The present invention relates to a printing element board and a printing apparatus including the printing element board.
In general, a printing element board mounted in a liquid discharge head includes a One Time Programmable (OTP) ROM to record unique information such as product information and setting information. As an example of the OTPROM, there is an OTPROM using an anti-fuse element.
When recording information in the anti-fuse element on the printing element board or reading out information from the anti-fuse element, signal are input from the outside to a logic circuit including a driving element connected in series with the anti-fuse element to select and control the driving element. The signals input from the outside include, for example, a CLK signal, a DATA signal, a LT signal (latch signal), and the like. The DATA signal is input to a shift register in a serial format in synchronism with the edge of the CLK signal, and the shift register temporarily stores the input data corresponding to each driving element. Then, if the LT signal in low level is input to a latch circuit, the data stored in the shift register is taken in the latch circuit. If the LT signal changes to high level, the data taken in the latch circuit is held. By repeating data transfer and driving of the anti-fuse driving elements as described above, information recording and information reading out with respect to the anti-fuse elements are performed. These control signals for the driving element are similarly used in heater control on a printing element board in a thermal inkjet printing apparatus.
On the other hand, the inkjet printing apparatus is demanded to improve performance by increasing the speed or the like. As a method of increasing the printing speed, there is a method of shortening a period of discharging ink from nozzles. However, shortening the period leads to transmitting many signals at a high frequency, and the influence of electromagnetic waves radiated therefrom becomes a problem.
Further, in the thermal inkjet printing apparatus, in addition to the control signals described above, a large current flowing when driving a heater or when recording in an anti-fuse element flows from the printing apparatus main body to the printhead through a long flexible cable or the like. Therefore, noise generated due to this current interferes with other signals, and this may lead to a malfunction of the printhead. To prevent this, it is essential to ensure immunity to noise induced by the current.
Japanese Patent No. 4788280 describes that a circuit for verifying data input to a driving unit mounted in a printhead within the driving unit is held, and the circuit detects a malfunction caused by a data transfer error. More specifically, print data is input to a calculation unit 80B with a delay of the number of clocks corresponding to the number of registers (the number of stored bits) of the shift register train of a data transfer input unit 68 after the print data is input to a calculation unit 80A. A comparison unit 82 compares the parity data for the print data from the first bit to the 256th bit output from a 1-bit register 84 of the calculation unit 80A with the parity data for the print data from the first bit to the 256th bit output from the T-FF of the calculation unit 80B. If the two parity data match, it is determined that a malfunction of a head driving unit 60 has not occurred, and the printing operation is continued. On the other hand, if the two parity data do not match, it is determined that a malfunction of the head driving unit 60 has occurred due to the influence of power supply noise described above or the like, and predetermined processing is executed.
However, the technique described in Japanese Patent No. 4788280 described above has a problem that, since the parity data is used to verify the data input to the driving unit mounted in the printhead, disturbance noise on the signal before being input to the printhead causes disturbance of the input signal, and this may cause a malfunction of the printhead.
The present invention provides a technique that eliminates an influence of disturbance noise or the like on a signal input to a printing element board to drive a memory element, thereby preventing a malfunction in driving of the memory element.
According to an aspect of the present invention, there is provided a printing element board comprising a plurality of memory modules each including a memory element and a driving circuit configured to drive the memory element, a plurality of discharge modules, a control data supply unit configured to select one of a memory module and a discharge module from the plurality of memory modules and the plurality of discharge modules and perform drive control of the selected module, and a logical product calculation unit configured to, when the memory module is selected, receive a first signal and a second signal output at the same timing, and supply a signal indicating a logical product of the first signal and the second signal to the control data supply unit, wherein when the signal indicating the logical product of the first signal and the second signal is not supplied from the logical product calculation unit, the control data supply unit does not perform drive control of the memory module.
Further features of the present invention will become apparent from the following description of exemplary embodiments (with reference to the attached drawings).
The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain principles of the invention.
Hereinafter, embodiments will be described in detail with reference to the attached drawings. Note, the following embodiments are not intended to limit the scope of the claimed invention. Multiple features are described in the embodiments, but limitation is not made an invention that requires all such features, and multiple such features may be combined as appropriate. Furthermore, in the attached drawings, the same reference numerals are given to the same or similar configurations, and redundant description thereof is omitted.
Note that as an example of the present invention, a thermal type printing element board will be described. However, the present invention is not limited to this, and can also be applied to a piezoelectric type printing element board.
The first embodiment of the present invention will be described with reference to
The liquid discharge head 200 is provided with two printing element boards 400 that discharge a liquid. The printing element board 400 includes a heater (not shown) configured to heat ink. The heater is heated, thereby generating bubbles in ink and discharging the liquid from discharge ports (nozzles) (not shown). Note that the discharge ports are divided into even-numbered lines and odd-numbered lines. Control system circuits and power supply system circuits also exist separately.
Next, circuits formed on the printing element board according to the first embodiment will be described with reference to
In
The discharge module 104 includes a pressure generation element (electrothermal transducer) Rh that generates energy to discharge the liquid from the discharge port (not shown) in the even-numbered line formed on the printing element board, and a driving element MD1 and a logic circuit AND1 configured to drive the pressure generation element Rh. In the first embodiment, the driving element MD1 is a MOS transistor. Here, the MOS transistor has the role of a switch that decides whether to apply a voltage to the pressure generation element Rh. The logic circuit AND1 is an AND circuit configured to drive the driving element MD1 based on a signal from the control data supply circuit 101, and performs logical calculation of a plurality of signals. When the driving element MD1 is driven to energize the pressure generation element Rh and generate heat, bubbles are generated in ink, and the ink is discharged from the discharge port, thereby performing printing. A power supply voltage VH1 (for example, 24 V) is supplied as a power supply voltage to the pressure generation element Rh. On the other hand, a ground potential GNDH is supplied to the source side of the MOS transistor MD1.
The memory module 106 includes an anti-fuse element (memory element) Ca, a parallel resistor Rp (resistor) connected in parallel with the anti-fuse element Ca, and a driving circuit including a driving element MD2 and a logic circuit AND2 configured to write information to the anti-fuse element Ca. The anti-fuse element Ca stationarily holds information when an overvoltage is supplied to it. That is, the anti-fuse element Ca functions as a One Time Programmable (OTP) ROM as a memory that can be programmed only once. Before the overvoltage is supplied, the anti-fuse element Ca is in an insulated state. When the overvoltage is supplied, the anti-fuse element Ca changes to a resistor element (resistor) and is set in an energized state. Hence, the memory function can be exhibited by, for example, determining the insulated state of the anti-fuse element Ca as “0” and the energized state as “1”. The parallel resistor Rp prevents information from being erroneously written to the anti-fuse element Ca as the overvoltage from a power supply voltage VID is applied to both ends of the anti-fuse element Ca although the driving element MD2 is in a nonconductive state. The driving element MD2 is, for example, a transistor. When recording information “1” in the anti-fuse element Ca, the driving element MD2 is driven to apply a voltage to the anti-fuse element Ca, and the anti-fuse element Ca is set in the energized state by the applied voltage, thereby storing the information “1”. The power supply voltage VID (for example, 24V) is supplied to the anti-fuse element Ca, and the ground potential GNDH is supplied to the source side of the MOS transistor MD2.
Note that although the power supply voltage VID and the power supply voltage VH1 use independent power supply lines, if the minimum value of the voltage needed for write to the anti-fuse element is equal to or less than the power supply voltage VH1, the power supply voltage VH1 may be used as the power supply voltage VID together with, for example, a step-down circuit.
The control data supply circuit 101 is a circuit configured to drive the driving elements MD1 and MD2, and includes, for example, a shift register (not shown) and a latch circuit (not shown). A clock signal (CLK), a data signal (DATA), a latch signal (LT), and a heat enable signal (HE) are input from the outside of the printing element board to the control data supply circuit 101 via terminals of the printing element board. The data signal (DATA) includes information for selecting the discharge module 104 and the memory module 106. The data signal (DATA) is input in a serial format in synchronism with the clock signal (CLK).
The control data supply circuit 101 receives the data signal (DATA) and generates a block selection signal, a group selection signal, and a switching signal based on the information included in the data signal (DATA). Based on these signals, the discharge module 104 in the even-numbered line and the memory module 106 are selected and driven. The control data supply circuit 101 supplies, to the logic circuits (AND1 and AND2), the block selection signal via a signal line 102, the group selection signal via a signal line 103, and the switching signal via a signal line 105.
To time-divisionally drive the discharge module 104 and the memory module 106, as shown in
Here, the group selection signal is a signal used to select which group is to be driven when the multiple discharge modules 104 are divided into a plurality of groups. The block selection signal is a signal used to select which pressure generation element Rh of a plurality of pressure generation elements Rh in the same group is to be driven. As the driving element MD1, a DMOS transistor (Double-diffused MOSFET) that is a MOS transistor and can resist a high voltage is used. Here, in the embodiment, as an example, the multiple discharge modules 104 are divided into eight groups (G1, . . . , G8) each including three discharge modules. However, the present invention is not limited to this, and the multiple discharge modules 104 may be divided into eight groups each including 16 discharge modules 104.
As has been described above, the control data supply circuit 101 can select and drive the anti-fuse element Ca by using the signal line 102 and the signal line 103. At this time, the switching signal line 105 is used. Based on the switching signal from the switching signal line 105, a case where the anti-fuse element Ca is driven and a case where the discharge module 104 is driven are switched. Hence, the block selection signal, the group selection signal, and the switching signal 105 are input to the logic circuit AND2 of the memory module 106. A signal according to the input signals is output from the logic circuit AND2 to the driving element MD2 of the memory module 106 to drive the anti-fuse element Ca, and the anti-fuse element Ca is changed from the insulated state to the energized state. As the driving element MD2 of the memory module 106, a DMOS transistor is used, like the driving element MD1 of the discharge module 104. The logic circuit AND2 of the memory module 106 is formed by a MOS transistor. In the example shown in
The malfunction preventing circuit 310 includes a logical product circuit (AND) 300 and a selector 301 configured to control the control data supply circuit 101 for controlling the discharge modules 104 corresponding to the discharge ports in the even-numbered line shown in
The selector 301 selects one of the even-numbered line control data signal (DATA_EVEN) and the even-numbered line composite data signal (DATA_EVEN′) in accordance with the switching signal 105, and outputs the selected signal as the output signal 312. When controlling the discharge module 104 shown in
In this manner, the malfunction preventing circuit 310 according to the first embodiment outputs the intended signal only if two input signals match. Accordingly, it is possible to obtain an effect of preventing a malfunction in driving of the anti-fuse element caused by disturbance noise on the input signal or the like.
The inkjet printing apparatus 501 includes the control unit 502 and a determination unit 503. The control unit 502 controls the operation of the printing element board 400. The determination unit 503 discriminates whether the anti-fuse element Ca of the memory module is in an insulated state or not. Also, based on the result of discrimination by the determination unit 503, the control unit 502 determines the information stored in the memory module, and controls the inkjet printing apparatus 501 based on the information.
Also, the control unit 502 performs switching control of a switch (SW1). If the switch SW1 is connected to a terminal C, the path between a readout power supply (for example, 5 V) and a terminal A of the anti-fuse element Ca is established. On the other hand, if the switch SW1 is connected to a terminal D, the path between a write power supply (for example, 24 V) and the terminal A of the anti-fuse element Ca is established.
Furthermore, the control unit 502 generates control data to be transmitted, via the CLK terminal and the DATA terminal of the printing element board 400, to the control data supply circuit 101 of the printing element board 400. The control data includes the clock signal (CLK), the data signal (DATA), the latch signal (LT), and the heat enable signal (HE). By the control data, selection and drive control of the driving element MD2 of the memory module 106 is performed.
The write power supply mounted in the inkjet printing apparatus 501 is connected to the terminal A of the printing element board 400, and the terminal B of the printing element board 400 is connected to ground mounted in the inkjet printing apparatus 501. To write information to the anti-fuse element Ca, the switch SW1 is connected to the terminal D to set the driving element MD2 of the memory module in an ON state. Thus, the high voltage VID is applied to a gate oxide film that forms the anti-fuse element Ca. The gate oxide film is thus broken, the anti-fuse element Ca is electrically set in a conductive state, and information is written. The anti-fuse element Ca that is a capacitive element before the write changes to a resistor element Ra after the write. Of the two memory modules 106 shown in
An operation when reading out information recorded in the anti-fuse element will be described next with reference to
As has been described above, according to the first embodiment, when driving the anti-fuse element, even if noises enter, at different timings, two input signals to be input to the printing element board, the influence of an external disturbance caused by the noise is removed, and an effect of preventing a malfunction in driving of the anti-fuse element can be obtained.
The second embodiment will be described using
In addition to the logical product circuit (AND) 300 and the selector 301 configured to control the control data supply circuit 101 and the control data supply circuit 201 shown in
In the second embodiment, an even-numbered line control data signal (DATA_EVEN) is input to the inverter circuit 600, logically inverted, and output. This output signal and an odd-numbered line control data signal (DATA_ODD) are input to the logical product circuit 300 to generate an even-numbered line composite data signal (DATA_EVEN′). When driving the memory module, the signal DATA_EVEN′ passes through the selector 301 and is input to a control data supply circuit 101 for even-numbered line control to control the memory module 106 shown in
As has been described above, according to the second embodiment, when driving the anti-fuse element, even if noises enter, at the same timing, two input signals to be input to the printing element board, the influence of an external disturbances caused by the noise is removed, and an effect of preventing a malfunction in driving of the anti-fuse element can be obtained.
In the malfunction preventing circuit 310b, an inverter circuit 800 is connected to a signal line for a signal DATA_ODD. The operation principle and output result in this case are similar to those in the above-described second embodiment, and a description thereof will be omitted.
As has been described above, according to the third embodiment, when driving the anti-fuse element, even if noises of the same size enter, at the same timing, two input signals to be input to the printing element board, which are originally inverted at the same timing, the influence of the noises is removed, and an effect of preventing a malfunction in driving of the anti-fuse element can be obtained.
Embodiment(s) of the present invention can also be realized by a computer of a system or apparatus that reads out and executes computer executable instructions (e.g., one or more programs) recorded on a storage medium (which may also be referred to more fully as a ‘non-transitory computer-readable storage medium’) to perform the functions of one or more of the above-described embodiment(s) and/or that includes one or more circuits (e.g., application specific integrated circuit (ASIC)) for performing the functions of one or more of the above-described embodiment(s), and by a method performed by the computer of the system or apparatus by, for example, reading out and executing the computer executable instructions from the storage medium to perform the functions of one or more of the above-described embodiment(s) and/or controlling the one or more circuits to perform the functions of one or more of the above-described embodiment(s). The computer may comprise one or more processors (e.g., central processing unit (CPU), micro processing unit (MPU)) and may include a network of separate computers or separate processors to read out and execute the computer executable instructions. The computer executable instructions may be provided to the computer, for example, from a network or the storage medium. The storage medium may include, for example, one or more of a hard disk, a random-access memory (RAM), a read only memory (ROM), a storage of distributed computing systems, an optical disk (such as a compact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™), a flash memory device, a memory card, and the like.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2022-046033, filed Mar. 22, 2022, which is hereby incorporated by reference herein in its entirety.
Number | Date | Country | Kind |
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2022-046033 | Mar 2022 | JP | national |