Ricoh B230 Service Manual
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B230/B237 6-6 SM
6.1.5 PRINTING PROCESS
This machine uses four PCUs, and four laser beams for color printing. Each PCU consists
of the drum unit and the development unit. Each drum unit has a drum, charge roller,
cleaning brush, and blade. From the left, the PCU stations are yellow, cyan, magenta, and
black.
The drum [A] is charged with a negative voltage, and is exposed by the laser from the laser
optics housing unit [B]. The laser neutralizes the negative charge on the surface of the
drum....](http://img.usermanuals.tech/thumb/64/100811/w64_b230-service-manual-1509630901_d-803.png "Page 804
B230/B237 6-6 SM
6.1.5 PRINTING PROCESS
This machine uses four PCUs, and four laser beams for color printing. Each PCU consists
of the drum unit and the development unit. Each drum unit has a drum, charge roller,
cleaning brush, and blade. From the left, the PCU stations are yellow, cyan, magenta, and
black.
The drum [A] is charged with a negative voltage, and is exposed by the laser from the laser
optics housing unit [B]. The laser neutralizes the negative charge on the surface of the
drum....")
SM 6-3 B230/B237 Detailed Descriptions 6.1.3 DRIVE LAYOUT 1. Scanner motor: Drives the scanner unit. 2. Drum drive motor-CMY: Drives the drums for magenta, cyan, and yellow. 3.ITB (Image Transfer Belt) contact motor: Moves the ITB into contact and away from the color PCUs. 4. Toner transport motor: Drives the toner attraction pumps and the toner collection coils from the PCUs, from the transfer belt unit, and inside the toner collection bottle. Also rotates the toner bottles. 5. Development drive motor-CMY: Drives the color development units (magenta/cyan/yellow). 6. Development clutch-K Turns on/off the drive power to the development unit-K.
B230/B237 6-4 SM 7. Paper feed clutch Switches the drive power between the tray 1 and tray 2. 8. Paper feed motor: Drives the paper feed mechanisms (tray 1/tray 2/by-pass tray). 9. Drum/Development drive motor-K: Drives the black drum and development unit. 10. Registration motor: Drives the registration roller. 11. Paper transfer contact motor Moves the paper transfer roller in contact with the image transfer belt. 12. ITB drive motor: Drives the image transfer belt unit. 13. Fusing/paper exit motor: Drives the fusing unit and paper exit section. 6.1.4 BOARD STRUCTURE Overview ƒ In the diagram, ‘MLB’ is the File Format Converter Descriptions BICU (Base Engine Control Unit): The BICU controls all the mechanical components. The BICU has six CPUs. The CPUs
SM 6-5 B230/B237 Detailed Descriptions control the following functions: ƒ Engine sequence ƒ Engine operation ƒ Polygon motor control ƒ Image processing Controller: The controller connects to the BICU through a PCI bus. The controller handles the following functions: ƒ Machine-to-host interface ƒ Operation panel interface ƒ Network interface ƒ Interfacing and control of the optional IEEE1284, Bluetooth, IEEE1394, IEEE802.11b (wireless LAN), USB Host, HDD, and DRAM DIMM LD Drive Board: This is the laser diode drive circuit board. SBU: The Sensor Board Unit has a CCD (charge-coupled device) and an analog-to-digital conversion circuit. Operation Panel Board: This controls the display panel, the LED and the keypad. Scanner I/O Board (SIO): The scanner I/O board is a circuit board that transmits control signals, image data, and electricity. I/O Board (IOB): Contains drivers for motors and other mechanical components. Motherboard: Connects the FCU board to the BICU. This board is supplied with the optional fax unit. FCU: The FCU (fax controller unit) controls the fax programs and communicates with the controller to share copier resources.
B230/B237 6-6 SM 6.1.5 PRINTING PROCESS This machine uses four PCUs, and four laser beams for color printing. Each PCU consists of the drum unit and the development unit. Each drum unit has a drum, charge roller, cleaning brush, and blade. From the left, the PCU stations are yellow, cyan, magenta, and black. The drum [A] is charged with a negative voltage, and is exposed by the laser from the laser optics housing unit [B]. The laser neutralizes the negative charge on the surface of the drum. So, the white parts of the image correspond to areas of the drum that still have a high negative charge. The toner has a negative charge, and it moves to the areas of the drum that have the smallest negative charge (i.e., the areas written by the laser beam). The image on each drum is moved to the transfer belt by the positive bias that is applied to the transfer belt [C]. All four toners are put on the belt at the same time. Then, the completed four-color image is moved to the paper by a negative charge applied to the ITB drive roller [D] (the transfer roller [E] is an idle roller). 1. Drum charge: The charge roller gives the drum a negative charge 2. Laser exposure: The laser beam from the laser diode (LD) goes through the lens and mirrors and reaches the drum. The machine turns the laser beam on and off to make a latent image on the drum. 3. Development: The development roller carries negatively charged toner to the latent image on the drum surface. This machine uses four independent development units (one for each color). 4. Transfer: Image transfer: Bias rollers opposite the OPC drums transfer toner from the drums to the transfer belt. Four toner images are super-imposed onto the belt. Paper transfer: Then, the ITB drive roller pushes the toner from the transfer belt to the paper (the transfer roller is an idle roller).
SM 6-7 B230/B237 Detailed Descriptions 5. Cleaning for OPC drum: The cleaning brush and blade remove remaining toner on the drum surface after image transfer to the paper. 6. Quenching for OPC drum: Quenching is done by illuminating the whole area of the drum with the laser at the end of every job. 7. Cleaning and quenching for transfer belt: The cleaning brush and blade clean the belt surface. The grounding roller inside the transfer belt unit removes the remaining charge on the belt. 8. ID sensors: The ID sensors detect the density of ID sensor patterns on the transfer belt. The ID sensor board contains three ID sensors for the line position adjustment (front, center, and rear) and four ID sensors for the process control. On this board, there are 7 ID sensors in total, as follows. ƒ [A]: Line position adjustment (front) ƒ [B] Process control (K) ƒ [C]: Process control (C) ƒ [D]: Line position adjustment (centre) ƒ [E] Process control (M) ƒ [F]: Process control (Y) ƒ [G]: Line position adjustment (rear) The ID sensor output is used for the following: ƒ Process control and for automatic line position ƒ Skew correction ƒ Color registration adjustments for the latent image.
B230/B237 6-8 SM 6.2 PROCESS CONTROL 6.2.1 OVERVIEW This machine has the following two forms of process control: ƒ Potential control ƒ Toner supply control The following machine components are used for process control: ƒ Four ID (image density) sensors (black, magenta, cyan and yellow). ƒ TD sensor. Normally, process control is not disabled. If process control is disabled, fixed supply mode is used for toner supply, and the VREF stored in SP 3222 is used. 6.2.2 POTENTIAL CONTROL Overview The machine determines VD using the ID sensor output, and then determines VB and VL. ƒ V D: Drum potential without exposure – to adjust this, the machine adjusts the charge roller voltage. ƒ V B: Development bias ƒ V L: Drum potential at the strongest exposure – to adjust this, the machine adjusts the laser power At the same time, the machine also determines VREF: Reference TD sensor output, used for toner supply control If potential control is disabled (SP3-041-001 is set to 0), V D and VB are fixed by the following SP mode settings. ƒ SP2-005 for V D, SP2-229 for VB If LD power control is disabled (SP3-041-002 is set to 0), the LD power is fixed by the following SP mode setting. ƒ SP2-221 for V L Process Control Self Check This machine uses the process control self check method to do the potential control. The machine uses seven types of process control self check. These are categorized according to their execution timing. The counter (SP3-510) is reset if a self-check is done (except for a forced self-check). ΔT = Temperature change between the temperature of the previous process control and the current temperature
SM 6-9 B230/B237 Detailed Descriptions ΔRH = RH (Relative Humidity) change between the relative humidity of the previous process control and the current relative humidity ΔAH = AH (Absolute Humidity) change between the absolute humidity of the previous process control and the current absolute humidity 1. Manual execution (forced): This is done when SP3-011-1 is used. 2. Initial This starts automatically when the power is turned on, or, when the machine recovers from energy saver mode. This is done automatically if one of these conditions occurs. ƒ a) ΔT is greater than or equal to Temperature Threshold (SP3-522-003: 10°C) ƒ b) ΔRH is greater than or equal to Relative Humidity Threshold (SP3-522-004: 50%RH) ƒ c) ΔAH is greater than or equal to Absolute Humidity Threshold (SP3-522-005: 6 g/m 3) ƒ d) If the following conditions both occur. BW Counter (SP3-510-003) is greater than or equal to Execution Interval (SP3-511-005) OR FC Counter (SP3-510-004) is greater than or equal to Execution Interval (SP3-511-006) Non-use Time is greater than or equal to SP3522-002 (default: 6 hours) 3. Interval: Job End This starts automatically at the end of a print job if the following condition occurs: BW Counter (SP3-510-001) is greater than or equal to Execution Interval (SP3-515-001) OR FC Counter (SP3-510-002) is greater than or equal to Execution Interval (SP3-515-002) 4. Interval: During a Job This interrupts printing and then starts automatically if the following condition occurs: BW Counter (SP3-510-001) is greater than or equal to Execution Interval (SP3-515-003) OR FC Counter (SP3-510-002) is greater than or equal to Execution Interval (SP3-515-004) After process control is completed, the machine continues to make prints.
B230/B237 6-10 SM 5. In standby mode This is done automatically if one of these conditions occurs. ƒ a) ΔT is greater than or equal to Temperature Threshold (SP3-531-002: 10°C) ƒ b) ΔRH is greater than or equal to Relative Humidity Threshold (SP3-531-003: 50%RH) ƒ c) ΔAH is greater than or equal to Absolute Humidity Threshold (SP3-531-004: 6 g/m3) ƒ d) Non-use Time is greater than or equal to SP3-531-001 (default: 6 hours) It is not done if the machine is in energy saver mode. The default non-use time is 6 hours (see condition 4 below), so normally it will only be done if the user disables energy saver mode. 6. After Toner End Recovery This starts after recovery from a toner end condition. 7. After Developer Initialization Developer initialization occurs automatically in the following conditions: ƒ After a new development unit has been installed ƒ After new developer is installed and 3902-005 to 008 is done, depending on the color (see ‘Maintenance’ for details). 6.2.3 PROCESS CONTROL SELF CHECK PROCEDURE Step 1: VSG Adjustment This machine uses four ID sensors (direct reflection type) for the process control. Each
SM 6-11 B230/B237 Detailed Descriptions sensor detects a pattern for each color (see the ‘Printing Process’ section). The ID sensor checks the bare transfer belt’s reflectivity. Then the machine calibrates the ID sensor until its output when reading the bare transfer belt (known as VSG) is as follows. ƒ VSG = 4.0 ± 0.5 Volts This calibration compensates for the transfer belt’s condition and the ID sensor condition. For example, dirt on the surface of the belt or ID sensor. VSG adjustment is always done during initial process control. But, at other times, it is only done if the VSG adjustment counter (SP3-510-007) is more than the value set with SP3-511-007 (default: 500) during a job or at job end. SC400 is displayed if VSG is out of adjustment range sequentially 3 times. SP3-321: Forced VSG Adjustment for each sensor SP 3-325: Shows the results of the VSG adjustment (automatic or forced VSG adjustment) - 7 digits (Front, Bk, C, Center, M, Y, Rear) Step 2: ID Sensor Solid Pattern Generation First, the machine agitates the developer for between 15 and 30 seconds until the fluctuation in TD sensor output becomes less than 0.3V. Second, the machine makes the grade patterns (see the diagram). This 10-grade pattern is made in black, yellow, cyan, and magenta (40 squares in total). ƒ The machine first makes the first five grades for each color (the first 20 squares), and then the second five grades for each color (the remaining 20 squares). The patterns are made by changing the development bias and charge roller voltage. The difference between development bias and charge roller voltage is always the same. But, the development potential changes for each pattern. ƒ The development potential is the difference between the development bias and the charge remaining on the drum where the laser writes a black area. The development bias changes for each grade, and the charge on black areas of the image is always the same, so the development potential also changes. Step 3: Sensor Pattern Detection The ID sensor measures the light reflected from each grade of the pattern, to detect the densities of each grade. This data goes to memory.
B230/B237 6-12 SM Step 4: Toner Amount Calculation The machine calculates the amount of toner on the transfer belt that is required to make each of the 10 grades of the sensor pattern. To do this, the machine uses the output values of the ID sensor from each grade of the pattern. The amounts of toner are expressed as M/A (mass per unit area, mg/cm 2) Step 5: V D, VB, VL Selection and VTREF Adjustment The machine determines the relationship between the amount of toner on the transfer belt and the development bias for each of the 10 grades. From this, the machine determines the best V D to get the target M/A for each color. Then, based on this V D, the machine determines the best VB and VL. This process ensures that enough toner is deposited to make black pixels. The machine also adjusts V TREF (toner density target) at the same time so that the development gamma used by the machine fall within the target development gamma range stored in the machine’s software. If it does not fall within this range, the amount of toner deposited on the latent image will be too high or too low. 6.2.4 TONER DENSITY ADJUSTMENT MODE If the toner density becomes too high or too low because of an incorrect development gamma, this is corrected by process control (see the previous section). But sometimes, it takes many copies before the toner density comes to the correct value. Toner density adjustment mode can be used to bring the toner concentration to the correct level much more quickly, if users complain about the toner density. SP 3-043 controls when the toner density adjustment mode is done. To do the toner density adjustment mode manually, execute SP 3-011-2. It is also done automatically before ACC, if SP3-041-4 is set to 2: TC Control (this is the default setting). During this procedure, the machine generates ID sensor patterns and detects the current development gamma. The gamma must be within ± 0.2 of the target development gamma. If the current gamma is too high (above the target by 0.2 or more: 0.2 limit is set with SP3-239-009), the machine consumes toner in the development unit until the development gamma is within the correct range. To consume toner, the machine generates solid patterns. If the current gamma is too low (below the target by more than 0.2: 0.2 limit is set with SP3-239-012), the machine supplies toner to the development unit until the development gamma is within the correct range.