HP Laserjet 4 Manual
Have a look at the manual HP Laserjet 4 Manual online for free. It’s possible to download the document as PDF or print. UserManuals.tech offer 1114 HP manuals and user’s guides for free. Share the user manual or guide on Facebook, Twitter or Google+.
![](/img/blank.gif)
PC (Tray 2) and LC (Tray 3) Tray Size Sensing System Trays inserted into the printer trigger specific microswitches, which define the tray size (see Table 5-4). Refer to Figure 7-1 for location. Switch Description PCA SW601 Door Open Sensing Switches (front and rear) Paper Control PCA SW602 Test Print Switch Paper Control PCA SW603 PC tray (Tray 2) Size Sensing Switches Paper Control PCA SW604 PC tray (Tray 2) Size Sensing Switches Paper Control PCA SW605 PC tray (Tray 2) Size Sensing Switches Paper Control PCA SW851 Lower Cassette (Tray 3) Size Sensing Switches Lower Cassette SW852 Lower Cassette (Tray 3) Size Sensing Switches Lower Cassette SW853 Lower Cassette (Tray 3) Size Sensing Switches Lower Cassette Table 5-3Microswitch Signals Tray Size SW603 (Upper)SW604 (Middle)SW605 (Lower) Letter ON OFF ON Legal ON ON OFF A4 OFF OFF ON Executive OFF ON ON Tray Not Installed OFF OFF OFF Table 5-4Switch Settings for PC (Tray 2) and LC (Tray 3) Trays Functional Overview 5-9
![](/img/blank.gif)
Motors The DC Controller controls the Exhaust Fan, the Main Motor, and the Laser/Scanner Motor. The remaining motors and solenoids are controlled by State Machines on the motor’s assembly. The condition of these motors and solenoids is monitored by the DC Controller through serial data lines. The Main Motor (M1) rotates after any printer door is opened and closed, during the Warm-up period, the Initial Rotation period, the Print period, or the Last Rotation Period. The Scanner Motor (M5) is controlled and monitored by the DC Controller PCA. M5 operates during the Initial Rotation period, the Print period, and the Last Rotation period. The Paper Feed Assembly Drive Motor (M2) runs during the Print Period. This motor provides the drive to pick paper from the PC tray, and deliver it to the Input/Registration Sensor (PS1). The LC Assembly Motor (M3) provides the drive to pick paper from the optional 500-sheet Lower Cassette, and deliver it to the Input/Registration Sensor (PS1). M3 is mounted on the 500-sheet Lower Cassette. The Envelope Feeder Drive Motor (M4) provides the drive to pick envelopes from the envelope feeder and deliver them to the Input/Registration Sensor (PS1). M4 is mounted on the optional Envelope Feeder. The Exhaust Fan Motor (FM1) is controlled and monitored by the DC Controller PCA. The Exhaust Fan Motor operates at low-speed during the Warm-up period, Standby period, and during PowerSave. It operates at high-speed during the Initial Rotation period, the Print period, and the Last Rotation period. The Paper Feed Assembly Motor (M2) is controlled by the Paper Control PCA. The Paper Feed Assembly Motor drives the pickup rollers through SL1 and SL2. These rollers pick media from either the PC tray (Tray 2) or the MP tray (Tray 1), and deliver the media to the Paper Registration Sensor (PS1). 5-10 Functional Overview
![](/img/blank.gif)
Paper Jam Detection The Input/Registration Sensor (PS1) and the Paper Exit Sensor (PS3) detect paper moving through the printer. If a paper jam is detected, the DC Controller PCA immediately stops the printing process and 13 PAPER JAM or REMOVE PAPER JAM message is displayed. A paper jam can be detected under any of the following conditions: •Input Paper Delay Jam: When paper does not reach the Input Paper Sensor (PS1) within the required time. •Input Paper Stationary Jam: When paper does not clear the Input Paper Sensor (PS1) within a specified time. •Paper Exit Delay Jam: When paper does not reach the Paper Exit Sensor (PS3) within the required time. •Paper Exit Stationary Jam: When paper does not clear the Paper Exit Sensor (PS3) within a specified time. •False Paper Jam: If the Rear Door is open, a paper jam message is displayed because PS3 senses a jam. NoteA defective PS5 (Paper End Sensor) can also cause a paper jam when paper is fed from the MP Tray (Tray 1). Motors Description M1 Main Motor (Gear Train Drive Motor) M2 Paper Input Assembly Drive Motor M3 500-sheet Lower Cassette Pickup Motor M4 Envelope Feeder Drive Motor M5 Scanner Motor FM1 Exhaust Fan Motor Table 5-5Motors Functional Overview 5-11
![](/img/blank.gif)
Formatter System The formatter is responsible for the following: •Receiving and processing ASCII data from printer interfaces. •Monitoring front panel input and relaying printer status information (through the front panel and bi-directional I/O). •Developing/coordinating data placement and timing with the print engine. •Storing font information. •Communicating with the host computer. The Formatter PCA can be divided into three functional areas: •I/O Control •Memory/Memory Management •Data Processing Formatter Feature LaserJet 4 LaserJet 4+ LaserJet 5 Processor 20 MHz 80960KA 25 MHz 80960KB 33 MHz 80960JF REt Yes Yes Yes MEt No Yes Yes Economode No Yes Yes Configurable I/O Buffer Size No Yes Yes Personality Resource SavingNo Yes Yes PowerSave Mode No Yes Yes Font Cartridge Slot Yes Yes No MIO Interface Level 5.0 5.1 6.0 Serial Ports RS-232/422 RS-232 RS-232 & SIR Parallel Port Bitronics IEEE-1284 Bitronics IEEE-1284 Bitronics Maximum RAM (PCL/PS) 34/22 MB 66/50 MB 66/52 MB SIMM Support RAM/ROM RAM/ROM RAM/ROM/Flash PCL Level 5 5E 6 On-Board Fonts 35 Intellifont/10 TT Line Printer35 Intellifont/10 TT Line Printer 45 TT & Dark Courier Line Printer Default Symbol Set Roman-8 Roman-8 PC-8 Paper Size Support Letter/Legal/A4/Exec Letter/Legal/A4/Exec Letter/Legal/A4/Exec/A5 MP (Tray 1) Modes First, Manual, Cassette First, Manual, Cassette First, Cassette Grayscale Hardware Assist No No Yes ROPS 3 Hardware Assist No No Yes Intuitive Control Panel No No Yes I/O Control The formatter I/O control is responsible for maintaining communications with the host system(s). The printer has three interfaces; serial, parallel (bitronic), and Modular I/O (MIO). The formatter maintains connections with hosts connected to these I/O’s including accepting data handshaking, and returning status. 5-12 Functional Overview
![](/img/blank.gif)
Figure 5-5 Formatter PCA—Functional Areas Functional Overview 5-13
![](/img/blank.gif)
Memory Management The printer uses several different types of memory. This memory can be divided into two different categories, Read Only Memory (ROM) and Random Access Memory (RAM). ROM memory consists of the memory located on the Formatter PCA and any font cartridges that may be installed in the printer. RAM memory consists of RAM memory resident on the Formatter PCA, SIMM memory installed in the printer, and the Non-Volatile Memory (NVRAM) located on the Formatter PCA. In general, the ROM is responsible for storing the instructions for the operation of the processor and font information. The RAM memory is used to store temporary information that will be used by the printer for a particular print job or a series of print jobs. This could consist of soft fonts, macros or graphics patterns. RAM memory is also used by the printer to store data that is being processed into the raster image that will control the laser and create the printed page. The NVRAM is used to store printer configuration information that can be input from the printer front panel. This information stored in NVRAM will remain resident in the printer even if the power to the printer is turned off. Data Processing The formatter CPU is responsible for the overall control of all functions related to the formatter. One of the CPU’s main functions is to maintain communication with the print engine. This is done by the print engine interface and the DC Controller PCA. The DC Controller PCA monitors all print engine functions such as fuser temperature and paper jam status. The print engine status is communicated by the DC Controller to the formatter CPU by the print engine interface. The CPU also controls the process that converts ASCII data received from the host into the raster data. This raster data is sent to the laser scanner assembly via the DC Controller. Finally the CPU comunicates printer status to the user through the control panel via the front panel interface. The front panel interface also transmits front panel inputs to the CPU. 5-14 Functional Overview
![](/img/blank.gif)
PJL Overview Printer Job Language (PJL) is an integral part of configuration, in addition to the standard Printer Command Language. With standard I/O cabling, PJL allows the printer to perform functions such as: •Allowing the printer to talk to the host computer through a Bi-directional parallel connection. The printer can tell the host such things as the control panel settings, and allow the control panel settings to be set from the host. •Dynamic I/O switching allows the printer to be configured with a host on each I/O. The printer can receive data from any I/O simultaneously. •Context-sensitive switching allows the printer to recognize automatically the personalities (PostScript or PCL) of each host and configure itself to serve that personality. •PJL can act as a spooler to print only sections of a print job as defined from the software. •PJL allows any print job to be protected from the effects of the previous print job. If a print job is sent to the printer in landscape mode, the subsequent print jobs print in landscape only if they are formatted for landscape printing. Functional Overview 5-15
![](/img/blank.gif)
Image Formation System Laser printing requires the interaction of several different technologies (such as electronics, optics, and electro-photographics) to provide a printed page. Each process functions independently and must be coordinated with all other printer processes. The image formation process centers around the photosensitive drum and consists of six stages: 1. Cleaning 4. Developing 2. Conditioning 5. Transferring 3. Writing 6. Fusing The toner cartridge houses the cleaning, conditioning, and developing stages of the electro-photographic (EP) process. Components of the image formation system that wear, degrade, or are consumed are built into the replaceable cartridge. The toner cartridge contains the photosensitive drum, primary charging roller, developing station, toner cavity, and cleaning station. This eliminates the need for a service call when replacement is required. Figure 5-6 Image Formation System 5-16 Functional Overview
![](/img/blank.gif)
Photosensitive Drum The photosensitive drum is the “heart” of the Image Formation System. The special properties of this drum allow an image to be formed on the drum’s surface and then transferred to paper. The drum is an extruded aluminum cylinder. The outside of the cylinder is coated with a layer of organic-photoconductive material (OPC) which is non-toxic. The aluminum base of the photosensitive drum is electrically connected to ground potential (see Figure 5-7). Drum Sensitivity The OPC material has properties similar to a photo-resistor. It becomes electrically conductive when exposed to light. When the photosensitive drum is exposed to light, the negative charges deposited on it are conducted to the ground potential of the drum’s base. Areas not exposed to light remain nonconductive and maintain their negative charge. CautionDo not expose the Toner Cartridge to any bright light source. Too much light permanently damages the drum. Figure 5-7 Photosensitive Drum Functional Overview 5-17
![](/img/blank.gif)
Cleaning Stage During the cleaning stage of the image formation process, the drum’s surface is physically cleaned, preparing it to hold an image. During printing, the drum is rotating constantly making several complete rotations per printed page. Before forming the image for a given section of print, a cleaning blade removes toner from the previous rotation of the drum. The excess toner is stored in the toner cartridge where it is prevented from being used in later print jobs. Figure 5-8 Drum Cleaning Station 5-18 Functional Overview