Minolta 8031052wone Datasets

4.

PIC Section

PIC: Print Image Control

1. LED Print Head (LPH)

2. LED Gradation Reproduction System

3. Outline of the PIC Section

4. PIC Image Processing Flow

5. Color Shift Correction System

4.1

LED

Print Head (LPH)

Perspective View

SLA (SELFOC Lens Array)

LED Unit

Side View

LED Chip (600 dpi = approx. 7,700 chips)

Positioning Pin

Circuit Board

LED Chip

4.1.1

(Similar to 7920)

Features

of LED

Print Head

Advantages

• The Optical System is designed compact.

• It is easier to achieve the goal of high-speed printing.

• The body is more resistant to deformation under changing environmental conditions.

• It is easier to make optical adjustments (optical path, optical axis, etc.).

Required New Technology (To increase LPH Efficiency)

• Intensity correction technology that makes the intensity of all light emitting bodies

uniform.

• Gradation reproduction technology that produces no uneven intensities on the image.

• Registration and Skew Correction technology that corrects any distortion in the LED

itself.

4.2

(Common with the 7920 System)

Direction

LED Gradation Reproduction System

Main Scanning Direction

Sub-Scanning

Screen

Sample

42.3 µ m

4bit 4bit

3 pixels X 3 pixels

4bit

48 gradation levels per 1 pixel (4bit X 3) < 256 gradation levels

4bit

432 gradation levels (48 X 9) > 256 gradation levels

4.2.1 Screen Patterns

Specific Processing Performed & Screen PatternSectionOriginal Mode

Black text discrimination + Dot discriminationReading Text & Photo

Writing

FEET + Screen optimized for resolution or

Screen optimized for gradation

Black text discrimination + Dot discriminationReadingPhoto Image

Screen optimized for gradation or

Screen optimized for resolution

SmoothingReadingPrinted Image

Screen optimized for gradation or

Screen optimized for resolution

Black text discrimination + Dot discriminationReadingText

FEET + Screen optimized for resolutionWriting

Black text discrimination + Dot discriminationReadingMap

Writing

FEET + Screen for Map modeWriting

Black text discrimination + Dot discriminationReadingCopied Image

FEET + Screen optimized for resolution or

Screen optimized for gradation

4.3

Transfer Belt

Outline of the PIC Section

Image Transfer

2nd Image Transfer Section

Y

PC Drum

LED Exposure Unit

LED Drive

Screen Control

Gamma Correction

GBTC Expansion

Color Shift Correction

GBTC

Y

Sequence

M

LED Exposure Unit LED Exposure Unit

LED Drive LED Drive

Screen Control Screen Control

Gamma Correction Gamma Correction

GBTC Expansion GBTC Expansion

Color Shift Correction Color Shift Correction

C Bk

Frame Memory

Paper Path

Registration Sensor

LED Exposure Unit

LED Drive

Screen Control

Gamma Correction

GBTC Expansion

Color Shift Correction

M

C

Bk

Compression

Frame Memory

4.4

PIC Image Processing Flow

2. Color Correction1. Image Area

Discrimination

3. Miscellaneous Processing: Improved reproduction of black text, edge emphasis, edge expansion, smoothing, color balance, γ correction, ACS Processing, and AE Processing

5. Input Buffer Memory

6. Memory Access Coordinator

7. Frame Memory 192 MB

PIC Board

11. GBTC Expansion

12. 1,800-dpi Color Shift/Skew Correction

13. Area Discrimination FEET

14. Interpolation4. GBTC Compression

15. Gamma Correction

16. Screening

8. Output Buffer Memory

9. 600-dpi Color Shift/Skew Correction

10. CD Position Correction

17. High-Speed LED Drive

18. Intensity Correction

LED Board

To Each LED Unit

4.4.1

Color Correction (1)

+L White

+b Yellow

+a Red

3D image of the L*a*b* color space

This color conversion system uses a positioning and selection operation to determine where the RGB (L*a*b*) colors will be placed in each of the CMYK colors.

Color Correction (2)

RGB

The most significant bit

Most significant bit

determines the cube's position.

Lab

Least significant bit

-a

+L

-b

+b

+a

The color space is divided into approx. 2,000 cube positions.

+L

+b

The data of the eight vertexes and the least significant bit of the input L*a*b* data are interpolated to calculate the output of the CMYK density data.

8-vertex interpolation

Enlarged view

-a

+a

-L

-b

3D Look-up Table

4.4.2

GBTC: General Block Truncation Coding

GBTC Compression/Expansion

Sub-scanning direction

4dots

Main scanning direction

Image data is divided Into a 4x4-dot section

D3D2D1D0

D8

Dc

D5D4

D9

Dd

D7D6

DbDa

DfDe

GBTC Compression

4dot

8031: 8bit+ 8bit + 4×4×3bit =64bit 8020: 8bit+ 8bit + 4×4×1bit =32bit

8bit 8bit

LA LD

D8

Dc

D5D4

D9

Dd

4dot

D3D2D1D0

D7D6

DbDa

DfDe

0 1 2 3 4 5 6 7 8 9 a b c d e f

4×4×9bit =144bit

GBTC Expansion

8031: 16dots x 3bit 8020: 16dots x 1bit

∅

4dots

4×4×9bit =144bit

(1) Calculates the maximum and minimum gradation levels. (2) Calculates the average data, gradation dynamic range, and quantization reference. (3) Quantizes each pixel to 1 bit (8020) or 3Bits (8031).

4.4.3

FEET: Fine Edge Enhanced Technology

FEET Processing

Conventional Image Reproduction New Image Reproduction

4.4.4

PIC Board

Intensity Correction

Chip Intensity Correction

Flash

ROM

LED Drive Board

Intensity Correction Data

EEP ROM

CPU

ASIC

Image Data

LPH Assy.

LED Intensity

0

Dot Intensity Correction

Approx. 7,700

LED Pixel Position

4.5

Outline of the Color Shift Correction

Color Shift Correction System (1)

feed

Rear Registration Sensor

Detection Pattern for Sub-Scanning Direction

Transfer Belt

Detection Pattern for Main Scanning Direction

Front Registration Sensor

Color Shift Correction System (2)

Construction of the Sensor

Amount of toner Attracted

LED

Large Amount

Small Amount

LED

Transfer Belt

Amount of toner

Attracted

OutputReflected Light

Intensity

LowLowLargeColor Toner

HighHighSmall

4.5.1

As the results of Color Shifting Detection, any skew in the Sub-Scanning direction is corrected with reference to the black image. (The address of the pixels is controlled over the different scanning directions)

Color Shift/ Skew

Skew

Color Shifting/Skew Correction

Correction at 600dpi

Skew Correction at 1800dpi

4.5.2

Color Shifting Sample: C & M

LPH Linearity Correction

Position of the Registration Sensor

Cause of Color Shifting

Position of the Registration Sensor

Result measured at 120 points

Correction Data is stored in EEPROM

Correction Data Flow

PIC Board

Flash

ROM

LED Drive Board

Intensity Correction Data

CPU

ASIC

Image Data

Printing after operating LPH Linearity Correction

EEP ROM

LPH Assy.

4.5.3

Correction of the Transfer Belt Rotation Speed

Transfer Belt Reference

Position Sensor

Reference Position

Mark for the Belt

Transfer Belt is thin

Slow Fast

Longer Exp. Time

Transfer Belt is thick

Shorter Exp. Time

Uniform (Divided into 224 portions)