Patent Description:
User replaceable fluid ejection devices (e.g., printheads) may include multiple exposed electrical pads that should form a reliable electrical connection to a fluid ejection system (e.g., printer) to operate correctly. These electrical pads, often referred to as dimple flex connections, may be susceptible to contamination or damage. In some cases, incorrect user handling or insertion may result in damage to electrical connections or damage to the permanent electrical interface in the fluid ejection system. The ability to verify proper electrical connectivity to each pad individually across multiple fluid ejection devices may provide an improved customer troubleshooting experience, improved safety and reliability of the fluid ejection devices, and a reduced rate of customer returns and service calls.

Accordingly, disclosed herein is a device to enable fluid ejection including pulldown devices for contact pads of the device. In one example, the pulldown devices corresponding to at least a portion of the contact pads may be enabled or disabled on a per-device basis based on signals on the contact pads. In another example, the pulldown devices corresponding to at least a portion of the contact pads may be enabled or disabled on a per-device basis based on data stored in a configuration register of the device.

Also disclosed herein is a device to enable fluid ejection including a programmable pulldown device electrically coupled to a contact pad of the device. In one example, the resistance of the programmable pulldown device may be set based on data stored in a configuration register of the device. The programmable pulldown device may be enabled or disabled based on data stored in the configuration register or signals applied to the contact pads of the fluid ejection device.

As used herein a "logic high" signal is a logic "<NUM>" or "on" signal or a signal having a voltage about equal to the logic power supplied to an integrated circuit (e.g., between about <NUM> V and <NUM> V, such as <NUM> V). As used herein a "logic low" signal is a logic "<NUM>" or "off" signal or a signal having a voltage about equal to a logic power ground return for the logic power supplied to the integrated circuit (e.g., about <NUM> V).

<FIG> is a block diagram illustrating one embodiment of the invention showing an integrated circuit <NUM> to drive a plurality of fluid actuation devices. The integrated circuit <NUM> is part of a fluid ejection die, which will be described below with reference to <FIG>. Integrated circuit <NUM> includes control logic <NUM>, a plurality of pulldown devices including a first pulldown device <NUM>, a second pulldown device <NUM>, and a third pulldown device <NUM>, and a plurality of contact pads including a first contact pad <NUM>, a second contact pad <NUM>, and a third contact pad <NUM>.

Each of the contact pads <NUM>, <NUM>, and <NUM> is electrically coupled to control logic <NUM> and to a corresponding pulldown device <NUM>, <NUM>, and <NUM> through a signal path <NUM>, <NUM>, and <NUM>, respectively. Control logic <NUM> is electrically coupled to first pulldown device <NUM> through a first enable (EN-<NUM>) signal path <NUM>, to second pulldown device <NUM> through a second enable (EN-<NUM>) signal path <NUM>, and to third pulldown device <NUM> through a third enable (EN-<NUM>) signal path <NUM>. While three pulldown devices and three corresponding contact pads are illustrated in <FIG>, in other examples integrated circuit <NUM> may include less than three pulldown devices and corresponding contact pads or more than three pulldown devices and corresponding contact pads.

Control logic <NUM> enables at least a portion of the pulldown devices <NUM>, <NUM>, and <NUM> in response to both a logic low signal on the first contact pad <NUM> and a logic low signal on the second contact pad <NUM>. In one example, control logic <NUM> enables at least the portion of the pulldown devices by providing a logic high enable signal on the corresponding enable signal paths <NUM>, <NUM>, and/or <NUM> in response to both a logic low signal on the first contact pad <NUM> and a logic low signal on the second contact pad <NUM>. Control logic <NUM> may disable at least the portion of the pulldown devices in response to a logic high signal on the first contact pad <NUM>. In one example, control logic <NUM> disables at least the portion of the pulldown devices by providing a logic low enable signal on the corresponding enable signal paths <NUM>, <NUM>, and/or <NUM> in response to a logic high signal on the first contact pad <NUM>.

In one example, control logic <NUM> enables the pulldown device <NUM> corresponding to the second contact pad <NUM> in response to a logic low signal on the first contact pad <NUM> and a logic high signal on the second contact pad <NUM>. In another example, control logic <NUM> enables the pulldown device <NUM> corresponding to the second contact pad <NUM> and disables the pulldown device <NUM> corresponding to the third contact pad <NUM> in response to a logic low signal on the first contact pad <NUM> and a logic high signal on the second contact pad <NUM>.

Control logic <NUM> may include a microprocessor, an application-specific integrated circuit (ASIC), or other suitable logic circuitry for controlling the operation of integrated circuit <NUM>. As will be described in more detail below with reference to <FIG>, each of the plurality of pulldown devices <NUM>, <NUM>, and <NUM> may include a transistor electrically coupled to the corresponding contact pad <NUM>, <NUM>, and <NUM> to produce a target resistance in response to the corresponding pulldown device <NUM>, <NUM>, and <NUM> being enabled.

When a pulldown device <NUM>, <NUM>, or <NUM> is enabled, the pulldown device presents a load to the electrical interface that is to be measured. A measured value that is lower than expected may indicate a shorted connection, such as an ink short, while a measured value that is higher than expected may indicate an open connection. A measured value that in within an expected range indicates a proper electrical connection.

<FIG> is a schematic diagram illustrating one example of a pulldown device <NUM> coupled to a contact pad <NUM>. In one example, each pulldown device <NUM>, <NUM>, and <NUM> and corresponding contact pad <NUM>, <NUM>, and <NUM> of <FIG> is similar to pulldown device <NUM> and contact pad <NUM>. Pulldown device <NUM> may include a transistor <NUM>. An electrostatic discharge circuit (ESD) <NUM> may also be coupled to contact pad <NUM>. In other examples, electrostatic discharge circuit <NUM> may be excluded.

Contact pad <NUM> is electrically coupled to electrostatic discharge circuit <NUM> and one side of the source-drain path of transistor <NUM> through a signal path <NUM>. Signal path <NUM> may be electrically coupled to control logic and/or other components (not shown) of the integrated circuit. The other side of the source-drain path of transistor <NUM> is electrically coupled to a common or ground <NUM>. The gate of transistor <NUM> is electrically coupled to an enable (EN) signal path <NUM>. In one example, each enable signal path <NUM>, <NUM>, and <NUM> of <FIG> is similar to enable signal path <NUM>. Enable signal path <NUM> may be electrically coupled to control logic, such as control logic <NUM> of <FIG>.

Electrostatic discharge circuit <NUM> protects internal circuitry of the integrated circuit from overvoltage conditions. In one example, transistor <NUM> is a field-effect transistor (FET) sized to produce a target resistance in response to an enable signal on enable signal path <NUM>. The target resistance may be any suitable value sufficient to detect a reliable electrical connection to contact pad <NUM> when transistor <NUM> is turned on (i.e., conducting). In one example, the target resistance is between <NUM> kOhms and <NUM> kOhms, such as <NUM> kOhms. Since pulldown device <NUM> produces a target resistance when enabled, pulldown device <NUM> may also be referred to as a static pulldown device.

<FIG> is a schematic diagram illustrating another example of a pulldown device <NUM> coupled to a contact pad <NUM>. In one example, each pulldown device <NUM>, <NUM>, and <NUM> and corresponding contact pad <NUM>, <NUM>, and <NUM> of <FIG> is similar to pulldown device <NUM> and contact pad <NUM>. Pulldown device <NUM> includes a transistor <NUM> as previously described and illustrated with reference to <FIG>. An electrostatic discharge circuit includes a first diode <NUM>, a second diode <NUM>, and a resistor <NUM>.

Contact pad <NUM> is electrically coupled to the anode of diode <NUM>, the cathode of diode <NUM>, one side of resistor <NUM>, and one side of the source-drain path of transistor <NUM> through a signal path 123a. The cathode of diode <NUM> is electrically coupled to a supply voltage (e.g., vdd) <NUM>. The anode of diode <NUM> is electrically coupled to a common or ground <NUM>. The other side of resistor <NUM> is electrically coupled to signal path 123b. Signal path 123b may be electrically coupled to control logic and/or other components (not shown) of the integrated circuit. Diodes <NUM> and <NUM> and resistor <NUM> prevent the buildup of static charge within the integrated circuit.

<FIG> is a block diagram illustrating another example of an integrated circuit <NUM> to drive a plurality of fluid actuation devices. In one example, integrated circuit <NUM> is part of a fluid ejection die, which will be described below with reference to <FIG>. Integrated circuit <NUM> includes control logic <NUM>, a configuration register <NUM>, and a plurality of pulldown devices including pulldown devices <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>. In addition, integrated circuit <NUM> also includes a plurality of contact pads including a data (DATA) contact pad <NUM>, a clock (CLK) contact pad <NUM>, a multipurpose input/output (SENSE) contact pad <NUM>, a logic reset (NRESET) contact pad <NUM>, a mode (MODE) contact pad <NUM>, and a fire (FIRE) contact pad <NUM>.

Each of the contact pads <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> is electrically coupled to control logic <NUM> and to a corresponding pulldown device <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> through a signal path <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>, respectively. Control logic <NUM> is electrically coupled to configuration register <NUM> through a signal path <NUM>. In addition, control logic <NUM> is electrically coupled to pulldown device <NUM> through an enable (DATA-EN) signal path <NUM>, pulldown device <NUM> through an enable (CLK-EN) signal path <NUM>, pulldown device <NUM> through an enable (SENSE-EN) signal path <NUM>, pulldown device <NUM> through an enable (NRESET-EN) signal path <NUM>, pulldown device <NUM> through an enable (MODE-EN) signal path <NUM>, and pulldown device <NUM> through an enable (FIRE-EN) signal path <NUM>. While six pulldown devices and six corresponding contact pads are illustrated in <FIG>, in other examples integrated circuit <NUM> may include less than six pulldown devices and corresponding contact pads or more than six pulldown devices and corresponding contact pads.

In one example, control logic <NUM> may enable each of the pulldown devices <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> in response to both a logic low signal on the logic reset contact pad <NUM> and a logic low signal on the data contact pad <NUM>. In one example, the logic reset contact pad may be an active-low reset contact pad. Control logic <NUM> may disable each of the pulldown devices other than the pulldown device <NUM> corresponding to the logic reset contact pad <NUM> in response to a logic high signal on the logic reset contact pad <NUM>. In one example, control logic <NUM> may enable the pulldown device <NUM> corresponding to the data contact pad <NUM> in response to a logic low signal on the logic reset contact pad <NUM> and a logic high signal on the data contact pad <NUM>. Control logic <NUM> may disable the pulldown devices <NUM>, <NUM>, and <NUM> corresponding to the clock contact pad <NUM>, the multipurpose input/output contact pad <NUM>, and the mode contact pad <NUM> in response to the logic low signal on the logic reset contact pad <NUM> and the logic high signal on the data contact pad <NUM>. In one example, pulldown devices <NUM> and <NUM> corresponding to the logic reset contact pad <NUM> and the fire contact pad <NUM> may be disabled based on data stored in the configuration register <NUM>.

Control logic <NUM> may include a microprocessor, an ASIC, or other suitable logic circuitry for controlling the operation of integrated circuit <NUM>. Configuration register <NUM> may be a memory device (e.g., nonvolatile memory, shift register, etc.) and may include any suitable number of bits (e.g., <NUM> bits to <NUM> bits, such as <NUM> bits). As previously described and illustrated with reference to <FIG>, each of the plurality of pulldown devices <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> may include a transistor electrically coupled to the corresponding contact pad <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>, respectively, to produce a target resistance in response to the corresponding pulldown device being enabled.

<FIG> is a block diagram illustrating one example of an integrated circuit 300a to drive a plurality of fluid actuation devices. In one example, integrated circuit 300a is part of a fluid ejection die, which will be described below with reference to <FIG>. Integrated circuit 300a includes a programmable pulldown device <NUM> and a contact pad <NUM>. Programmable pulldown device <NUM> is electrically coupled to the contact pad <NUM> through a signal path <NUM>. As will be described in more detail below with reference to <FIG>, the programmable pulldown device <NUM> may be set to any one of a plurality of resistances. In one example, programmable pulldown device <NUM> may replace each static pulldown device previously described and illustrated with reference to <FIG>.

Programmable pulldown device <NUM> may be used to further improve the detection capability of contact pad interconnect status compared to the static pulldown devices previously described. For example, programmable pulldown device <NUM> may be used to improve the sensitivity of ink shorts detection and provide a fabrication process specific load profile that may be cross referenced for identifying genuine devices (as opposed to counterfeit devices). When enabled, programmable pulldown device <NUM> presents a load to the electrical interface that may be measured. By forcing a known voltage or current onto the contact pad <NUM> (externally), and changing the pulldown voltage bias value (internally), expected changes in contact pad resistance may be observed for devices operating correctly (i.e., pad leakage is below an acceptable threshold). Deviations from the expected response may indicate a malfunction.

<FIG> is a block diagram illustrating another example of an integrated circuit 300b to drive a plurality of fluid actuation devices. In one example, integrated circuit 300b is part of a fluid ejection die, which will be described below with reference to <FIG>. Integrated circuit 300b includes a programmable pulldown device <NUM>, a configuration register <NUM>, and a contact pad <NUM>. Programmable pulldown device <NUM> is electrically coupled to the contact pad <NUM> through a signal path <NUM> and to the configuration register <NUM> through a signal path <NUM>. In this example, the resistance of the programmable pulldown device <NUM> may be set based on data stored in the configuration register. In one example, programmable pulldown device <NUM> may also be enabled or disabled based on data stored in the configuration register.

<FIG> is a block diagram illustrating another example of an integrated circuit 300c to drive a plurality of fluid actuation devices. In one example, integrated circuit 300c is part of a fluid ejection die, which will be described below with reference to <FIG>. Integrated circuit 300c includes a programmable pulldown device <NUM>, a static pulldown device <NUM>, and a contact pad <NUM>. Contact pad <NUM> is electrically coupled to programmable pulldown device <NUM> and static pulldown device <NUM> through a signal path <NUM>. In one example, static pulldown device <NUM> is similar to pulldown device <NUM> or <NUM> previously described and illustrated with reference to <FIG>, respectively.

Programmable pulldown device <NUM> and static pulldown device <NUM> may be enabled or disabled by control logic (not shown) and/or based on data stored in a configuration register (e.g., configuration register <NUM> of <FIG>). In one example, programmable pulldown device <NUM> and static pulldown device <NUM> may both be disabled. In another example, programmable pulldown device <NUM> may be enabled and static pulldown device <NUM> may be disabled. In another example, programmable pulldown device <NUM> may be disabled and static pulldown device <NUM> may be enabled. In another example, programmable pulldown device <NUM> and static pulldown device <NUM> may both be enabled.

<FIG> is a schematic diagram illustrating one example of a programmable pulldown device <NUM> coupled to a contact pad <NUM>. In one example, each programmable pulldown device <NUM> of <FIG> is similar to programmable pulldown device <NUM>. Programmable pulldown device <NUM> includes a voltage bias generator <NUM>, a first transistor <NUM>, and a second transistor <NUM>. An electrostatic discharge circuit (ESD) <NUM> may also be coupled to contact pad <NUM>. In other examples, electrostatic discharge circuit <NUM> may be excluded.

Contact pad <NUM> is electrically coupled to electrostatic discharge circuit <NUM> and one side of the source-drain path of first transistor <NUM> through a signal path <NUM>. Signal path <NUM> may be electrically coupled to control logic and/or other components (not shown) of the integrated circuit. The other side of the source-drain path of first transistor <NUM> is electrically coupled to one side of the source-drain path of second transistor <NUM> through a signal path <NUM>. The other side of the source-drain path of second transistor <NUM> is electrically coupled to a common or ground <NUM>. The gate of second transistor <NUM> is electrically coupled to an enable (EN) signal path <NUM>. An input of voltage bias generator <NUM> receives a voltage bias (VBIAS) magnitude signal on a signal path <NUM>. An output of voltage bias generator <NUM> is electrically coupled to the gate of the first transistor <NUM> through a voltage bias (VBIAS) signal path <NUM>.

Electrostatic discharge circuit <NUM> protects internal circuitry of the integrated circuit from overvoltage conditions. Voltage bias generator <NUM> provides a bias voltage to the gate of first transistor <NUM> in response to the bias magnitude on signal path <NUM>. In one example, the bias magnitude may be stored in configuration register <NUM> (<FIG>) or be set by control logic. In one example, the bias magnitude may include a multi-bit value (e.g., <NUM> bit value) such that programmable pulldown device <NUM> is settable to any one of <NUM> different resistance values. In other examples, the bias magnitude may include values having another number of bits, such as a four bit or six bit value.

The bias voltage sets the programmable pulldown device <NUM> to one of a plurality of resistances by setting the resistance of first transistor <NUM> in response to the bias voltage. In one example, the first transistor <NUM> produces a resistance between <NUM> kOhms and <NUM> kOhms based on the bias voltage. Second transistor <NUM> enables or disables the programmable pulldown device <NUM> in response to an enable signal on enable signal path <NUM>. Enable signal path <NUM> may be electrically coupled to control logic and/or to a configuration register. In one example, programmable pulldown device <NUM> is enabled based on data stored in a configuration register <NUM> (<FIG>). For example, a logic high enable signal may be provided on enable signal path <NUM> to turn on second transistor <NUM> in response to a logic high programmable pulldown device enable bit stored in the configuration register. A logic low enable signal may be provided on enable signal path <NUM> to turn off second transistor <NUM> in response to a logic low programmable pulldown device enable bit stored in the configuration register.

<FIG> is a schematic diagram illustrating another example of a programmable pulldown device <NUM> coupled to a contact pad <NUM>. In one example, each programmable pulldown device <NUM> of <FIG> is similar to programmable pulldown device <NUM>. Programmable pulldown device <NUM> includes a voltage bias generator <NUM>, a first transistor <NUM>, and a second transistor <NUM> as previously described and illustrated with reference to <FIG>. In addition, an electrostatic discharge circuit includes a first diode <NUM>, a second diode <NUM>, and a resistor <NUM>.

Contact pad <NUM> is electrically coupled to the anode of diode <NUM>, the cathode of diode <NUM>, one side of resistor <NUM>, and one side of the source-drain path of first transistor <NUM> through a signal path 311a. The cathode of diode <NUM> is electrically coupled to a supply voltage (e.g., vdd) <NUM>. The anode of diode <NUM> is electrically coupled to a common or ground <NUM>. The other side of resistor <NUM> is electrically coupled to a signal path 311b. Signal path 311b may be electrically coupled to control logic and/or other components (not shown) of the integrated circuit. Diodes <NUM> and <NUM> and resistor <NUM> prevent the buildup of static charge within the integrated circuit.

<FIG> is a block diagram illustrating another example of an integrated circuit <NUM> to drive a plurality of fluid actuation devices. In one example, integrated circuit <NUM> is part of a fluid ejection die, which will be described below with reference to <FIG>. Integrated circuit <NUM> includes components of integrated circuit <NUM> previously described and illustrated with reference to <FIG>, including static pulldown devices <NUM>, <NUM>, and <NUM>, and contact pads <NUM>, <NUM>, and <NUM>. In addition, integrated circuit <NUM> includes a programmable pulldown device <NUM> as previously described and illustrated with reference to <FIG>, control logic <NUM>, and a configuration register <NUM>.

Each of the contact pads <NUM>, <NUM>, and <NUM> is electrically coupled to control logic <NUM> and a corresponding static pulldown device <NUM>, <NUM>, and <NUM> through a signal path <NUM>, <NUM>, and <NUM>, respectively. The programmable pulldown device <NUM> is also electrically coupled to the third contact pad <NUM> through signal path <NUM>. Control logic <NUM> is electrically coupled to configuration register <NUM> through a signal path <NUM>. Control logic <NUM> is electrically coupled to static pulldown device <NUM> through a first enable (EN-<NUM>) signal path <NUM>, to static pulldown device <NUM> through a second enable (EN-<NUM>) signal path <NUM>, to static pulldown device <NUM> through a third enable (EN-<NUM>) signal path <NUM>, and to programmable pulldown device <NUM> via a programmable pulldown device enable (EN-P) signal path <NUM>. While three static pulldown devices and three corresponding contact pads are illustrated in <FIG>, in other examples integrated circuit <NUM> may include less than three static pulldown devices and corresponding contact pads or more than three pulldown devices and corresponding contact pads. Likewise, while one programmable pulldown device is illustrated in <FIG>, in other examples integrated circuit <NUM> may include more than one programmable pulldown device corresponding to more than one contact pad.

Control logic <NUM> may include a microprocessor, an ASIC, or other suitable logic circuitry for controlling the operation of integrated circuit <NUM>. Configuration register <NUM> may be a memory device (e.g., nonvolatile memory, shift register, etc.) and may include any suitable number of bits (e.g., <NUM> bits to <NUM> bits, such as <NUM> bits). As previously described above, each static pulldown device <NUM>, <NUM>, and <NUM> may be enabled or disabled by control logic <NUM> based on signals on first contact pad <NUM> and second contact pad <NUM> and/or based on data stored in configuration register <NUM>. In addition, in one example, programmable pulldown device <NUM> may be enabled or disabled and the resistance of programmable pulldown device <NUM> may be set based on data stored in configuration register <NUM>.

In another example, programmable pulldown device <NUM> may be enabled in response to both a logic low signal on the first contact pad <NUM> and a logic low signal on the second contact pad <NUM>. In yet another example, programmable pulldown device <NUM> may be electrically coupled to first contact pad <NUM> instead of to third contact pad <NUM>. In this case, control logic <NUM> may enable the programmable pulldown device <NUM> in response to both a logic low signal on the second contact pad <NUM> and a logic low signal on the third contact pad <NUM>.

<FIG> is a block diagram illustrating another example of an integrated circuit <NUM> to drive a plurality of fluid actuation devices. In one example, integrated circuit <NUM> is part of a fluid ejection die, which will be described below with reference to <FIG>. Integrated circuit <NUM> includes components of integrated circuit <NUM> previously described and illustrated with reference to <FIG>, including static pulldown devices <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>, and contact pads <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>. In addition, integrated circuit <NUM> includes a programmable pulldown device <NUM> as previously described and illustrated with reference to <FIG>, control logic <NUM>, and a configuration register <NUM>.

Each of the contact pads <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> is electrically coupled to control logic <NUM> and to a corresponding static pulldown device <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> through a signal path <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>, respectively. The programmable pulldown deice <NUM> is also electrically coupled to the mode contact pad <NUM> through signal path <NUM>. Control logic <NUM> is electrically coupled to configuration register <NUM> through a signal path <NUM>. Control logic <NUM> is electrically coupled to static pulldown device <NUM> through an enable (DATA-EN) signal path <NUM>, static pulldown device <NUM> through an enable (CLK-EN) signal path <NUM>, static pulldown device <NUM> through an enable (SENSE-EN) signal path <NUM>, static pulldown device <NUM> through an enable (NRESET-EN) signal path <NUM>, static pulldown device <NUM> through an enable (MODE-EN) signal path <NUM>, and static pulldown device <NUM> through an enable (FIRE-EN) signal path <NUM>. Control logic <NUM> is electrically coupled to programmable pulldown device <NUM> through an enable (PMODE-EN) signal path <NUM>. While six static pulldown devices and six corresponding contact pads are illustrated in <FIG>, in other examples integrated circuit <NUM> may include less than six static pulldown devices and corresponding contact pads or more than six static pulldown devices and corresponding contact pads. Likewise, while one programmable pulldown device is illustrated in <FIG> coupled to the mode contact pad <NUM>, in other examples the programmable pulldown device may be coupled to a different contact pad and/or integrated circuit <NUM> may include more than one programmable pulldown device corresponding to more than one contact pad.

Control logic <NUM> may include a microprocessor, an ASIC, or other suitable logic circuitry for controlling the operation of integrated circuit <NUM>. Configuration register <NUM> may be a memory device (e.g., nonvolatile memory, shift register, etc.) and may include any suitable number of bits (e.g., <NUM> bits to <NUM> bits, such as <NUM> bits). As previously described, each of the static pulldown devices <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> may be enabled or disabled by control logic <NUM> based on signals on the logic reset contact pad <NUM> and the data contact pad <NUM> or based on data stored in configuration register <NUM>. In one example, static pulldown devices <NUM> and <NUM> corresponding to the logic reset contact pad <NUM> and the fire contact pad <NUM> may be enabled or disabled based on data stored in the configuration register <NUM>. In addition, programmable pulldown device <NUM> may be enabled or disabled and the resistance of programmable pulldown device <NUM> may be set based on data stored in configuration register <NUM>.

The following table summarizes one example for when each of the pulldown devices of <FIG> is enabled or disabled. In addition, the programmable pulldown device of the MODE contact pad and the static pulldown devices of the NRESET and FIRE contact pads may be enabled and disabled via the configuration register. In one example, the programmable pulldown device of the MODE contact pad defaults to disabled and the static pulldown devices of the NRESET and FIRE contact pads default to enabled as shown in the following table.

<FIG> illustrates one example of a fluid ejection die <NUM> and <FIG> illustrates an enlarged view of the ends of fluid ejection die <NUM>. Die <NUM> includes a first column <NUM> of contact pads, a second column <NUM> of contact pads, and a column <NUM> of fluid actuation devices <NUM>. The second column <NUM> of contact pads is aligned with the first column <NUM> of contact pads and at a distance (i.e., along the Y axis) from the first column <NUM> of contact pads. The column <NUM> of fluid actuation devices <NUM> is disposed longitudinally to the first column <NUM> of contact pads and the second column <NUM> of contact pads. The column <NUM> of fluid actuation devices <NUM> is also arranged between the first column <NUM> of contact pads and the second column <NUM> of contact pads. In one example, fluid actuation devices <NUM> are nozzles or fluidic pumps to eject fluid drops.

In one example, the first column <NUM> of contact pads includes six contact pads. The first column <NUM> of contact pads may include the following contact pads in order: a data contact pad <NUM>, a clock contact pad <NUM>, a logic power ground return contact pad <NUM>, a multipurpose input/output contact pad <NUM>, a first high voltage power supply contact pad <NUM>, and a first high voltage power ground return contact pad <NUM>. Therefore, the first column <NUM> of contact pads includes the data contact pad <NUM> at the top of the first column <NUM>, the first high voltage power ground return contact pad <NUM> at the bottom of the first column <NUM>, and the first high voltage power supply contact pad <NUM> directly above the first high voltage power ground return contact pad <NUM>. While contact pads <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> are illustrated in a particular order, in other examples the contact pads may be arranged in a different order.

In one example, the second column <NUM> of contact pads includes six contact pads. The second column <NUM> of contact pads may include the following contact pads in order: a second high voltage power ground return contact pad <NUM>, a second high voltage power supply contact pad <NUM>, a logic reset contact pad <NUM>, a logic power supply contact pad <NUM>, a mode contact pad <NUM>, and a fire contact pad <NUM>. Therefore, the second column <NUM> of contact pads includes the second high voltage power ground return contact pad <NUM> at the top of the second column <NUM>, the second high voltage power supply contact pad <NUM> directly below the second high voltage power ground return contact pad <NUM>, and the fire contact pad <NUM> at the bottom of the second column <NUM>. While contact pads <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> are illustrated in a particular order, in other examples the contact pads may be arranged in a different order.

In one example, data contact pad <NUM> may provide DATA contact pad <NUM> of <FIG> or <FIG>. Clock contact pad <NUM> may provide CLK contact pad <NUM> of <FIG> or <FIG>. Multipurpose input/output contact pad <NUM> may provide SENSE contact pad <NUM> of <FIG> or <FIG>. Logic reset contact pad <NUM> may provide NRESET contact pad <NUM> of <FIG> or <FIG>. Mode contact pad <NUM> may provide MODE contact pad <NUM> of <FIG> or <FIG>. Fire contact pad <NUM> may provide FIRE contact pad <NUM> of <FIG> or <FIG>.

Data contact pad <NUM> may be used to input serial data to die <NUM> for selecting fluid actuation devices, memory bits, thermal sensors, configuration modes (e.g. via a configuration register <NUM> or <NUM> of <FIG> and <FIG>, respectively), etc. Data contact pad <NUM> may also be used to output serial data from die <NUM> for reading memory bits, configuration modes, status information, etc. Clock contact pad <NUM> may be used to input a clock signal to die <NUM> to shift serial data on data contact pad <NUM> into the die or to shift serial data out of the die to data contact pad <NUM>. Logic power ground return contact pad <NUM> provides a ground return path for logic power (e.g., about <NUM> V) supplied to die <NUM>. In one example, logic power ground return contact pad <NUM> is electrically coupled to the semiconductor (e.g., silicon) substrate <NUM> of die <NUM>. Multipurpose input/output contact pad <NUM> may be used for analog sensing and/or digital test modes of die <NUM>.

First high voltage power supply contact pad <NUM> and second high voltage power supply contact pad <NUM> may be used to supply high voltage (e.g., about <NUM> V) to die <NUM>. First high voltage power ground return contact pad <NUM> and second high voltage power ground return contact pad <NUM> may be used to provide a power ground return (e.g., about <NUM> V) for the high voltage power supply. The high voltage power ground return contact pads <NUM> and <NUM> are not directly electrically connected to the semiconductor substrate <NUM> of die <NUM>. The specific contact pad order with the high voltage power supply contact pads <NUM> and <NUM> and the high voltage power ground return contact pads <NUM> and <NUM> as the innermost contact pads may improve power delivery to die <NUM>. Having the high voltage power ground return contact pads <NUM> and <NUM> at the bottom of the first column <NUM> and at the top of the second column <NUM>, respectively, may improve reliability for manufacturing and may improve ink shorts protection.

Logic reset contact pad <NUM> may be used as a logic reset input to control the operating state of die <NUM>. Logic power supply contact pad <NUM> may be used to supply logic power (e.g., between about <NUM> V and <NUM> V, such as <NUM> V) to die <NUM>. Mode contact pad <NUM> may be used as a logic input to control access to enable/disable configuration modes (i.e., functional modes) of die <NUM>. Fire contact pad <NUM> may be used as a logic input to latch loaded data from data contact pad <NUM> and to enable fluid actuation devices or memory elements of die <NUM>.

Die <NUM> includes an elongate substrate <NUM> having a length <NUM> (along the Y axis), a thickness <NUM> (along the Z axis), and a width <NUM> (along the X axis). In one example, the length <NUM> is at least twenty times the width <NUM>. The width <NUM> may be <NUM> or less and the thickness <NUM> may be less than <NUM> microns. The fluid actuation devices <NUM> (e.g., fluid actuation logic) and contact pads <NUM>-<NUM> are provided on the elongate substrate <NUM> and are arranged along the length <NUM> of the elongate substrate. Fluid actuation devices <NUM> have a swath length <NUM> less than the length <NUM> of the elongate substrate <NUM>. In one example, the swath length <NUM> is at least <NUM>. The contact pads <NUM>-<NUM> may be electrically coupled to the fluid actuation logic. The first column <NUM> of contact pads may be arranged near a first longitudinal end <NUM> of the elongate substrate <NUM>. The second column <NUM> of contact pads may be arranged near a second longitudinal end <NUM> of the elongate substrate <NUM> opposite to the first longitudinal end <NUM>.

<FIG> illustrates one example of a fluid ejection device <NUM>. In one example, fluid ejection device <NUM> is a printhead assembly for ejecting fluid of three different colors (e.g., cyan, magenta, and yellow). Fluid ejection device <NUM> includes a carrier <NUM> and a plurality of fluid ejection dies 600a-600c. As previously described and illustrated with reference to <FIG>, each fluid ejection die 600a-600c includes an elongate substrate 640a-640c, respectively. The plurality of elongate substrates 640a-640c are arranged parallel to each other on the carrier <NUM>. Each of the plurality of elongate substrates 640a-640c may include a single color substrate and each single color substrate may be of a different color. Elongate substrates 640a-640c may be embedded in or adhered to carrier <NUM>. Carrier <NUM> may be a rigid carrier including an epoxy or another suitable material.

Carrier <NUM> includes electrical routing (e.g. conductive lines <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> described below) to electrical interconnect pads (e.g., electrical interconnect pads <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> described below) to connect a fluid ejection system circuit (e.g., a printer circuit) to the contact pads of the elongate substrates 640a-640c. In one example, the electrical routing may be arranged between the elongate substrates 640a-640c.

The plurality of fluid ejection devices includes a first fluid ejection die 600a, a second fluid ejection die 600b, and a third fluid ejection die 600c. The first fluid ejection die 600a includes a first plurality of contact pads including a first contact pad (e.g., a logic reset contact pad <NUM>) and a second contact pad (e.g., a data contact pad <NUM>), a first plurality of pulldown devices (not shown) as previously described, and first control logic (not shown) as previously described. Each of the first plurality of pulldown devices is electrically coupled to a corresponding contact pad of the first plurality of contact pads. The first control logic enables at least a portion of the pulldown devices of the first plurality of pulldown devices in response to both a logic low signal on the first contact pad (e.g., the logic reset contact pad <NUM>) and a logic low signal on the second contact pad (e.g., the data contact pad <NUM>).

The second fluid ejection die 600b includes a second plurality of contact pads comprising a third contact pad (e.g., a logic reset contact pad <NUM>) and a fourth contact pad (e.g., a data contact pad <NUM>), a second plurality of pulldown devices (not shown) as previously described, and second control logic (not shown) as previously described. Each of the second plurality of pulldown devices is electrically coupled to a corresponding contact pad of the second plurality of contact pads. The second control logic enables at least a portion of the pulldown devices of the second plurality of pulldown devices in response to both a logic low signal on the third contact pad (e.g., the logic reset contact pad <NUM>) and a logic low signal on the fourth contact pad (e.g., the data contact pad <NUM>).

A conductive line <NUM> electrically couples the first contact pad (e.g., the logic reset contact pad <NUM> of the first fluid ejection die 600a) to the third contact pad (e.g., the logic reset contact pad <NUM> of the second fluid ejection die 600b). In one example, conductive line <NUM> is also electrically coupled to a contact pad (e.g., the logic reset contact pad <NUM>) of the third fluid ejection die 600c. The second contact pad (e.g., the data contact pad <NUM> of the first fluid ejection die 600a) is electrically isolated from the fourth contact pad (e.g., the data contact pad <NUM> of the second fluid ejection die 600b). In one example, a contact pad (e.g., the data contact pad <NUM>) of the third fluid ejection die 600c is also electrically isolated from the second contact pad (e.g., the data contact pad <NUM> of the first fluid ejection die 600a) and the fourth contact pad (e.g., the data contact pad <NUM> of the second fluid ejection die 600b).

Conductive line <NUM> may electrically couple the logic reset contact pad <NUM> of each of the plurality of fluid ejection dies 600a-600c to an electrical interconnect pad <NUM>. A conductive line <NUM> may electrically couple the data contact pad <NUM> of the first fluid ejection die 600a to an electrical interconnect pad <NUM>. A conductive line <NUM> may electrically couple the data contact pad <NUM> of the second fluid ejection die 600b to an electrical interconnect pad <NUM>. Likewise, a conductive line <NUM> may electrically couple the data contact pad <NUM> of the third fluid ejection die 600c to an electrical interconnect pad <NUM>. Since each data contact pad of the plurality of fluid ejection dies 600a-600c is electrically isolated from the other data contact pads of the plurality of fluid ejection dies 600a-600c, signals applied to the data contact pads may be used to individually enable or disable the pulldown devices of each of the plurality of fluid ejection dies 600a-600c. In this way, the electrical connections to each fluid ejection die 600a-600c may be individually tested.

Carrier <NUM> may include a conductive line <NUM> electrically coupling a first contact pad of each elongate substrate 640a-640c (e.g., the first high voltage power supply contact pad <NUM> of each elongate substrate 640a-640c) to a second contact pad of each elongate substrate 640a-640c (e.g., the second high voltage power supply contact pad <NUM> of each elongate substrate 640a-640c). Carrier <NUM> may also include a conductive line <NUM> electrically coupling a first contact pad of each elongate substrate 640a-640c (e.g., first high voltage power ground return contact pad <NUM> of each elongate substrate 640a-640c) to a second contact pad of each elongate substrate 640a-640c (e.g., second high voltage power ground return contact pad <NUM> of each elongate substrate 640a-640c).

The conductive line <NUM> may be electrically coupled to an electrical interconnect pad <NUM>, and the conductive line <NUM> may be electrically coupled to an electrical interconnect pad <NUM>. The electrical interconnect pads <NUM> and <NUM> may be used to supply high voltage power from a fluid ejection system to elongate substrates 640a-640c. Additional conductive lines and additional electrical interconnect pads may be electrically coupled to the other contact pads of elongate substrates 640a-640c to provide electrical connections between elongate substrates 640a-640c and a fluid ejection system. The orientation of the contact pads of elongate substrates 640a-640c enables the multiple dies to be bonded in parallel with fewer flex wires and connections.

<FIG> is a block diagram illustrating one example of a fluid ejection system <NUM>. Fluid ejection system <NUM> includes a fluid ejection assembly, such as printhead assembly <NUM>, and a fluid supply assembly, such as ink supply assembly <NUM>. In the illustrated example, fluid ejection system <NUM> also includes a service station assembly <NUM>, a carriage assembly <NUM>, a print media transport assembly <NUM>, and an electronic controller <NUM>. While the following description provides examples of systems and assemblies for fluid handling with regard to ink, the disclosed systems and assemblies are also applicable to the handling of fluids other than ink.

Printhead assembly <NUM> includes at least one printhead or fluid ejection die <NUM> previously described and illustrated with reference to <FIG>, which ejects drops of ink or fluid through a plurality of orifices or nozzles <NUM>. In one example, the drops are directed toward a medium, such as print media <NUM>, so as to print onto print media <NUM>. In one example, print media <NUM> includes any type of suitable sheet material, such as paper, card stock, transparencies, Mylar, fabric, and the like. In another example, print media <NUM> includes media for three-dimensional (3D) printing, such as a powder bed, or media for bioprinting and/or drug discovery testing, such as a reservoir or container. In one example, nozzles <NUM> are arranged in at least one column or array such that properly sequenced ejection of ink from nozzles <NUM> causes characters, symbols, and/or other graphics or images to be printed upon print media <NUM> as printhead assembly <NUM> and print media <NUM> are moved relative to each other.

Ink supply assembly <NUM> supplies ink to printhead assembly <NUM> and includes a reservoir <NUM> for storing ink. As such, in one example, ink flows from reservoir <NUM> to printhead assembly <NUM>. In one example, printhead assembly <NUM> and ink supply assembly <NUM> are housed together in an inkjet or fluid-jet print cartridge or pen. In another example, ink supply assembly <NUM> is separate from printhead assembly <NUM> and supplies ink to printhead assembly <NUM> through an interface connection <NUM>, such as a supply tube and/or valve.

Carriage assembly <NUM> positions printhead assembly <NUM> relative to print media transport assembly <NUM>, and print media transport assembly <NUM> positions print media <NUM> relative to printhead assembly <NUM>. Thus, a print zone <NUM> is defined adjacent to nozzles <NUM> in an area between printhead assembly <NUM> and print media <NUM>. In one example, printhead assembly <NUM> is a scanning type printhead assembly such that carriage assembly <NUM> moves printhead assembly <NUM> relative to print media transport assembly <NUM>. In another example, printhead assembly <NUM> is a non-scanning type printhead assembly such that carriage assembly <NUM> fixes printhead assembly <NUM> at a prescribed position relative to print media transport assembly <NUM>.

Service station assembly <NUM> provides for spitting, wiping, capping, and/or priming of printhead assembly <NUM> to maintain the functionality of printhead assembly <NUM> and, more specifically, nozzles <NUM>. For example, service station assembly <NUM> may include a rubber blade or wiper which is periodically passed over printhead assembly <NUM> to wipe and clean nozzles <NUM> of excess ink. In addition, service station assembly <NUM> may include a cap that covers printhead assembly <NUM> to protect nozzles <NUM> from drying out during periods of non-use. In addition, service station assembly <NUM> may include a spittoon into which printhead assembly <NUM> ejects ink during spits to ensure that reservoir <NUM> maintains an appropriate level of pressure and fluidity, and to ensure that nozzles <NUM> do not clog or weep. Functions of service station assembly <NUM> may include relative motion between service station assembly <NUM> and printhead assembly <NUM>.

Electronic controller <NUM> communicates with printhead assembly <NUM> through a communication path <NUM>, service station assembly <NUM> through a communication path <NUM>, carriage assembly <NUM> through a communication path <NUM>, and print media transport assembly <NUM> through a communication path <NUM>. In one example, when printhead assembly <NUM> is mounted in carriage assembly <NUM>, electronic controller <NUM> and printhead assembly <NUM> may communicate via carriage assembly <NUM> through a communication path <NUM>. Electronic controller <NUM> may also communicate with ink supply assembly <NUM> such that, in one implementation, a new (or used) ink supply may be detected.

Electronic controller <NUM> receives data <NUM> from a host system, such as a computer, and may include memory for temporarily storing data <NUM>. Data <NUM> may be sent to fluid ejection system <NUM> along an electronic, infrared, optical or other information transfer path. Data <NUM> represent, for example, a document and/or file to be printed. As such, data <NUM> form a print job for fluid ejection system <NUM> and includes at least one print job command and/or command parameter.

In one example, electronic controller <NUM> provides control of printhead assembly <NUM> including timing control for ejection of ink drops from nozzles <NUM>. As such, electronic controller <NUM> defines a pattern of ejected ink drops which form characters, symbols, and/or other graphics or images on print media <NUM>. Timing control and, therefore, the pattern of ejected ink drops, is determined by the print job commands and/or command parameters. In one example, logic and drive circuitry forming a portion of electronic controller <NUM> is located on printhead assembly <NUM>. In another example, logic and drive circuitry forming a portion of electronic controller <NUM> is located off printhead assembly <NUM>.

Claim 1:
An integrated circuit (<NUM>) configured to drive a fluid ejection device comprising a plurality of fluid actuation devices, the integrated circuit (<NUM>) comprising:
a plurality of contact pads (<NUM>,<NUM>,<NUM>) comprising a first contact pad (<NUM>) and a second contact pad (<NUM>);
a plurality of pulldown devices (<NUM>,<NUM>,<NUM>), each pulldown device (<NUM>, <NUM>, <NUM>) to present a load to the corresponding contact pad (<NUM>, <NUM>, <NUM>) that is to be measured to determine proper electrical connection of the contract pad (<NUM>, <NUM>, <NUM>) when the pulldown device (<NUM>, <NUM>, <NUM>) is enabled, each of the pulldown devices (<NUM>,<NUM>,<NUM>) electrically coupled to a corresponding contact pad (<NUM>,<NUM>,<NUM>) by a respective first signal path (<NUM>, <NUM>, <NUM>); and
control logic (<NUM>) to enable at least a portion of the pulldown devices (<NUM>,<NUM>,<NUM>) in response to both a logic low signal on the first contact pad (<NUM>) and a logic low signal on the second contact pad (<NUM>), the control logic (<NUM>) coupled to the plurality of pulldown devices (<NUM>, <NUM>, <NUM>) by respective second signal paths (EN, EN-<NUM>, EN-<NUM>) different to the first signal paths (<NUM>, <NUM>, <NUM>).