JP2011137938A - Recording material discrimination apparatus and image forming apparatus - Google Patents
Recording material discrimination apparatus and image forming apparatus Download PDFInfo
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Abstract
Description
本発明は、記録材の表面平滑性を検出する検出装置並びに記録材の表面平滑性の検出結果から画像条件を制御するインクジェットプリンタ、複写機、レーザプリンタ等の画像形成装置に関する。 The present invention relates to a detection device that detects the surface smoothness of a recording material, and an image forming apparatus such as an ink jet printer, a copying machine, and a laser printer that controls image conditions based on the detection result of the surface smoothness of the recording material.
複写機、レーザプリンタ等の画像形成装置は、潜像担持体に潜像を担持し、現像装置により潜像担持体に現像剤を付与することによって潜像を現像剤像として可視化する。所定方向に搬送される記録材に転写手段により現像剤像を転写し、転写手段によって現像剤像が転写された記録材を、定着装置により所定の定着処理条件にて加熱及び加圧することで現像剤像を記録材に定着させる。従来、かかる画像形成装置においては、例えば、画像形成装置本体に設けられた操作パネル等に記録材のサイズや種類(以下、紙種ともいう)がユーザによって設定される。そして、その設定に応じて現像条件、転写条件、定着処理条件(例えば、定着温度や定着装置を通過する記録材の搬送速度)又は画像処理を変える制御を行う。また例えばホストコンピュータからユーザが印字時に紙種を設定することにより、画像形成装置は指定された紙種に応じて、現像条件、転写条件、定着処理条件又は画像処理を変える制御を行う。 An image forming apparatus such as a copying machine or a laser printer carries a latent image on a latent image carrier and visualizes the latent image as a developer image by applying a developer to the latent image carrier by a developing device. The developer image is transferred to a recording material conveyed in a predetermined direction by a transfer unit, and the recording material on which the developer image has been transferred by the transfer unit is heated and pressed under a predetermined fixing processing condition by a fixing device. Fix the agent image on the recording material. Conventionally, 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. Then, in accordance with the setting, control is performed to change development conditions, transfer conditions, fixing processing conditions (for example, fixing temperature and conveyance speed of the recording material passing through the fixing device) or image processing. Further, for example, when the user sets the paper type at the time of printing from the host computer, the image forming apparatus performs control to change the development condition, the transfer condition, the fixing processing condition, or the image processing according to the designated paper type.
また特許文献1には次のような構成が提案されている。記録材の表面映像をCMOSセンサによって撮像し、表面映像の最大濃度のピクセルDmaxと、最低濃度のピクセルDminと、DmaxとDminの差であるコントラストとを導き、このコントラストによって記録材の表面平滑性(表面の繊維の状態)を判別する。画像形成に使用される記録材には、普通紙、普通紙よりも表面の繊維が圧縮されている光沢紙、普通紙よりも表面の繊維が圧縮されていないラフ紙等の複数種類の記録材がある。画像形成装置は、このような記録材の種類によって、現像条件、転写条件又は定着条件を可変制御して、記録材の種類に応じた適正な画像になるように画像形成する。 Patent Document 1 proposes the following configuration. The surface image of the recording material is imaged by a CMOS sensor, and the maximum density pixel Dmax, the minimum density pixel Dmin of the surface image, and the contrast which is the difference between Dmax and Dmin are derived. (Surface fiber state) is determined. The recording material used for image formation includes multiple types of recording materials, such as plain paper, glossy paper whose surface fibers are compressed than plain paper, and rough paper whose surface fibers are not compressed than plain paper There is. The image forming apparatus variably controls development conditions, transfer conditions, or fixing conditions according to the type of the recording material, and forms an image so that an appropriate image according to the type of the recording material is obtained.
従来の画像形成装置における記録材判別は、記録材の撮影映像の画素間のコントラスト差から表面平滑度を算出し記録材の判別を行う方式であり、検出及び判別方法が簡易であり、上記の普通紙、光沢紙、ラフ紙について判別可能な精度が得られている。しかしながら、画像形成に用いられる記録材の種類は多種類あり、その表面平滑性も様々である。例えば、ラフ紙の中でも複数種類あり、夫々の表面平滑性に違いがある。従来の記録材判別の方式では、このような微妙な表面平滑性の違いを判別するには限界があった。 The recording material discrimination in the conventional image forming apparatus is a method for determining the recording material by calculating the surface smoothness from the contrast difference between the pixels of the captured image of the recording material, and the detection and discrimination method is simple, Accuracy that can be discriminated for plain paper, glossy paper, and rough paper is obtained. However, there are many kinds of recording materials used for image formation, and their surface smoothness is also various. For example, there are multiple types of rough paper, and there are differences in the surface smoothness of each. The conventional recording material discrimination method has a limit in discriminating such a slight difference in surface smoothness.
本発明は、このような状況のもとでなされたもので、記録材の特徴量を正確に抽出することができ、より精度の高い記録材判別を行うことを目的とする。 The present invention has been made under such circumstances, and an object of the present invention is to accurately extract the characteristic amount of a recording material and to perform recording material discrimination with higher accuracy.
前記課題を解決するために、本発明は以下の構成を備える。 In order to solve the above problems, the present invention comprises the following arrangement.
(1)記録材の表面の映像を読み取る読取手段を備える記録材判別装置であって、前記読取手段により読み取られた映像を2次元の空間周波数領域のデータに変換する変換手段と、前記変換手段により変換された前記空間周波数領域のデータから振幅スペクトルを算出し、算出した前記振幅スペクトルの分布に基づき前記記録材の特徴量を抽出する抽出手段と、前記抽出手段により抽出された前記特徴量に基づき前記記録材の種類を判別する判別手段とを備えることを特徴とする記録材判別装置。 (1) A recording material discriminating apparatus comprising a reading means for reading an image on the surface of a recording material, the converting means for converting the image read by the reading means into two-dimensional spatial frequency domain data, and the converting means An amplitude spectrum is calculated from the data of the spatial frequency domain converted by the above, and an extraction unit that extracts a feature amount of the recording material based on the calculated distribution of the amplitude spectrum, and the feature amount extracted by the extraction unit And a discriminating means for discriminating the type of the recording material based on the recording material.
(2)像担持体上に静電潜像を形成する露光手段と、前記静電潜像を現像して現像剤像を形成する現像手段と、所定の搬送速度で搬送された記録材上に前記現像剤像を転写する転写手段と、転写された前記現像剤像を定着する定着手段とを備える画像形成装置であって、前記記録材の種類を判別する前記(1)に記載の記録材判別装置と、前記記録材判別装置により判別した記録材の種類に基づき、前記露光手段、前記現像手段、前記転写手段、前記定着手段又は前記搬送速度を制御する制御手段と、を備えることを特徴とする画像形成装置。 (2) An exposure unit that forms an electrostatic latent image on the image carrier, a developing unit that develops the electrostatic latent image to form a developer image, and a recording material conveyed at a predetermined conveyance speed. The recording material according to (1), wherein the recording material includes a transfer unit that transfers the developer image and a fixing unit that fixes the transferred developer image, and determines the type of the recording material. And a control unit that controls the exposure unit, the developing unit, the transfer unit, the fixing unit, or the conveyance speed based on the type of the recording material determined by the recording material determination unit. An image forming apparatus.
本発明によれば、記録材の特徴量を正確に抽出することができ、より精度の高い記録材判別を行うことができる According to the present invention, it is possible to accurately extract a feature amount of a recording material, and to perform recording material discrimination with higher accuracy.
以下本発明を実施するための形態を、実施例により詳しく説明する。 The mode for carrying out the present invention will be described in detail below with reference to examples.
[記録材判別装置の構成]
図1(a)は、記録材の表面平滑性及び反射光量又は透過光量検出を行う記録材判別装置の概略構成を示す模式的断面図である。映像読取センサ123は、第一の光照射手段たる反射用LED1111、記録材1114に対して反対側に設置された透過光量検出用の第二の光照射手段たる透過用LED1112を備える。さらに映像読取センサ123は、読取手段たるCMOSエリアセンサ等のセンサ1110を備えるが、センサ1110はCMOSエリアセンサに限らずCCDセンサやフォトダイオードセンサでもよい。また結像レンズたるレンズ1113を備える。反射用LED1111を光源とする光は、記録材1114表面に対し照射される。記録材1114からの反射光は、レンズ1113を介し集光されてセンサ1110に結像される。これにより映像読取センサ123は記録材1114の表面の映像を読み取る。本実施例では、反射用LED1111は、LED光が記録材1114表面に対し、図1(a)に示すように所定の角度をもって斜めより光を照射させるよう配置される。
[Configuration of recording material discrimination device]
FIG. 1A is a schematic cross-sectional view showing a schematic configuration of a recording material discriminating apparatus that performs surface smoothness of a recording material and detection of a reflected light amount or a transmitted light amount. The image reading sensor 123 includes a reflective LED 1111 serving as a first light irradiating unit, and a transmitting LED 1112 serving as a second light irradiating unit for detecting a transmitted light amount installed on the opposite side of the recording material 1114. Further, the image reading sensor 123 includes a sensor 1110 such as a CMOS area sensor serving as a reading unit. However, the sensor 1110 is not limited to the CMOS area sensor, and may be a CCD sensor or a photodiode sensor. A lens 1113 as an imaging lens is provided. Light that uses the LED 1111 for reflection as a light source is applied to the surface of the recording material 1114. The reflected light from the recording material 1114 is collected through the lens 1113 and imaged on the sensor 1110. As a result, the image reading sensor 123 reads the image on the surface of the recording material 1114. In this embodiment, the reflecting LED 1111 is arranged so that the LED light irradiates the recording material 1114 surface obliquely at a predetermined angle as shown in FIG.
[映像読取センサの出力とディジタル処理]
図1(b)は、映像読取センサ123のセンサ1110によって読み取られる記録材1114の表面とセンサ1110からの画像データの出力を8×8ピクセルにディジタル処理した例との関係を示す図である。ディジタル処理は、センサ1110からのアナログ出力を変換手段たるA/D変換(図示せず)により8ビットのピクセルデータに変換することによって行われる。40は、記録材の表面性において比較的粗く記録材の繊維による凹凸が判別しやすいラフ紙の記録材Aの表面拡大映像である。41は、一般のオフィスで普通に使用される普通紙の記録材Bの表面拡大映像であり、42は、紙の繊維の圧縮が十分になされている光沢紙(以下グロス紙と呼ぶ)の記録材Cの表面拡大映像である。センサ1110に読み込まれたこれらの映像40〜42が、ディジタル処理され図1(b)に示す映像43〜45となる。このように、記録材の種類によって、表面の映像は異なる。これは、主に紙の表面における繊維の状態が異なるために起こる現象である。またこのとき、それぞれの画素に入力された光の合計若しくは平均値から記録材の反射光量を検出する。記録材の反射光量は、主に記録材表面の白色度に左右され、記録材の種類によって異なる。センサ1110で記録材表面を読み込まれディジタル処理された映像により、記録材の紙繊維の表面状態を識別することができ、これに加え反射光量も算出することによって、より正確な記録材の判別が可能となる。
[Output of image reading sensor and digital processing]
FIG. 1B is a diagram showing the relationship between the surface of the recording material 1114 read by the sensor 1110 of the video reading sensor 123 and an example in which the output of image data from the sensor 1110 is digitally processed to 8 × 8 pixels. The digital processing is performed by converting the analog output from the sensor 1110 into 8-bit pixel data by A / D conversion (not shown) as conversion means. Reference numeral 40 denotes an enlarged image of the surface of the recording material A of rough paper, which is relatively rough in the surface property of the recording material and in which irregularities due to the fibers of the recording material can be easily identified. 41 is an enlarged image of the surface of the recording material B of plain paper that is normally used in a general office, and 42 is a record of glossy paper (hereinafter referred to as gloss paper) in which the paper fibers are sufficiently compressed. It is a surface expansion picture of material C. These images 40 to 42 read by the sensor 1110 are digitally processed into images 43 to 45 shown in FIG. Thus, the image on the surface varies depending on the type of recording material. This is a phenomenon that occurs mainly because the fiber state on the paper surface is different. At this time, the reflected light amount of the recording material is detected from the total or average value of the light input to each pixel. The amount of reflected light of the recording material mainly depends on the whiteness of the surface of the recording material and varies depending on the type of recording material. The surface state of the paper fiber of the recording material can be identified from the digital image processed by reading the surface of the recording material by the sensor 1110. In addition to this, the amount of reflected light is also calculated, so that the recording material can be more accurately identified. It becomes possible.
記録材1114の透過率測定方法について説明する。透過用LED1112を光源とする光は、記録材1114に対し映像読取センサ123の反対側から、記録材上の映像読取センサ123の読取エリアを照射する。図1(c)は、透過用LED1112を用いて、映像読取センサ123のセンサ1110によって読み取られる記録材1114の表面とセンサ1110からの出力を8×8ピクセルにディジタル処理した例との関係を示す図である。記録材1114の透過光は、レンズ1113を介し集光されてセンサ1110に照射される。このとき、センサ1110のエリア全体、若しくは所定の範囲におけるそれぞれの画素に入力された光の合計値若しくは平均値から透過光量を判断する。このとき複数の受光画素のうちひとつだけの結果を用いても良い。 A method for measuring the transmittance of the recording material 1114 will be described. The light having the transmission LED 1112 as a light source irradiates the reading area of the image reading sensor 123 on the recording material from the opposite side of the image reading sensor 123 to the recording material 1114. FIG. 1C shows the relationship between the surface of the recording material 1114 read by the sensor 1110 of the video reading sensor 123 and the example in which the output from the sensor 1110 is digitally processed to 8 × 8 pixels using the transmissive LED 1112. FIG. Light transmitted through the recording material 1114 is collected through the lens 1113 and irradiated to the sensor 1110. At this time, the amount of transmitted light is determined from the total value or average value of light input to the entire area of the sensor 1110 or each pixel in a predetermined range. At this time, only one result among the plurality of light receiving pixels may be used.
[坪量と透過光量との関係]
図2に坪量と透過光量の関係図を示す。例えば、厚紙のように坪量の大きい記録材は透過光量が少ないが、薄紙のような坪量の小さい記録材は透過光量が多い。これは、主に紙の表面における繊維の状態及び紙の繊維の圧縮状態が異なるために起こる現象である。
[Relationship between basic weight and transmitted light amount]
FIG. 2 shows the relationship between the basis weight and the amount of transmitted light. For example, a recording material having a large basis weight such as thick paper has a small amount of transmitted light, but a recording material having a small basis weight such as thin paper has a large amount of transmitted light. This is a phenomenon that occurs mainly because the fiber state on the paper surface and the compressed state of the paper fiber are different.
[センサの制御回路]
図3を用いて、センサ1110の制御回路ブロック図について説明する。判断部であるCPU501は、制御レジスタ507に対してセンサ1110の動作指示を与えると、センサ1110により記録材表面映像の撮像を開始する。つまり、センサ1110に電荷の蓄積が開始される。インターフェース回路504から、Sl_select信号によってセンサ1110を選択し、所定のタイミングにてSYSCLK信号を生成すると、センサ1110からSl_out信号を経由して、撮像されたディジタル映像データが送信される。インターフェース回路504を経由して受信した撮像データは、制御回路502の直交変換回路508や演算回路505にて後述する演算方法に基づき演算される。演算結果は、記録材表面の空間周波数として、記録材の演算結果をセットするためのレジスタA〜D 506のうち例えばレジスタA 506にセットされる。CPU501は、レジスタA 506の値から、記録材の表面平滑性を判断する。上述のCPU501は、センサ1110からの映像サンプリング処理、ゲイン及びフィルタ演算処理をリアルタイムにて処理する必要があるため、ディジタルシグナルプロセッサを用いることが望ましい。
[Sensor control circuit]
A control circuit block diagram of the sensor 1110 will be described with reference to FIG. When the CPU 501 serving as the determination unit gives an operation instruction of the sensor 1110 to the control register 507, the sensor 1110 starts imaging the recording material surface image. That is, charge accumulation in the sensor 1110 is started. When the sensor 1110 is selected by the Sl_select signal from the interface circuit 504 and the SYSCLK signal is generated at a predetermined timing, the imaged digital video data is transmitted from the sensor 1110 via the Sl_out signal. The imaging data received via the interface circuit 504 is calculated based on a calculation method described later in the orthogonal transformation circuit 508 and the calculation circuit 505 of the control circuit 502. The calculation result is set in, for example, the register A 506 among the registers A to D 506 for setting the calculation result of the recording material as a spatial frequency on the surface of the recording material. The CPU 501 determines the surface smoothness of the recording material from the value of the register A 506. Since the CPU 501 described above needs to process video sampling processing, gain and filter calculation processing from the sensor 1110 in real time, it is desirable to use a digital signal processor.
[センサの回路]
図4は、センサ1110の回路ブロック図である。Sl_select信号613をアクティブとすると、例えば8×8画素分のセンサがエリア状に配置されたCMOSセンサ部601は受光した光に基づく電荷の蓄積を開始する。次に、SYSCLK(システムクロック)606を与えると、タイミングジェネレータ607によって、垂直方向シフトレジスタ602及び603は読み出す画素の列を順次選択し、出力バッファ604にデータを順次セットする。出力バッファ604にセットされたデータは、水平方向シフトレジスタ605によってA/Dコンバータ608ヘと転送される。A/Dコンバータ608でディジタル変換された画素データは、出力インターフェース回路609によって所定のタイミングで制御されて、Sl_select信号613がアクティブの期間、Sl_out信号610に出力される。一方、制御回路611によって、Sl_in信号612よりA/Dコンバータ608のA/D変換ゲインが可変制御できる。例えば、撮像した映像のコントラストが得られない場合は、CPU501はA/Dコンバータ608のA/D変換ゲインを大きくすることによりコントラストを増加させ、常に最良なコントラストで撮像することができる。
[Sensor circuit]
FIG. 4 is a circuit block diagram of the sensor 1110. When the S1_select signal 613 is activated, for example, the CMOS sensor unit 601 in which sensors for 8 × 8 pixels are arranged in an area starts to accumulate charges based on the received light. Next, when SYSCLK (system clock) 606 is applied, the vertical shift registers 602 and 603 sequentially select the pixel columns to be read out by the timing generator 607 and sequentially set the data in the output buffer 604. The data set in the output buffer 604 is transferred to the A / D converter 608 by the horizontal shift register 605. The pixel data digitally converted by the A / D converter 608 is controlled by the output interface circuit 609 at a predetermined timing, and is output to the Sl_out signal 610 while the Sl_select signal 613 is active. On the other hand, the A / D conversion gain of the A / D converter 608 can be variably controlled by the control circuit 611 from the Sl_in signal 612. For example, if the contrast of the captured image cannot be obtained, the CPU 501 can increase the contrast by increasing the A / D conversion gain of the A / D converter 608 and always capture with the best contrast.
[空間周波数演算方法]
図5を用いて、記録材表面の空間周波数演算方法について説明する。画像70〜72は記録材の表面の映像をディジタル処理した画像である。記録材A 70は、記録材の表面性において比較的粗く記録材の繊維による凹凸や紙目が判別しやすいラフ紙の表面拡大映像である。記録材B 71は、一般のオフィスで普通に使用される普通紙の表面拡大映像であり、記録材C 72は、紙の繊維の圧縮が十分になされているグロス紙の表面拡大映像である。センサ1110のセンサ部から出力されたアナログ信号が、A/D変換されて8ビットのピクセルデータに変換され、画像の明るさに比例した8ビットデータとして、制御回路502に送られる。インターフェース回路504を経由して、直交変換回路508に送られたピクセルデータは、離散フーリエ変換である式(1−1)により空間周波数領域のデータである周波数成分へと変換される(73〜75)。
[Spatial frequency calculation method]
A method for calculating the spatial frequency on the surface of the recording material will be described with reference to FIG. Images 70 to 72 are digitally processed images of the surface of the recording material. The recording material A 70 is an enlarged image of the surface of rough paper that is relatively rough in the surface properties of the recording material and that allows easy recognition of irregularities and paper grain due to the fibers of the recording material. The recording material B 71 is an enlarged image of the surface of plain paper normally used in a general office, and the recording material C 72 is an enlarged image of the surface of gloss paper in which the fibers of the paper are sufficiently compressed. The analog signal output from the sensor unit of the sensor 1110 is A / D converted to 8-bit pixel data, and is sent to the control circuit 502 as 8-bit data proportional to the brightness of the image. The pixel data sent to the orthogonal transformation circuit 508 via the interface circuit 504 is transformed into frequency components which are data in the spatial frequency domain by Expression (1-1) which is a discrete Fourier transform (73 to 75). ).
ここで、N,Mはセンサ1110の縦(y方向)及び横(x方向)の画素数、f(x,y)はx列y行の画素の明るさ、uはx方向の空間周波数、vはy方向の空間周波数を示す。また周波数成分とは、ピクセルデータを周波数毎に分解し、その振幅の大きさをスペクトルとして示したもので、以降振幅スペクトルという。このスペクトルには、元となった映像の特徴が示される。 Here, N and M are the number of pixels in the vertical (y direction) and horizontal (x direction) of the sensor 1110, f (x, y) is the brightness of pixels in x columns and y rows, u is the spatial frequency in the x direction, v indicates a spatial frequency in the y direction. Further, the frequency component is obtained by decomposing pixel data for each frequency and indicating the magnitude of the amplitude as a spectrum, and is hereinafter referred to as an amplitude spectrum. This spectrum shows the characteristics of the original video.
演算回路505では、式(1−2)により空間周波数ごとの振幅スペクトル
を算出し、レジスタA 506にセットする。なお、図5の73〜75は振幅スペクトルの分布を示すもので、70〜72に示すそれぞれの記録材に対応して特徴的な分布を示すことがわかる。
In the arithmetic circuit 505, the amplitude spectrum for each spatial frequency is obtained by the equation (1-2).
Is calculated and set in the register A 506. Note that reference numerals 73 to 75 in FIG. 5 indicate distributions of amplitude spectra, and it can be seen that characteristic distributions corresponding to the respective recording materials 70 to 72 are shown.
[2次元振幅スペクトル]
次に図6を用いて、2次元振幅スペクトルについて説明する。画像中心は、x方向およびy方向のDC成分を表している。y方向の画像中心(図6中A1〜A4およびG1〜G4)は、x方向のDC成分を表している。同様にx方向の画像中心(図6中D1〜D4およびJ1〜J4)は、y方向のDC成分を表している。画像中央部(図6中A1〜L1)は低周波成分を表し、画像周辺部(図6中A4〜L4)は高周波成分を表している。具体的には、記録材Aのように表面の紙繊維の凹凸が多い場合には、さまざまな太さの繊維の影が数多く発生する(図5 70)。その結果、さまざまな濃淡の幅が発生するため、大きな振幅スペクトルが高周波領域まで発生する(図5 76)。一方、記録材Cのような表面では、繊維の影が少ない(図5 72)。その結果、濃淡の変化が穏やかであり、振幅スペクトルは、DC領域に集中する(図5 78)。この比較によって、記録材の紙種を判別する。ここでは振幅スペクトルの算出に、離散フーリエ変換を用いたものの、画素数を2nとして高速フーリエ変換を用いても、また他の直交変換によって周波数成分に変換しても良い。
[Two-dimensional amplitude spectrum]
Next, a two-dimensional amplitude spectrum will be described with reference to FIG. The image center represents the DC component in the x direction and the y direction. The image center in the y direction (A1 to A4 and G1 to G4 in FIG. 6) represents the DC component in the x direction. Similarly, the image center in the x direction (D1 to D4 and J1 to J4 in FIG. 6) represents the DC component in the y direction. The central portion of the image (A1 to L1 in FIG. 6) represents a low frequency component, and the peripheral portion of the image (A4 to L4 in FIG. 6) represents a high frequency component. Specifically, when recording paper A has many irregularities on the surface of the paper fibers, many shadows of fibers of various thicknesses are generated (FIG. 570). As a result, various shade widths are generated, and a large amplitude spectrum is generated up to the high frequency region (FIG. 576). On the other hand, on the surface such as the recording material C, the shadow of the fiber is small (FIG. 572). As a result, the change in shading is gentle, and the amplitude spectrum is concentrated in the DC region (FIG. 578). By this comparison, the paper type of the recording material is determined. Here, although discrete Fourier transform is used for the calculation of the amplitude spectrum, fast Fourier transform may be used with the number of pixels being 2 n , or may be converted into frequency components by other orthogonal transform.
[記録材の特徴量の抽出と記録材種類の判別]
画像形成装置101に備えられた印字条件制御手段たるCPU501による制御フローについて説明する。演算回路505は、空間周波数を領域ごとに分割する。併せて領域の集合を3つ定義する。
DC領域801(図6中A1〜A4,D1〜D4,G1〜G4及びJ1〜J4)
低周波領域802(図6中A2〜L2)
高周波領域803(図6中A3〜L3)
[Extraction of recording material features and discrimination of recording material type]
A control flow by the CPU 501 serving as a printing condition control unit provided in the image forming apparatus 101 will be described. The arithmetic circuit 505 divides the spatial frequency for each region. In addition, three sets of areas are defined.
DC region 801 (A1-A4, D1-D4, G1-G4 and J1-J4 in FIG. 6)
Low frequency region 802 (A2 to L2 in FIG. 6)
High frequency region 803 (A3 to L3 in FIG. 6)
振幅スペクトルが一定以上(所定値以上)の周波数の総数をこの領域ごとに計数し、記録材表面の空間周波数演算結果F801〜F803として定義する。また、図5の76〜78は、73〜75に、記録材の特徴量がわかるように図6に示す空間周波数領域を複数の領域に分割したものを重ねて示したものである。なお、本実施例の特徴量は記録材の種類に起因して抽出されるものである。 The total number of frequencies whose amplitude spectrum is greater than or equal to a certain value (predetermined value or more) is counted for each region and defined as spatial frequency calculation results F801 to F803 on the surface of the recording material. Further, 76 to 78 in FIG. 5 are obtained by superimposing those obtained by dividing the spatial frequency region shown in FIG. 6 into a plurality of regions so that the characteristic amount of the recording material can be understood. Note that the feature amount of this embodiment is extracted due to the type of recording material.
CPU501は演算回路505が演算した記録材表面の空間周波数演算結果F801〜F803をレジスタA 506より取得し、リファレンス値R1〜R3に基づいて以下のように記録材の種類を判別する。ここでリファレンス値R1〜R3は、空間周波数演算結果F801〜F803(以下、単にF801等と記す)に対応したしきい値である。
a)F801≧R1 グロスフィルムと判別
b)F803≧R3 ラフ紙と判別
c)F803<R3&F802≧R2 普通紙と判別
d)その他 未定義と判別
The CPU 501 acquires the spatial frequency calculation results F801 to F803 on the surface of the recording material calculated by the arithmetic circuit 505 from the register A 506, and determines the type of the recording material based on the reference values R1 to R3 as follows. Here, the reference values R1 to R3 are threshold values corresponding to the spatial frequency calculation results F801 to F803 (hereinafter simply referred to as F801 etc.).
a) F801 ≧ R1 discriminated as gloss film b) F803 ≧ R3 discriminated as rough paper c) F803 <R3 & F802 ≧ R2 discriminated as plain paper d) other discriminated as undefined
図8はCPU501が実行する記録材判別処理のフローチャートである。S101でCPU501はF801がR1以上であると判断すると、S107で記録材はグロスフィルムであると判別する。S101でCPU501は、F801がR1以上ではないと判断すると、S102でF803がR3以上であるか否かを判断する。CPU501は、S102でF803がR3以上であると判断すると、S106で記録材はラフ紙と判別する。S102でCPU501は、F803がR3以上ではないと判断すると、S103でF803がR3未満でかつF802がR2以上であるか否かを判断する。S103でCPU501は、F803がR3未満かつF802がR2以上であると判断すると、S105で記録材は普通紙と判別する。S103でCPU501は、F803がR3未満かつF802がR2以上ではないと判断すると、S104で記録材は未定義のものであると判別する。 FIG. 8 is a flowchart of the recording material determination process executed by the CPU 501. If the CPU 501 determines that F801 is equal to or greater than R1 in S101, it determines that the recording material is a gloss film in S107. If the CPU 501 determines that F801 is not equal to or greater than R1 in S101, it determines whether or not F803 is equal to or greater than R3 in S102. If the CPU 501 determines that F803 is equal to or greater than R3 in S102, the CPU 501 determines that the recording material is rough paper in S106. If the CPU 501 determines that F803 is not equal to or greater than R3 in S102, it determines whether or not F803 is less than R3 and F802 is equal to or greater than R2 in S103. If the CPU 501 determines in step S103 that F803 is less than R3 and F802 is equal to or greater than R2, in step S105, the CPU 501 determines that the recording material is plain paper. If the CPU 501 determines that F803 is less than R3 and F802 is not equal to or greater than R2 in S103, it determines that the recording material is undefined in S104.
[リファレンス値と空間周波数演算結果の関係]
次に図7を用いてリファレンス値R1〜R3と空間周波数演算結果F801〜F803の関係を説明する。図7(a)は、リファレンス値R1とDC領域801における空間周波数演算結果F801の関係を示す。記録材Cのような滑らかな表面では、繊維の影が少なく、振幅スペクトルはDC領域に集中する。そのため記録材CのDC領域における空間周波数演算結果F801がリファレンス値R1を上回る。図7(c)は、リファレンス値R3と高周波領域803における空間周波数演算結果F803の関係を示す。記録材Aのように表面の紙繊維の凹凸が多い場合には、さまざまな太さの繊維の影が数多く発生し、大きな振幅スペクトルが高周波領域まで発生する。そのため記録材Aの高周波領域における空間周波数演算結果F803がリファレンス値R3を上回る。最後に図7(b)は、リファレンス値R2と低周波領域802における空間周波数演算結果F802の関係を示す。記録材Bのように表面の紙繊維の凹凸が中庸の場合には、低周波領域における空間周波数演算結果F802がリファレンス値R2を上回る。しかしながら高周波領域における空間周波数演算結果F803がリファレンス値R3を上回らない。以上の組み合わせにより記録材を判別することができる。以上の判別は、x方向及びy方向の情報を同時に処理するため、紙目の影響を受けない。よって縦目・横目のどちらの記録材であっても良好な判別結果を得ることができる。
[Relationship between reference value and spatial frequency calculation result]
Next, the relationship between the reference values R1 to R3 and the spatial frequency calculation results F801 to F803 will be described with reference to FIG. FIG. 7A shows the relationship between the reference value R 1 and the spatial frequency calculation result F 801 in the DC region 801. On a smooth surface such as the recording material C, the shadow of the fiber is small and the amplitude spectrum is concentrated in the DC region. Therefore, the spatial frequency calculation result F801 in the DC region of the recording material C exceeds the reference value R1. FIG. 7C shows the relationship between the reference value R 3 and the spatial frequency calculation result F 803 in the high frequency region 803. When there are many irregularities on the surface of the paper fiber as in the recording material A, many shadows of fibers of various thicknesses are generated, and a large amplitude spectrum is generated up to the high frequency region. Therefore, the spatial frequency calculation result F803 in the high frequency region of the recording material A exceeds the reference value R3. Finally, FIG. 7B shows the relationship between the reference value R 2 and the spatial frequency calculation result F 802 in the low frequency region 802. When the unevenness of the paper fiber on the surface is medium like the recording material B, the spatial frequency calculation result F802 in the low frequency region exceeds the reference value R2. However, the spatial frequency calculation result F803 in the high frequency region does not exceed the reference value R3. The recording material can be discriminated by the above combination. The above determination is not affected by the paper grain because the information in the x direction and the y direction is processed simultaneously. Therefore, a good discrimination result can be obtained for both longitudinal and lateral recording materials.
[画像形成装置への応用]
図9は、本実施例にて説明する画像形成装置の概略構成を示す。ここではタンデム型のカラー画像形成装置を例にあげる。画像形成装置101は、イエロー(Y)、マゼンタ(M)、シアン(C)、ブラック(Bk)の4色の画像形成手段である画像形成部を備える。各画像形成部は、像担持体上に静電潜像を形成する露光手段である露光装置118〜121、像担持体である感光ドラム106〜109、転写手段である転写ローラ110〜113を備える。感光ドラム106〜109は着脱可能なカートリッジ114〜117に含まれる。給紙カセット102からピックアップローラ103で給紙された記録材は、映像読取装置である映像読取センサ123により紙種の判別がなされる。映像読取センサ123により読み取られた記録材表面の映像は、ディジタル処理を施され、図3で説明した直交変換回路508にて空間周波数成分に変換され、演算回路505により記録材の特徴量が抽出される。CPU501は記録材の特徴量から記録材判別を行い、記録材の表面性、記録材の厚みなどの諸特性に応じて、画像処理や、現像バイアス、定着ユニットの温度制御値又は記録材搬送速度を可変制御することによって最適な画像を得ることができる。記録材は駆動モータ104により回転駆動される搬送ベルト105により感光ドラム106〜109と転写ローラ110〜113とのニップ部に搬送され、各色の画像形成部で現像剤像が順次重畳転写されて、記録材上にカラーの画像が形成される。記録材は定着装置122により現像剤像の加熱、定着がなされて画像形成装置の機外へと搬送される。
[Application to image forming equipment]
FIG. 9 shows a schematic configuration of the image forming apparatus described in the present embodiment. Here, a tandem color image forming apparatus is taken as an example. The image forming apparatus 101 includes an image forming unit that is an image forming unit for four colors of yellow (Y), magenta (M), cyan (C), and black (Bk). Each image forming unit includes exposure devices 118 to 121 that are exposure units that form an electrostatic latent image on the image carrier, photosensitive drums 106 to 109 that are image carriers, and transfer rollers 110 to 113 that are transfer units. . The photosensitive drums 106 to 109 are included in removable cartridges 114 to 117. The recording material fed by the pickup roller 103 from the paper feed cassette 102 is discriminated by the video reading sensor 123 which is a video reading device. The image on the surface of the recording material read by the image reading sensor 123 is digitally processed and converted into a spatial frequency component by the orthogonal transformation circuit 508 described with reference to FIG. 3, and the characteristic amount of the recording material is extracted by the arithmetic circuit 505. Is done. The CPU 501 determines the recording material from the characteristic amount of the recording material, and performs image processing, development bias, temperature control value of the fixing unit, or recording material conveyance speed according to various characteristics such as the surface property of the recording material and the thickness of the recording material An optimal image can be obtained by variably controlling. The recording material is conveyed to a nip portion between the photosensitive drums 106 to 109 and the transfer rollers 110 to 113 by a conveying belt 105 that is rotationally driven by a driving motor 104, and a developer image is sequentially superimposed and transferred at each color image forming portion. A color image is formed on the recording material. The recording material is heated and fixed by the fixing device 122 and conveyed outside the image forming apparatus.
次にCPU501が行う判別した記録材に最適な画像形成条件を設定する方法について説明する。CPU501が実行する各種の画像形成条件の制御としては、次のようなものが挙げられる。例えば、CPU501は、記録材の種類がグロス紙の場合は、画像処理の際に普通紙とはγカーブを変更し、色味を変化させる制御を行う。これは、グロス紙を用いてプリントする場合、記録材上のコントラストを高くすることが望まれているからである。さらに、CPU501は、給紙された記録材の種類を判別し、その結果に応じて記録材の搬送速度を変更するように制御する。具体的には、記録材の表面性が普通紙よりも粗いラフ紙の場合、記録材表面の定着フィルムとの接触性が低く、定着ニップ部で記録材への熱の伝播が不均一であり、トナーを溶融させるために必要な熱量が記録材側に十分伝わらない。このためラフ紙では熱量が不足し定着性が低下してしまうという問題がある。そこで、CPU501は記録材の種類がラフ紙であると判別した場合は、単位時間あたりにラフ紙に供給される熱量が大きくなるように、記録材の搬送速度を普通紙を通紙する場合の搬送速度よりも遅く設定する。また、OHTあるいはグロスフィルムなどの場合において、これらを判別して記録材の表面に付着するトナーの定着性を上げ、グロスを高めて画質の向上を図ることもできる。判別結果が未定義だった場合は、CPU501は画像形成装置本体に最もダメージが少ないと考えられる搬送速度、また定着温度となるような定着条件で制御を行う。 Next, a method performed by the CPU 501 for setting optimal image forming conditions for the determined recording material will be described. Examples of the control of various image forming conditions executed by the CPU 501 include the following. For example, when the type of the recording material is glossy paper, the CPU 501 performs control to change the color by changing the γ curve for plain paper during image processing. This is because when printing is performed using gloss paper, it is desired to increase the contrast on the recording material. Further, the CPU 501 determines the type of the fed recording material, and controls to change the recording material conveyance speed in accordance with the result. Specifically, when the surface of the recording material is rough paper, which is rougher than plain paper, the contact with the fixing film on the surface of the recording material is low, and heat transfer to the recording material is uneven at the fixing nip. The amount of heat necessary for melting the toner is not sufficiently transmitted to the recording material side. For this reason, the rough paper has a problem that the heat amount is insufficient and the fixing property is lowered. Therefore, when the CPU 501 determines that the type of the recording material is rough paper, the recording material conveyance speed is set so that the amount of heat supplied to the rough paper per unit time increases. Set slower than the transport speed. Further, in the case of an OHT or a gloss film, it is possible to improve the image quality by discriminating these and improving the fixability of the toner adhering to the surface of the recording material and increasing the gloss. If the determination result is undefined, the CPU 501 performs control under a fixing condition such that the conveyance speed and the fixing temperature are considered to cause the least damage to the image forming apparatus main body.
このように本実施例では、記録材表面の映像を周波数成分に変換し、空間周波数演算結果を算出することにより記録材判別を行うことを特徴とする。本実施例によれば、2次元スペクトルは紙目の影響を容易に除去でき、また周波数成分においては、記録材を構成している繊維の特徴を容易に抽出することが可能であり、高い判別精度を得ることができる。また、様々な条件下においても最適な電子写真プロセスで画像形成処理を施し良好な画像を得ることができる。 As described above, this embodiment is characterized in that the recording material is discriminated by converting the image on the surface of the recording material into a frequency component and calculating the spatial frequency calculation result. According to the present embodiment, the two-dimensional spectrum can easily remove the effect of the paper grain, and the frequency component can easily extract the characteristics of the fibers constituting the recording material, which is highly discriminating. Accuracy can be obtained. In addition, a favorable image can be obtained by performing an image forming process by an optimum electrophotographic process under various conditions.
[紙目判別処理]
実施例2では2次元周波数成分を用いた記録材の特徴量の抽出による紙目判別の詳細について説明する。記録材表面映像の信号処理方法以外の、基本的な構成は実施例1と同様であるため詳細な説明は省略し、同じ符号を用いて説明する。なお、本実施例の特徴量は記録材の紙目に起因して抽出されるものである。図10は2次元周波数成分を用いた紙目判別の詳細を説明する図である。直交変換回路508は、記録材D 1003及び記録材E 1005のピクセルデータを周波数成分に変換する(1004及び1006)。ここで記録材Dは縦目の記録材であり、記録材Eは紙目の無い記録材である。縦目の記録材Dは、紙目の影響によりx方向に強い高周波スペクトルが発生するものの、y方向には高周波スペクトルが発生しない(1004)。一方、紙目のない記録材Eのような表面では、振幅スペクトルは、DC領域に集中する(1006)。
[Paper detection processing]
In the second embodiment, details of the paper grain discrimination by extracting the characteristic amount of the recording material using the two-dimensional frequency component will be described. Since the basic configuration other than the signal processing method for the recording material surface image is the same as that of the first embodiment, detailed description thereof will be omitted, and description will be made using the same reference numerals. Note that the feature amount of this embodiment is extracted due to the grain of the recording material. FIG. 10 is a diagram for explaining the details of the paper grain discrimination using the two-dimensional frequency component. The orthogonal transform circuit 508 converts the pixel data of the recording material D 1003 and the recording material E 1005 into frequency components (1004 and 1006). Here, the recording material D is a vertical recording material, and the recording material E is a paperless recording material. The longitudinal recording material D generates a strong high frequency spectrum in the x direction due to the effect of the paper pattern, but does not generate a high frequency spectrum in the y direction (1004). On the other hand, on the surface such as the recording material E having no paper, the amplitude spectrum is concentrated in the DC region (1006).
まず演算回路505は、実施例1と同様に演算を行った空間周波数を領域ごとに分割する。併せて領域の集合を2つ定義する。
横目領域(1001)(図6中C1〜C4,E1〜E4,I1〜I4及びK1〜K4)
縦目領域(1002)(図6中B1〜B4,F1〜F4,H1〜H4及びL1〜L4)
First, the arithmetic circuit 505 divides the spatial frequency, which is calculated in the same manner as in the first embodiment, for each region. In addition, two sets of areas are defined.
Horizontal region (1001) (C1 to C4, E1 to E4, I1 to I4 and K1 to K4 in FIG. 6)
Longitudinal area (1002) (B1 to B4, F1 to F4, H1 to H4 and L1 to L4 in FIG. 6)
演算回路505は、振幅スペクトルが一定以上の周波数の総数をこの領域ごとに計数し、記録材表面の紙目演算結果F1001及びF1002として定義し、例えばレジスタB 506に保存する。 The arithmetic circuit 505 counts the total number of frequencies having an amplitude spectrum equal to or larger than a certain value for each region, defines them as the paper grain calculation results F1001 and F1002 on the surface of the recording material, and stores them in the register B 506, for example.
CPU501は演算回路505が演算した記録材表面の紙目演算結果F1001〜F1002をレジスタB 506より取得し、記録材の紙目を判別する。記録材の紙目の判別には、横目領域1001の紙目演算結果F1001と縦目領域1002の紙目演算結果F1002との差を求め、その差とリファレンス値R4又はR5に基づいて次のように判別する。リファレンス値R4及びR5は、紙目演算結果F1001,F1002に対応したしきい値である。
e)F1001−F1002≧R4 横目と判別
f)F1002−F1001≧R5 縦目と判別
g)その他 紙目無しと判別
The CPU 501 obtains the paper grain calculation results F1001 to F1002 on the surface of the recording material calculated by the arithmetic circuit 505 from the register B 506, and determines the paper texture of the recording material. In order to discriminate the recording paper, the difference between the paper grain calculation result F1001 of the horizontal eye area 1001 and the paper grain calculation result F1002 of the vertical eye area 1002 is obtained, and based on the difference and the reference value R4 or R5, To determine. The reference values R4 and R5 are threshold values corresponding to the paper grain calculation results F1001 and F1002.
e) F1001-F1002 ≧ R4 discriminated from horizontal eye f) F1002-F1001 ≧ R5 discriminated from vertical eye g) Other
図11(a)にCPU501が実行する記録材判別処理のフローチャートを示す。S201でCPU501は、F1001とF1002の差がR4以上であるか否かを判断する。S201でCPU501は、F1001とF1002の差がR4以上であると判断すると、S205で記録材は横目であると判断する。S201でCPU501は、F1001とF1002の差がR4以上ではないと判断すると、S202でF1002とF1001の差がR5以上か否かを判断する。S202でCPU501は、F1002とF1001の差がR5以上であると判断すると、S204で記録材は縦目であると判別する。S202でCPU501は、F1002とF1001の差がR5以上でないと判断すると、S203で記録材は紙目無しと判別する。 FIG. 11A shows a flowchart of the recording material discrimination process executed by the CPU 501. In S201, the CPU 501 determines whether the difference between F1001 and F1002 is R4 or more. If the CPU 501 determines in S201 that the difference between F1001 and F1002 is equal to or greater than R4, it determines that the recording material is horizontal in S205. If the CPU 501 determines in S201 that the difference between F1001 and F1002 is not equal to or greater than R4, in S202, the CPU 501 determines whether or not the difference between F1002 and F1001 is equal to or greater than R5. If the CPU 501 determines in S202 that the difference between F1002 and F1001 is equal to or greater than R5, it determines that the recording material is a vertical eye in S204. If the CPU 501 determines in S202 that the difference between F1002 and F1001 is not equal to or greater than R5, in S203, the CPU 501 determines that the recording material has no paper.
[紙目に適した画像形成条件の設定]
図11(b)を用いてCPU501が判別した記録材の紙目に最適な画像形成条件設定方法について説明する。CPU501は、判別した記録材の紙目が横目の場合(S1401)、搬送速度及び定着温度を通常よりも低下させる制御を行う(S1405)。これは紙目のある記録材を用いてプリントする場合、定着装置122により高温に加熱されることにより記録材に含まれる水分が蒸発し、記録材には紙目に沿ったカールが生じる。横目の記録材の場合、カールが搬送方向に対し直角に発生するため、紙詰まりの原因となる。搬送速度及び定着温度を低下させることにより、カール量を低減させ紙詰まりの発生を抑えることができる。CPU501は、判別した記録材の紙目が縦目の場合(S1402)、搬送速度及び定着温度を通常どおり制御する(S1404)。縦目の記録材の場合、カールが搬送方向に発生するため、紙詰まりの発生確率が低いためである。CPU501は、判別した記録材の紙目が横目でも縦目でもなく紙目無しと判別した場合、搬送速度及び定着温度を通常どおり制御する(S1403)。紙目の無い記録材の場合、カールの発生確率が低いためである。さらにCPU501は、画像形成装置に推奨される紙目と判別した紙目が異なる場合、表示手段である表示パネルに警告を表示し、使用者に紙の搬送方向を変えさせることもできる。
[Setting image forming conditions suitable for paper texture]
An image forming condition setting method that is optimal for the grain of the recording material determined by the CPU 501 will be described with reference to FIG. When the determined recording material has a horizontal grain (S1401), the CPU 501 performs control to lower the conveyance speed and the fixing temperature than usual (S1405). This is because when printing is performed using a recording material having a paper pattern, moisture contained in the recording material is evaporated by being heated to a high temperature by the fixing device 122, and the recording material is curled along the paper texture. In the case of a horizontal recording material, curling occurs at right angles to the transport direction, which causes a paper jam. By reducing the conveyance speed and the fixing temperature, the curl amount can be reduced and the occurrence of paper jam can be suppressed. When the determined recording material has a vertical grain (S1402), the CPU 501 controls the conveyance speed and the fixing temperature as usual (S1404). This is because, in the case of a longitudinal recording material, curling occurs in the transport direction, and the occurrence probability of paper jam is low. If the CPU 501 determines that the paper of the determined recording material is neither horizontal nor vertical and has no paper, the CPU 501 controls the conveyance speed and the fixing temperature as usual (S1403). This is because the probability of curling is low in the case of a recording material having no paper. Further, when the paper pattern determined to be different from the recommended paper pattern for the image forming apparatus is different, the CPU 501 can display a warning on the display panel, which is a display unit, and allow the user to change the paper conveyance direction.
これまで説明したように本実施例では、記録材表面映像を周波数成分に変換し、紙目演算結果を算出することにより記録材の紙目判別を行うことを特徴とする。本実施例によれば、記録材の特徴量を正確に抽出することができ、精度の高い紙目判別を行うことができる。また、様々な条件下においても最適な電子写真プロセスで処理を施し良好な画像を得ることができる。また、紙目判別結果から適切な電子写真プロセスを選択し、記録材の搬送信頼性及び排紙積載性を向上させることができる。 As described above, this embodiment is characterized in that the recording material surface image is converted into a frequency component, and the paper grain judgment of the recording material is performed by calculating the paper grain calculation result. According to the present embodiment, the feature amount of the recording material can be accurately extracted, and the paper grain discrimination with high accuracy can be performed. Further, even under various conditions, it is possible to obtain a good image by performing an optimal electrophotographic process. In addition, an appropriate electrophotographic process can be selected from the paper eye discrimination result, and the conveyance reliability and discharge stackability of the recording material can be improved.
実施例3は、記録材表面映像の信号処理方法以外の、基本的な構成は実施例1と同様であるため詳細な説明は省略する。特許文献1において提案されているように、従来の記録材の種類判別は、画像読取装置から出力される連続信号を処理することによってなされている。具体的には、記録材の表面画像をライン状に取得し、その1ライン内の最大輝度ピクセルと最小輝度ピクセルのコントラストによって記録材の表面平滑性を判断し、記録材の種類を判別する。図1(b)の記録材Aのように表面の紙繊維がガサついている場合には、繊維の影が多く発生する。その結果、明るい個所と暗い個所の差が大きく出るため、コントラストは大きくなる。一方、図1(b)の記録材Cのような表面では、繊維の影が少なく、コントラストは小さくなる。この比較によって、記録材の紙種を判定する。 Since the basic configuration of the third embodiment is the same as that of the first embodiment except for the signal processing method for the recording material surface image, detailed description thereof is omitted. As proposed in Japanese Patent Application Laid-Open No. H10-228867, conventional recording material type discrimination is performed by processing a continuous signal output from an image reading apparatus. Specifically, the surface image of the recording material is acquired in a line shape, the surface smoothness of the recording material is determined based on the contrast between the maximum luminance pixel and the minimum luminance pixel in the one line, and the type of the recording material is determined. When the paper fiber on the surface is rough like the recording material A in FIG. 1B, many shadows of the fiber are generated. As a result, the difference between the bright part and the dark part becomes large, and the contrast becomes large. On the other hand, on the surface such as the recording material C in FIG. 1B, the shadow of the fiber is small and the contrast is small. This comparison determines the paper type of the recording material.
[記録材表面のコントラスト検出]
図12を用いて、記録材表面のコントラスト検出方法について詳細を説明する。図12において、画像130は記録材の表面の映像をディジタル処理した画像である。センサ1110のセンサ部から出力されたアナログデータが、A/D変換されて8ビットのピクセルデータに変換され、画像の明るさに比例して8ビットデータが決まる。そのとき、最大コントラスト131は、8×8画素のうち最初の1ライン内における最も暗い部分であり、図の例では’80’h、最小コントラスト132は8×8画素のうち最初の1ライン内における最も明るい部分であり、図の例では’10’hとなる。このとき、2つの値の差は、’80’h−’10’h=’70’hである。つまり、第1ラインにおけるコントラスト最大値と最小値の差は’70’hになる。同様に、最大コントラスト133は第2ライン目の値であり最も暗い部分であり’80’h、最小コントラスト134は第2ライン目の値であり最も明るい部分であり’20’h、差は’80’h−’20’h=’60’hである。最大コントラスト135は第8ライン目の値であり最も暗い部分であり’80’h、最小コントラスト136は第8ライン目の値であり最も明るい部分であり’10’h、差は’80’h−’10’h=’70’hとなる。このように横方向の各ラインごとに最大値と最小値の差を全ライン分加算した値を、記録材表面のコントラスト演算結果値として定義し、この大小によって記録材の表面平滑性を判断し、紙種の判別を行うことができる。
[Contrast detection of recording material surface]
The details of the method for detecting the contrast of the surface of the recording material will be described with reference to FIG. In FIG. 12, an image 130 is an image obtained by digitally processing the image of the surface of the recording material. Analog data output from the sensor unit of the sensor 1110 is A / D converted to 8-bit pixel data, and 8-bit data is determined in proportion to the brightness of the image. At that time, the maximum contrast 131 is the darkest part in the first line of 8 × 8 pixels. In the example shown in the figure, “80” h, and the minimum contrast 132 is in the first line of 8 × 8 pixels. Is the brightest part, and is “10” h in the example of the figure. At this time, the difference between the two values is '80'h-'10'h ='70'h. That is, the difference between the maximum contrast value and the minimum value in the first line is “70” h. Similarly, the maximum contrast 133 is the value of the second line and is the darkest part '80'h, the minimum contrast 134 is the value of the second line and the brightest part'20'h, and the difference is'80'h-'20'h = '60'h. The maximum contrast 135 is the value of the eighth line and is the darkest part '80'h, the minimum contrast 136 is the value of the eighth line and the brightest part'10'h, and the difference is'80'h-'10'h = '70'h. The value obtained by adding the difference between the maximum and minimum values for each line in the horizontal direction for all lines is defined as the contrast calculation result value on the surface of the recording material, and the surface smoothness of the recording material is determined based on this magnitude. The paper type can be discriminated.
しかしながら、前述のように記録材の中には紙目を有するものがある。そのため、記録材に対して画像読取装置を斜めに設置し、縦目/横目のどちらであっても同一の判別性能が得られるように構成する場合もある。しかし、記録材の判別のためには、記録材を構成している繊維の太さを検出することも重要であり、画像読取装置を斜めに設置すると繊維の太さを判別する性能が低下する可能性がある。そこで本実施例で説明する記録材判別装置は、記録材の表面画像をライン状に取得する方向を紙目によって変更することを特徴とする。具体的には、実施例2で説明した紙目判別結果が縦目だった場合、横(図12中x方向)に判別を行う。同様に紙目判別結果が横目だった場合、縦(図12中y方向)に判別を行う。すなわち、紙目を判別するために、実施例2で説明した記録材の特徴量を抽出する構成とする。以上の操作により、常に繊維に対して(紙目に対して)垂直に演算を行うことが可能となり、記録材の紙目によらず安定した記録材判別が行える。ここでは、記録材の判別方法に画素の輝度ピクセルのコントラストを使用したものの、本実施例の効果はこの判別方法にとどまらず、ライン状に判別を行う判別方法全てに適応することが可能である。 However, as described above, some recording materials have grain. For this reason, the image reading device may be installed obliquely with respect to the recording material so that the same discrimination performance can be obtained regardless of whether the image is vertical or horizontal. However, for discriminating the recording material, it is also important to detect the thickness of the fibers constituting the recording material, and the performance of discriminating the thickness of the fibers decreases when the image reading device is installed obliquely. there is a possibility. Therefore, the recording material discriminating apparatus described in the present embodiment is characterized in that the direction in which the surface image of the recording material is acquired in a line shape is changed depending on the paper pattern. Specifically, when the paper grain discrimination result described in the second embodiment is a vertical grain, the discrimination is performed horizontally (x direction in FIG. 12). Similarly, if the paper eye discrimination result is a horizontal eye, the discrimination is performed vertically (y direction in FIG. 12). That is, in order to discriminate the paper pattern, the feature amount of the recording material described in the second embodiment is extracted. By the above operation, it becomes possible to always perform the calculation perpendicular to the fiber (to the paper grain), and stable recording material discrimination can be performed regardless of the paper grain of the recording material. Here, although the contrast of the luminance pixel of the pixel is used as the recording material discrimination method, the effect of the present embodiment is not limited to this discrimination method, and can be applied to all discrimination methods for discrimination in a line shape. .
これまで説明したように本実施例では、紙目判別結果により、記録材判別方法を変更し記録材の判別性能を向上することを特徴とする。本実施例によれば、記録材の特徴量を正確に抽出することができ、記録材の紙目によらず安定した記録材判別を行うことができる。また、様々な条件下においても最適な電子写真プロセスで処理を施し良好な画像を得ることができる。 As described above, the present embodiment is characterized in that the recording material discrimination method is changed according to the paper grain discrimination result to improve the discrimination performance of the recording material. According to the present embodiment, the characteristic amount of the recording material can be accurately extracted, and stable recording material discrimination can be performed regardless of the grain of the recording material. Further, even under various conditions, it is possible to obtain a good image by performing an optimal electrophotographic process.
123 映像読取センサ
501 判断部(CPU)
502 制御回路
505 演算回路
508 直交変換回路
123 Image Reading Sensor 501 Judgment Unit (CPU)
502 control circuit 505 arithmetic circuit 508 orthogonal transform circuit
Claims (6)
前記読取手段により読み取られた映像を2次元の空間周波数領域のデータに変換する変換手段と、
前記変換手段により変換された前記空間周波数領域のデータから振幅スペクトルを算出し、算出した前記振幅スペクトルの分布に基づき前記記録材の特徴量を抽出する抽出手段と、
前記抽出手段により抽出された前記特徴量に基づき前記記録材の種類を判別する判別手段と、
を備えることを特徴とする記録材判別装置。 A recording material discriminating device comprising a reading means for reading an image of the surface of a recording material,
Conversion means for converting the video read by the reading means into two-dimensional spatial frequency domain data;
An extraction means for calculating an amplitude spectrum from the data of the spatial frequency domain converted by the conversion means, and extracting a characteristic amount of the recording material based on the distribution of the calculated amplitude spectrum;
Discriminating means for discriminating the type of the recording material based on the feature amount extracted by the extracting means;
A recording material discriminating apparatus comprising:
前記記録材の種類を判別する請求項1乃至4のいずれか1項に記載の記録材判別装置と、
前記記録材判別装置により判別した記録材の種類に基づき、前記露光手段、前記現像手段、前記転写手段、前記定着手段又は前記搬送速度を制御する制御手段と、を備えることを特徴とする画像形成装置。 An exposure unit that forms an electrostatic latent image on an image carrier; a developing unit that develops the electrostatic latent image to form a developer image; and the developer on a recording material conveyed at a predetermined conveyance speed. An image forming apparatus comprising: transfer means for transferring an image; and fixing means for fixing the transferred developer image,
The recording material discrimination device according to any one of claims 1 to 4, wherein the type of the recording material is discriminated.
An image forming apparatus comprising: the exposure unit, the developing unit, the transfer unit, the fixing unit, or a control unit that controls the conveyance speed based on the type of the recording material determined by the recording material determination device. apparatus.
前記記録材の紙目を判別する請求項3に記載の記録材判別装置と、
前記記録材判別装置により判別した記録材の紙目に応じて、前記定着手段及び前記搬送速度を制御する制御手段と、を備えることを特徴とする画像形成装置。 An exposure unit that forms an electrostatic latent image on an image carrier; a developing unit that develops the electrostatic latent image to form a developer image; and the developer on a recording material conveyed at a predetermined conveyance speed. An image forming apparatus comprising: transfer means for transferring an image; and fixing means for fixing the transferred developer image,
The recording material discriminating apparatus according to claim 3, wherein the recording material discriminating paper is discriminated.
An image forming apparatus comprising: the fixing unit and a control unit that controls the conveyance speed according to the grain of the recording material determined by the recording material determination device.
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