JPH106505A - Carriage mounted printed circuit assembly having pen driver and power circuit incorporated therein - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the use of an inexpensive pen, in constitution such that one or more pen is supported on a printing head carriage in a detachable manner, by providing a pen driver converting a data signal to a nozzle selection signal acting on the pen to output the same to the pen through a pen connector. SOLUTION: The shuttle assembly 14 of an ink jet printer is equipped with a carriage 20 sliding in both directions along an elongated rod 12 and printing heads 30, 32 are attached to the carriage 20 as pens in a detachable manner. The first pen 30 is used in monochromatic (black) printing and the second pen 32 is a multicolor pen. A pair of pen connectors electrically connected to the respective pens 30, 32 are provided to the carriage 20 and a carriage PCA containing a pen driver receiving data from a fixed PCA(printed circuit assembly) 40 is also provided. A data signal is converted into a nozzle selection signal by the pen driver to be outputted to the pens 30, 32.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ink jet printer, and more particularly, to a pen control system for operating an ink jet pen used in an ink jet printer.

[0002]

2. Description of the Related Art An ink jet printer is a type of non-impact printer that forms characters and other images by controllably applying drops of ink from a printhead. A conventional type of ink jet printhead consists of a replaceable cartridge or pen removably mounted on a movable carriage. The pen controlslably ejects liquid ink through a plurality of nozzles across small air gaps and in the form of drops deposited on a recording medium.

[0003] Ink droplets are ejected from individual nozzles by local heating. A small heating element, typically in the form of a thermal resistor, is located at each nozzle. An electric current passes through the element and heats it. The heated element evaporates a minute volume of ink ejected through the nozzle.
The heating element is usually formed on a single silicon wafer chip, which makes the replaceable pen easy to assemble and makes production less expensive.

[0004] A pen driver circuit is connected to the heating element to provide energy for controllably dispensing ink drops.
Supplying pulse. The pen driver activates selected nozzles to form a desired image in response to a character generator or other image forming circuitry. The amount of energy that is effective to apply ink droplets from the pen
The pulse is called an "energizing pulse".

In earlier generations of ink jet printers, carriage mounted pens have 30 to 50 nozzles. The pen driver was located beside the carriage path on a fixed printed circuit board (PCB). A bundle of flexible conductors was connected between the PCB and the pen, allowing the carriage to reciprocate. The bundle of conductors consisted of a single conductor connected between the pen driver and the corresponding nozzle heating element and multiple conductors for power and signal.
The pen driver transmits the energizing pulse through a dedicated conductor,
The corresponding nozzle heating element was energized.

Mounting one conductor per nozzle has been effective for pens with a small number of nozzles (eg, 30 to 50 nozzles). However, as pens evolved, the number of nozzles increased to allow high quality printing of 300 to 600 dpi (dots per inch).
For example, some pens on the market today have as many as 300 nozzles. As the number of nozzles increases, the approach of implementing one conductor per nozzle is more controllable in terms of coordination or physically assembling hundreds of conductors in the printer housing It has become unmanageable.

To reduce the number of conductors, inkjet printer manufacturers have developed pens that incorporate low-level logic into a resistor silicon wafer. An activation signal in the form of a row and column address was sent to the pen over a smaller cable, and the logic used that address to select the appropriate nozzle. A 16-row and 14-column address combination could be used to drive a pen with 300 nozzles. Using a small ribbon cable with as few as 30 to 40 conductor wires, the address is passed from the pen driver to the pen in parallel, thereby substantially reducing the cable layout requirements for implementing higher resolution printers. Less. Hewlett-Packard HP Des
The kjet 850 and 1200 printers are examples of printers that incorporate such logic-based pens.

[0008] Logic-based pens are relatively inexpensive to produce because the logic circuitry is incorporated into the same silicon chip used to hold the heating resistors. However, this implementation provides control and timing of the energizing pulse transmitted from the pen driver to the movable pen via the ribbon conductor, as the energizing frequency increases, and the energizing requirement provides more precise control of the energizing pulse energy. Has the disadvantage that it becomes more and more difficult as it is needed. Modern printers continue to push for development for higher throughput, which equates to higher firing speeds and more control over energy pulses. As a result, another control circuit is incorporated into the PCB that ensures control and timing accuracy of the activation pulse signal.

To reduce the need for such control accuracy, some more recent pens have been introduced which provide additional decoding capabilities to the pen IC. Print data is sent serially to the pen from a pen driver on a fixed PCB via a serial conductor. Decoding circuitry built into the pen decodes the serial bit stream into the appropriate column and row addresses, which are then provided to the selection logic to fire the selected nozzles.

While this pen simplifies operation and helps to reduce delay and timing problems with the energizing signal, the resulting pen must manufacture and implement more sophisticated ICs. Therefore, the manufacturing cost is high. However, these pens are designed to be replaceable and / or disposable, meeting other manufacturing goals of providing an efficient way to replenish spent ink supplies.

[0011]

Accordingly, there remains a need to modify and simplify the operation of pens with multiple nozzles without increasing the cost of manufacturing replaceable pens.

[0012]

SUMMARY OF THE INVENTION A pen control system for an ink jet printer comprises a fixed printed circuit assembly (PCA) mounted on the frame of the ink jet printer.
And a carriage printed circuit assembly (PCA) mounted on the movable carriage. Series conductor fixed P
The CA is interconnected to the carriage PCA to transfer data, power, and ground signals from the fixed PCA to the carriage PCA in series.

The carriage PCA has a pen driver connected to receive data signals from the fixed PCA. The pen driver converts the data signal into a nozzle selection signal that functions to apply ink from selected pens of the pen. The nozzle selection signal is transferred to the pen via an electrical pen connector that is electrically connected to logic on the pen when the pen is installed on the carriage.

[0014] The carriage PCA also includes a power adjustment circuit and a temperature control circuit. The power conditioning circuit regulates the power signal received from the stationary PCA to various voltage levels used internally by the carriage PCA and to select and activate the pen nozzles. The temperature control circuit provides local control of the pen temperature.

By implementing the pen driver and power conditioning circuitry in the carriage-based PCA, the energizing pulses are generated locally and transferred directly to the pen, as opposed to communicating over long conductors. Is done. This design virtually eliminates the problems associated with precise control of the activation pulse because the activation pulse is transferred from the stationary PCB to the movable pen. Moreover, the control system supports the use of inexpensive pens, thereby avoiding the manufacturing costs associated with producing densely packed pens.

[0016]

FIG. 1 is an ink jet printer.
10 shows a printing mechanism part. The inkjet printer includes a platen 12, a shuttle assembly 14, and a control system 16. The platen 12 is a fixed or rotatable element that supports a recording medium during printing. Shuttle assembly 14 includes a carriage 20 slidably mounted on a fixed elongate rod 22 and moving bidirectionally across platen 12. Shuttle assembly 14 also includes a drive assembly (not shown), such as a stepper motor or DC motor mechanically coupled to the carriage, that mechanically moves carriage 20 back and forth along rod 22. I have.

The shuttle assembly 14 includes a carriage 20
And one or more ink jet printheads mounted on the printhead. Two printheads 30 and 32 are shown for illustrative purposes. Print heads 30 and 32
When mounted on the carriage 20, it is adjacent to the platen 12, but is located slightly away therefrom. Friction roller,
Alternatively, using a media supply mechanism (not shown), such as a tractor supply subassembly, print media is advanced between the platen 12 and the printheads 30, 32 through the printer. The carriage 20 moves the print heads 30, 32 in a reciprocating motion over the printing surface. The sweep of each print is called "print swath."

According to one type of known construction, the printheads 30, 32 are implemented as replaceable, disposable pens removably mounted on the carriage 20. Such pens include a self-contained ink supply, a nozzle pattern formed at the tip of the pen, and a heating element (eg,
Resistors) and a pen integrated circuit (IC) with selection logic for those elements. In this configuration, each replaceable pen essentially forms the entire printhead. As used herein, the terms "pen" and "printhead" are substantially interchangeable.

The first pen 30 is used for monochrome printing such as black. It is a high resolution pen (e.g., 600 dpi), with 300 rows of vertical 150 nozzles installed in an array of two rows of vertical 150 nozzles, alternating with an offset equal to half the distance between nozzles. It has an exemplary nozzle pattern composed of nozzles. The second pen 32
A multicolor pen that can print three different colors, such as cyan, magenta, and yellow. The pen 32 has 64 nozzles for each color, and has a total of 192 nozzles.
The resolution of the multicolor pen 32 is smaller than that of the black pen 30, and the exemplary resolution is 300 dpi.

FIG. 2 shows an electrical representation of the energizing resistors on each pen IC 36. The biasing resistors are arranged in an M × N matrix pattern. Row of resistors ("primitive"
), COLN and common ground lines GND1, GND2,..., GNDN.
The rows of resistors (also called "addresses") share common control or select lines ROW1, ROW2,..., ROMM. When one address line (eg, ROW1) is selected and one column line (eg, COL2) is activated, the address line ROW1
And the nozzle resistor at the intersection of column line COL2 is energized. A corresponding transistor directs current through a resistor between the energized column line and ground, heating the resistor to an effective temperature at which ink drops evaporate and eject through a corresponding nozzle.

In the exemplary embodiment with two pens 30, 32, the same address lines ROW1, ROW2,..., ROMM are shared by two pens (one pen as many as the other). Although the address line may not be used). Each pen is provided with its own unique column signal line.
During activation, one address line is selected and potentially all column lines are activated to activate multiple nozzles simultaneously.

The control system 16 includes a fixed printed circuit assembly (PCA) 40 mounted on a fixed fixture of the inkjet printer 10, such as a frame or housing.
It has. The control system 16 further includes a carriage print circuit assembly (PC
A) 42 and a conductor 44 interconnecting the stationary PCA 40 to the carriage PCA 42. The fixed PCA 40 functions as the primary logic or motherboard and controls aspects that do not involve all pens. Carriage PCA 42 controls aspects associated with all pens.

In general, the fixed PCA 40 has print data, power,
And a ground signal to the carriage PCA 42. Carriage PCA 42 is connected to a conductor cable 44 for data, power,
And an input connector for receiving a ground signal from the fixed PCA 40. Carriage PCA 42 also includes a pair of pen connectors in the form of conductive contacts that are electrically connected to contact pads formed on pens 30 and 32. The contact pads on the removable pen engage the contacts of the carriage PCA 42 when the pen is mounted on the carriage 20.

FIG. 3 shows a block diagram of the control system 16. The fixed PCA 40 includes an I / O circuit 50 that handles I / O tasks with an external device such as a host computer. The fixed PCA 40 further includes a carriage control circuit 52 for managing the carriage position and moving speed, a media control circuit 54 for controlling the printer feeding mechanism, and a panel I / O for adjusting the user interface functions of the main panel and display of the printer. An O circuit 56 is provided. The fixed PCA 40 also includes a data / control formatting circuit 58 that formats data received from the host via the I / O circuit 50 into a serial bit stream transmitted to the carriage PCA 42 via conductors 44. I have.

The serial interface manages communication between the stationary PCA 40 and the carriage PCA 42. The serial interface is bidirectional and includes a serial conductor 44. Serial interface provides fixed PCA 40 to carriage PCA for setup information, row / column selection data, power and ground signals
Communicate to 42. The serial interface also transfers temperature data and status information from the carriage PCA 42 back to the fixed PCA.
Communicate to 40.

In one embodiment, the bidirectional interface comprises:
Five signals, DIn1 (data input 1), DIn2, DOut, DClk,
And DLoad. All signals except DOut are inputs to fixed PCA 40. Serial input data is split and communicated over two physical conductors to reduce clock speed and electromagnetic emissions. When signals are transferred between the stationary PCA 40 and the carriage PCA 42 via a long flexible cable 44 (eg, 40 cm), they are controlled to minimize EMI.

The first bit of the serial input word is an address bit that defines what type of data is being transmitted. The value ADIN = 0 means that print data is being transmitted, and the value ADIN = 1 means that setup data is being transmitted. The two different input words can be sent in any order. Data written in either input format is latched by carriage PCA 42 until overwritten or cleared. Table 1 below shows exemplary combinations of input bit assignments in their transfer order.

[0028]

[Table 1]

Carriage PCA 42 includes a serial digital circuit 60 that receives the serial data stream from cable 44, latches the data, and converts the serial stream into a parallel format for high speed use inside carriage PCA. I have. The print data is transmitted when ADIN = 0 and includes bits for selecting the columns and rows of the energizing resistors to be driven. The serial digital circuit 60 includes a row and column driver 6 that outputs an appropriate activation control signal to select and activate the resistors in the pen activation matrices 36, 37.
This print data is transmitted to 2, 64, and thereby the ink is applied from the corresponding nozzles 38, 39. The row and column drivers 62, 64 decode the five row select bits and activate the appropriate rows of the activation matrices 36, 37 according to decoding table 2 below.

[0030]

[Table 2]

In this embodiment, the row address for rows 23-31 is 300 pen nozzles in rows 1-22 and columns 1-14.
Is not specified because it is properly addressed using These other addresses can be used for other setup / control data, or can be reserved for use if the pen is to be manufactured with a larger number of nozzles in the future.

Two power signals, 18V and 5V, are supplied to the carriage PCA 42 via conductors 44. Carriage PCA
42, power signal used inside carriage PCA, pen 3
Voltage adjustment circuit 66 that adjusts to various voltage levels that drive 0
It has. The voltage adjustment circuit 66 has the following four voltage adjustment circuits.

(1) The pen voltage regulator regulates the unregulated 18V signal to a voltage level Vpen of about 8 to 12V. Vpen is used as a resistor resistor source for the nozzle and is added to the column lines COL1, COL2,. Vpen
The voltage is shared by the two pens 30, 32 since one pen is energized at a time. The Vpen voltage is also programmable. The fixed PCA 40 sends a signal (eg, four bits in the format of the setup data in Table 2) to the carriage PCA 42 and sets the voltage level Vpen.

(2) The row voltage adjuster adjusts the 18V signal to a voltage level Vrow of about 12V. The voltage level Vrow is used to select the row lines ROW1, ROW2, ..., ROMM of the pen activation matrices 36,37.

(3) The gate voltage regulator converts the 18V power signal to V
Adjust to a voltage level Vgate approximately equal to pen + 13V. Vga
te powers the row and column pen drivers 62,64.

(4) The boost voltage regulator regulates the 18V power signal to Vboost, a higher voltage level of about 36V.

The placement of the voltage adjustment circuit 66 on the carriage PCA 42 allows for more precise control of the energizing pulse to the pen. Unlike prior art systems, the activation pulse is no longer transmitted to the pen by a long cable. Instead, the various voltage levels, and particularly the variable Vpen voltage, are generated at the carriage PCA 42 and communicated closely to the pen. Problems associated with delays or interference caused by transmission over the cable, which make precision control more difficult, have been substantially eliminated by this design.

The pens 30, 32 are designed to operate optimally at a substantially constant temperature. A temperature control circuit 70 is provided on the carriage PCA 42 to maintain the pen at a desired operating temperature.
The temperature control circuit 70 includes a pulse warming circuit 72, a digital / analog (D / A) converter 74, and an analog / digital (A / D) converter 76. The temperature control circuit 70 sets a temperature threshold, and the D / A converter 74 generates a voltage that is applied to allow the pen to warm to the target temperature.

The temperature control circuit 70 receives, from each pen, feedback information indicating the temperature of the pen. In one embodiment,
A thermal sensing resistor is built into the pen and is used to measure the actual temperature of the pen. Thermal sensing resistors increase in resistance as the pen warms up. This change in resistance is received as feedback information from the pen and is manifested as a rising analog voltage signal that is converted to a digital signal by A / D converter 76. This digital value is measured against a threshold. If the actual pen temperature is below the desired minimum operating temperature, the pulse warming circuit 72 preheats the pen to its minimum operating temperature.

The carriage PCA 42 is provided with another monitoring / control circuit 80 for handling the classification of the operation state. For example, a circuit
80 tracks over / under voltage, row / column over current, and other control conditions.

The carriage PCA 42 transfers fixed data and status information to the fixed PCA 40 via a bidirectional serial interface.
Is output in reverse. Carriage PC as well as input data
The output data from A 42 includes address bits ADOUT that communicate what type of data is being transferred. Value A
DOUT = 0 indicates that status data is being sent and the value
ADOUT = 1 indicates that temperature data is being transmitted.
Table 3 shows an example setting input bit assignment in transfer order.

[0042]

[Table 3]

In compliance with the statute, the invention has been described in language more or less specific as to structure and method characteristics. However, it is to be understood that this invention is not limited to the particular features described, as the means disclosed herein comprise embodiments having the features of the invention. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted in accordance with the principles of equivalents and other applicable judicial principles.

The embodiments of the present invention will be listed below.

1. A carriage print circuit assembly for mounting to a printhead carriage of an inkjet printer, wherein the printhead carriage supports one or more detachable pens, wherein the data, power, and ground signals are transmitted to the printhead carriage. An input connector, located remotely from the printhead carriage, for electrically connecting to a conductor carried from the one or more sources, a pen connector for providing easy electrical connection to the pen,
And receiving a data signal from an input connector and converting the data signal into a nozzle selection signal that acts on a pen to apply ink from a selected nozzle, the nozzle selection signal being transmitted through a pen connector. And a pen driver for outputting to the pen.

2. Further receive power from the input connector,
The carriage and printed circuit assembly of claim 1, further comprising a voltage regulation circuit connected to regulate the power to at least one voltage level.

3. And a pen for receiving power from the input connector and using the power as a bias source operative to apply ink from the selected nozzle.
Item 1 includes a pen voltage adjustment circuit for adjusting a voltage level output at a connector and a pen voltage adjustment circuit for adjusting the voltage level in response to a control signal received from an input connector. Carriage
Printed circuit assembly.

4. Furthermore, it is connected to the pen connector,
The carriage / print circuit assembly according to item 1, further comprising a temperature control circuit that receives feedback representing the pen temperature from the pen and controls the pen temperature based on the feedback.

5. An inkjet printer comprising the carriage printed circuit assembly according to item 1.

6. A control system for an inkjet printer, the inkjet printer comprising a movable carriage for supporting at least one pen and positioning it on a printing surface, the inkjet printer being external to the carriage. Fixed printed circuit assembly (PC
A), a carriage printed circuit assembly (PCA) that is adjusted to be mounted on the movable carriage,
Interconnect CA to said carriage PCA for data, power,
And a conductor for transferring a ground signal between the fixed PCA and the carriage PCA, receiving a data signal from the fixed PCA via the conductor, and applying the data signal to a pen from a selected nozzle. A carriage PCA having a pen driver connected to convert to a working nozzle selection signal, and an electrical pen connector for easily making an electrical connection to the pen for transferring the nozzle selection signal from the pen driver to the pen The control system, characterized in that the control system includes a carriage PCA having:

7. Carriage PCA also fixed power P
Item 7. The control system of item 6, comprising a voltage adjustment circuit received from the CA and connected to adjust the power to at least one voltage level.

8. A carriage PCA also receives the power from the fixed PCA and regulates the power to a voltage level output at the pen connector for use as a bias source that acts to apply ink from selected nozzles. 7. The control system according to item 6, wherein the control system has a pen voltage adjustment circuit, and the fixed PCA transmits data to the carriage PCA and sets the voltage level generated by the pen voltage adjustment circuit.

9. The carriage PCA also includes a temperature control circuit connected to the pen connector for receiving feedback indicating pen temperature from the pen and controlling the pen temperature based on the feedback. 7. The control system according to 6.

10. An inkjet printer comprising the control system described in item 6.

[0055]

According to the present invention, a pen driver and a power adjustment circuit are mounted on a carriage-based PCA,
An ink jet printer design is provided in which the energizing pulse is generated locally and transferred directly to a pen without passing through a long conductor. This design virtually eliminates the problems associated with precise control of the activation pulse because the activation pulse is transferred from the stationary PCB to the movable pen. In addition, the control system supports the use of inexpensive pens, thereby reducing the cost of manufacturing densely integrated pens.

[Brief description of the drawings]

FIG. 1 illustrates a portion of an inkjet printer illustrating a control system according to one aspect of the present invention.

FIG. 2 is an electric circuit diagram of a biasing resistor employed in the ink-jet pen.

FIG. 3 is a block diagram of a control system.

[Explanation of symbols]

 10 Inkjet printer 16 Control system 20 Printhead carriage 30, 32 Pen 40 Stationary PCA 42 Carriage PCA 44 Conductor 62, 64 Pen driver 70 Temperature control circuit

Claims (1)

[Claims] 1. A carriage print circuit assembly for mounting to a printhead carriage of an ink jet printer, wherein the printhead carriage supports one or more removable pens. Connect the ground signal to the print head
An input connector, electrically connected to a conductor carried from the one or more sources, remote from the carriage, a pen connector for easy electrical connection to the pen, and receiving data signals from the input connector. Connected to convert the data signal into a nozzle selection signal that acts on a pen to apply ink from a selected nozzle;
A pen driver that outputs the nozzle selection signal to a pen via a pen connector,
The carriage print circuit assembly.