JPS60214352A - Copy density adjusting device - Google Patents

Abstract

PURPOSE:To improve the detection precision of original ground density by setting a comparison condition to a density level above a predetermined ground density detection area. CONSTITUTION:The density of an original is measured at plural positions by a measuring means 1. A ground density deciding means 2 sets the comparison condition to the density level above the predetermined ground density detection area to compare density measured values of plural positions of the original from the measuring means 1 with the comparison condition and also compares the number of measured values higher than the comparison condition with a preset number. When the number of measured values above the comparison condition is smaller than the set number, said hugh-density measured values are regarded as density measured values of an image part and removed, and the ground density of the original is calculated from measured values of density lower than the comparison condition. When the number of measured values of density higher than the comparison condition is larger than the set number, the ground density of the original is calculated from all measured values. Then, an adjusting means 3 adjusts copy density with the output signal of the deciding means 2.

Description

【発明の詳細な説明】 （技術分野） 本発明は複写機において原稿の地肌濃度を検出して複写
画像濃度を自動的に調整する複写濃度調整装置に関する
。DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a copy density adjusting device that detects the background density of a document in a copying machine and automatically adjusts the density of a copied image.

（従来技術） 従来、複写濃度調整装置には原稿における複数個所の濃
度を測定し、その測定値を全て演算して、例えば平均値
を計算して原稿の地肌濃度を認識し複写濃度を調整する
方式が知られている。しかしこの方式では濃度測定点が
原稿の地肌部に常に位置するとは限らず、文学部や写真
のベタ黒部等の画像部の濃度を測定する可能性が大きい
。濃度測定点が画像部に轟たると、原稿の地肌濃度を実
際より濃く認識してしまい、原稿を複写する時に複写画
像の画像とび（画像消失）を発生させることになる。(Prior art) Conventionally, a copy density adjustment device measures the density at multiple locations on a document, calculates all the measured values, calculates an average value, recognizes the background density of the document, and adjusts the copy density. The method is known. However, in this method, the density measurement point is not always located in the background area of the document, and there is a high possibility that the density of the image area, such as a literature section or a solid black area of a photograph, is measured. If the density measurement points appear in the image area, the background density of the original will be perceived to be darker than it actually is, which will cause image skipping (image disappearance) in the copied image when copying the original.

（目的） 本発明は原稿地肌濃度の検出精度を高めて画像とびをな
くすようにした複写濃度調整装置を提供することを目的
とする。(Objective) It is an object of the present invention to provide a copy density adjusting device that improves the accuracy of detecting the background density of a document and eliminates image skipping.

（構成） 以下図面を参照しながら本発明の詳細な説明する。(composition) The present invention will be described in detail below with reference to the drawings.

本発明の構成を第１図で説明すると、複写機において、
原稿における複数個所の濃度を測定手段１により測定す
る。地肌濃度判別手段２は予め定めた地肌濃度検出領域
より濃度が高いレベルに比較条件を設定してとの比較条
件と測定手段１からの原稿における複数個所の濃度測定
値とを比較すると共に、比較条件より高濃度の濃度測定
値の個数を予め設定した個数と比較し、比較条件より高
濃度の濃度測定値の個数が上記設定個数よシ少ない場合
には比較条件より高濃度の濃度測定値を画像部の濃度測
定値とみなして削除して比較条件よシ低濃度の濃度測定
値よシ原稿地肌濃度を演算し、比較条件より高濃度の濃
度測定値の個数が上記設定個数より多い場合には全ての
濃度測定値より原稿地肌濃度を演算する。そして調整手
段３は地肌濃度判別手段２の出力信号により複写濃度を
調整する。To explain the configuration of the present invention with reference to FIG. 1, in a copying machine,
The measuring means 1 measures the density at a plurality of locations on the document. The background density determination means 2 sets a comparison condition to a level where the density is higher than a predetermined background density detection area, and compares the comparison condition with the density measurement values at a plurality of locations on the document from the measurement means 1. Compare the number of concentration measurement values with a higher concentration than the comparison condition with the preset number, and if the number of concentration measurement values with a concentration higher than the comparison condition is less than the set number, set the concentration measurement value with a concentration higher than the comparison condition. The background density of the document is calculated based on the density measurement value of the lower density, and the number of density measurement values of the higher density than the comparison condition is greater than the set number. calculates the original background density from all the measured density values. Then, the adjusting means 3 adjusts the copy density based on the output signal of the background density determining means 2.

第２図は本発明を応用した複写機の一例を示す。FIG. 2 shows an example of a copying machine to which the present invention is applied.

この複写機ではプリントスイッチが押されると、光学ス
キャナを移動させて原稿の地肌濃度を検出した後に通常
コピーモードに入り現像バイアス電圧をその地肌濃度に
対応した値として原稿の複写を設定枚数分だけくり返す
。When the print switch is pressed, this copying machine moves the optical scanner to detect the background density of the original, enters the normal copy mode, and sets the developing bias voltage to a value corresponding to the background density and copies the original for the set number of sheets. Repeat.

通常コピーモードでは感光体ドラム１１はメインモータ
１０によシ回転駆動されて帯電用コロナ放電器１２によ
シ一様に帯電された後にイレーザ９で画像非形成部が除
電され、スリット露光装置により原稿像が投影されてそ
の静電潜像が形成される。この場合スリット露光装置で
は露光用ランプ１３が点灯して透明な原稿台１４と圧板
１５との間にセットされている原稿を照明し、その反射
光像が第１ミラー１６．第２ミラー１．γ、第３ミラー
１８．スルーレンズ１９．第４ミラー２０．防塵ガラス
２１を介して感光体ドラム１１に投影されると共に光学
スキャナが走査されて、っま如露光用ランプ１３及びミ
ラー１６〜１８が右方向に移動して（又は原稿台１４及
び圧板１５が左方向に移動して）原稿像のスリット露光
が行なわれる。In the normal copy mode, the photoreceptor drum 11 is rotationally driven by the main motor 10 and uniformly charged by the charging corona discharger 12, after which the non-image forming area is removed by the eraser 9, and then by the slit exposure device. An original image is projected to form an electrostatic latent image thereof. In this case, in the slit exposure device, the exposure lamp 13 is turned on to illuminate the original set between the transparent original platen 14 and the pressure plate 15, and the reflected light image is reflected on the first mirror 16. Second mirror 1. γ, third mirror 18. Through lens 19. Fourth mirror 20. The image is projected onto the photoreceptor drum 11 through the dust-proof glass 21 and scanned by the optical scanner, and the exposure lamp 13 and mirrors 16 to 18 are moved rightward (or the document table 14 and pressure plate 15 are slit exposure of the original image is performed.

感光体ドラム１１上に形成された静電潜像は現像装置２
２により現像され、一方力セット２３内の転写紙かに紙
コロ２４にょシ給送されてレジストローラ２５により感
光体ドラム１１上の顕像に合わせて送出される。この転
写紙は転写用コロナ放電器２６によシ感光体ドラム１１
上の顕像が転写されて転写用コロナ放電器２７及び分離
爪２８により感光体ドラム１１から分離され、搬送装置
２９によシ搬送されて定着装置３ｏにょシ像が定着され
、排紙ローラ３１によりコピー受け３２ヘコピーとして
排出される。寸だ感光体ドラム１１は転写紙の分離後に
クリーニング装置３３にょシフリーニングされ、除電用
ランプ３４にょシ残留電位が除去されて次の複写動作に
備える。このような複写動作が設定枚数分たけくシ返さ
れる。The electrostatic latent image formed on the photoreceptor drum 11 is transferred to the developing device 2.
On the other hand, the transfer paper in the force set 23 is fed to the paper roller 24 and sent out by the registration roller 25 in accordance with the developed image on the photoreceptor drum 11. This transfer paper is transferred to the photosensitive drum 11 by the transfer corona discharger 26.
The upper developed image is transferred and separated from the photoreceptor drum 11 by a transfer corona discharger 27 and a separation claw 28, and is transported by a transport device 29, where the image is fixed on a fixing device 3o, and then transferred to a paper discharge roller 31. The image is then discharged as a copy to the copy receiver 32. After the transfer paper is separated, the photosensitive drum 11 is cleaned by a cleaning device 33, and residual potential is removed by a static elimination lamp 34 in preparation for the next copying operation. Such a copying operation is repeated as many times as the set number of copies.

上記現像装置２２は現像スリーブ３５により現像剤を感
光体トラム１１に供給して静電潜像を現像するものであ
り、現像時には現像スリーブ３５に現像バイアス装置か
ら現像バイアス電圧が印加される。また原稿地肌濃度測
定用光センサー３６はスリット露光装置の光路に対して
進退可能に設けられていて通常は光路から退避し、ソレ
ノイド３７によシ引かれることによシ光路中に進出して
露光光量を測定する。The developing device 22 supplies developer to the photoreceptor tram 11 through a developing sleeve 35 to develop the electrostatic latent image. During development, a developing bias voltage is applied to the developing sleeve 35 from a developing bias device. Further, the optical sensor 36 for measuring the background density of the original is provided so as to be able to move forward and backward with respect to the optical path of the slit exposure device, and normally retreats from the optical path, but when pulled by the solenoid 37, advances into the optical path and exposes. Measure the amount of light.

第３図は上記複写機の制御回路を示す。FIG. 3 shows a control circuit of the copying machine.

制御部３８はＮＥＣ製１チツプマイクロコンビコータ７
８１１Ｇよりなシ、電源部３９よシ給電されて原稿地肌
濃度の判別などを行う。この制御部３８は光センサ−３
６の出力信号が増幅器４０を介して入力されると共にプ
リントスイッチ４１．ホームポジ／ヨンスイノチＨＰＳ
Ｗ等からの信号が入力され、現像バイアス装置４２．ソ
レノイド３７や光学スキャナ駆動部、露光用ランプ１３
の駆動部等に出力信号を出す。制御部３８は内部のリー
ドオンリーメモリに格納されているプログラムに従って
第４図に示すように動作し、プリントスイッチがオンさ
れると、原稿地肌濃度を測定する／Ｃめに光学スキャナ
の空走査を行なわせる（実質的な複写動作を行なわせず
に光学スキャナの走査だけを行なわせる）。すなわちま
ず露光用ランプ１３を点灯させ、ソレノイド３７をオン
させて光センサ−３６を光路中に進出させる。次に光学
スキャナを通常停止位置から移動させ、同時にタイマー
Ｔ、をセットする。このタイマーＴ１がタイムアツプし
た時点より原稿濃度の測定を開始し、原稿濃度を光セン
サ−３６で測定した値を増幅器４０を介してとり込んで
デジタル化しＲＡＭよりなるデータメモリ４３の各エリ
アＭ、〜Ｍ８に順次格納するという動作をタイマーＴ２
の設定時間おきに設定回数例えば８回縁シ返す。したが
って原稿上の８個所の濃度が測定されてデータメモリ４
３の各エリアＭ。The control unit 38 is a 1-chip micro combi coater 7 manufactured by NEC.
From the 811G, power is supplied from the power supply unit 39 to determine the background density of the document. This control unit 38 is the optical sensor 3
The output signals of print switches 41 . Home Posi/Yonsui Nochi HPS
Signals from W, etc. are input to the developing bias device 42. Solenoid 37, optical scanner drive unit, exposure lamp 13
output signal to the drive unit, etc. The control unit 38 operates as shown in FIG. 4 according to the program stored in the internal read-only memory, and when the print switch is turned on, it measures the background density of the original and starts the blank scan of the optical scanner. (allows only the optical scanner to scan without actually performing a copying operation). That is, first, the exposure lamp 13 is turned on, the solenoid 37 is turned on, and the optical sensor 36 is moved into the optical path. Next, the optical scanner is moved from its normal stop position, and at the same time a timer T is set. When the timer T1 times out, measurement of the original density is started, and the value measured by the optical sensor 36 is taken in through the amplifier 40 and digitized. Timer T2 performs the operation of sequentially storing data in M8.
The edge is repeated a set number of times, for example, 8 times, every set time. Therefore, the density at 8 locations on the document is measured and the data memory 4
3 each area M.

〜Ｍ８に格納されることになる。その後は光学スキャナ
の移動を逆転させて露光、用ランプ１３をオフさせ、同
時にソレノイド３７をオフさせて光センサ−３６を光路
外に退避させる。光学スキャナが通常停止位置に戻った
ことがホームポジションスイッチで検出されると、光学
スキャナを停止させる。次に通常コピーモードで複写動
作が開始されるまでにデータメモリ４３内のエリアＭ１
〜Ｍ８のデータから原稿地肌濃度をめる演算を行う。す
なわちメモリエリアＭ、〜Ｍ８内のデータを高濃度比較
条件と比較してこの比較条件以下のデータの個数にとそ
のデータの合計りを算出すると共に比較条件よシ大きい
データの個数りとそのデータの合計Ｈを算出する。ここ
に高濃度比較条件は予め定めた地肌濃度検出領域よシ濃
度が高いレベルに設定しておく。例えば地肌濃度検出領
域を濃度的０〜０．５とし、濃度的６より高い濃度を文
字等の画像部と定め、濃度０．０〜０．５の測定値が増
幅器４゜から制御部３８にＯ〜５Ｖの入力信号電圧とし
て（濃度０．０→ＯＶ、濃度０．５→５ｖのように）入
力されるようにして上記高濃度比較条件を濃度０．６に
対応するレベルに設定しておく。データの個数は８であ
るから、Ｋ＋Ｌ＝８になれば次のステップに進む。高濃
度比較条件より濃度が高いデータの個数りが設定値例え
ば６（全データ数８の７５％）以上であればこのＬ個の
データは画像部でなく原稿地肌の一部の濃度測定値であ
ると判断して全データの平均値（Ｈ−１−Ｄ）／８を演
算して原稿地肌濃度のデータＤＡＴＡとする。しかしＬ
が７５％未満（５以下）である場合には高濃度比較条件
より濃度が低いＬ個のデータは偶然に文字、写真等の画
像部の濃度を測定したものであると判断してこれを削除
しＤ／Ｋを演算して原稿地肌濃度のデータＤＡＴＡとす
る。この原稿地肌濃度のデータＤＡＴＡはコード変換し
、例えばＯＶ≦ＤＡＴＡ　＜　０．７Ｖすら００００と
し、０．７　Ｖ≦ＤＡＴＡ　＜　１．．４Ｖなら０００
１とし、１．４■≦ＤＡＴＡ　（２，Ｉ　Ｖなら００１
０とし、２．１Ｖ≦ＤＡＴＡ　＜　２．８　Ｖなら００
１１とし、２．８ｖ≦ＤＡＴＡ　＜３．．５’ｌ：ら０
１００とし、３．５　Ｖ　≦ＤＡＴＡ（４，２Ｖなら０
１０１とし、４．２■≦ＤＡＴＡなら０１１０とし、こ
のコードを現像バイアス装置４２に出力する。次に通常
コピーモードに移行させて複写動作を開始させ、設定枚
数分の複写動作が終！した時にデータ１つＡ　Ｔ　Ａを
初期化する（ＤＡＴＡ＝φとする）。現像バイアス装置
４２は制御部３８からのコードに対応した現像バイアス
電圧を複写動作が行なわれている時に連続的に現像スリ
ーブ３５に印加し、複写動作が行なわれていない時には
現像スリーブ３５に現像バイアス電圧を印加しない。１
枚の原稿を１枚だけ複写する場合には複写動作の開始前
にその都度原稿地肌濃度のデータＤＡＴＡがめられ、１
枚の原稿を複数枚複写する場合には最初の複写動作の開
始前に（プリントスイッチ４１がオンした直後に）原稿
地肌濃度のデータＤＡＴＡがめられてこのデータＤＡＴ
Ａにより複数回の複写動作時における現像バイアス電圧
が決定される。現像バイアス装置４２は制御部３８から
のコードにより現像バイアス電圧を次表のように決定す
る。It will be stored in ~M8. Thereafter, the movement of the optical scanner is reversed to turn off the exposure lamp 13, and at the same time, the solenoid 37 is turned off to move the optical sensor 36 out of the optical path. When the home position switch detects that the optical scanner has returned to the normal stop position, the optical scanner is stopped. Next, in the normal copy mode, the area M1 in the data memory 43 is
A calculation is performed to calculate the background density of the document from the data of ~M8. That is, the data in memory areas M, to M8 are compared with the high concentration comparison condition, and the number of data that is below this comparison condition and the total sum of the data are calculated, and the number of data that is greater than the comparison condition and that data are calculated. Calculate the total H. Here, the high density comparison condition is set to a level where the density is higher than the predetermined background density detection area. For example, the background density detection area is set to 0 to 0.5 in terms of density, the density higher than 6 is set as the image part such as characters, and the measured value of density 0.0 to 0.5 is sent from the amplifier 4° to the control unit 38. The high concentration comparison condition is set to a level corresponding to a concentration of 0.6 by inputting it as an input signal voltage of 0 to 5V (concentration 0.0→OV, concentration 0.5→5V, etc.). put. Since the number of data is 8, if K+L=8, the process advances to the next step. If the number of pieces of data with a higher density than the high density comparison condition is greater than the set value, for example 6 (75% of the total number of data 8), these L pieces of data are the measured density values of a part of the background of the document, not the image area. It is determined that there is, and the average value (H-1-D)/8 of all the data is calculated and used as data DATA of the background density of the document. But L
If it is less than 75% (5 or less), it is determined that the L data whose density is lower than the high density comparison condition is the result of accidentally measuring the density of image areas such as text and photographs, and these are deleted. Then, D/K is calculated and used as original background density data DATA. This original background density data DATA is code-converted, and for example, even if OV≦DATA<0.7V, it is set to 0000, and if 0.7V≦DATA<1. ．． 000 for 4V
1, 1.4■≦DATA (001 if 2, I V
0, and if 2.1V≦DATA<2.8V, then 00
11, and 2.8v≦DATA<3. ．． 5'l:ra0
100, 3.5 V ≦DATA (0 if 4.2V
If 4.2≦DATA, the code is set to 101, and if 4.2≦DATA is set to 0110, this code is output to the developing bias device 42. Next, shift to normal copy mode and start copying, and the copying operation for the set number of sheets is completed! When this happens, one data A TA is initialized (DATA=φ). The developing bias device 42 continuously applies a developing bias voltage corresponding to a code from the control unit 38 to the developing sleeve 35 when a copying operation is being performed, and applies a developing bias voltage to the developing sleeve 35 when a copying operation is not being performed. No voltage applied. 1
When copying only one sheet of an original, the original background density data DATA is displayed each time before the start of the copying operation.
When copying a plurality of sheets of original, the data DATA of the original background density is displayed before the start of the first copying operation (immediately after the print switch 41 is turned on).
The developing bias voltage during multiple copying operations is determined by A. The developing bias device 42 determines the developing bias voltage according to the code from the control section 38 as shown in the table below.

令弟５図（ａ）に示すような原稿像４４を光学スキャナ
で走査してその濃度を光センサー３６で図示矢印のよう
に測定した場合光センサ−３６の出力η〕、圧が第５図
（ｂ）に示すようになり、これを制御部３８によりタイ
ミングｔ１〜ｔ８でとり込むと、そのデータは帆８Ｖ、
　２Ｖ、　５Ｖ、　］、、５Ｖ、　０．８Ｖ、　０．８
Ｖ。When a document image 44 as shown in FIG. 5(a) is scanned by an optical scanner and its density is measured by an optical sensor 36 as shown by the arrow in the figure, the output η of the optical sensor 36 and the pressure are as shown in FIG. The data becomes as shown in (b), and when this is taken in by the control unit 38 at timings t1 to t8, the data becomes sail 8V,
2V, 5V, ], 5V, 0.8V, 0.8
V.

０．６Ｖ　、　１．ＩＶになる。このデータは濃度帆６
に対応する３゜５■の高濃度比較条件より大きい５ｖが
削除されて平均値が演算され ＤＡＴＡ−０・８−１−２＋１．５＋０・８＋０・８−
４−０６４−１・１＝　１：　１（Ｖ）と々る。このデ
ータＤＡＴＡは００１０のコードに変換され、上述の表
から現像バイアス電圧を２００Ｖに調整することになる
。0.6V, 1. Becomes an IV. This data is density sail 6
5V larger than the high concentration comparison condition of 3°5■ corresponding to is deleted and the average value is calculated. DATA-0・8-1-2+1.5+0・8+0・8-
4-064-1・1= 1: 1 (V). This data DATA is converted to a code of 0010, and the developing bias voltage is adjusted to 200V from the above table.

なお上記複写機では原稿地肌濃度のデータＤＡＴＡによ
り現像バイアス電圧を調整することで複写み度を調整し
ているが、データＤＡＴＡによ如露光用ランプ１３の入
力電圧を調整して露光量を調整し、又はデータＤＡＴＡ
により現像バイアス電圧及び露光用ランプ１３の入力電
圧を調整するようにしてもよい。また制御部３８は光セ
ンサ−３６から増幅器４０を介してデータを読み込んで
いるが、これは読み込みタイミング時にその瞬間のデー
タを読み込む方法でも、データを各読み込みタイミング
で１０〜２０ｍ５ｅＣ程度の時間ずつ読み込んでその処
理中に各々積分して８個のデータとする方法でもよい。Note that in the copying machine described above, the degree of copying is adjusted by adjusting the developing bias voltage using the data DATA of the background density of the original, and the exposure amount is adjusted by adjusting the input voltage of the exposure lamp 13 using the data DATA. or data DATA
The developing bias voltage and the input voltage of the exposure lamp 13 may be adjusted by the following. Furthermore, the control unit 38 reads data from the optical sensor 36 via the amplifier 40, but this can also be done by reading the instantaneous data at each reading timing, or by reading the data at a time of about 10 to 20 m5eC at each reading timing. Then, during the processing, each of the data may be integrated to obtain eight pieces of data.

また光センサ−３６を原稿の幅方向（光学スキャナの走
査方向と直角な方向）に複数個配列してそれらの出力信
号を原稿先端部の濃度測定時にサンプリングして制御部
３８に複数個所の濃度測定値として入力するようにして
もよい。制御部３８においては複数のデータの平均値を
めて原稿地肌濃度としているが、複数のデータの最大値
又は最小値等を演算して原稿地肌濃度としてもよい。さ
らに原稿上の複数個所の濃度測定は光センサ−３６によ
シ行なっているが、感光体ドラム１１上に原稿の静電潜
像を形成してその複数個所の電位を表面電位計で測定す
るようにしてもよい。In addition, a plurality of optical sensors 36 are arranged in the width direction of the document (perpendicular to the scanning direction of the optical scanner), and their output signals are sampled when measuring the density at the leading edge of the document, and the control unit 38 measures the density at multiple points. It may also be input as a measured value. In the control unit 38, the average value of a plurality of data is used as the document background density, but the document background density may be calculated by calculating the maximum value, minimum value, etc. of the plurality of data. Furthermore, although density measurements at multiple locations on the document are performed using the optical sensor 36, an electrostatic latent image of the document is formed on the photoreceptor drum 11, and the potentials at multiple locations are measured using a surface electrometer. You can do it like this.

（効果） 以上のように本発明によれば原稿における複数個所の濃
度を測定して原稿地肌濃度を演算し複写濃度を調整する
複写濃度調整装置において予め定めた地肌濃度検出領域
よシ濃度が高いレベルに比較条件を設定して比較条件よ
り高濃度の濃度設定値の個数が設定個数より少ない場合
には比較条件より高濃度の濃度測定値を画像部の濃度測
定値とみなして削除し、比較条件より高濃度の濃度測定
値の個数が設定値より多い場合には全ての濃度１ｊｌｌ
ｌ定値を原稿の地肌濃度測定値とするので、画像部じの
濃度測定値を地肌濃度測定値とすること７５＝なくなっ
て原稿地肌濃度の検出精度を高めること力≦でき、画像
とびをなくすことができる。(Effects) As described above, according to the present invention, in a copy density adjustment device that measures the density at multiple locations on a document, calculates the document background density, and adjusts the copy density, the density is higher than the predetermined background density detection area. If a comparison condition is set for the level and the number of density setting values with a density higher than the comparison condition is less than the set number, the density measurement value with a density higher than the comparison condition is regarded as the density measurement value of the image area and deleted, and then compared. If the number of concentration measurement values higher than the conditions is greater than the set value, all concentrations 1jll
Since the constant value is taken as the measured value of the background density of the original, the measured value of the density of the image part is used as the measured value of the background density. I can do it.

【図面の簡単な説明】[Brief explanation of the drawing]

第１図は本発明の構成を示すブロック図、第２図は本発
明を応用した複写機の一例を示す断面図、第３図は同複
写機の制御回路を示すフ゛ロック図、第４図は同制御回
路の制御内容を示すフローチャー１・、第５図は同制御
回路の制御動作例を説明するだめの図である。 １・測定手段、２・・・地肌濃度判別手段、３・・・調
整手段。 代理人　樺　山　二芹郷屑ｈFig. 1 is a block diagram showing the configuration of the present invention, Fig. 2 is a sectional view showing an example of a copying machine to which the invention is applied, Fig. 3 is a block diagram showing a control circuit of the copying machine, and Fig. 4 is a block diagram showing the control circuit of the copying machine. Flowchart 1 showing the control contents of the control circuit and FIG. 5 are diagrams for explaining an example of the control operation of the control circuit. 1. Measuring means, 2. Background density determination means, 3. Adjustment means. Agent Kabayama Niserigo Kuzuh

Claims (1)

【特許請求の範囲】[Claims] 複写機において、原稿における複数個所の濃度を測定す
る測定手段と、予め定めた地肌濃度検出領域よシ濃度が
高いレベルに比較条件を設定してこの比較条件と前記測
定手段からの原稿における複数個所の濃度測定値とを比
較すると共に比較条件より高濃度の濃度測定値の個数を
予め設定した個数と比較し比較条件より高濃度の濃度測
定値の個数が上記設定個数よシ少ない場合には比較条件
より高濃度の濃度測定値を画像部の濃度測定値とみなし
て削除して比較条件よシ低濃度の濃度測定値から原稿地
肌濃度を演算し比較条件より高濃度の濃度測定値の個数
が上記設定値より多い場合には全ての濃度測定値より原
稿地肌濃度を演算する地肌濃度判別手段と、この地肌濃
度判別手段の出力信号により複写濃度を調整する調整手
段とを備えた複写濃度調整装置。In a copying machine, a measuring means for measuring the density at a plurality of places on a document is provided, a comparison condition is set to a level where the density is higher than a predetermined background density detection area, and the comparison condition and the plurality of points on the document from the measuring means are set. At the same time, the number of concentration measurement values higher than the comparison condition is compared with a preset number, and if the number of concentration measurement values higher than the comparison condition is less than the set number, the comparison is performed. Density measurement values with higher densities than the comparison conditions are treated as density measurement values of the image area and deleted, and the original background density is calculated from the density measurement values with lower densities than the comparison conditions. A copying density adjusting device comprising a background density determining means for calculating the original background density from all measured density values when the density is greater than the above set value, and an adjusting means for adjusting the copying density based on the output signal of the background density determining means. .