by heating and pressing under predetermined fixing processing conditions.

  In such an image forming apparatus, for example, the size and type (hereinafter also referred to as “paper type”) of a recording material are set by a user on an operation panel or the like provided in the main body of the image forming apparatus. In accordance with the setting, control is performed such that the fixing process conditions, for example, the fixing temperature and the conveyance speed of the recording paper passing through the fixing device are set.

  As an image forming apparatus, an image forming apparatus having a sensor for determining a recording material is known. For example, a surface image of the recording material is picked up by a CMOS sensor, the type of the recording material is determined by a method of detecting the surface smoothness of the recording material, and development conditions, transfer conditions or fixing conditions are variably controlled. (See Patent Document 1)

  Further, there has been proposed an apparatus for determining the thickness of a recording paper by transmitted light by providing a light source at a position facing a sensor for determining the recording material and detecting the transmitted light. (See Patent Document 2)

JP 2002-182518 A JP 2001-139189 A

  However, since the threshold value for discriminating the recording material is fixed, it is difficult to accurately detect all types of recording materials on the market.

  Accordingly, an object of the present invention is to propose an image forming apparatus that can solve the above-described problems and can further improve the recording material discrimination accuracy.

In order to achieve the above object, an image forming apparatus according to the present invention devised by the present applicant includes: a light emitting unit that emits light to a recording material; and a light receiving unit that receives light emitted from the light emitting unit to the recording material. means and, by comparing the threshold value for discriminating the kind of recording material and a value corresponding to the light received by said light receiving means, a control hand stage you determine the type of a plurality of recording materials, wherein said control means as the determination result includes a storage means for storing the number of each type of the recording material, wherein the control means, according to the number of each type of printing materials stored in the storage means, the type of the recording medium It is characterized in that the threshold value for discriminating between is varied .

Here, the control means discriminates between the first discriminating area and the second discriminating area which are separated by the threshold value, based on the number of recording materials discriminated in the first discriminating area and the second discriminating area. The threshold value may be changed so that the number of the discriminating regions of the first discriminating region or the second discriminating region is larger than the original discriminating region .

Further, the control means may vary a threshold for determining the type of the recording material in accordance with a value obtained by multiplying the number of the recording material types stored in the storage means by a coefficient .

により算出するものであってよい。
Further, the control means sets the number of sheets for each type of recording material as “a” for the number of plain papers, “b” for the number of thick papers, “c” for the number of glossy papers, and w ₁ , w _{2. When} the coefficients used for calculating the transmittance determination threshold are w ₃ and w ₄ , the gloss threshold variation range is R ₁ , and the transmittance threshold variation range R ₂ , the gloss discrimination thresholds r ₁₁ and r ₁₂ are transmitted. Rate discrimination thresholds r ₂₁ and r ₂₂ are expressed by the following equations:

It may be calculated by.

The light receiving means may receive reflected light emitted from the light emitting means and reflected from the recording material, or transmitted light emitted from the light emitting means and transmitted through the recording material .

In order to achieve the above object, another image forming apparatus according to the present invention devised by the present applicant includes a light emitting means for emitting light to a recording material, and light received from the light emitting means to the recording material. light receiving means for, by comparing the threshold value for discriminating the kind of recording material and a value corresponding to the light received by said light receiving means, and control means for discriminating the type of a plurality of recording materials, serial Rokuzai The input means for inputting the type information, the type of the recording material determined by the control means, and the number of mismatches in which the type of the recording material input by the input means did not match Storage means for storing, and the control means varies a threshold value for determining the type of the recording material in accordance with the number of matches and the number of mismatches stored in the storage means. And

Here, the control means may vary a threshold for determining the type of the recording material in accordance with a value obtained by multiplying the coincidence count and the mismatch count stored in the storage means by a coefficient. .

により算出するものであってよい。
Further, the control means sets the number of coincidence of each of plain paper, cardboard, and glossy paper to m ₁ , m ₂ , m ₃ , and sets the number of mismatches of plain paper, cardboard, and glossy paper to n ₁ , n ₂ , n ₃ , coefficients λ _i (i = 1, 2), w _ij (i = 1, 2, j = 1 to 3), the type of recording material determined by the control means, and input by the input means P _j = m _j / (m _j + n _j ) (i = 1, 2, j = 1 to 3), and the ratio of the number of times of coincidence with the type of the recorded recording material, The ratio of the number of times that the type does not match the type of the recording material input by the input means is p _j = n _j / (m _j + n _j ) (i = 1, 2, j = 1 to 3) When the threshold fluctuation amounts Δα and Δβ are expressed as follows:

It may be calculated by .

  According to the present invention, since it is configured as described above, it is possible to further improve the discrimination accuracy of the type of recording material.

<First Embodiment>
FIG. 1 shows a first embodiment of the present invention. This is an example of an image forming apparatus. The recording material discrimination sensor 200 includes an LED 201 as a first irradiation unit, an LED 204 as a second irradiation unit, a phototransistor 203 as a first reading unit, and a phototransistor 202 as a second reading unit. Yes. The light emitting element driving unit 305 drives the LEDs 201 and 204, and the main control unit 306 controls the light emitting element driving unit 305. The signal processing unit 307 performs A / D conversion on the output values from the phototransistors 202 and 203 with a resolution of 16 bits, and calculates the output values of the phototransistors 202 and 203. For example, in the calculation of the output value, a value indicating the glossiness of the recording material (regular reflection output / diffuse reflection output) and a regular transmission output value indicating the light transmittance of the recording material (output of the phototransistor 202) are obtained.

  The comparison operation unit 308 performs a comparison operation with the set value stored in advance in the memory 309 based on the result performed by the signal processing unit 307. The memory 309 is a nonvolatile memory such as an EEPROM, and stores setting values for recording material discrimination. The memory 309 stores two kinds of different emission light quantity values for the LED 201, and one kind of emission light quantity value for the LED 204. For example, the regular reflection light quantity and irregular reflection light quantity from the reference paper are detected using the reference paper at the time of factory shipment, and the light emission light quantity values for the phototransistors 202 and 203 are stored in the memory 309 based on the result. The reason for setting the emitted light quantity value for each of the phototransistors 202 and 203 is that the sensitivity variation of the light receiving element can be canceled by changing the emitted light quantity.

  Similarly, the LED 204 detects the normal transmitted light amount from the reference paper using the same reference paper as described above at the time of factory shipment, and stores the light emission light amount value obtained from the result in the memory 309.

  FIG. 2 shows the configuration of the recording material discrimination sensor 200 of FIG. Light having the LED 201 as a light source is applied to the surface of the recording material P on the recording material conveyance guide 205 through the slit 211. In the present embodiment, the recording material conveyance guide 205 is provided with a window for irradiating light from the back side of the recording material. The reflected light from the recording material P is collected through the slits 212 and 213 and received by the phototransistors 202 and 203. Thereby, the glossiness of the recording material P is detected.

  Light using the LED 204 as a light source is applied to the back surface of the recording material P through a light collecting guide 214 for collecting the light. The transmitted light from the recording material P is received by the phototransistors 202 and 203 through the slits 212 and 213. As a result, the amount of light transmitted from the recording material P is detected. In the present embodiment, the LED 201 is disposed so that the LED light is irradiated obliquely at a predetermined angle with respect to the surface of the recording material P as shown in FIG. The LED 204 is arranged so that the LED light is irradiated to the back surface of the recording material P from a position directly below the phototransistor 202 as shown in FIG.

  Next, a recording material determination procedure will be described. When the user receives a print start command from a personal computer after a recording material is set on a cassette tray (not shown), an optional tray (not shown), or a multi-tray (not shown), printing is started. When the recording material reaches the position of the recording material discrimination sensor 200, the LEDs 201 and 204 of the recording material discrimination sensor 200 emit light with the light emission amount value stored in the memory 309, and the phototransistors 202 and 203 receive the reflected light. The LED 204 emits light with the light emission amount value stored in the memory 309 after the LED 201 is turned off, and the phototransistor 202 receives the transmitted light amount of the recording material. After the LED 204 is turned off, a comparison calculation is performed with the detection result value based on the recording material discrimination threshold. From the calculation result, the type of recording material is determined.

The procedure for determining the type of recording material by this comparison operation will be described with reference to FIG. The glossiness a of the recording material obtained from the output values of the phototransistors 202 and 203 is compared with the glossiness determination threshold value α.
When a> α, it is determined as gloss paper.
When a ≦ α, the transmittance b of the recording material obtained from the output value of the phototransistor 202 is compared with the transmittance determination threshold value β.
If b> β, the paper is determined to be cardboard.
If b ≦ β, it is determined as plain paper.

  Next, a method for changing the discrimination threshold performed after the above-described recording material discrimination will be described. FIG. 4 shows the discrimination threshold in the initial state and the measured value distribution for each type of recording material. In FIG. 4, black dots indicate the distribution of measured values for thick paper, and gradets indicate the distribution of measured values for glossy paper. FIG. 5 shows the discrimination threshold after fluctuation.

  Among various types of recording materials on the market, there are those in which the distribution of measured values overlaps even though the paper type is different as shown in FIG. It is difficult to accurately identify the material. Therefore, the fact that there is a high possibility that the same type of recording material is continuously fed is used.

After determining the recording material as described above, the glossiness determination threshold and the transmittance determination threshold are set in advance so that the recording material type (thick paper) determined by the recording material determination as shown in FIG. The threshold value is varied by the variation amounts Δα _p and Δβ _p set for each. That is, the glossiness determination threshold value is changed from the initial threshold value α ₀ to α ₁ (= α ₀ + Δα _p ). Further, the transmittance determination threshold value is changed from the initial threshold value β ₀ to β ₁ (= β ₀ + Δβ _p ).

Similarly, for the second sheet, based on the paper type p that has been passed through the second sheet, the discrimination threshold is changed to α ₂ = α ₁ + Δα _p and β ₂ = β ₁ + Δβ _p . Similarly for the third and subsequent sheets, the threshold value is changed based on the paper type detected every time the paper is passed. However, the discrimination threshold can be varied only within a predetermined range.

  This makes it possible to stably determine the recording material when the same type of recording material is passed. Further, when a plurality of recording materials are detected, it is possible to reduce the problem that the printing mode is suddenly changed although the threshold is exceeded and the same recording material is printed.

  The above threshold fluctuation amount is set for each type of recording material and for each sheet feeding port. The recording material is generally fed from either a multi-tray, a cassette tray, or an optional tray. Among these trays, the cassette tray and the optional tray can set recording materials in units of 100 sheets, and therefore there is a high possibility that the same type of recording material is passed from these trays. On the other hand, since various types of recording materials can be fed from the multi-tray, it is less likely that the same type of recording materials are continuous than the cassette tray or the optional tray. For this reason, the threshold fluctuation amount of the cassette tray and the option tray is set large, and the multi-tray fluctuation amount is set small. The range in which the threshold value can be changed is also set for different paper feed ports, and is set to a wide range for the cassette tray and the option tray, and to a narrow range for the multi-tray than the cassette tray and the option tray.

  The discrimination threshold returns to the initial value under the following conditions. If the difference between the value of the detection result of the print and the detection result immediately before the print is greater than or equal to a predetermined value, the possibility of erroneous detection is high, so the threshold value is returned to the initial value and the control of the threshold value variation is started again.

  If the user opens or closes the cassette tray or option tray and the number of recording materials loaded in the tray changes, the recording material may have been replenished or replaced by the user. The threshold value is returned to the initial value.

  As described above, according to the present embodiment, it is possible to improve the recording material discrimination accuracy regardless of variations in the recording material.

<Second Embodiment>
The present embodiment is an example in which a recording material history used by a user is stored in a nonvolatile memory, and the recording material determination threshold is changed based on the history.

  FIG. 6 is a flowchart relating to the procedure for storing the history of the recording material used by the user. Recording material discrimination control (S41) similar to that of the first embodiment is performed to determine the type of recording material (S42). In order to store the number of passing sheets of the recording material, the number of passing sheets is stored in the volatile memory for each type of recording material after the recording material determination (S43). In order to hold the number of sheets of recording material to be passed even when the power is turned off, the number of sheets stored in the volatile memory is stored as a non-volatile memory 309 each time a predetermined number of sheets are passed or every elapse of a predetermined time (S44) (S45). The recording material determination threshold value is updated based on the number of sheets to be passed for each type of recording material (S46).

Next, a method for changing the recording material determination threshold based on the above-described recording material history will be described. FIG. 7 explains the variation amount of the discrimination threshold. The number of sheets of recording material written as described above when the power is turned on is read from the memory 309. An initial value is set in the memory 309 in advance at the time of shipment. The recording material discrimination threshold is changed for each print based on the number of sheets that have been read. The number of sheets to be passed is updated for each print in the same procedure as described above. Here, the number of sheets of plain paper passed is a, the number of sheets of thick paper is b, and the number of sheets of glossy paper is c. Then, the glossiness determination threshold value is obtained by adding the weights w ₁ and w ₂ to the ratio of the glossy sheet passing number c and the other sheet passing number a + b, respectively, according to the following formula, and calculating the glossiness threshold fluctuation range R ₁ . It is determined by dividing by the specific gravity of r ₁₁ and r ₁₂ .

Similarly, the transmittance determination threshold value is obtained by adding weights w ₃ and w ₄ to the ratio between the number of plain paper sheets a and the number of thick paper sheets b, and the transmittance threshold fluctuation range R ₂ is a specific gravity of r ₂₁ and r ₂₂ . Determined by dividing by. The reason why the weight is added is to make it easier to detect high-cost paper types and paper types for which image formation is difficult. These weights w ₁ , w ₂ , w ₃ , and w ₄ may be optimized in advance from the above-mentioned costs, image forming characteristics, etc., and stored in the nonvolatile memory 309, for example. By performing such discrimination control based on the number of sheets to be passed, it becomes easier to detect the type of recording material having a higher sheet passing frequency.

  As described above, it is possible to perform appropriate record discrimination control according to the usage status of the user.

<Third Embodiment>
The present embodiment is an example in which the user designates the type of recording material.

FIG. 8 is a flowchart showing a procedure for changing the discrimination threshold in the user designation mode in which the user designates the paper type. 9 to 11 show graphs of the discrimination threshold value in the user designation mode. After the user designates the paper type of the print using the personal computer or the printer operation panel before starting printing (S61), the initial threshold values α ₀ and β ₀ are set to the designated paper type as shown in FIG. The initial determination threshold values α ₁ and β ₁ are changed to suitable ones (S62). Here, FIG. 9 shows an example in which a thick paper is designated. The initial determination threshold values α ₁ and β ₁ are set in advance for each paper type. This makes it possible to perform recording material discrimination control according to the paper type designated by the user.

  After the start of printing (S63), the same recording material discrimination control as in the first and second embodiments is performed (S64), and the paper type is determined (S65). After the paper type is determined, it is confirmed whether the detected paper type matches the paper type specified by the user (S66).

A case where the paper type designated by the user does not match the detected paper type will be described with reference to FIG. The fact that the paper type designated by the user does not match the detected paper type is hereinafter referred to as “media mismatch”. FIG. 10 shows a case where the measured value is in the plain paper area even though the user has designated thick paper. In this case, the initial determination threshold values α ₁ and β ₁ are changed to the determination threshold values α ₂ and β ₂ so that the detection region of the detected paper type becomes wider (S68). By performing such control, it becomes easier to detect the user-specified paper type.

On the other hand, a case where the paper type designated by the user matches the detected paper type will be described with reference to FIG. The coincidence between the paper type designated by the user and the detected paper type is hereinafter referred to as “media coincidence”. The example of FIG. 11 is a case where the user designates cardboard and the measured value is in the cardboard area. In this case, the initial determination threshold values α ₁ and β ₁ are changed to the determination threshold values α ₃ and β ₃ so as to narrow the detection sheet type determination region (S67). The amount of variation at this time is small compared to the case of media mismatch.

Next, a method for changing the recording material discrimination threshold in the auto mode in which the user does not specify the paper type will be described with reference to FIG. The number of media matches (m _j ) and the number of media mismatches (n _j ) for each paper type are stored in the volatile memory in advance in the user designation mode (j = 1 to 3). However, the media coincidence numbers of plain paper, thick paper, and glossy paper are m ₁ , m ₂ , and m ₃ , respectively, and the media mismatch numbers are n ₁ , n ₂ , and n ₃ , respectively. In addition, the media coincidence number and the media inconsistency number are written in the nonvolatile memory after the predetermined number of sheets have passed or a predetermined time has elapsed. In the auto mode, the discrimination threshold is changed from the initial thresholds α ₀ and β ₀ to α ₀ + Δα and β ₀ + Δβ as in the following equation.

Here, λ _i (i = 1, 2) and w _ij (i = 1, 2, j = 1 to 3) are weights. Further, the fluctuation amounts Δα and Δβ are the media matching rate p _j = m _j / (m _j + n _j ) and the media mismatch rate p _j = n _j / (m _j + n _j ) before the printing. ) And the weights λ _i , w _ij , and w ′ _ij . i = 1, 2 and j = 1-3. The weights λ _i , w _ij , and w ′ _ij are optimized in advance from the image forming characteristics and the like. The reason for performing such control is that the number of false detections is considered to be proportional to the number of media mismatches, and threshold fluctuations are performed in consideration of false detections.

  As described above, according to the present embodiment, it is possible to accurately determine the recording material by using the determination result in the user designation mode.

  In the embodiment described above, the recording material discrimination sensor 200 has been described as having the LEDs 201 and 204 as the issuing elements and the phototransistors 202 and 203 as the light receiving elements. However, the present invention is not limited to this, and for example, a type of recording material may be determined based on video data obtained by imaging a video in a predetermined range using a CMOS sensor as a light receiving element.

It is a block diagram which shows the 1st Embodiment of this invention. FIG. 2 is a diagram illustrating a configuration of a recording paper discrimination sensor 200 in FIG. 4 is a graph showing a recording material determination threshold value and a measured value in the first embodiment of the present invention. It is a graph which shows the threshold value of an initial state in the 1st Embodiment of this invention. It is a graph which shows when a threshold value fluctuates in the 1st embodiment of the present invention. Control flow chart for recording material history storage in the second embodiment of the present invention 10 is a graph showing the amount of change in the recording material determination threshold in the second embodiment of the present invention. 14 is a flowchart illustrating a control procedure of a recording material determination threshold value in a user designation mode in the third embodiment of the present invention. It is a graph which shows the initial determination threshold value at the time of user designation | designated mode in the 3rd Embodiment of this invention. It is a graph which shows the threshold value at the time of media mismatch in the 3rd Embodiment of this invention. It is a graph which shows the threshold value at the time of media matching in the 3rd Embodiment of this invention. It is a graph which shows the threshold value at the time of auto mode in the 3rd Embodiment of this invention.

Explanation of symbols

200 Recording material discrimination sensor 201, 204, 301, 302 LED
202, 203, 303, 304 Phototransistors 211 to 213 Slit 214 Condensing guide 305 Light emitting element driving unit 306 Main control unit 307 Signal processing unit 308 Comparison unit 309 Memory

Claims (8)

A light emitting means for emitting light to the recording material;
A light receiving means for receiving light emitted to the recording material from the light emitting means;
Compares the threshold value for discriminating the kind of recording material and a value corresponding to the light received by said light receiving means, a control hand stage you determine the type of a plurality of recording materials,
As the result of the determination control means includes a storage means for storing the number of each type of the recording material, and
The image forming apparatus according to claim 1, wherein the control unit varies a threshold for determining the type of the recording material in accordance with the number of recording materials stored in the storage unit . The control means is configured to determine the number of recording materials discriminated in the first discriminating area and the recording material discriminated in the second discriminating area in the first discriminating area and the second discriminating area adjacent to each other divided by the threshold value. 2. The threshold value is varied so that a larger number of discriminating regions of the first discriminating region or the second discriminating region are wider than the original discriminating region . Image forming apparatus. The control means varies the threshold for determining the type of recording material according to a value obtained by multiplying the number of recording materials of each type stored in the storage means by a coefficient. or an image forming apparatus according to 2. The control means sets the number of sheets for each type of recording material as a number of plain papers a, a number of thick papers b, a number of glossy papers c, and coefficients used for calculating glossiness determination thresholds w ₁ , w ₂ , When the coefficients used for calculating the transmittance determination threshold are w ₃ and w ₄ , the glossiness threshold fluctuation range is R ₁ , and the transmittance threshold fluctuation range R ₂ , the glossiness determination thresholds r ₁₁ and r _{12 are} determined. The threshold values r ₂₁ and r ₂₂ are set as follows:

The image forming apparatus according to claim 4 , wherein the image forming apparatus is calculated by: 2. The image forming apparatus according to claim 1, wherein the light receiving unit receives reflected light irradiated from the light emitting unit and reflected from the recording material, or transmitted light irradiated from the light emitting unit and transmitted through the recording material. . A light emitting means for emitting light to the recording material;
A light receiving means for receiving light emitted to the recording material from the light emitting means;
A control unit for comparing a value according to the light received by the light receiving unit and a threshold for determining the type of the recording material, and for determining a plurality of types of the recording material ;
And input means for inputting information on the type of record material,
Storage means for storing the number of coincidence that did not coincide with the number of coincidence of the type of recording material determined by the control unit and the type of recording material inputted by the input unit ,
The image forming apparatus according to claim 1 , wherein the control unit varies a threshold for determining the type of the recording material in accordance with the number of coincidences and the number of mismatches stored in the storage unit . The control means according to claim 6, wherein the stored in the storage means and the match count and according to the value obtained by multiplying the coefficients to the mismatch count, varying the threshold value for discriminating the kind of recording material The image forming apparatus described in 1. The control means sets the number of coincidence of each of plain paper, cardboard, and glossy paper to m ₁ , m ₂ , and m ₃ , and sets the number of mismatches of plain paper, cardboard, and glossy paper to n ₁ , n ₂ , n ₃ , respectively. Λ _i (i = 1, 2), w _ij (i = 1, 2, j = 1-3), the type of recording material determined by the control means, and the input means P _j = m _j / (m _j + n _j ) (i = 1, 2, j = 1 to 3), the ratio of the number of times of coincidence with the recording material type, and the recording material type determined by the control means When the ratio of the number of times that the type of the recording material input by the input means does not match is p _j = n _j / (m _j + n _j ) (i = 1, 2, j = 1 to 3) The threshold fluctuation amounts Δα and Δβ are expressed as follows:

The image forming apparatus according to claim 7 , wherein the image forming apparatus is calculated by:

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