JPH03174173A - Optical sensor - Google Patents
Optical sensorInfo
- Publication number
- JPH03174173A JPH03174173A JP2039801A JP3980190A JPH03174173A JP H03174173 A JPH03174173 A JP H03174173A JP 2039801 A JP2039801 A JP 2039801A JP 3980190 A JP3980190 A JP 3980190A JP H03174173 A JPH03174173 A JP H03174173A
- Authority
- JP
- Japan
- Prior art keywords
- light
- directivity
- receiving element
- emitting element
- optical sensor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 230000003287 optical effect Effects 0.000 title claims abstract description 43
- 230000007423 decrease Effects 0.000 abstract description 7
- 238000001514 detection method Methods 0.000 abstract description 4
- 230000008021 deposition Effects 0.000 abstract 1
- 108091008695 photoreceptors Proteins 0.000 description 12
- 238000010586 diagram Methods 0.000 description 7
- 238000000034 method Methods 0.000 description 6
- 230000005855 radiation Effects 0.000 description 4
- 230000005540 biological transmission Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- 230000035945 sensitivity Effects 0.000 description 2
- 235000000722 Celosia argentea Nutrition 0.000 description 1
- 240000008365 Celosia argentea Species 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 210000000988 bone and bone Anatomy 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 230000003292 diminished effect Effects 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 230000003595 spectral effect Effects 0.000 description 1
Landscapes
- Investigating Or Analysing Materials By Optical Means (AREA)
- Developing For Electrophotography (AREA)
- Dry Development In Electrophotography (AREA)
- Control Or Security For Electrophotography (AREA)
- Color Electrophotography (AREA)
Abstract
Description
【発明の詳細な説明】
！ ＝ｌｆｌ ｌ壮公１−
本発明は、像担持体上に形成されたトナー付着パターン
の濃度を光学センサで検知し、その出力により画像濃度
制御を行なう画像形成装置の上記光学センサに関する。[Detailed description of the invention]! =lfl l Soko 1- The present invention relates to the optical sensor of an image forming apparatus that detects the density of a toner adhesion pattern formed on an image carrier with an optical sensor and controls the image density based on the output thereof.
【東炎糺
電子写真複写機、プリンタ、ファクシミリ等の電子写真
プロセスを利用した画像形成装置では、感光体等像担持
体の経時的劣化、現像剤中のトナー濃度の低下により形
成される画像の濃度が低下する。[In image forming devices that use electrophotographic processes, such as Toen-ten electrophotographic copiers, printers, and facsimile machines, images formed due to deterioration of image carriers such as photoreceptors over time and a decrease in toner concentration in the developer. concentration decreases.
これを補正する方法として、例えば電子写真複写機の場
合、原稿載置領域外の原稿載置面近傍に一定濃度を有す
る基準パターンを設け、露光々源でこの基準パターンを
照明しその反射光を感光体に露光し、現像器で現像し、
感光体上に形成されたトナー付着パターンの濃度を光学
センサで検知し、制御設定値と比較して現像剤中のトナ
ー濃度、帯電４位、露光々量、現像バイアス等の画像濃
度決定条件を制御して画像濃度を所定の濃度に補正する
方法が知られている４上記の光学センサは一般にＰセン
サと呼ばれ、こｈを使用した画像濃度制御方法はＰセン
サ法と呼ばれている。As a method to correct this, for example, in the case of an electrophotographic copying machine, a reference pattern with a constant density is provided near the document placement surface outside the document placement area, and this reference pattern is illuminated with various exposure sources to absorb the reflected light. Expose the photoreceptor to light, develop it with a developer,
The density of the toner adhesion pattern formed on the photoconductor is detected by an optical sensor, and compared with the control setting values, image density determination conditions such as toner density in the developer, charge level, exposure amount, and development bias are determined. A method of correcting the image density to a predetermined density by controlling is known.4 The above-mentioned optical sensor is generally called a P sensor, and an image density control method using this is called the P sensor method.
Ｐセンサとして用いられる光学センサは、第１図に例示
する如く、発光素子３と受光素子４とを近接させて並置
して戒り、これを感光体１に対設し、その上に形成され
たトナー付着パターン２を発光ダイオード（ＬＥＤ）等
の発光素子３により照射し、その反射光をホトトランジ
スタ（ＰＴ）又はホトダイオード（ＰＤ）等の受光素子
４により検知してトナー付着パターン２の濃度、すなわ
ちトナー付着量を検知する反射型光電センサが広く使用
されている。感光体が透明な場合は、感光体を挟んでそ
の両側に発光素子と受光素子とを対設した透過型光学セ
ンサも使用される。As illustrated in FIG. 1, the optical sensor used as the P sensor has a light emitting element 3 and a light receiving element 4 juxtaposed in close proximity to each other, and is placed opposite to a photoreceptor 1. The toner adhesion pattern 2 is irradiated with a light emitting element 3 such as a light emitting diode (LED), and the reflected light is detected by a light receiving element 4 such as a phototransistor (PT) or a photodiode (PD) to determine the density of the toner adhesion pattern 2. That is, reflective photoelectric sensors that detect the amount of toner adhesion are widely used. When the photoreceptor is transparent, a transmission type optical sensor in which a light-emitting element and a light-receiving element are provided oppositely on both sides of the photoreceptor is also used.
さて、近年、カラー画像に対する市場の要望が強くなり
、カラートナー現像装置を有するカラー複写機等カラー
画像形成装置の開発、商品化が積極的に行なわれている
。この場合、カラー画像濃度の制御も上記の光学センサ
で検知して制御する必要がある。Now, in recent years, there has been a strong demand for color images in the market, and color image forming apparatuses such as color copying machines having color toner developing devices have been actively developed and commercialized. In this case, it is also necessary to control the color image density by detecting it with the above-mentioned optical sensor.
−かし、カラートナーを従来の光学センサで検出した場
合、以下に述べるような不具合が発生した、
（′Ｌ） 第２図に示す如く、乱反射型光学センサの場
合も、正反射型光学センサの場合も、トナー付着量が未
だ少ない領域で反射光量の変化、ひいては受光素子出力
の変化かは一′飽和してしまう。- However, when color toner was detected using a conventional optical sensor, the following problems occurred. Even in this case, the change in the amount of reflected light and, by extension, the change in the output of the light-receiving element reaches a point of saturation in an area where the amount of toner adhesion is still small.
（２） トナー付着量の変化に対する反射光量の変化幅
が少ないため、受光素子の出力に高分解特性が要求され
るという不具合があることが判明した。(2) It has been found that there is a problem in that the output of the light-receiving element is required to have high resolution characteristics because the range of change in the amount of reflected light with respect to the change in the amount of toner adhesion is small.
その原因を検討したところ、以下の事項によることか判
明した。When we investigated the cause, we found that it was due to the following items.
（ａ） 光学センサの発光素子であるＬＥＤ （発光
ダイオード）の発光波長はカラートナーの色に無関係に
使用できるように、換言すれば１つの発光素子で全ての
カラートナーを検出することかできるように、通常９５
０ｎｍ程度の波長の赤外光が用いられているが、第３図
に示す如く、この波長では、黒トナーは入射光を吸収す
るが、カラートナーでは吸収率は低く、入射光の多くの
部分がトナー表面で反射、あるいは透過してしまう。(a) The emission wavelength of the LED (light emitting diode), which is the light emitting element of the optical sensor, can be used regardless of the color of the color toner, in other words, it is possible to detect all color toners with one light emitting element. Usually 95
Infrared light with a wavelength of about 0 nm is used, but as shown in Figure 3, black toner absorbs incident light at this wavelength, but color toner has a low absorption rate and a large portion of the incident light is absorbed. is reflected or transmitted by the toner surface.
（ｂ） その結果、黒トナーに対しては、正反射位置
に受光素子を置けば、正反射光の減衰として濃度を十分
検出できるが、カラートナーの場合は、正反射光の減衰
に対して、乱反射光の増加が起り、両者を分離して検出
しなければならない。(b) As a result, for black toner, if the light-receiving element is placed at the specular reflection position, the density can be detected sufficiently as the attenuation of the specularly reflected light, but for color toner, the density can be detected as the attenuation of the specularly reflected light. , an increase in diffusely reflected light occurs, and both must be detected separately.
（ｃ） 透過光測定の場合、感光体を挟んで発光素子
と受光素子とを正確に対向させるのが難しく、位置ずれ
により、検出光量不足が発生し易い。(c) In the case of transmitted light measurement, it is difficult to accurately align the light emitting element and the light receiving element with the photoreceptor in between, and positional deviations tend to cause an insufficient amount of detected light.
％Ｂわ（解決しようとする課題
本発明は、従来の画像濃度制御のための光学センサの上
記の欠点にかんがみ、カラートナーの検知に対しても反
射光あるいは透過光を効率よく検出することのできる光
学センサを提供することを課題とする。% B (Problems to be Solved) In view of the above-mentioned drawbacks of conventional optical sensors for controlling image density, the present invention has developed a method for efficiently detecting reflected light or transmitted light even when detecting color toner. The objective is to provide an optical sensor that can
０、題 ゛のための
本発明は、上記の課題を解決させるため、（）） 光
学センサが正反射型光学センサの場合は、受光素子の指
向性を発光素子の指向性より快くし、
（２） 光学センサが乱反射型又は透過型光学センサの
場合は、受光素子の指向性を発光素子の指向性より広く
したことを特徴とする。In order to solve the above-mentioned problems, the present invention for the title ゛ ()) When the optical sensor is a specular reflection type optical sensor, the directivity of the light receiving element is made easier than the directivity of the light emitting element, and ( 2) When the optical sensor is a diffuse reflection type or a transmission type optical sensor, it is characterized in that the directivity of the light receiving element is wider than the directivity of the light emitting element.
作 用
以下に、本発明の作用を図面に基づいて詳細に説明する
。Function The function of the present invention will be explained in detail below based on the drawings.
本発明が問題としている発光素子、受光素子の指向性と
は、それぞれ、放射強度、感度強度の素子を中心とする
各方向の分布を云うものである。The directivity of a light-emitting element and a light-receiving element, which are the subject of the present invention, refers to the distribution of radiation intensity and sensitivity intensity in each direction centered on the element, respectively.
理論的な点光源から発生する光線の放射強度は各方向と
も光源からの距離の２乗に反比例し、指向性はないが、
実際の光源では、それを取付ける基板による遮光、反射
、出射面の開口、保護ガラスの形状等によって指向性を
生じ、一般に、放射、感度強度は発光素子、受光素子正
面光軸方向が最大であり、光軸からの角度が大きくなる
に従って減少する。第７図には指向性の異る２つのサン
プルが示されており、サンプル１は光軸を中心として両
側に漸次放射強度が減少してゆき±６０°で放射強度は
５０％になるのに対して、サンプル２は光軸を中心とし
て放射強度は急激に減少して行き±８°位で放射強度は
５０％に減ってしまう。The radiant intensity of light rays generated from a theoretical point light source is inversely proportional to the square of the distance from the light source in each direction, and has no directivity.
In an actual light source, directivity occurs due to light shielding and reflection by the board on which it is attached, the opening of the output surface, the shape of the protective glass, etc., and in general, the radiation and sensitivity intensity are greatest in the direction of the optical axis in front of the light emitting element and light receiving element. , decreases as the angle from the optical axis increases. Figure 7 shows two samples with different directivity.In sample 1, the radiant intensity gradually decreases on both sides around the optical axis, and the radiant intensity reaches 50% at ±60°. On the other hand, in sample 2, the radiation intensity rapidly decreases around the optical axis, and the radiation intensity decreases to 50% at about ±8°.
この場合サンプル２はサンプル１に比して指向性が狭い
と云う。In this case, sample 2 is said to have narrower directivity than sample 1.
次に、正反射型、乱反射型及び透過型の各型の光学セン
サについて受光素子と発光素子との備えるべき指向性の
広狭関係について考察する。Next, the relationship between the directivity of the light-receiving element and the light-emitting element for each of the specular reflection type, diffuse reflection type, and transmission type optical sensors will be considered.
（１） 正反射型光学センサ
第１図の構成の正反射型光学センサにおいては、正反射
光の減衰のみを検出し、ノイズとなる乱反射光は極力排
除する必要があるが受光素子の指向性が広いと、正反射
方向に対する検知面積が広くなり、乱反射光がより多く
入射してしまうことになる。したがって、指向性を狭く
することにより、検知面積を縮小するのと同じ効果が発
生し、乱反射光が入射する割合を減らすことができる。(1) Specular reflection type optical sensor In the specular reflection type optical sensor with the configuration shown in Figure 1, it is necessary to detect only the attenuation of the specularly reflected light and eliminate as much as possible the diffusely reflected light that becomes noise. If is wide, the detection area in the specular reflection direction will be wide, and more diffusely reflected light will be incident. Therefore, by narrowing the directivity, the same effect as reducing the detection area occurs, and it is possible to reduce the incidence of diffusely reflected light.
たゾし、発光素子の指向性は、受光素子と同様には快く
できない。その理由は、発光素子の指向性をあまり狭く
すると光学センサと感光体の相互位置のばらつきにより
正反射光の光路と受光素子の受光光路がずれてしまい、
検出光量の減少あるいは受光素子の指向性を狭くした効
果が減殺される故である。However, the directivity of the light-emitting element cannot be as easily determined as that of the light-receiving element. The reason for this is that if the directivity of the light-emitting element is made too narrow, the optical path of the specularly reflected light and the light-receiving optical path of the light-receiving element will be misaligned due to variations in the relative positions of the optical sensor and the photoreceptor.
This is because the effect of reducing the amount of detected light or narrowing the directivity of the light receiving element is diminished.
第４図は、感光体上にトナーが付着していない場合の反
射光分布及びカラートナーが付着している場合の反射光
分布の一例を示す図であり、カラートナーが付着してい
る場合は反射光分布が広く拡がっている。しかし、本発
明により光学センサの受光素子の指向性を狭くすること
により、乱反射光の入射割合を減らし、正反射光の検知
割合を向上することができる。FIG. 4 is a diagram showing an example of the reflected light distribution when no toner is attached to the photoconductor and the reflected light distribution when color toner is attached. The reflected light distribution is widely spread. However, by narrowing the directivity of the light receiving element of the optical sensor according to the present invention, it is possible to reduce the incidence rate of diffusely reflected light and improve the detection rate of specularly reflected light.
（２） 乱反射型光学センサ
乱反射型光学センサにおいては、あらゆる方向へ反射さ
れる乱反射光を効率よく検出する為に受光素子の指向性
を広くする必要がある。但し、発光素子の指向性は、乱
反射光のなかに正反射光が混入しない様できるだけ狭く
する必要がある。このことは、第４図から容易に理解で
きよう。(2) Diffuse-reflection type optical sensor In a diffuse-reflection type optical sensor, in order to efficiently detect diffusely reflected light reflected in all directions, it is necessary to widen the directivity of the light-receiving element. However, the directivity of the light emitting element needs to be as narrow as possible so that specularly reflected light does not mix into the diffusely reflected light. This can be easily understood from FIG.
（３） 透過型光学センサ
第５図に透明感光体１を透過した透過光の強度分布を、
感光体上にトナーがあるときと、トナーがない時につい
て示した。この図より理解できるように、
発光素子と受光素子の対向ずれを補うには、■受光素子
の指向性狭く子骨光素子の指向性広く２ ツノ
広く十 ツノ 狭くの組み合わ
せが考えられるが、発光々量を効率よく検出する為には
、■の組み合わせの方がよい。(3) Transmissive optical sensor Figure 5 shows the intensity distribution of transmitted light transmitted through the transparent photoreceptor 1.
It shows when there is toner on the photoreceptor and when there is no toner. As can be understood from this figure, in order to compensate for the misalignment between the light emitting element and the light receiving element, a combination of ■Narrow directivity of the light receiving element and Wide directivity of the bone optical element can be considered. In order to detect the amount efficiently, the combination (■) is better.
第６図に本発明の各型の光学センサによるカラートナー
の付着量と受光素子出力との関係曲線を示す。これらの
曲線から明らかなように、本発明の各型の光学センサで
はトナー付着量の変化に対する受光素子出力の変化が充
分大きくなる。FIG. 6 shows a relationship curve between the amount of color toner adhered to each type of optical sensor of the present invention and the light receiving element output. As is clear from these curves, in each type of optical sensor of the present invention, the change in the light receiving element output with respect to the change in the amount of toner adhesion is sufficiently large.
以上、正反射型、乱反射型、透過型光学センサの発光・
受光素子の指向性について述べたが、いずれの場合にお
いても反射あるいは透過光を効率よく検出する為に、各
素子の指向性を互いに、異なったものにする必要がある
。しかし、受光素子、発光素子の指向性は比較的自由に
設計することができ、その製法も特別難しくはない。The above describes the light emission and
Although the directivity of the light receiving elements has been described, in any case, in order to efficiently detect reflected or transmitted light, it is necessary to make the directivity of each element different from each other. However, the directivity of the light-receiving element and the light-emitting element can be designed relatively freely, and the manufacturing method thereof is not particularly difficult.
影−４
以上の如く、本発明によれば、簡単な構成でコストの上
昇も殆どなく、比較的容易にカラートナーに対するトナ
ー付着パターンの濃度センサとして十分なセンサ特性を
得ることが可能となる。Shadow 4 As described above, according to the present invention, it is possible to relatively easily obtain sufficient sensor characteristics as a density sensor for toner adhesion patterns for color toners with a simple configuration and almost no increase in cost.
第１図は本発明が適用される光学センサの構成の１例を
示す説明図、第２図は従来の光学センサによるカラート
ナーの付着量と受光素子出力の関係を示す曲線図、第３
図は黒トナー及びカラートナーの分光反射率曲線、第４
図は第１図のセンサの発光素子により感光体面を照射し
た場合のトナーがない時とカラートナーがある時の反射
光分布を示す説明図、第５図は発光素子により照射され
た感光体上にトナーがない時とカラートナーがある時の
透過光分布を示す説明図、第６図は本発明の光学センサ
によるカラートナーの付着量と受光素子出力の関係を示
す曲線図、第７図は発光素子の指向性の広狭を説明する
説明図である。
１・・・感光体、
２・・・付着トナー
３・・・発光素子、
４・・・受光素子
、逢FIG. 1 is an explanatory diagram showing an example of the configuration of an optical sensor to which the present invention is applied, FIG. 2 is a curve diagram showing the relationship between the amount of color toner adhered to a conventional optical sensor and the light receiving element output, and FIG.
The figure shows the spectral reflectance curves of black toner and color toner.
The figure is an explanatory diagram showing the distribution of reflected light when there is no toner and when there is color toner when the photoreceptor surface is irradiated by the light emitting element of the sensor shown in Figure 1. Figure 5 shows the distribution of reflected light on the photoreceptor surface irradiated by the light emitting element. 6 is an explanatory diagram showing the transmitted light distribution when there is no toner and when color toner is present. FIG. 6 is a curve diagram showing the relationship between the amount of color toner adhered to the optical sensor of the present invention and the output of the light receiving element. FIG. 2 is an explanatory diagram illustrating the width and narrowness of the directivity of a light emitting element. DESCRIPTION OF SYMBOLS 1...Photoreceptor, 2...Adhesive toner 3...Light emitting element, 4...Light receiving element,
Claims (2)
素子と受光素子とを有して成る光学センサの発光素子よ
り出射される光線で上記パターンを照射し、その正反射
光の光量を上記光学センサの受光素子で測定し、上記パ ターンのトナー付着量を検知する像形成装置の上記光学
センサにおいて、 上記受光素子の指向性を発光素子の指向性 より狭くしたことを特徴とする光学センサ。(1) Form a toner adhesion pattern on an image carrier, irradiate the pattern with a light beam emitted from a light emitting element of an optical sensor comprising a light emitting element and a light receiving element, and calculate the amount of specularly reflected light. The optical sensor of the image forming apparatus detects the toner adhesion amount of the pattern by measuring with a light receiving element of the optical sensor, characterized in that the directivity of the light receiving element is narrower than the directivity of the light emitting element. .
素子と受光素子とを有して成る光学センサの発光素子よ
り出射される光線で上記パターンを照射し、その乱反射
光の光量を上記光学センサの受光素子で測定し、上記パ ターンのトナー付着量を検知する画像形成装置の上記光
学センサにおいて、 上記受光素子の指向性を発光素子の指向性 より広くしたことを特徴とする光学センサ。(2) Form a toner adhesion pattern on the image carrier, irradiate the pattern with a light beam emitted from a light emitting element of an optical sensor comprising a light emitting element and a light receiving element, and adjust the amount of diffusely reflected light to The optical sensor of the image forming apparatus detects the amount of toner adhesion of the pattern by measuring with a light receiving element of the optical sensor, characterized in that the directivity of the light receiving element is wider than the directivity of the light emitting element.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2039801A JP3029628B2 (en) | 1989-09-05 | 1990-02-22 | Image forming device |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1-228265 | 1989-09-05 | ||
| JP22826589 | 1989-09-05 | ||
| JP2039801A JP3029628B2 (en) | 1989-09-05 | 1990-02-22 | Image forming device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH03174173A true JPH03174173A (en) | 1991-07-29 |
| JP3029628B2 JP3029628B2 (en) | 2000-04-04 |
Family
ID=26379198
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2039801A Expired - Lifetime JP3029628B2 (en) | 1989-09-05 | 1990-02-22 | Image forming device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3029628B2 (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH1063058A (en) * | 1996-08-13 | 1998-03-06 | Konica Corp | Controller for image forming process |
| EP1081558A1 (en) * | 1999-08-30 | 2001-03-07 | Ricoh Company, Ltd. | Image forming apparatus |
| US7443535B2 (en) | 2002-03-25 | 2008-10-28 | Ricoh Company, Limited | Misalignment correction pattern formation method and misalignment correction method |
| JP2012103567A (en) * | 2010-11-11 | 2012-05-31 | Ricoh Co Ltd | Image forming apparatus |
| JP2020042120A (en) * | 2018-09-10 | 2020-03-19 | キヤノン株式会社 | Image forming device, optical sensor |
-
1990
- 1990-02-22 JP JP2039801A patent/JP3029628B2/en not_active Expired - Lifetime
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH1063058A (en) * | 1996-08-13 | 1998-03-06 | Konica Corp | Controller for image forming process |
| EP1081558A1 (en) * | 1999-08-30 | 2001-03-07 | Ricoh Company, Ltd. | Image forming apparatus |
| US6343198B1 (en) | 1999-08-30 | 2002-01-29 | Ricoh Company, Ltd. | Image forming apparatus including interlocking light emitting and receiving portions |
| US7443535B2 (en) | 2002-03-25 | 2008-10-28 | Ricoh Company, Limited | Misalignment correction pattern formation method and misalignment correction method |
| US8279491B2 (en) | 2002-03-25 | 2012-10-02 | Ricoh Company, Limited | Color image formation apparatus for forming a reference pattern with a plurality of lines having a black color as reference color and for correcting misalignment with respect to the reference pattern |
| JP2012103567A (en) * | 2010-11-11 | 2012-05-31 | Ricoh Co Ltd | Image forming apparatus |
| JP2020042120A (en) * | 2018-09-10 | 2020-03-19 | キヤノン株式会社 | Image forming device, optical sensor |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3029628B2 (en) | 2000-04-04 |
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