The present application is based on, and claims priority from JP Application Serial Number 2018-179823, filed Sep. 26, 2018, the disclosure of which is hereby incorporated by reference herein in its entirety.
The present disclosure relates to a display driver, an electronic apparatus, a mobile body, and the like.
In a display driver, control signals for setting operations of analog circuits such as a power supply circuit and a drive circuit are stored in a register. Various operation settings relating to a power supply voltage to be generated by a built-in power supply and the size of a panel to be driven by the display driver are set based on the control signals stored in the register. If these operation settings are set to a setting that is inhibited from a design viewpoint or due to a specification issue, it is possible that the display driver operates anomalously, or an IC in the display driver fails. In order to protect the display driver from such an anomaly or failure, whether the operation setting is an inhibited setting is detected by monitoring each control signal stored in the register inside a logic circuit. If the operation setting is an inhibited setting, the logic circuit changes the corresponding control signal in the register to an initial value, and transmits error information to a host device.
Technology for protecting a display driver from an anomaly or failure is disclosed in JP-A-2016-143029, for example. In JP-A-2016-143029, in order to prevent deterioration of display pixels due to a power cutoff or data cutoff of the display driver, a power cutoff detection circuit and a data cutoff detection circuit are provided, and the power cutoff detection circuit and the data cutoff detection circuit perform appropriate shutdown control.
Since the inhibited setting is monitored inside a logic circuit in a known technology, as described above, there is a problem in that whether the setting is actually an inhibited setting cannot be monitored on an analog circuit side. That is, if an anomaly occurs in a control signal line through which a control signal is output from the register to the analog circuit, it is possible that, in spite of the control signal being normal on the logic circuit side, the control signal is in an inhibited setting on the analog circuit side. For example, if a disconnection occurs in the control signal line, and the control signal line is short-circuited to a power supply or the like on the analog circuit side, the level of the control signal may differ between the logic circuit side and the analog circuit side. As described above, there is a problem in that an inhibited setting may occur on the analog circuit side by merely monitoring whether an inhibited setting occurs inside the logic circuit.
One aspect of the present disclosure relates to a display driver including: a power supply circuit that generates at least one power supply voltage; a drive circuit that drives an electro-optical panel based on the at least one power supply voltage; a control circuit that controls the power supply circuit based on a control signal; a first monitoring circuit that monitors the control signal on the control circuit side; and a second monitoring circuit that monitors the control signal on the power supply circuit side.
The disclosure will be described with reference to the accompanying drawings, wherein like numbers reference like elements.
The following is a detailed description of preferred embodiments of the present disclosure. Note that the embodiments described below are not intended to unduly limit the content of the invention recited in the claims, and all of the configurations described in the embodiments are not necessarily essential as solutions provided by the present disclosure.
1. First Exemplary Configuration
The power supply circuit 60 generates at least one power supply voltage. That is, the power supply circuit 60 generates one or more power supply voltages. For example, the power supply circuit 60 generates various power supply voltages needed to drive the electro-optical panel 150. Specifically, the power supply circuit 60 generates a plurality of power supply voltages to be used by the drive circuit 20 by performing a voltage step-up operation and a voltage step-down operation based on a power supply voltage that is input from the outside, and supplies the generated power supply voltages to the drive circuit 20. For example, the power supply circuit 60 generates power supply voltages needed to drive data lines and scan lines of the electro-optical panel 150, and supplies the generated power supply voltages to the drive circuit 20. This power supply circuit 60 can be realized by a DC/DC converter, a linear regulator, and the like. Specifically, the power supply circuit 60 can be realized by a charge pump circuit that performs a charge pumping operation such as a step-up operation using a charge pump capacitor, or the like.
The control circuit 50 is a logic circuit that performs various types of control processing such as display control of the electro-optical panel 150, control of circuits in the display driver 10, and interface processing with an external device. The control circuit 50 executes these types of control processing by outputting a control signal. The control circuit 50 can be realized by a gate array or the like that is designed with use of an automatic placement and routing method. The control circuit 50 controls the power supply circuit 60 based on the control signal. For example, the control circuit 50 sets the voltage value of the power supply voltage to be generated by the power supply circuit 60, for example. For example, the control circuit 50 sets a step-up magnification rate of a DC/DC converter, and sets an output voltage value of a linear regulator. The control signal is constituted by a multi-bit signal or a 1-bit signal. If the control signal is constituted by a multi-bit signal, the control signal may be a parallel signal or a serial signal. When the control signal is a parallel signal, the signal of each bit is transmitted through one control signal line. When the control signal is a serial signal, a multi-bit signal is transmit through one control signal line as a time division signal. Note that, in the following, a case will be described where the control circuit 50 controls the power supply circuit 60 using 3-bit control data as the control signal, and the 3-bit control data is transmitted through three control signal lines as a parallel signal, as an example, but there is no limitation thereto. That is, the control circuit 50 need only control the power supply circuit 60 based on a multi-bit signal or a 1-bit signal. Also, the control circuit 50 may output the multi-bit control data to the power supply circuit 60 as a serial signal. In this case, the number of control signal lines is less than the number of bits of the control data.
The control signal from the control circuit 50 is transmitted to the power supply circuit 60 through the control signal lines LPW1 to LPW3. The control circuit 50 outputs a 1-bit signal to one control signal line. That is, a signal at a high level or a low level is output to each of the control signal lines LPW1 to LPW3. The control signal lines LPW1 to LPW3 constitutes a signal path through which a parallel-signal control signal is transmitted. The control signal lines LPW1 to LPW3 are realized by an aluminum interconnect layer or the like that is formed on a semiconductor substrate of a display driver 10, which is a semiconductor chip. Note that the number of control signal lines is not limited to three, and it is sufficient that the display driver 10 is provided with at least one control signal line.
The electro-optical panel 150 is a panel for displaying images, and is realized by a liquid-crystal panel, an organic EL panel, or the like. An active matrix type panel that uses a switch element such as a thin film transistor (TFT) can be adopted as the liquid-crystal panel. Specifically, the display panel, which is the electro-optical panel 150, includes a plurality of pixels. For example, the electro-optical panel 150 includes a plurality of pixels that are arranged in a matrix. Also, the electro-optical panel 150 includes a plurality of data lines and a plurality of scan lines that are routed in a direction that intersects the plurality of data lines. The data line is also referred to as a source line, and the scan line is also referred to as a gate line. Also, in the electro-optical panel 150, a plurality of pixels are provided at respective areas where the data lines intersect the scan lines. Also, in a case of an active matrix type panel, a switch element such as a thin film transistor is provided in each pixel region. Also, the electro-optical panel 150 realizes the display operation by changing the optical property of an electro-optical element at each pixel region. The electro-optical element is a liquid crystal element, an EL element, or the like. Note that, in a case of an organic EL panel, a pixel circuit for current-driving an EL element is provided in each pixel region.
The drive circuit 20 drives the electro-optical panel 150 based on the power supply voltages. For example, the drive circuit 20 drives the data lines of the electro-optical panel 150 based on a power supply voltage for driving data lines that is supplied from the power supply circuit 60. For example, the drive circuit 20 drives each data line of the electro-optical panel 150 by outputting a data voltage corresponding to display data to the data line. For example, the drive circuit 20 selects a voltage corresponding to the display data from a plurality of tone voltages supplied from a tone voltage generation circuit, and outputs the selected voltage to the data line as the data voltage. Note that the electro-optical panel 150 may be provided with demultiplexing switch elements, and each amplifier circuit included in the drive circuit 20 may output data voltages corresponding to a plurality of data lines of the electro-optical panel 150 in a time division manner. Also, the drive circuit 20 drives the scan lines of the electro-optical panel 150 based on a power supply voltage for driving scan lines that is supplied from the power supply circuit 60. For example, the drive circuit 20 performs driving for selecting a scan line using a scan line selection voltage corresponding to the power supply voltage for driving scan lines. For example, the drive circuit 20 performs an operation such that the plurality of scan lines are line-sequentially selected.
The monitoring circuit M1 is a circuit that monitors the control signal on the control circuit 50 side. The monitoring circuit M2 is a circuit that monitors the control signal on the power supply circuit 60 side. A 3-bit signal is output to the control signal lines LPW1 to LPW3. The monitoring circuits M1 and M2 monitor the control signal by determining whether or not the combination of logic levels of the 3 bits is an inhibited setting. The monitoring circuit M1 is a first monitoring circuit, and the monitoring circuit M2 is a second monitoring circuit.
Specifically, the monitoring circuit M1 monitors the voltages at nodes N11 to N13, of the control signal lines LPW1 to LPW3, that are closer to the control circuit 50 than to the power supply circuit 60. Also, the monitoring circuit M1 outputs the monitoring result to the control circuit 50. For example, the monitoring circuit M1 outputs the monitoring result to the control circuit 50 as a detection signal Q1. The nodes, of the control signal lines LPW1 to LPW3, that are closer to the control circuit 50 than to the power supply circuit 60 are nodes, on routes of the control signal lines LPW1 to LPW3, whose distances to the control circuit 50 are smaller than those to the power supply circuit 60. That is, as shown in
For example, the monitoring circuit M1 is provided inside the control circuit 50. That is, the monitoring circuit M1 is placed in the placement region of the control circuit 50. Also, the monitoring circuit M1 monitors the control signal at the output nodes N11 to N13 to the control signal lines LPW1 to LPW3 in the control circuit 50. That is, the monitoring circuit M1 monitors the control signal of the control signal lines LPW1 to LPW3 inside the control circuit 50.
The monitoring circuit M2 monitors the voltages at nodes N21 to N23, of the control signal lines LPW1 to LPW3, that are closer to the power supply circuit 60 than to the control circuit 50. Also, the monitoring circuit M2 outputs the monitoring result to the control circuit 50. For example, the monitoring circuit M2 outputs the monitoring result to the control circuit 50 as a detection signal Q2. The nodes, of the control signal lines LPW1 to LPW3, that are closer to the power supply circuit 60 than to the control circuit 50 are nodes, on routes of the control signal lines LPW1 to LPW3, whose distances to the power supply circuit 60 are smaller than those to the control circuit 50. That is, as shown in
For example, the monitoring circuit M2 is provided inside the power supply circuit 60. That is, the monitoring circuit M2 is placed in the placement region of the power supply circuit 60. Also, the monitoring circuit M2 monitors the control signal at the input nodes N21 to N23 of the control signal lines LPW1 to LPW3 in the power supply circuit 60. That is, the monitoring circuit M2 monitors the control signal of the control signal lines LPW1 to LPW3 inside the power supply circuit 60.
In the present embodiment, as described above, the two monitoring circuits M1 and M2 are provided as the circuits for monitoring the control signal of the control signal lines LPW1 to LPW3. As a result of monitoring the control signal of the control signal lines LPW1 to LPW3 by providing the monitoring circuits M1 and M2 in this way, an inhibited setting caused by a disconnection of the control signal lines LPW1 to LPW3 or the like can be prevented, and the analysis when an inhibited setting has occurred can be facilitated. The inhibited setting refers to a setting that is inhibited due to a specification issue or from a design viewpoint, because the setting may incur an anomaly in operation, a failure, a breakdown, or the like of the analog circuit.
For example, as a method of a comparative example of the present embodiment, a method is conceivable in which the monitoring circuit is provided only on the control circuit 50 side. With this method of the comparative example, when the control signal output from the control circuit 50 is in an inhibited setting, this fact can be detected and appropriate measures can be taken. For example, when the monitoring circuit detects an inhibited setting, the control circuit 50 initializes the setting and outputs a control signal corresponding to its initial value. With this, an anomaly in operation, failure, breakdown, or the like caused by the inhibited setting can be prevented.
However, with the method of the comparative example, when an anomaly such as a disconnection in the control signal lines LPW1 to LPW3 has occurred, this anomaly cannot be detected. For example, if a disconnection occurs in the control signal line LPW3, as shown by A1 in
In contrast, with the display driver 10 of the present embodiment, when an anomaly occurs such as a disconnection in the control signal lines LPW1 to LPW3, the occurrence of the anomaly can be detected by the monitoring circuit M2 provided on the power supply circuit 60 side monitoring the control signal at the nodes N21 to N23. That is, not only an anomaly on the control circuit 50 side, but also an anomaly on the power supply circuit 60 side can be detected. Also, the control circuit 50 can be notified of the occurrence of an anomaly using the detection signal Q2, and as a result, anomalous operation due to an inhibited setting can be prevented from being performed and the reliability thereof can be improved. Also, when an anomaly in which the control circuit 50 does not output an appropriate control signal has occurred, the occurrence of the anomaly can be detected by the monitoring circuit M1 provided on the control signal side monitoring the control signal at the nodes N11 to N13. Also, the control circuit 50 can be notified of the occurrence of an anomaly using the detection signal Q1, and as a result, anomalous operation due to an inhibited setting can be prevented from being performed and the reliability thereof can be improved. Accordingly, the display driver 10 can be provided that can be favorably installed in an electronic apparatus such as an on-board apparatus requiring high reliability.
Also, with the display driver 10 of the present embodiment, when an anomalous operation or the like of the analog circuit has occurred, it is possible to easily analyze whether the anomalous operation or the like is an anomaly caused by an inadequate control signal having been output from the control circuit 50, or an anomaly caused by a disconnection or the like in the control signal lines LPW1 to LPW3. For example, if the detection signal Q1 from the monitoring circuit M1 indicates an anomaly, it can be analyzed that the anomaly is caused by an inadequate control signal having been output from the control circuit 50. On the other hand, if the detection signal Q2 from the monitoring circuit M2 indicates an anomaly, it can be analyzed that the anomaly is caused by a disconnection or the like in the control signal lines LPW1 to LPW3. Therefore, the analysis to be performed when an anomaly has occurred can be facilitated.
The display driver 10 includes the interface circuit 80, as shown in
The interface circuit 80 is an interface circuit between the display driver 10 and an external device. The interface circuit 80 is an I/O circuit of the display driver 10, which is an integrated circuit device, and is provided with a plurality of I/O cells. Each I/O cell is provided with a terminal, which is a pad, an input buffer and an output buffer or an input/output buffer, and a protection circuit such as an electrostatic protection circuit.
The register unit 52 includes a register to which an external device such as a host can access via the interface circuit 80. For example, the register unit 52 includes a register RG1 that stores an error detection result based on the detection signal Q1 and a register RG2 that stores an error detection result based on the detection signal Q2.
The control circuit 50 performs processing for notifying an external device of the error, when one of the monitoring result of the monitoring circuit M1 and the monitoring result of the monitoring circuit M2 indicates that an error has been detected. For example, the control circuit 50 detects an error indicated by the monitoring result of the monitoring circuit M1 based on the detection signal Q1 from the monitoring circuit M1. That is, the control circuit 50 detects error information of the control signal at the nodes N11 to N13 based on the detection signal Q1. Also, the control circuit 50 detects an error indicated by the monitoring result of the monitoring circuit M2 based on the detection signal Q2 from the monitoring circuit M2. That is, the control circuit 50 detects error information of the control signal at the nodes N21 to N23 based on the detection signal Q2. When an error occurs that is an anomaly in which an appropriate control signal is not output from the control circuit 50, the control circuit 50 is notified of the error using the detection signal Q1. Also, when an error occurs that is an anomaly in which a disconnection or the like occurs in the control signal lines LPW1 to LPW3, the control circuit 50 is notified of the error using the detection signal Q2. Also, the control circuit 50 performs processing for notifying an external device, such as a host, of an occurrence of this error. In this way, the external device can execute appropriate processing for handling the error that has occurred. For example, the external device such as a host, upon determining that an error has occurred in the output of the control signal based on the monitoring result of the monitoring circuit M1, initializes the setting stored in the register of the register unit 52 via the interface circuit 80. The setting here is a setting corresponding to the control signal of the control signal lines LPW1 to LPW3. Also, the external device such as a host, upon determining that an error such as a disconnection has occurred in the control signal lines LPW1 to LPW3 based on the monitoring result of the monitoring circuit M2, instructs to turn off display of the electro-optical panel 150, and to turn off the operation of the power supply circuit 60.
Also, the display driver 10 of the present embodiment includes a terminal TER for outputting an error detection signal ERD to an external device. For example, the terminal TER is provided in the interface circuit 80, in
A detection flag based on the monitoring result of the monitoring circuit M1 is set to the register RG1, and a detection flag based on the monitoring result of the monitoring circuit M2 is set to the register RG2. The register RG1 is a first register, and the register RG2 is a second register. The registers RG1 and RG2 can be realized by a flip-flop circuit or the like. The registers RG1 and RG2 may also be realized by a semiconductor memory such as a RAM. When the monitoring circuit M1 has detected an error, the detection flag of the register RG1 is set to “1”, for example. When the monitoring circuit M2 has detected an error, the detection flag of the register RG2 is set to “1”, for example. Also, the external device can access the registers RG1 and RG2 via the interface circuit 80. Therefore, the external device can determine that the monitoring circuit M1 or M2 has detected an error by reading out the detection flags of the registers RG1 and RG2. Specifically, when one of the plurality of error detection circuits including the monitoring circuits M1 and M2 has detected an error, the error detection signal ERD is output from the terminal TER, as an interrupt signal to the external device. That is, the error detection signal ERD is activated. When the detection signal ERD is activated in this way, the external device accesses the register unit 52, and analyses the error factor. Then, if the detection flag of the register RG1 is set to “1”, the external device determines that the monitoring circuit M1 has detected an error. If the error detection flag of the register RG2 is set to “1”, the external device determines that the monitoring circuit M2 has detected an error. With this, the external device can execute appropriate processing for handling the detected error.
2. Detailed Exemplary Configuration
A configuration in which the inhibited setting is “HHH” is shown in
For example, ends of one side of the control signal lines LPW1 to LPW3 are connected to the register unit 52, and the ends of other side of the control signal lines LPW1 to LPW3 are connected to the regulator 62 of the power supply circuit 60. That is, a register of the register unit 52 outputs the control signal to the control signal lines LPW1 to LPW3, and the control signal is input to the regulator 62 through the control signal lines LPW1 to LPW3. The regulator 62 outputs a power supply voltage having a voltage value corresponding to the received control signal. For example, the nodes N11 to N13 are output nodes to the control signal lines LPW1 to LPW3 in the register unit 52, and the nodes N21 to N23 are input nodes, in the regulator 62, of the control signal lines LPW1 to LPW3.
In
In this exemplary connection, although the control signal is transmitted via the register unit 61, the control signal of the control signal lines LPW1 to LPW3 and the control signal of the control signal lines LPW1′ to LPW3′ are the same control signal. That is, in this exemplary connection as well, the monitoring circuit M1 monitors the control signal on the control circuit 50 side, and the monitoring circuit M2 monitors the control signal on the power supply circuit 60 side.
For example, assume a case where the control signal stored in the register unit 61 is re-written, due to an anomaly such as noise, to an inhibited setting. According to this exemplary connection, as a result of the monitoring circuit M2 monitoring the control signal output from the register unit 61 to the control signal lines LPW1′ to LPW3′, an anomaly in which the control signal stored in the register unit 61 is changed to an inhibited setting can be detected. Also, there is a risk that an inhibited setting is stored in the register unit 61 due to a disconnection or the like in the control signal lines LPW1 to LPW3. According to this exemplary connection, in such a case as well, an anomaly in which the control signal stored in the register unit 61 has been changed to an inhibited setting can be detected.
Note that, when the control circuit 50 outputs the control signal as a serial signal, the following configuration may be adopted, for example. That is, the control circuit 50 includes a parallel/serial conversion circuit that performs parallel/serial conversion on the control signal from the register unit 52. Also, the power supply circuit 60 includes a serial/parallel conversion circuit that performs serial/parallel conversion on the serial signal from the parallel/serial conversion circuit. The register unit 61 stores the parallel signal from the serial/parallel conversion circuit as the control signal. The parallel/serial conversion circuit and the serial/parallel conversion circuit are connected by one control signal line, for example.
The drive circuit 20 includes a scan line drive circuit 21 that drives scan lines of the electro-optical panel 150, and a data line drive circuit 22 that drives data lines of the electro-optical panel 150. The power supply circuit 60 generates power supply voltages VEE and VDDHG, and the scan line drive circuit 21 operates with the power supply voltages VEE and VDDHG. The power supply voltage VEE is a first power supply voltage, and the power supply voltage VDDHG is a second power supply voltage. The control circuit 50 outputs the control signal for setting the voltage values of the power supply voltages VEE and VDDHG to the power supply circuit 60. The monitoring circuits M1 and M2 monitor the control signal for setting the voltage values of the power supply voltages VEE and VDDHG.
Specifically, the power supply circuit 60 includes regulators RR1 to RR3 and DC/DC converters DCC1 and DCC2. The control circuit 50 outputs control data PB[1:0] to the regulator RR1, outputs control data PA[3:0] to the regulator RR2, and outputs control data PC[4:0] to the regulator RR3. Here, the control data PB[1:0], PA[3:0], and PC[4:0] are setting values, in hexadecimal number, for designating voltages VOFREG, VONREG, and VGL, as shown in later-described
The bit signals of control data PB[1:0], PA[3:0], and PC[4:0] each correspond to the control signal described above. That is, the control signals are transmitted through eleven control signal lines LPW1 to LPW11 in
The breakdown voltage of a transistor is the breakdown voltage of transistors included in the scan line drive circuit 21. Specifically, the scan line drive circuit 21 includes a buffer circuit BFC for outputting a driving signal to a scan line, as shown in
Note that one buffer circuit that drives one scan line is illustrated in
In
The voltage values of the power supply voltage VDDHG with respect to the respective voltage values of the voltages VGL and VONREG are shown in
As described above, the settings of the pieces of control data PB[1:0], PA[3:0], PC[4:0] with which the resultant voltage exceeds the breakdown voltage of transistors are determined as the inhibited settings. The monitoring circuits M1 and M2 are constituted by combinational circuits of logic elements that detect such inhibited settings.
According to the present embodiment, because the settings with which the resultant voltage exceeds the breakdown voltage of transistors can be detected as the inhibited settings, transistors can be prevented from being applied the voltages exceeding the breakdown voltage. That is, when a disconnection or the like in the control signal lines occurs, it is possible that, in spite of the control circuit 50 outputting an appropriate control signal, the control signal that is input to the power supply circuit 60 is in an inhibited setting. According to the present embodiment, even in such a case, as a result of the monitoring circuit M2 monitoring the control signal on the power supply circuit 60 side, transistors can be prevented from being applied the voltages exceeding the breakdown voltage.
3. Second Exemplary Configuration
The control circuit 50 controls the drive circuit 20 based on a control signal. For example, the control circuit 50 controls an operation sequence such as a drive sequence of the drive circuit 20. For example, the control circuit 50 controls the drive sequence of data lines of the drive circuit 20, and controls the selection sequence of scan lines of the drive circuit 20. Note that, as described in
The control signal from the control circuit 50 is transmitted to the drive circuit 20 through the control signal lines LPWB1 to LPWB3. The control circuit 50 outputs a 1-bit signal to one control signal line. That is, a signal at a high level or a low level is output to each of the control signal lines LPWB1 to LPWB3. The control signal lines LPWB1 to LPWB3 constitutes a signal path through which a parallel-signal control signal is transmitted. The control signal lines LPWB1 to LPWB3 are realized by an aluminum interconnect layer or the like that is formed on a semiconductor substrate of a display driver 10, which is a semiconductor chip. Note that the number of control signal lines is not limited to three, and it is sufficient that the display driver 10 is provided with at least one control signal line.
The monitoring circuit MB1 is a circuit that monitors the control signal on the control circuit 50 side. The monitoring circuit MB2 is a circuit that monitors the control signal on the drive circuit 20 side. A 3-bit signal is output to the control signal lines LPWB1 to LPWB3. The monitoring circuits MB1 and MB2 monitor the control signal by determining whether or not the combination of logic levels of the 3 bits is an inhibited setting. The monitoring circuit MB1 is a first monitoring circuit, and the monitoring circuit MB2 is a second monitoring circuit.
Specifically, the monitoring circuit MB1 monitors the voltages at nodes NB11 to NB13, of the control signal lines LPWB1 to LPWB3, that are closer to the control circuit 50 than to the drive circuit 20. Also, the monitoring circuit MB1 outputs the monitoring result to the control circuit 50. For example, the monitoring circuit MB1 outputs the monitoring result to the control circuit 50 as a detection signal QB1. The nodes, of the control signal lines LPWB1 to LPWB3, that are closer to the control circuit 50 than to the drive circuit 20 are nodes, on routes of the control signal lines LPWB1 to LPWB3, whose distances to the control circuit 50 are smaller than those to the drive circuit 20. That is, as shown in
For example, the monitoring circuit MB1 is provided inside the control circuit 50. That is, the monitoring circuit MB1 is placed in the placement region of the control circuit 50. Also, the monitoring circuit MB1 monitors the control signal at the output nodes NB11 to NB13 to the control signal lines LPWB1 to LPWB3 in the control circuit 50. That is, the monitoring circuit MB1 monitors the control signal of the control signal lines LPWB1 to LPWB3 inside the control circuit 50.
The monitoring circuit MB2 monitors the voltages at nodes NB21 to NB23, of the control signal lines LPWB1 to LPWB3, that are closer to the drive circuit 20 than to the control circuit 50. Also, the monitoring circuit MB2 outputs the monitoring result to the control circuit 50. For example, the monitoring circuit MB2 outputs the monitoring result to the control circuit 50 as a detection signal QB2. The nodes, of the control signal lines LPWB1 to LPWB3, that are closer to the drive circuit 20 than to the control circuit 50 are nodes, on routes of the control signal lines LPWB1 to LPWB3, whose distances to the drive circuit 20 are smaller than those to the control circuit 50. That is, as shown in
For example, the monitoring circuit MB2 is provided inside the drive circuit 20. That is, the monitoring circuit MB2 is placed in the placement region of the drive circuit 20. Also, the monitoring circuit MB2 monitors the control signal at the input nodes NB21 to NB23 of the control signal lines LPWB1 to LPWB3 in the drive circuit 20. That is, the monitoring circuit M2 monitors the control signal of the control signal lines LPWB1 to LPWB3 inside the drive circuit 20.
Note that the monitoring circuits MB1 and MB2 can be realized by combinational circuits of logic elements similarly to the monitoring circuits M1 and M2 in
According to the present embodiment, when an anomaly such as a disconnection occurs in the control signal lines LPWB1 to LPWB3, the occurrence of the anomaly can be detected by the monitoring circuit MB2 provided on the drive circuit 20 side monitoring the control signal at the nodes NB21 to NB23. That is, not only an anomaly on the control circuit 50 side, but also an anomaly on the drive circuit 20 side can be detected. Also, the control circuit 50 can be notified of the occurrence of an anomaly using the detection signal QB2, and as a result, anomalous operation due to an inhibited setting can be prevented from being performed and the reliability thereof can be improved. Also, when an anomaly in which the control circuit 50 does not output an appropriate control signal has occurred, the occurrence of the anomaly can be detected by the monitoring circuit MB1 provided on the control signal side monitoring the control signal at the nodes NB11 to NB13. Also, the control circuit 50 can be notified of the occurrence of an anomaly using the detection signal QB1, and as a result, anomalous operation due to an inhibited setting can be prevented from being performed and the reliability thereof can be improved. Accordingly, the display driver 10 can be provided that can be favorably installed in an electronic apparatus such as an on-board apparatus requiring high reliability.
Also, according to the present embodiment, when an anomalous operation or the like of the analog circuit has occurred, it is possible to easily analyze whether the anomalous operation or the like is an anomaly caused by an inadequate control signal having been output from the control circuit 50, or an anomaly caused by a disconnection or the like in the control signal lines LPWB1 to LPWB3. For example, if the detection signal QB1 from the monitoring circuit MB1 indicates an anomaly, it can be analyzed that the anomaly is caused by an inadequate control signal having been output from the control circuit 50. On the other hand, if the detection signal QB2 from the monitoring circuit MB2 indicates an anomaly, it can be analyzed that the anomaly is caused by a disconnection or the like in the control signal lines LPWB1 to LPWB3. Therefore, the analysis to be performed when an anomaly has occurred can be facilitated.
The display driver 10 includes the interface circuit 80, as shown in
The register unit 52 includes a register RGB1 to which an error detection result based on the detection signal QB1 is stored, and a register RGB2 to which an error detection result based on the detection signal QB2 is stored.
The control circuit 50 performs processing for notifying an external device of the error, when one of the monitoring result of the monitoring circuit MB1 and the monitoring result of the monitoring circuit MB2 indicates that an error has been detected. For example, the control circuit 50 detects an error indicated by the monitoring result of the monitoring circuit MB1 based on the detection signal QB1 from the monitoring circuit MB1. That is, the control circuit 50 detects error information of the control signal at the nodes NB11 to NB13 based on the detection signal QB1. Also, the control circuit 50 detects an error indicated by the monitoring result of the monitoring circuit MB2 based on the detection signal QB2 from the monitoring circuit MB2. That is, the control circuit 50 detects error information of the control signal at the nodes NB21 to NB23 based on the detection signal QB2. When an error occurs that is an anomaly in which an appropriate control signal is not output from the control circuit 50, for example, the control circuit 50 is notified of the error using the detection signal QB1. Also, when an error occurs that is an anomaly in which a disconnection or the like occurs in the control signal lines LPWB1 to LPWB3, the control circuit 50 is notified of the error using the detection signal QB2. Also, the control circuit 50 performs processing for notifying an external device, such as a host, of an occurrence of this error. In this way, the external device can execute appropriate processing for handling the error that has occurred. For example, the external device such as a host, upon determining that an error has occurred in the output of the control signal based on the monitoring result of the monitoring circuit MB1, initializes the setting stored in the register of the register unit 52 via the interface circuit 80. The setting here is a setting corresponding to the control signal of the control signal lines LPWB1 to LPWB3. Also, the external device such as a host, upon determining that an error such as a disconnection of the control signal lines LPWB1 to LPWB3 has occurred based on the monitoring result of the monitoring circuit MB2, instructs to turn off the operation of the power supply circuit 60.
Also, the display driver 10 of the present embodiment includes the terminal TER for outputting the error detection signal ERD to an external device. The external device such as a host can determine that the monitoring circuit M1 or M2 has detected an error using the error detection signal ERD output from the terminal TER.
A detection flag based on the monitoring result of the monitoring circuit MB1 is set to the register RGB1, and a detection flag based on the monitoring result of the monitoring circuit MB2 is set to the register RGB2. The register RGB1 is a first register, and the register RGB2 is a second register. The registers RGB1 and RGB2 can be realized by a flip-flop circuit or the like. The registers RGB1 and RGB2 may also be realized by a semiconductor memory such as a RAM. When the monitoring circuit MB1 has detected an error, the detection flag of the register RGB1 is set to “1”, for example. When the monitoring circuit MB2 has detected an error, the detection flag of the register RGB2 is set to “1”, for example. Also, the external device can access the registers RGB1 and RGB2 via the interface circuit 80. Therefore, the external device can determine that the monitoring circuit MB1 or MB2 has detected an error by reading out the detection flags of the registers RGB1 and RGB2. Specifically, when one of the plurality of error detection circuits including the monitoring circuits MB1 and MB2 has detected an error, the error detection signal ERD is output from the terminal TER, as an interrupt signal to the external device. That is, the error detection signal ERD is activated. When the detection signal ERD is activated in this way, the external device accesses the register unit 52, and analyses the error factor. Then, if the detection flag of the register RGB1 is set to “1”, the external device determines that the monitoring circuit MB1 has detected an error. If the error detection flag of the register RGB2 is set to “1”, the external device determines that the monitoring circuit MB2 has detected an error. With this, the external device can execute appropriate processing for handling the detected error.
4. Detailed Exemplary Configuration
The scan line drive circuit 21 includes a plurality of buffer circuits that drives a plurality of scan lines of the electro-optical panel 150. A buffer circuit BFCi drives a scan line Gi. That is, the buffer circuit BFCi selects the scan line Gi by outputting a driving signal to the scan line Gi. i is an integer of one or more and 512 or less. Note that, here, a case where the scan line drive circuit 21 includes 512 buffer circuits BFC1 to BFC512 as the plurality of buffer circuits will be described as an example, but any number of the buffer circuits can be included in the scan line drive circuit 21.
The control circuit 50 outputs an address AD[9:0] for designating the scan line to be selected to the scan line drive circuit 21. As shown in
As shown in
The bit signals of the address AD[9:0] constitute the above-described control signal. That is, in
5. Electronic Apparatus and Mobile Body
The processing device 310 performs processing for controlling the electronic apparatus 300, various types of signal processing, and the like. The processing device 310 is a host, which is an external device, for example. The processing device 310 can be realized by a processor such as a CPU or an MPU, an ASIC, or the like. The memory 320 stores data from the operation interface 330 and the communication interface 340, and functions as a work memory of the processing device 310, for example. The memory 320 can be realized by a semiconductor memory such as a RAM or ROM, or a magnetic storage device such as a hard disk drive, for example. The operation interface 330 is a user interface for accepting various operations made by a user. For example, the operation interface 330 can be realized by a button, a mouse, and a keyboard, or a touch panel mounted in an electro-optical panel 150. The communication interface 340 is an interface for performing communication of image data and control data. The communication processing of the communication interface 340 may be wired communication processing or wireless communication processing.
As described above, the display driver of the present embodiment includes a power supply circuit that generates at least one power supply voltage, a drive circuit that drives an electro-optical panel based on the at least one power supply voltage, and a control circuit that controls the power supply circuit based on a control signal. Also, the display driver includes a first monitoring circuit that monitors the control signal on the control circuit side, and a second monitoring circuit that monitors the control signal on the power supply circuit side.
According to the present embodiment, a control signal output by the control circuit is supplied to the power supply circuit, and the power supply circuit generates a power supply voltage based on the control signal from the control circuit. Also, the first monitoring circuit monitors the control signal on the control circuit side, and the second monitoring circuit monitors the control signal on the power supply circuit side. With this configuration, in addition to an anomaly in the control signal itself output from the control circuit or the like being able to be monitored by the first monitoring circuit, an anomaly in the control signal on the power supply circuit side can be monitored by the second monitoring circuit. With this, an anomaly in which the control signal for controlling the power supply circuit is set to an inhibited setting can be prevented, and the analysis when such an anomaly has occurred can be facilitated.
Also, in the present embodiment, the display driver may include a control signal line through which the control signal is transmitted. The first monitoring circuit may monitor the control signal at a node, of the control signal line, that is closer to the control circuit than to the power supply circuit. The second monitoring circuit may monitor the control signal at a node, of the control signal line, that is closer to the power supply circuit than to the control circuit.
According to the present embodiment, the first monitoring circuit monitors the control signal at a node, of the control signal line, that is closer to the control circuit, and the second monitoring circuit monitors the control signal at a node, of the control signal line, that is closer to the power supply circuit. With this configuration, in addition to an anomaly in the control signal itself output from the control circuit or the like being able to be monitored by the first monitoring circuit, an anomaly in the control signal such as a disconnection can be monitored by the second monitoring circuit.
Also, in the present embodiment, the control circuit may control the power supply circuit using control data constituted by a plurality of bits as the control signal. The first monitoring circuit may monitor, on the control circuit side, whether or not the combination of logic levels of the plurality of bits is an inhibited setting. The second monitoring circuit may monitor, on the power supply circuit side, whether or not the combination of logic levels of the plurality of bits is an inhibited setting.
According to the present embodiment, as a result of the first and second monitoring circuits monitoring whether or not the combination of logic levels of the plurality of bits in the control data is an inhibited setting, an anomaly can be prevented in which the operation setting of the power supply circuit is set to an inhibited setting. The inhibited setting refers to a setting that is inhibited due to a specification issue or from a design viewpoint, because the setting may incur an anomalous operation, a failure, or a breakdown of the power supply circuit.
Also, in the present embodiment, the power supply circuit may generate a first power supply voltage and a second power supply voltage, as the at least one power supply voltage. The first monitoring circuit may monitor, on the control circuit side, whether or not the setting of the control signal is an inhibited setting in which the voltage difference between the first power supply voltage and the second power supply voltage exceeds the breakdown voltage of a transistor. The second monitoring circuit may monitor, on the power supply circuit side, whether or not the setting of the control signal is an inhibited setting in which the voltage difference between the first power supply voltage and the second power supply voltage exceeds the breakdown voltage of a transistor.
According to the present embodiment, as a result of the first and second monitoring circuits monitoring whether or not the setting of the control signal is an inhibited setting in which the voltage difference between the first power supply voltage and the second power supply voltage exceeds the breakdown voltage of a transistor, an anomaly can be prevented in which a voltage exceeding the breakdown voltage is applied to a transistor of the drive circuit.
Also, in the present embodiment, the display driver includes a drive circuit that drives an electro-optical panel, and a control circuit that control the drive circuit based on a control signal. Also, the display driver includes a first monitoring circuit that monitors the control signal on the control circuit side, and a second monitoring circuit that monitors the control signal on the drive circuit side.
According to the present embodiment, a control signal output from the control circuit is supplied to the drive circuit, and the drive circuit drives the electro-optical panel based on the control signal from the control circuit. Also, the first monitoring circuit monitors the control signal on the control circuit side, and the second monitoring circuit monitors the control signal on the drive circuit side. With this configuration, in addition to an anomaly in the control signal itself output from the control circuit or the like being able to be monitored by the first monitoring circuit, an anomaly in the control signal on the power supply circuit side can be monitored by the second monitoring circuit. With this, an anomaly in which the control signal for controlling the power supply circuit is set to an inhibited setting can be prevented, and the analysis when such an anomaly has occurred can be facilitated.
Also, in the present embodiment, the display driver may include a control signal line through which a control signal is transmitted. The first monitoring circuit may monitor the control signal at a node, of the control signal line, that is closer to the control circuit than to the drive circuit. The second monitoring circuit may monitor the control signal at a node, of the control signal line, that is closer to the drive circuit than to the control circuit.
According to the present embodiment, the first monitoring circuit monitors the control signal at a node, of the control signal line, that is closer to the control circuit, and the second monitoring circuit monitors the control signal at a node, of the control signal line, that is closer to the drive circuit. With this configuration, in addition to an anomaly in the control signal itself output from the control circuit or the like being able to be monitored by the first monitoring circuit, an anomaly in the control signal such as a disconnection can be monitored by the second monitoring circuit.
Also, in the present embodiment, the control circuit may control the drive circuit using control data constituted by a plurality of bits as the control signal. The first monitoring circuit may monitor, on the control circuit side, whether or not the combination of logic levels of the plurality of bits is an inhibited setting. The second monitoring circuit may monitor, on the drive circuit side, whether or not the combination of logic levels of the plurality of bits is an inhibited setting.
According to the present embodiment, as a result of the first and second monitoring circuits monitoring whether or not the combination of logic levels of the plurality of bits in the control data is an inhibited setting, an anomaly can be prevented in which the operation setting of the drive circuit is set to an inhibited setting. The inhibited setting refers to a setting that is inhibited due to a specification issue or from a design viewpoint, because the setting may incur an anomalous operation, a failure, or a breakdown of the drive circuit.
Also, in the present embodiment, the drive circuit may include a plurality of buffer circuits that drive a plurality of scan lines of the electro-optical panel. The control signal may be an address signal for designating which of the plurality of buffer circuits will be enabled. The first monitoring circuit may monitor, on the control circuit side, whether or not the address is in an inhibited setting. The second monitoring circuit may monitor, on the drive circuit side, whether or not the address is in an inhibited setting.
According to the present embodiment, as a result of the first and second monitoring circuits monitoring whether or not the setting of an address for designating which of the plurality of buffer circuits is to be enabled is an inhibited setting, an anomalous operation of the plurality of buffer circuits that drive the plurality of scan lines can be prevented.
Also, in the present embodiment, when one of the monitoring result of the first monitoring circuit and the monitoring result of the second monitoring circuit indicates that an error has occurred, the control circuit may perform processing for notifying an external device of the error.
In this way, the external device can execute appropriate processing for handling the error that has occurred.
Also, in the present embodiment, the display driver may include a terminal for outputting an error detection signal to an external device.
Accordingly, the external device can determine that the first or second monitoring circuit has detected an error using the error detection signal output from the terminal.
Also, in the present embodiment, the display driver may include a first register to which an error detection flag is set depending of the monitoring result of the first monitoring circuit, and a second register to which an error detection flag is set depending on the monitoring result of the second monitoring circuit.
In this way, when the first or second monitoring circuit has detected an error, the error factor can be appropriately notified using the error detection flags.
Also, the present embodiment relates to an electronic apparatus including the display driver described above.
Also, the present embodiment relates to a mobile body including the display driver described above.
Note that although an embodiment has been described in detail above, a person skilled in the art will readily appreciate that it is possible to implement numerous variations and modifications that do not depart substantially from the novel aspects and effect of the invention. Accordingly, all such variations and modifications are also to be included within the scope of the invention. For example, terms that are used within the description or drawings at least once together with broader terms or alternative synonymous terms can be replaced by those other terms at other locations as well within the description or drawings. Also, all combinations of the embodiment and variations are also encompassed in the range of the invention. Moreover, the configuration and operation of the display driver, the electro-optical panel, the electro-optical device, the electronic apparatus, and the mobile body are not limited to those described in the present embodiment, and various modifications are possible.
Number | Date | Country | Kind |
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JP2018-179823 | Sep 2018 | JP | national |
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20110241725 | Ikenaga | Oct 2011 | A1 |
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2008-203410 | Sep 2008 | JP |
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Number | Date | Country | |
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20200098319 A1 | Mar 2020 | US |