JPS6341975U - - Google Patents
Info
- Publication number
- JPS6341975U JPS6341975U JP13602286U JP13602286U JPS6341975U JP S6341975 U JPS6341975 U JP S6341975U JP 13602286 U JP13602286 U JP 13602286U JP 13602286 U JP13602286 U JP 13602286U JP S6341975 U JPS6341975 U JP S6341975U
- Authority
- JP
- Japan
- Prior art keywords
- level
- white
- image information
- white peak
- information signal
- 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
- 238000010586 diagram Methods 0.000 description 5
- 239000003990 capacitor Substances 0.000 description 1
Landscapes
- Facsimile Image Signal Circuits (AREA)
Description
第１図は本考案に係る画像読取装置における白
黒レベル判別回路の実施例を示す回路図、第２図
ａ，ｂは灰色部分が長く続く場合の放電時定数の
変化を説明する波形図、第３図ａ，ｂは白レベル
変動が大きい場合の放電時定数の変化を説明する
波形図、第４図は従来の白黒レベル判別回路を示
す回路図、第５図ａ，ｂ，ｃはそれぞれ第４図に
おける各部の信号波形を例示する波形図、第６図
ａ〜ｄは灰色部分が長く存在した場合の放電時定
数の大小に伴う出力変化を説明するグラフ、第７
図ａ〜ｄは白変動が大きい場合の放電時定数の大
小に伴う出力変化を説明するグラフである。
１……オペアンプ、２……コンパレータ（第２
の比較手段）、５，７……抵抗、６……コンデン
サ、１４……コンパレータ（第１の比較手段）。
FIG. 1 is a circuit diagram showing an embodiment of a black and white level discriminating circuit in an image reading device according to the present invention, FIGS. Figures 3a and 3b are waveform diagrams illustrating changes in the discharge time constant when white level fluctuations are large, Figure 4 is a circuit diagram showing a conventional black and white level discrimination circuit, and Figures 5a, b, and c are waveform diagrams illustrating changes in the discharge time constant when white level fluctuations are large. 4 is a waveform diagram illustrating the signal waveform of each part in FIG.
Figures a to d are graphs illustrating changes in output due to the magnitude of the discharge time constant when the white fluctuation is large. 1... operational amplifier, 2... comparator (second
(comparison means), 5, 7...resistor, 6...capacitor, 14...comparator (first comparison means).
Claims (1)
より画像を読取る装置において、画像情報信号の
白ピーク値レベルを保持するとともに、該画像情
報信号の低下に応じて前記白ピーク値レベルを所
定の時定数で低減させる放電回路を備えた白ピー
クレベル保持手段と、前記白ピーク値レベルより
低い第１のスライスレベル信号と画像情報信号と
を比較する第１の比較手段と、該第１の比較手段
の比較結果に応じて前記放電回路の時定数を切換
える切換手段と、前記第１のスライスレベル信号
より低い第２のスライスレベル信号と画像情報信
号との比較により白黒レベルを決定する第２の比
較手段を備えたことを特徴とする画像読取装置に
おける白黒レベル判別回路。 In a device that reads an image using a line sensor arranged in a line in the scanning direction, the white peak value level of an image information signal is maintained, and the white peak value level is adjusted to a predetermined time constant according to a decrease in the image information signal. a white peak level holding means comprising a discharge circuit for reducing the white peak level; a first comparing means for comparing a first slice level signal lower than the white peak value level with the image information signal; a switching means for switching the time constant of the discharge circuit according to a comparison result; and a second comparing means for determining a black and white level by comparing a second slice level signal lower than the first slice level signal and the image information signal. What is claimed is: 1. A black and white level discrimination circuit in an image reading device, comprising:
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1986136022U JPH0543564Y2 (en) | 1986-09-04 | 1986-09-04 |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1986136022U JPH0543564Y2 (en) | 1986-09-04 | 1986-09-04 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6341975U true JPS6341975U (en) | 1988-03-19 |
| JPH0543564Y2 JPH0543564Y2 (en) | 1993-11-02 |
Family
ID=31038756
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1986136022U Expired - Lifetime JPH0543564Y2 (en) | 1986-09-04 | 1986-09-04 |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0543564Y2 (en) |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5416918A (en) * | 1977-07-07 | 1979-02-07 | Mitsubishi Electric Corp | Background density compensating circuit |
| JPS5534719A (en) * | 1978-09-02 | 1980-03-11 | Ricoh Co Ltd | Picture information reader |
| JPS56135285A (en) * | 1980-03-25 | 1981-10-22 | Nec Corp | White level tracking circuit |
-
1986
- 1986-09-04 JP JP1986136022U patent/JPH0543564Y2/ja not_active Expired - Lifetime
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5416918A (en) * | 1977-07-07 | 1979-02-07 | Mitsubishi Electric Corp | Background density compensating circuit |
| JPS5534719A (en) * | 1978-09-02 | 1980-03-11 | Ricoh Co Ltd | Picture information reader |
| JPS56135285A (en) * | 1980-03-25 | 1981-10-22 | Nec Corp | White level tracking circuit |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0543564Y2 (en) | 1993-11-02 |
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