WO2021126240A1

WO2021126240A1 - Printed circuit assembly detection

Info

Publication number: WO2021126240A1
Application number: PCT/US2019/067815
Authority: WO
Inventors: Paul D. Bliley; Michael Walters; David Jos VAINIKKA
Original assignee: Hewlett-Packard Development Company, L.P.
Priority date: 2019-12-20
Filing date: 2019-12-20
Publication date: 2021-06-24

Abstract

In an example, a printer system can detect a printed circuit assembly. The printer system includes a first printed circuit assembly having a door switch and a second first printed circuit assembly having an analog-to-digital converter connected to a first node. The second printed circuit assembly is to generate three different analog voltage values at the first node based in part on the door switch. Each analog voltage value is converted by the analog-to-digital converter into a corresponding digital value to detect the first printed circuit assembly.

Description

PRINTED CIRCUIT ASSEMBLY DETECTION

BACKGROUND

[0001] Printing platforms such as inkjet printers utilize ink or other fluids passed through fluidic channels and an array of nozzles to forcibly eject the ink onto a print medium such as a sheet of paper. The inkjet platform may have a fluid (or ink) supply door through which the ink supply is replenished. That is, when depleted, the ink supply can be replenished via this fluid supply door so that the inkjet printer platform can continue to output high quality text and images.

BRIEF DESCRIPTION OF THE DRAWINGS

[0002] FIG. 1 illustrates an example printer system according to the present disclosure.

[0003] FIG. 2A illustrates an example table having values for three different states of the door printed circuit assembly (PCA) and the door for an active mode of the printer system of FIG. 1.

[0004] FIG. 2B illustrates an example table having values for three different states of the door PCA and the door for a sleep mode of the printer system of FIG. 1.

[0005] FIG. 3 illustrates the printer system of FIG. 1 with an example inverter circuit.

DETAILED DESCRIPTION

[0006] As noted above, a printing platform may have a fluid (or ink) supply door. When the printer’s fluid supply is exhausted, the fluid supply can be replenished via the fluid supply door. This fluid supply door is connected to the main printer engine via a two-wire cable. Thus, the main printer engine can detect when the fluid supply door is improperly installed or is not functioning correctly.

[0007] The fluid supply door is itself associated with a door printed circuit assembly (PCA) that can detect the fluid supply door. This door PCA can be uninstalled for service by opening the fluid supply door and disengaging the door PCA. Upon completion of service, the door PCA is then reinstalled via the fluid supply door. Once reinstalled, the main printer engine needs to detect that the door PCA (in addition to the fluid supply door itself) has been properly installed. Because a two-wire cable is used to connect the fluid supply door to the main printer engine, the number of cables for additional detection of the door PCA has to increase. However, severe space constraints make adding standard cable detects undoable. Such space constraints make adding extra cabling, extra conductors and larger connector sizes impractical.

[0008] The present disclosure provides a printer system with a print engine PCA that can detect the door PCA without adding additional cabling or cable connects. The print engine PCA can generate three different analog voltage values at a first node based in part on the door switch of the door PCA. Each analog voltage value is converted by an analog-to-digital converter of the print engine PCA into a corresponding digital value to detect the door PCA.

[0009] The three different analog voltages and corresponding digital values represent three states of the door PCA and the door such as whether the door PCA is present or not. In other words, the printer system can detect both the presence of the door PCA and the door switch position, which itself indicates the fluid supply door position. Thus, if after a service call, the door PCA is left out by accident, an additional service call that increases costs as well as customer dissatisfaction can be avoided.

[0010] The three different states to detect the door PCA and the door are attained without increasing the number of cables or conductors or connectors used to connect the door PCA to the print engine PCA. The present disclosure saves costs because extra cabling, extra conductors and larger connector sizes can increase costs up to 1/3 the cost of the connectors. Moreover, the solution of the present disclosure adapts within the severe space constraints to maintain the current architecture.

[0011] FIG. 1 illustrates an example printer system 100 according to the present disclosure.

[0012] In FIG. 1 , printer system 100 includes a first printed circuit assembly or “door” PCA 104 having a door switch Sw. Printer system 100 also includes a second printed circuit assembly 102 or “print engine” PCA 102 having an analog-to-digital converter (ADC) 122 connected to a first node X. Print engine PCA 102 can generate three different analog voltage values V_xi, V_X2 and V_X3 at node X based in part on door switch Sw. Each analog voltage value V_xi, V_X2 or V_X3 can be converted by ADC 122 into a corresponding digital value output at nodes G and H to detect door PCA 104.

[0013] Printer system 100 itself may be an inkjet printer with multiple nozzles per printhead to selectively eject ink drops via the nozzles onto a printed medium such as a sheet of paper. When the ink supply of printer system 100 is depleted, the ink supply may be replenished via a fluid supply door or “door” 108. Although not shown, in one example, printer system 100 may be a laser printer having a consumable supply door that can be accessed to replace a consumable such as toner. As another example, printer system 100 may be a 3D printer having a consumable supply door to replace a consumable such as a filament.

[0014] Door PCA 104 is the printed circuit assembly that is associated with and can detect door 108. As noted above, door PCA 104 can be removed for servicing via door 108. Thereafter, upon reinstallation of door PCA 104, printer system 100 can be detected whether door PCA 104 is properly reinstalled or is missing. Door PCA 104 is itself detachable via a two-wire connector 116, which uses a wire 112 to couple nodes A and C and a wire 114 to couple node B to node D of print engine PCA 102. As noted, door PCA 104 includes door switch Sw. In one example, door switch Sw in conjunction with a resistor R1 that is connected in parallel provides a voltage divider circuit so that switch Sw can be open or closed to present two different resistances at node C and to generate two of the three analog voltage values V_xi, V_X2 or V_X3 at node X. [0015] Print engine PCA 102 is the main printed circuit assembly in printer system 100. Print engine PCA 102 may control many of printer system 100 functions and may be housed separately in the main housing of printer system 100. Example print engine PCAs 102 as described in the present disclosure can detect whether door PCA 104 is installed and whether door 108 is open or closed. In other words, the status of door PCA 104 and the status of door 108 can be determined without making changes to door PCA 104 or to the two-wire connector 116 that detachably couples door PCA 104 to print engine PCA 102.

[0016]Among other components, print engine PCA 102 includes ADC 122 that receives its input from node X to generate a corresponding output at nodes G and H as shown. That is, from node X, ADC 122 can receive three different analog voltage values V_xi, V_X2 and V_X3 that are converted to respective digital values for output at nodes G and H as further discussed below. Node X itself is powered by a power source ENG 3.3V that is on when printer system 100 is in an active mode and is off in a sleep mode.

[0017] Print engine PCA 102 further includes a logic circuit 120 to receive different analog voltage values at node C and to output corresponding digital values at node F. In an example, the digital values can also indicate whether door 108 is open or closed and may cause printer system 100 to switch from a sleep mode to an active mode. Print engine PCA 102 further includes a resistor R2, a resistor R3, and a Schottky diode 118 to facilitate generation of V_xi, V_X2 and V_X3 during the active mode. Resistor R2 connects node C and always 3.3V source. Resistor R3, node X and Schottky diode 118 are in series between node C and ENG 3.3V voltage source.

[0018] As noted above, print engine PCA 102 can generate these different analog voltage values V_xi, V_X2 and V_X3 at node X based in part on door switch Sw of door PCA 104. In an example, V_xi may be 3.3V, V_X2 may be 2.8V and Vx3 may be 0.3V as shown in example table 200A of FIG. 2A. In this example, Vx2 of 2.8V may be generated as follows: R1=100 KW, R2= 33 KW, R3= 50 KW, Schottky diode 118 turn-on voltage drop = 0.3V, ENG 3.3V is on; here, the combination of R2, R3, and Schottky diode 118 is in series with R1 between voltage level 3.3V and ground GND. As a result, this combination of R2, R3, and Schottky diode 118 forms with R1 a voltage divider having output Vc (voltage at node C). Vc and V_X2 can be calculated using the formula:

[0019] Vc = 3.3V x R1/(R1 + Z)

[0020]where R1 and Z are impedances of resistor R1 and the combination, respectively. The result is Vc = 2.7V. Similarly, R3 forms with Schottky diode 118 another voltage divider between voltage level 3.3V and Vc, with Vx2 being the output of this voltage divider. As a result, Vx2 is 2.8V. The other values of Vx (Vxi, Vxs) and Vc in table 200A (FIG. 2A) and table 200B (FIG. 2A) can be determined in a similar manner. Note that as used herein the analog voltage value Vx at node X is used interchangeably with any one of the analog voltage values Vxi, Vx2 and Vx3 at node X.

[0021] Referring now to FIG. 1 , each analog voltage value Vxi, V_X2 and Vx3 is converted by ADC 122 into a corresponding digital value to detect door PCA 104. As an example, Vx2 of 2.8V may be converted to the digital value 01 for output at nodes G and H to indicate both a state of door PCA 104 and a status of door 108. Here, the state of door PCA 104 can be either of two states: present or not present. The status of door 108 can be open or closed. An example of a digital value for output at nodes G and H may be “10” in binary, which indicates that door PCA 104 is present and door 108 is open.

[0022] Three states of door PCA 104 and door 108 are represented by the analog voltage value Vxi, V_X2 and V_X3.: In a first state, door PCA 104 is detected as not being present. As such, door PCA 104 is not connected to print engine PCA 102 so that an analog voltage value Vxi of 3.3V is generated. In a second state, door PCA 104 is present and door 108 is closed. In other words, door PCA 104 is connected to print engine PCA 102 and door switch Sw is open, and analog voltage value Vx22.8V is generated. In a third state, door PCA 104 is detected as present and door 108 is open. In other words, door PCA 104 is connected to print engine PCA 102 and door switch Sw is closed and analog voltage value V_X30.3V is generated.

[0023] In this manner and based on the above states, when a service technician has completed service of door PCA 104 and forgets to reinstall door PCA 104, printer system 100 can detect that door PCA 104 is not installed even where door 108 is closed, this detection being attained without increasing the number of standard detect cables.

[0024] FIG. 2A illustrates the example table 200A having values for the three different states of door PCA 104 and door 108 in an active mode of printer system 100. In the active mode, printer system 100 is operating with normal power levels sufficient to output print jobs. Voltage source ENG 3.3V is on in this active mode.

[0025] In table 200A, in one example, when Vx is 3.3V, door PCA 104 is not present as shown. Further yet, in an example, when Vx is 2.8V, door PCA 104 is present and door 108 is closed. Further, as an example, when Vx is 0.3V, door PCA is present and door 108 is open. Here, ADC 122 may receive and convert the above analog voltage levels for output at its nodes G and H. As an example, ADC 122 may convert Vx 3.3V into a digital value 00 for output so that the Nodes G and H Output of table 200A is 00 as shown.

[0026] It is noted that the values of resistors to output the analog voltage values are chosen to allow for sufficient differences between the three analog voltage levels so that ADC 122 can easily distinguish between the three analog voltage levels and to compensate for errors caused by leakage currents and analog-to-digital measurement errors. As a result, in table 200A, print engine PCA 102 uses the digital value at nodes G and H to determine the applicable state of door PCA 104 and door 108. If the digital value at nodes G and H is 00, for example, then print engine PCA 102 determines that door PCA 104 is not present and therefore displays an error “Error! Door Printed Circuit Assembly Missing” on a front panel display.

[0027] Further, in an example, rather than examining the digital output values at nodes G and H (FIG. 1 ) for detection of the applicable state of door PCA 104 and door 108, nodes G and F may be examined to determine this state. In particular, ADC 122 may convert a first analog voltage value Vx 3.3V into a first digital value (e.g., 0) for output at node G (see table 200A). A second analog voltage value Vx 2.8V is converted into a second digital value (e.g. 1 ) for output at node G. A third analog voltage value Vx 0.3V is converted into the second digital value (e.g., 1) also for output at node G. See node G output of table 200A. In this example, logic circuit 120 is an inverter with a threshold voltage of Vt=1V. As a result, because a fourth analog voltage value Vc 3.3V is higher than the inverter threshold, logic circuit 120 converts the fourth analog voltage value Vc 3.3V into a third digital value (i.e. 1) for output at node F. A fifth analog voltage value Vc 2.7V is converted into the third digital value (e.g., 0) for output at node F. A sixth analog voltage value Vc 0.3V is converted into a fourth digital value (e.g., 1) for output at node F. As a result, by examining both the digital values at node G and node F, print engine PCA 102 can determine the applicable state of door PCA 104 and door 108. In one example, if digital value at node G is 0 and at node F is 0 (see node G output and node F output of table 200A), then door PCA 104 is not present and is not connected to print engine PCA 102. In an example, if the digital value at node G is 1 and at node F is 0, then door PCA 104 is present and connected to print engine PCA 102, and door 108 is closed.

[0028] Further yet, in one example, the digital values at nodes G and F are not contemporaneously examined. Instead, the digital value at node G is examined first. If the digital value at node G is 0, then door PCA 104 is not present, and the digital value at node F need not be examined because the first column is 0 at node G. If the digital value at node G is 1 , print engine PCA 102 can then examine the digital value at node F. If the digital value at node F is 0, then door PCA 104 is present and door 108 is closed. But if the digital value at node F is 1 , then door PCA 104 is present and door 108 is open.

[0029] FIG. 2B is an example table 200B having values for the three different states of door PCA 104 and door 108 in a sleep mode of printer system 100. In the sleep mode, print engine PCA 102 may pull voltage source ENG 3.3V to 0V to power off ADC 122. As a result, printer 100 consumes less energy. Print engine PCA 102 may also pull Vx down to substantially 0V as shown in table 200A to prevent ADC 122 from being back biased.

[0030] When door 108 is opened during the sleep mode, print engine PCA 102 increases ENG 3.3V from 0V to 3.3V to wake up ADC 122. In one example, this implementation is based on logic circuit 120 or inverter 310 (FIG. 3) with a threshold voltage of Vt=1V. Referring to FIG. 3, an example of inverter 310 may be an N-channel MOSFET 312 having a load resistor R4. In the sleep mode, when door 108 is open, the gate voltage of transistor 312 is Vc=0V as shown in table 200B. As a result, transistor 312 is off and a digital value of 1 is output at node F. Thus, during the sleep mode, if the digital value at node F is a previously specified value of 1 , print engine PCA 102 turns on source voltage ENG 3.3V from 0V to 3.3V, wakes up ADC 122. Based on table 200B, of the three sleep modes, the third column (with Vc=0V<Vt=1V) is the voltage level for which logic circuit 120 results in a 1 . That is, when the digital value at node F is 1 , door 108 is open. [0031] While the above is a complete description of specific examples of the disclosure, additional examples are also possible. Thus, the above description should not be taken as limiting the scope of the disclosure, which is defined by the appended claims along with their full scope of equivalents.

Claims

Claims: 1. A printer system to detect a printed circuit assembly, the printer system comprising: a first printed circuit assembly having a door switch; and a second printed circuit assembly having an analog-to-digital converter connected to a first node, wherein the second printed circuit assembly is to generate three different analog voltage values at the first node based in part on the door switch, wherein each analog voltage value is converted by the analog-to-digital converter into a corresponding digital value to detect the first printed circuit assembly.

2. The printer system of claim 1 , wherein a first analog voltage value is generated when the first printed circuit assembly is not connected to the second printed circuit assembly.

3. The printer system of claim 2, wherein a second analog voltage value is generated when the first printed circuit assembly is connected to the second printed circuit assembly and the door switch is open.

4. The printer system of claim 3, wherein a third analog voltage value is generated when the first printed circuit assembly is connected to a second printed circuit assembly and the door switch is closed.

5. The printer system of claim 1 , wherein a fourth analog voltage value is generated at the first node when the printer system is in a sleep mode.

6. The printer system of claim 1 , wherein during a sleep mode, the second printed circuit assembly is to power off the analog-to-digital converter and pull the first node to substantially zero volts.

7. The printer system of claim 6, wherein the second printed circuit assembly further comprises a logic circuit connected to a second node, wherein the logic circuit is to convert a voltage at the second node into a digital signal, and wherein the second printed circuit assembly is to wake up the analog-to-digital converter from the sleep mode when the digital signal has a previously specified value.

8. A printer system comprising: a fluid supply door printed circuit assembly (PCA) having a door switch; and a main printed circuit assembly (PCA) having: an analog-to-digital converter (ADC) connected to a first node; a logic circuit connected to a second node, wherein the main PCA is to generate at the first node, analog voltage values converted by the ADC into corresponding digital values, and at the second node, analog voltage values converted by the logic circuit into corresponding digital values, and wherein the digital values converted by the ADC and the digital values converted by the logic circuit are to detect the fluid supply door PCA and a status of the door switch.

9. The printer system of claim 8, wherein the analog voltage values at the first node include a first, a second and a third analog voltage value converted by the ADC into corresponding digital values.

10. The printer system of claim 9, wherein the analog voltage values at the second node include a fourth, a fifth and a sixth analog voltage value converted by the logic circuit into corresponding digital values.

11 . The printer system of claim 10, wherein the first and fourth analog voltage values are generated when the fluid supply door PCA is not coupled to the main PCA, wherein the second and fifth analog voltage values are generated when the fluid supply door PCA is coupled to the main PCA and the door switch is open, wherein the third and sixth analog voltage values are generated when the fluid supply door PCA is coupled to the main PCA and the door switch is closed.

12. The printer system of claim 8, wherein during a sleep mode, the main PCA is to power off the ADC and pull the first node to low voltage values.

13. The printer system of claim 12, wherein the main PCA is to wake up the ADC from the sleep mode when the digital values converted by the logic circuit are previously specified.

14. A printer system comprising: a secondary printed circuit assembly (PCA) including a door switch; a main printed circuit assembly (PCA); and a two-wire connector to detachably couple the main PCA and the secondary PCA, wherein the main PCA includes an analog-to-digital converter (ADC) connected to a node, wherein the node is to receive three different analog voltage values based in part on the door switch, wherein the three different analog voltage values are converted by the ADC into digital values to detect the secondary PCA.

15. The printer system of claim 14, wherein the door switch is in parallel with a resistor.