DE19642565C2 - Printed carriage circuit for mounting on a print carriage of an inkjet printer - Google Patents

Description

This invention relates to a printed carriage scarf device for mounting on a print head carriage of an ink jet printer, according to the preamble of claim 1.

WO 95/32865 relates to an ink jet head, which a System includes to draw ink out of the head's nozzles float. This system is only on the printhead carriage a high voltage conversion circuit is arranged so that Low voltage signals in corresponding cables, which do not need to meet a high voltage specification from which Printer can be led to the print head carriage. Only that Connection between the carriage and the individual print heads requires the use of special high-voltage cables. The An control of the print head nozzles is done in a conventional way by supplying external signals to registers on the Minds.

In the article by Alfred Holt Mebane IV, et. al. "Electronic and Firmware Design of the HP DesignJet Drafting Plotter "in Hewlett-Packard Journal December 1992, pages 16-23 an electronic circuit for an inkjet printer fenbart, the two printheads, each with at least 50 nozzles having. The circuit comprises two ASICs, one on a motherboard of the printer is provided, and the on the printhead carriage. On the printhead carriage orderly circuit includes the necessary logic scarf to address signals for the addressing of be agreed to generate nozzles on the printhead, taking this Addresses a printhead arranged on the printhead be fed via.

The object of the present invention is a Printed circuit for one attached to a cart To create inkjet printers that are simplified and improved operation of print heads with a large number allows from nozzles without the manufacturing cost of the exchangeable printheads.

The carriage circuit has a print head driver that is connected to the data signals from the stationary PCA (Printed Circuit Assembly). The print head free converts the data signals into nozzle selection signals that are effective to cause a printhead to run out of ink ejects selected nozzles. The nozzle selection signals are via an electrical printhead connector, which is an elec trical coupling to the logic circuit on the print head when the printhead is installed in the carriage, transferred to the printhead.

The carriage circuit also has a voltage regulator scarf device and a temperature control circuit. The tension regulator circuit regulates power signals from the statio nary PCA can be received at different voltage levels, which are used internally by the carriage circuit select and shoot the printhead nozzles. The tempe ratur control circuit provides localized control of the Print head temperature.

By implementing the printhead driver and the span voltage regulator circuit on the PCA arranged on the trolley, the launch pulses are generated locally and directly to the Print head transfer, as opposed to transfer via a long ladder. This design essentially eliminates lichen the problems of high-precision control of the Firing pulses are assigned if the same from a sta tional PCB to a movable printhead the. In addition, the control system offers little use complex printheads, which ver the manufacturing costs to be avoided, the production of highly integrated  Print heads are assigned.

Preferred embodiments of the present invention are referred to below with reference to the attached drawing nations explained in more detail. Show it:

Fig. 1 is a schematic representation of a portion ei nes ink jet printer showing a control system accelerator as claimed aspect of this invention;

Fig. 2 is an illustration of the electrical circuitry from shot resistors used in a printhead; and

Fig. 3 is a block diagram of the control system.

Fig. 1 shows a portion of a printing mechanism of an inkjet printer 10. The inkjet printer has a platen roller 12 , reciprocal movement assembly 14, and control system 16 . The platen roller 12 is a stationary or rotatable member that carries a recording medium during printing. The reciprocal movement assembly 14 has a carriage 20 which is slidably mounted on a solid, elongated Chen rod 22 to move bidirectionally over the platen roller 12 . The reciprocal movement assembly 14 also includes a drive subassembly (not shown), such as a pacer or DC motor, mechanically connected to the carriage 20 that mechanically maneuvers the carriage 20 back and forth along the rod 22 .

The reciprocal movement assembly 14 has one or more ink jet printheads mounted on the carriage 20 . Two printheads 30 and 32 are shown for purposes of explanation. When attached to the carriage 20 , the printheads 30 and 32 are adjacent, but somewhat spaced from the platen roller 12 . A media feed mechanism (not shown), such as friction rollers or a traction device feed subassembly, is used to move the print medium through the printer and between the platen 12 and printheads 30 , 32 . The carriage 20 guides the print heads 30 , 32 in a reciprocal movement over a printing surface. Each print run is referred to as a "print ribbon".

According to a known type of construction, printheads 30 , 32 are implemented as replaceable, disposable pens that are removably attached to carriage 20 . Such pens have an ink supply contained therein, a nozzle pattern which is formed at the pen tip, and an integrated pen circuit (IC) with heating elements (ie resistors) and a selection logic for these elements. With this configuration, each replaceable pen essentially forms an entire printhead. The terms "pen" and "printhead" as used herein are essentially interchangeable.

The first pen 30 is used for monochrome printing, for example black. It is a high resolution pen (e.g. 600 dpi) with an exemplary nozzle pattern consisting of 300 nozzles arranged in two vertical arrays of 150 nozzles, which are relative to each other by an offset equal to half a nozzle-to-nozzle distance is staggered. The second pen 32 is a multicolor pen that is capable of printing three different colors, for example cyan, magenta and yellow. The pin 32 has 64 nozzles for each color, making a total of 192 nozzles. The resolution of the color pen 32 is less than that of the black pen 30 , an exemplary resolution being 300 dpi.

Fig. 2 shows an electrical representation of the launch resistance in each pin IC 36th The launch resistors are arranged in an MxN matrix pattern. The columns of resistors (which are also called "basic patterns") share a common power line COL1, COL2, ... COLN and a common ground line GND1, GND2, ..., GNDN. The rows of resistors (which are also called "addresses") use a common control or selection line ROW1, ROW2, ..., ROWM. If an address line is selected (for example ROW1) and a row line is live (for example COL2), the nozzle resistance is fired at the intersection of the address line ROW1 and the column line COL2. The corresponding transistor conducts current through the resistance between the current-carrying row line and ground to increase the resistance to an effective temperature, which causes the evaporation and the ejection of an ink drop through the corresponding nozzle.

In the illustrated implementation with two pins 30 , 32 , the same address lines ROW1, ROW2, ... ROWM are used in common by both pins (although one pin cannot use as many address lines as the other). Each pin 30 , 32 has its own unique column signal lines. During firing, an address line and possibly each column line becomes live to fire multiple nozzles at the same time.

The control system 16 has a stationary printed circuit arrangement (PCA) 40 , which is attached to a stationary device in front of the ink jet printer 10 , for example the frame or the housing. The control system 16 also includes a printed carriage circuitry (PCA) 42 attached to the carriage 20 and a conductor 44 that connects the stationary PCA 40 to the carriage PCA 42 . The stationary PCA 40 works as the primary logic or the motherboard and controls all aspects not related to the pen. The carriage PCA 42 controls all aspects related to the pen.

Generally, the stationary PCA 40 sends data, power, and ground signals to the car PCA 42 . The carriage PCA 42 has an input connector that connects to the conductor cable 44 to receive the data, power and ground signals from the stationary PCA 40 . Carriage PCA 42 also includes a pair of pin connectors in the form of conductive contacts that electrically couple to contact pads formed on pins 30 and 32 . The contact pads on the removable pins engage the contacts of the Wa gen PCA 42 when the pins in the carriage 20 are built.

Fig. 3 shows a block diagram of the control system 16. The stationary PCA 40 contains an I / O circuit 50 (I / O = In put / Output = to input / output) to handle I / O tasks to external devices, such as a host computer. The stationary PCA 40 also includes a carriage control circuit 52 for managing the carriage position and rate of movement, a media control circuit 54 for controlling the media feed mechanism, and a control panel I / O circuit 56 for capturing user interface functions for the button panel and displaying the Printer. The stationary PCA 40 also includes a data / control formatter 58 that formats the data received from the host via the I / O circuit 50 into a serial bit stream that is routed to the carriage via the conductor 44 -PCA 42 is being sent.

A serial interface manages the communication between the stationary PCA 40 and the car PCA 42 . The serial interface is bidirectional and includes the serial conductor 44 . The serial interface transmits setting information, row / column selection data, power signals and a ground signal from the stationary PCA 40 to the car PCA 42 . The serial interface also transfers temperature data and status information from the car PCA 42 back to the stationary PCA 40 .

In one implementation, the bidirectional interface is implemented using five signals: DIn1 (data input 1), DIn2, DOut, DClk and DLoad. All signals with the exception of DOUT are entries in the stationary PCA 42 . The serial input data is shared and transmitted over two physical conductors in order to reduce the clock rate and the electromagnetic radiation. The signals are controlled to minimize interference radiation (EMI) while they are transmitted over a long flexible cable 44 (for example 40 cm) between the stationary PCA 40 and the car PCA 42 .

The first bit of the serial input word is an address bit that defines which data type is sent. A value ADIN = 0 means that print data will be sent, while a value ADIN = 1 means that setting data will be sent. The two different input words can be sent in any order. Data written by each of the input types is cached in the carriage PCA 42 until overwritten or deleted. The following Table 1 shows an example of a set of input bit assignments in the order of their transmission.

Table 1: Serial input bit assignments

The carriage PCA 42 includes a serial digital circuit 60 that receives the serial data stream from the cable 44, caches the data, and converts the serial stream to a parallel format internally in the carriage PCA 42 for very fast use. The print data is sent when ADIN = 0 and includes the bits for the selection of columns and rows of launch resistors to be operated. The serial digital circuit 60 sends this print data to row and column drivers 62 , 64 which output the appropriate firing control signals to select and fire resistors in the pen firing matrices 36 , 37 to thereby cause ink to be ejected from the respective nozzles 38 , 39 to effect. The row and column drivers 62 , 64 decode the five row selection bits to activate the corresponding rows in the firing matrixes 36 , 37 according to the following decoding table 2.

Table 2: Row address decoding

In this implementation, the row addresses are for the Lines 23 to 31 undefined because the 300 pen nozzles are adequate using rows 1 through 22 and columns 1 through 14 can be addressed. These additional addresses can be used for additional setting / control data or, for future use, if Stif te with more nozzles are reserved.

Two power signals of 18 V and 5 V are supplied to the car PCA 42 via the conductor 44 . The carriage PCA 42 has a voltage regulator circuit 66 that regulates the power signals to various voltage levels used in the carriage PCA to drive the pen 30 . The voltage regulator circuit 66 has four voltage regulator circuits:

• 1. A pin voltage regulator regulates the unregulated 18 V signal to a voltage level Vpen of approximately 8 V -12 V. Vpen is used as a resistance firing source for the nozzles, and is used in the column lines COL1, COL2, ..., COLN in the Firing matrices 36 , 37 fed. The voltage Vpen is shared by both pins 30 , 32 since each pin is activated individually. The voltage Vpen is also programmable. The stationary PCA 40 sends a signal (e.g., 4 bits in the setting data format in Table 2) to the carriage PCA 42 to set the voltage level Vpen.
• 2. A row voltage regulator regulates the 18 V signal to a voltage level Vrow of approximately 12 V. Vrow is used to select row lines ROW1, ROW2, ..., ROWM in the pin launching dies 36 , 37 .
• 3. A gate voltage regulator regulates the 18 V power signal to a voltage level Vgate which is approximately equal to Vpen + 13 V. Vgate is effective to power the row and column pen drivers 62 , 64 .
• 4. A boost voltage regulator regulates the 18 V Lei signal to a higher voltage level Vboost of approximately 36 V.

Placing the voltage regulator circuit 66 on the carriage PCA 52 allows more precise control of the pen firing pulses. Unlike known systems, the firing pulses are no longer transmitted to the pen over a long cable. Instead, the various voltage levels and especially the sensitive voltage Vpen are generated in the car PCA 42 and briefly transmitted to the car 20 . Problems associated with delays or interference due to transmission over a cable, which makes precise control more difficult, are essentially eliminated in this design.

The pins 30 , 32 are designed to work optimally at a near constant temperature. The carriage PCA 42 is equipped with a temperature control circuit 70 to maintain the pins at their desired operating temperature. The temperature control circuit 70 has a pulse heating circuit 72 , a digital / analog converter 74 (D / A converter) and an analog / digital converter 76 (A / D). The temperature control circuit 70 sets a threshold temperature value while the D / A converter 74 generates the voltage applied to warm the pen to the target temperature.

The temperature control circuit 70 receives feedback information from each pen indicating the pen temperature. In one implementation, thermal sensing resistors are built into the pen and are used to measure the actual temperature of the pen. The thermal detection resistors show an increase in resistance when the pen heats up. This resistance change shows up as an increasing analog voltage signal, which is received as feedback information from the stylus and is converted into a digital signal by the A / D converter 76 . The digital value is measured against a threshold. If the temperature is tatsäch Liche pin operating temperature below the desired minimum Be, warms the pulse heating circuit 72 in front of the pin to the minimum operating temperature.

The carriage PCA 42 has further monitoring and control circuits 80 which handle a range of operating conditions. For example, circuits 80 track over / under voltage, row / column overcurrent, and other control conditions.

The carriage PCA 42 outputs certain data and status information to the stationary PCA 40 via the bidirectional serial interface. Like the input data, the output data from the carriage PCA 42 has an address bit ADOUT which indicates which data type is being transmitted. The value ADOUT = 0 indicates that status data is being sent, while the value ADOUT = 1 indicates that temperature data is being sent. Table 3 shows an example of input bit assignments set in the order of their transmission.

Table 3: Output bit assignments

Claims (4)

1. Printed carriage circuit ( 42 ) for attachment to a print head carriage ( 20 ) of an inkjet printer ( 10 ), where the print head carriage ( 20 ) carries one or more replaceable print heads ( 30 , 32 ) with

• 1. an input connector for establishing an electrical connection to a conductor ( 44 ), the power and mass signals from one or more sources to the carriage circuit ( 42 ), which sources separately from the printhead carriage ( 20 ) fixed in the Ink jet printers ( 10 ) are arranged,
• 2. a printhead connector for an electrical connec tion between the printhead ( 30 , 32 ) and the carriage circuit ( 42 ), and
• 3. a voltage regulator circuit ( 66 ) for regulating power signals received from the input connector to a voltage level suitable for the operation of the print heads ( 30 , 32 ),

characterized by

• 1. that the input connector receives data signals, which in the carriage circuit ( 42 ) arranged printhead drivers ( 62 , 64 ) in nozzle selection signals for the printheads ( 30 , 32 ) converts, and
• 2. that the printhead connector transmits the nozzle selection signals generated by the printhead driver ( 62 , 64 ) arranged in the carriage circuit ( 42 ) to the printheads ( 30 , 32 ).

2. Printed carriage circuit ( 42 ) according to claim 1, characterized in that the voltage regulator circuit ( 66 ) responds to a control signal for adjusting the voltage level, which control signal is received by the input connector. 3. Printed carriage circuit ( 42 ) according to one of claims 1 or 2, characterized in that it contains a temperature control circuit ( 70 ) which receives via the printhead binder temperature data of the printheads ( 30 , 32 ) and as a function of this temperature data Temperature of the print heads ( 30 , 32 ) controls. 4. Inkjet printer, characterized in that it has a printed carriage circuit ( 42 ) according to one of claims 1 to 3.