Electric circuit and electronic apparatus

Abstract

An electric circuit (1, 1', 1") comprises: a control terminal (2) that outputs a control signal; a first rectification element (3a, 3b) that allows passage of a current supplied from the control terminal; a first capacitor (4) that stores electric charge when a current is supplied from the control terminal through the first rectification element; a first output (5) in which the voltage value varies in accordance with the electric charge amount of the first capacitor; a second capacitor (6) that stores electric charge when a current is supplied from the control terminal through the first rectification element; a second output (7) in which the voltage value varies in accordance with the electric charge amount of the second capacitor; a second rectification element (8a, 8b) that allows passage of a current flowing when the first capacitor and the second capacitor are discharged; and a first electronic component (9) that interrupts the current flowing from the first rectification element to the second capacitor and the current flowing from the first capacitor to the second rectification element.

Description

Electrical circuits and electronic devices

[0001] The present invention relates to electrical circuits and electronic devices.

[0002] Japanese Patent Application Laid-Open No. 2020-50061 discloses an image sensor having multiple power supplies.

[0003] Typically, such an image sensor requires multiple power supplies to be turned on and off at different times according to a predetermined power supply sequence. Each of the multiple power supplies is provided with a power supply IC, and the on / off of the power supply is controlled via the power supply IC. In this case, in order to turn the multiple power supplies on and off at different times, it is conceivable to provide the same number of signal lines as the number of power supply ICs. It is also conceivable to use the multiple signal lines to control the on / off of electronic components other than the power supplies.

[0004] However, the number of signal lines for control components is limited, and there is a need to use signal lines for more complex control or other purposes.

[0005] In view of the above problems, an object of the present invention is to turn on and off a plurality of electronic components at different timings using a single signal line from a control component.

[0006] The gist of the present disclosure is as follows.

[0007] (1) An electric circuit comprising: a control terminal that outputs a control signal; a first rectifying element that passes a current supplied from the control terminal; a first capacitor that stores an electric charge when a current is supplied from the control terminal through the first rectifying element; a first output whose voltage value fluctuates according to an amount of electric charge in the first capacitor; a second capacitor that stores an electric charge when a current is supplied from the control terminal through the first rectifying element; a second output whose voltage value fluctuates according to an amount of electric charge in the second capacitor; a second rectifying element that passes a current that flows when the first capacitor and the second capacitor are discharged; and a first electronic component that prevents a current flow from the first rectifying element to the second capacitor and a current flow from the first capacitor to the second rectifying element.

[0008] (2) The electric circuit is connected to an image sensor having a first power supply and a second power supply, the first output is a first power supply IC that switches the first power supply on and off, and the second output is a second power supply IC that switches the second power supply on and off, when current is supplied from the control terminal to the first capacitor and the second capacitor, the first power supply is turned on by the first power supply IC, and then the second power supply is turned on by the second power supply IC, when the first capacitor and the second capacitor are discharged, the second power supply is turned off by the second power supply IC, and then the first power supply is turned off by the first power supply IC.

[0009] (3) The electric circuit according to (1) or (2) further comprises: a third capacitor that stores charge when current is supplied from the control terminal through the first rectifier element; a third output whose voltage value fluctuates according to the amount of charge in the third capacitor; and a second electronic component, wherein the second rectifier element passes current that flows when the third capacitor is discharged; the first electronic component prevents current from flowing from the first rectifier element to the second capacitor and the third capacitor, and from the first capacitor to the second rectifier element; and the second electronic component prevents current from flowing from the first rectifier element to the third capacitor, and from the first capacitor and the second capacitor to the second rectifier element.

[0010] (4) The electric circuit according to any one of (1) to (3), wherein the first rectifying element and the second rectifying element are diodes.

[0011] (5) The electric circuit according to any one of (1) to (3), wherein the first rectifying element and the second rectifying element are transistors.

[0012] (6) The electric circuit according to any one of (1) to (5), wherein the first electronic component is a resistor.

[0013] (7) An electronic device comprising an electric circuit, a control component for controlling the electric circuit, and a device connected to the electric circuit, wherein the electric circuit comprises: a control terminal for outputting a control signal; a first rectifying element for passing a current supplied from the control terminal; a first capacitor for storing an electric charge when a current is supplied from the control terminal through the first rectifying element; a first output whose voltage value fluctuates according to the amount of electric charge of the first capacitor; a second capacitor for storing an electric charge when a current is supplied from the control terminal through the first rectifying element; a second output whose voltage value fluctuates according to the amount of electric charge of the second capacitor; a second rectifying element for passing a current that flows when the first capacitor and the second capacitor are discharged; and a first electronic component for preventing a current flow from the first rectifying element to the second capacitor and a current flow from the first capacitor to the second rectifying element.

[0014] (8) An electric circuit comprising: a control terminal for outputting a control signal; a current supply circuit connected to the control terminal and having a first rectifying element for passing a current supplied from the control terminal; a first output circuit connected to the current supply circuit and having a first capacitor and a first output whose voltage value varies depending on the amount of charge on the first capacitor; a first connection circuit having a first electronic component for obstructing the flow of current; a second output circuit connected to the current supply circuit via the first connection circuit and having a second capacitor and a second output whose voltage value varies depending on the amount of charge on the second capacitor; and a discharge circuit having a second rectifying element for passing a current that flows when the first capacitor and the second capacitor are discharged.

[0015] (9) An electronic device comprising an electric circuit, a control component for controlling the electric circuit, and a device connected to the electric circuit, wherein the electric circuit comprises: a control terminal for outputting a control signal; a current supply circuit connected to the control terminal and having a first rectifying element for passing a current supplied from the control terminal; a first output circuit connected to the current supply circuit and having a first capacitor and a first output whose voltage value varies depending on the amount of charge on the first capacitor; a first connection circuit having a first electronic component for hindering the flow of current; a second output circuit connected to the current supply circuit via the first connection circuit and having a second capacitor and a second output whose voltage value varies depending on the amount of charge on the second capacitor; and a discharge circuit having a second rectifying element for passing a current that flows when the first capacitor and the second capacitor are discharged.

[0016] According to the present invention, a single signal line from a control component can be used to turn on and off a plurality of electronic components at different timings.

[0017] FIG. 1 is a diagram showing an electric circuit according to a first embodiment of the present invention. FIG. 2 is a diagram showing temporal changes in voltage values ​​of a first power supply IC and a second power supply IC realized by the electric circuit according to the first embodiment of the present invention. FIG. 3 is a diagram showing a power supply sequence realized by the electric circuit according to the first embodiment of the present invention. FIG. 4 is a diagram schematically showing an example of an electronic device equipped with an electric circuit. FIG. 5 is a diagram showing an electric circuit according to a second embodiment of the present invention. FIG. 6 is a diagram showing temporal changes in voltage values ​​of a first power supply IC and a second power supply IC realized by the electric circuit according to the second embodiment. FIG. 7 is a diagram showing an electric circuit according to a third embodiment of the present invention. FIG. 8 is a diagram showing a power supply sequence realized by the electric circuit according to the third embodiment of the present invention.

[0018] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, like components are designated by like reference numerals.

[0019] First Embodiment First, a first embodiment of the present invention will be described with reference to Figures 1 to 4. Figure 1 is a diagram showing an electric circuit 1 according to the first embodiment of the present invention. In this embodiment, the electric circuit 1 is configured to turn two power sources on and off at different times. For example, the electric circuit 1 is connected to an image sensor having a first power source and a second power source, and controls the on / off of the first power source and the second power source.

[0020] 1 , the electric circuit 1 includes a control terminal 2, a first diode 3a, a first capacitor 4, a first power supply IC 5, a second capacitor 6, a second power supply IC 7, a second diode 8a, and a first resistor 9. The first diode 3a, the first power supply IC 5, the second power supply IC 7, the second diode 8a, and the first resistor 9 are examples of a first rectifying element, a first output, a second output, a second rectifying element, and a first electronic component, respectively. In this embodiment, the electric circuit 1 also includes a current supply circuit 21, a first output circuit 22, a second output circuit 23, a first connection circuit 24, and a discharge circuit 25.

[0021] The control terminal 2 outputs a voltage control signal. The control terminal 2 is connected to a control component (for example, a CPU (Central Processing Unit) of a System on a Chip (SoC)) via a signal line 20 and is controlled by the control component. In this embodiment, when the control terminal 2 outputs 1 (High) as the control signal, a voltage of a predetermined value (for example, 1.8 V) is applied to the control terminal 2, and current is supplied from the control terminal 2 to the first capacitor 4 and the second capacitor 6. On the other hand, when the control terminal 2 outputs 0 (Low) as the control signal, the voltage of the control terminal 2 becomes 0 V, and the first capacitor 4 and the second capacitor 6 are discharged.

[0022] The current supply circuit 21 is connected to the control terminal 2 and includes a first diode 3a. The first diode 3a passes current in only one direction, allowing current to flow from left to right and prohibiting current to flow from right to left in the example of Figure 1. Therefore, the first diode 3a passes current supplied from the control terminal 2 and blocks current supplied to the control terminal 2.

[0023] The first output circuit 22 is connected to the current supply circuit 21 and includes a first capacitor 4 and a first power supply IC 5 whose voltage value varies depending on the amount of charge in the first capacitor 4. The first capacitor 4 stores charge when current is supplied from the control terminal 2 through the first diode 3a. One terminal of the first capacitor 4 is connected to ground, and the other terminal of the first capacitor 4 is connected to the first power supply IC 5. Therefore, the voltage across the first capacitor 4 is equal to the voltage value of the first power supply IC 5.

[0024] The first power supply IC5 switches the first power supply on and off depending on its voltage value, and is configured as, for example, an enable terminal. In this embodiment, when the voltage value of the first power supply IC5 is equal to or higher than a predetermined upper threshold, the signal level of the first power supply IC5 becomes high, and when the voltage value of the first power supply IC5 is equal to or lower than a predetermined lower threshold that is lower than the upper threshold, the signal level of the first power supply IC5 becomes low. When the signal level of the first power supply IC5 is high, the first power supply IC5 turns on the first power supply, and when the signal level is low, the first power supply IC5 turns off the first power supply.

[0025] When a charge is stored in the first capacitor 4 due to the current supply from the control terminal 2, the voltage across the first capacitor 4 increases, which in turn increases the voltage value of the first power supply IC 5. When the voltage value of the first power supply IC 5 reaches the upper threshold, the signal level of the first power supply IC 5 becomes High, and the first power supply is turned on by the first power supply IC 5.

[0026] The second output circuit 23 has a second capacitor 6 and a second power supply IC 7 whose voltage value varies depending on the amount of charge on the second capacitor 6. In the electric circuit 1, the second capacitor 6 is connected in parallel to the first capacitor 4, and the second power supply IC 7 is connected in parallel to the first power supply IC 5.

[0027] The second capacitor 6 stores electric charge when a current is supplied from the control terminal 2 through the first diode 3a. One terminal of the second capacitor 6 is connected to ground, and the other terminal of the second capacitor 6 is connected to the second power supply IC 7. Therefore, the voltage across the terminals of the second capacitor 6 is equal to the voltage value of the second power supply IC 7. In this embodiment, the capacitance of the second capacitor 6 is equal to the capacitance of the first capacitor 4.

[0028] The second power supply IC 7 switches the second power supply on and off depending on its voltage value, and is configured as, for example, an enable terminal. In this embodiment, when the voltage value of the second power supply IC 7 is equal to or higher than a predetermined upper threshold, the signal level of the second power supply IC 7 becomes high. When the voltage value of the second power supply IC 7 is equal to or lower than a predetermined lower threshold that is lower than the upper threshold, the signal level of the second power supply IC 7 becomes low. In this embodiment, the upper and lower thresholds for the second power supply IC 7 are set to the same values ​​as the upper and lower thresholds for the first power supply IC 5. When the signal level of the second power supply IC 7 is high, the second power supply IC 7 turns on the second power supply, and when the signal level is low, the second power supply IC 7 turns off the second power supply.

[0029] When a charge is stored in the second capacitor 6 due to the current supply from the control terminal 2, the voltage across the second capacitor 6 rises, which in turn raises the voltage value of the second power supply IC 7. When the voltage value of the second power supply IC 7 reaches the upper threshold, the signal level of the second power supply IC 7 becomes High, and the second power supply IC 7 turns on the second power supply.

[0030] In this embodiment, the first output circuit 22 is directly connected to the current supply circuit 21, and the second output circuit 23 is connected to the current supply circuit 21 via a first connection circuit 24. The first connection circuit 24 connects the branch point between the first diode 3a and the first capacitor 4 to the branch point between the second diode 8a and the second capacitor 6. The first connection circuit 24 has a first resistor 9, and the first resistor 9 is provided between the first diode 3a and the second capacitor 6. Therefore, a current is supplied to the first capacitor 4 directly from the first diode 3a, and a current is supplied to the second capacitor 6 from the first diode 3a via the first resistor 9.

[0031] The first resistor 9 makes it difficult for current to flow through the first connection circuit 24, preventing current from flowing from the first diode 3a to the second capacitor 6 when current is supplied from the control terminal 2. Therefore, when current is supplied to the second capacitor 6, the voltage of the second power supply IC 7 rises in accordance with the time constant of the RC circuit consisting of the first resistor 9 and the second capacitor 6. Meanwhile, when current is supplied to the first capacitor 4, the voltage of the first power supply IC 5 rises in synchronization with the control signal of the control terminal 2. As a result, the voltage of the first power supply IC 5 reaches the upper threshold before the voltage of the second power supply IC 7. Therefore, when current is supplied from the control terminal 2 to the first capacitor 4 and the second capacitor 6, the first power supply is turned on by the first power supply IC 5, and then the second power supply is turned on by the second power supply IC 7.

[0032] The discharge circuit 25 connects the current supply circuit 21 upstream (toward the control terminal) of the first diode 3a to the second output circuit 23, and includes a second diode 8a. In the electric circuit 1, the second diode 8a is connected in parallel to the first diode 3a.

[0033] 1, the second diode 8a allows current to flow from right to left and prohibits current to flow from left to right. Therefore, the second diode 8a passes the current supplied to the control terminal 2, i.e., the current that flows when the first capacitor 4 and the second capacitor 6 are discharged, and blocks the current supplied from the control terminal 2.

[0034] When the first capacitor 4 is discharged and charge is released from the first capacitor 4, the voltage across the first capacitor 4 drops, and accordingly the voltage value of the first power supply IC 5 drops. When the voltage value of the first power supply IC 5 reaches the lower threshold, the signal level of the first power supply IC 5 becomes Low, and the first power supply is turned off by the first power supply IC 5.

[0035] Similarly, when the second capacitor 6 is discharged and charge is released from the second capacitor 6, the voltage across the second capacitor 6 decreases, and accordingly the voltage value of the second power supply IC 7 decreases. When the voltage value of the second power supply IC 7 reaches the lower threshold, the signal level of the second power supply IC 7 becomes Low, and the second power supply IC 7 turns off the second power supply.

[0036] In this embodiment, the first output circuit 22 is connected to the discharge circuit 25 via a first connection circuit 24, and the second output circuit 23 is connected directly to the discharge circuit 25. The first connection circuit 24 has a first resistor 9, and the first resistor 9 is provided between the first capacitor 4 and the second diode 8a. Therefore, the current supplied from the first capacitor 4 is supplied to the second diode 8a via the first resistor 9, and the current supplied from the second capacitor 6 is supplied to the second diode 8a without passing through the first resistor 9. The currents supplied from the first capacitor 4 and the second capacitor 6 are passed through the discharge circuit 25, the current supply circuit 21, the control terminal 2, and the signal line 20 to the ground of the control component.

[0037] The first resistor 9 prevents current from flowing from the first capacitor 4 to the second diode 8a when the first capacitor 4 is discharged. Therefore, when the first capacitor 4 is discharged, the voltage of the first power supply IC 5 drops in accordance with the time constant of the RC circuit consisting of the first resistor 9 and the first capacitor 4. On the other hand, when the second capacitor 6 is discharged, the voltage of the second power supply IC 7 drops in synchronization with the control signal at the control terminal 2. As a result, the voltage of the second power supply IC 7 reaches the lower threshold before the voltage of the first power supply IC 5. Therefore, when the first capacitor 4 and the second capacitor 6 are discharged, the second power supply is turned off by the second power supply IC 7, and then the first power supply is turned off by the first power supply IC 5.

[0038] 2 is a diagram showing the time variations in the voltage values ​​of the first power supply IC 5 and the second power supply IC 7 realized by the electric circuit 1 according to the first embodiment of the present invention. In Fig. 2, the solid line indicates the voltage value of the control signal at the control terminal 2, the dashed line indicates the voltage value of the first power supply IC 5, and the dashed line indicates the voltage value of the second power supply IC 7.

[0039] As shown in FIG. 2 , when a voltage value of 1.8V is output as a control signal, the voltage values ​​of the first power supply IC 5 and the second power supply IC 7 begin to rise. The voltage value of the first power supply IC 5 rises from 0V to approximately 1.6V in synchronization with the control signal, and then gradually rises to 1.8V. The change in the voltage value from approximately 1.6V to 1.8V over time is due to the voltage difference generated across the first diode 3a. Meanwhile, the voltage value of the second power supply IC 7 gradually rises from 0V to 1.8V according to the time constant of the RC circuit consisting of the first resistor 9 and the second capacitor 6. Therefore, the voltage value of the second power supply IC 7 has a time delay with respect to the voltage value of the first power supply IC 5. In this embodiment, the upper threshold at which the first and second power supplies are turned on is set to a value in the voltage range in which the voltage value of the first power supply IC 5 is synchronized with the control signal, for example, a value between 0.9V and 1.6V. Therefore, the voltage value of the first power supply IC 5 reaches the upper threshold value before the voltage value of the second power supply IC 7, and the first power supply is turned on before the second power supply.

[0040] Subsequently, when a voltage value of 0 V is output as a control signal while the first and second power supplies are on, the voltage values ​​of the first power supply IC5 and the second power supply IC7 begin to decrease. The voltage value of the second power supply IC7 decreases from 1.8 V to approximately 0.2 V in synchronization with the control signal, and then gradually decreases to 0 V. The change in the voltage value from approximately 0.2 V to 0 V over time is due to the voltage difference generated across the second diode 8a. Meanwhile, the voltage value of the first power supply IC5 gradually decreases from 1.8 V to 0 V in accordance with the time constant of the RC circuit consisting of the first resistor 9 and the first capacitor 4. Therefore, the voltage value of the first power supply IC5 is delayed with respect to the voltage value of the second power supply IC7. In this embodiment, the lower threshold at which the first and second power supplies are turned off is set to a value in the voltage range in which the voltage value of the second power supply IC7 is synchronized with the control signal, for example, a value from 0 V to 0.4 V. Therefore, the voltage value of the second power supply IC 7 reaches the lower threshold value before the voltage value of the first power supply IC 5, and the second power supply is turned off before the first power supply.

[0041] Therefore, the electric circuit 1 realizes a power supply sequence as shown in FIG. 3 . For example, the first power supply is the interface power supply (DOVDD) of the image sensor, and the second power supply is the digital power supply (DVDD) of the image sensor. In this power supply sequence, the first power supply is turned on, followed by the second power supply, and then the second power supply is turned off, followed by the first power supply. That is, the order in which the power supplies are turned on and the order in which the power supplies are turned off are reversed for the two power supplies. Therefore, the electric circuit 1 allows two electronic components (the first power supply and the second power supply) to be turned on and off at different times using a single signal line 20 from the control component.

[0042] Instead of the first power supply IC 5 and the second power supply IC 7, other ICs, for example, other switching components that turn on and off electronic components other than power supplies, may be used as the first output and the second output. Also, instead of the first resistor 9, a first inductor that prevents current flow may be used. Also, the discharge circuit 25 may be directly connected to a ground or the like provided in the electric circuit 1.

[0043] The above-described electric circuit 1 is mounted, for example, in an electronic device. Fig. 4 is a diagram schematically showing an electronic device 100 mounted with the electric circuit 1. The electronic device 100 is, for example, a portable electronic device, such as a portable game console, a tablet terminal, a smartphone, a mobile monitor, or an e-book reader.

[0044] 4 , electronic device 100 includes an electric circuit 1, a control component 30 that controls electric circuit 1, and a device 40 connected to electric circuit 1. Control component 30 is, for example, a CPU of an SoC, and controls electric circuit 1 via signal line 20. Device 40 is, for example, an image sensor, an infrared sensor, or the like, and includes multiple electronic components (for example, multiple power supplies) that are turned on and off by electric circuit 1.

[0045] Second Embodiment The electric circuit according to the second embodiment is basically the same as the electric circuit according to the first embodiment, except for the points described below. Therefore, the second embodiment of the present invention will be described below, focusing on the differences from the first embodiment.

[0046] 5 is a diagram showing an electric circuit 1′ according to a second embodiment of the present invention. In the second embodiment, the electric circuit 1′ includes a first transistor 3b instead of the first diode 3a as a first rectifying element that passes a current supplied from the control terminal 2. Like the first diode 3a, the first transistor 3b passes a current in only one direction, and in the example of FIG. 5, it allows a current to flow from left to right and prohibits a current to flow from right to left. Therefore, the first transistor 3b passes a current supplied from the control terminal 2 and blocks a current supplied to the control terminal 2.

[0047] Furthermore, in the second embodiment, the electric circuit 1′ includes a second transistor 8b instead of the second diode 8a as a second rectifying element that passes the current that flows when the first capacitor 4 and the second capacitor 6 are discharged. In the electric circuit 1′, the second transistor 8b is connected in parallel with the first transistor 3b. The second transistor 8b passes current in only one direction, allowing current to flow from right to left and prohibiting current to flow from left to right in the example of FIG. 5 . Therefore, the second transistor 8b passes the current supplied to the control terminal 2, i.e., the current that flows when the first capacitor 4 and the second capacitor 6 are discharged, and blocks the current supplied from the control terminal 2.

[0048] 6 is a diagram showing the time variations in the voltage values ​​of the first power supply IC 5 and the second power supply IC 7 realized by the electric circuit 1' according to the second embodiment of the present invention. In Fig. 6, the solid line indicates the voltage value of the control signal at the control terminal 2, the dashed line indicates the voltage value of the first power supply IC 5, and the dashed line indicates the voltage value of the second power supply IC 7.

[0049] 6, when a voltage value of 1.8 V is output as the control signal, the voltage values ​​of the first power supply IC 5 and the second power supply IC 7 begin to rise. Unlike the first embodiment, the voltage value of the first power supply IC 5 rises from 0 V to 1.8 V in synchronization with the control signal. Note that in FIG. 6, the solid line indicating the voltage value of the control signal and the dashed line indicating the voltage value of the first power supply IC 5 overlap.

[0050] Therefore, when the first rectifier element is configured as a transistor, unlike when the first rectifier element is configured as a diode, there is no region in which the voltage value of the first power supply IC 5 rises gradually. Therefore, even if the upper threshold values ​​for the first power supply IC 5 and the second power supply IC 7 are set to a value (e.g., 1.7 V) close to the voltage of the control terminal 2 (1.8 V in this embodiment), a difference can be reliably generated between the timing at which the voltage value of the first power supply IC 5 reaches the upper threshold value and the timing at which the voltage value of the second power supply IC 7 reaches the upper threshold value. On the other hand, when the first rectifier element is configured as a diode, the electric circuit can be realized more inexpensively than when the first rectifier element is configured as a transistor.

[0051] Thereafter, when a voltage value of 0 V is output as a control signal while the first power supply and the second power supply are on, the voltage values ​​of the first power supply IC 5 and the second power supply IC 7 begin to decrease. Unlike the first embodiment, the voltage value of the second power supply IC 7 decreases from 1.8 V to 0 V in synchronization with the control signal. Note that in FIG. 6 , the solid line indicating the voltage value of the control signal and the dashed line indicating the voltage value of the second power supply IC 7 overlap.

[0052] Therefore, when the second rectifier element is configured as a transistor, unlike when the second rectifier element is configured as a diode, there is no region in which the voltage value of the second power supply IC 7 gradually decreases. Therefore, even if the lower thresholds for the first power supply IC 5 and the second power supply IC 7 are set to a value (e.g., 0.1 V) close to the voltage of the control terminal 2 (0 V in this embodiment), a difference can be reliably generated between the timing at which the voltage value of the second power supply IC 7 reaches the lower threshold and the timing at which the voltage value of the first power supply IC 5 reaches the lower threshold. On the other hand, when the second rectifier element is configured as a diode, the electric circuit can be realized more inexpensively than when the second rectifier element is configured as a transistor.

[0053] Third Embodiment The electric circuit according to the third embodiment is basically the same as the electric circuit according to the first embodiment, except for the points described below. Therefore, the following description of the third embodiment of the present invention will focus on the differences from the first embodiment.

[0054] FIG. 7 is a diagram showing an electric circuit 1 ″ according to a third embodiment of the present invention. The electric circuit 1 ″ is configured to turn on and off three power sources at different timings.

[0055] In the third embodiment, the electric circuit 1" includes a third capacitor 10, a third power supply IC 11, and a second resistor 12 in addition to the electronic components shown in FIG. 1. The third power supply IC 11 and the second resistor 12 are examples of a third output and a second electronic component, respectively. In the third embodiment, the electric circuit 1" is also configured with a current supply circuit 21, a first output circuit 22, a second output circuit 23, a first connection circuit 24, a discharge circuit 25, a third output circuit 26, and a second connection circuit 27.

[0056] The third output circuit 26 has a third capacitor 10 and a third power supply IC 11 whose voltage value varies depending on the amount of charge on the third capacitor 10. In the electric circuit 1", the third capacitor 10 is connected in parallel to the first capacitor 4 and the second capacitor 6, and the third power supply IC 11 is connected in parallel to the first power supply IC 5 and the second power supply IC 7.

[0057] The third capacitor 10 stores electric charge when a current is supplied from the control terminal 2 through the first diode 3a. One terminal of the third capacitor 10 is connected to ground, and the other terminal of the third capacitor 10 is connected to the third power supply IC 11. Therefore, the voltage across the terminals of the third capacitor 10 becomes equal to the voltage value of the third power supply IC 11.

[0058] The third power supply IC 11 switches the third power supply on and off depending on its voltage value and is configured as, for example, an enable terminal. In this embodiment, when the voltage value of the third power supply IC 11 is equal to or higher than a predetermined upper threshold, the signal level of the third power supply IC 11 becomes high. When the voltage value of the third power supply IC 11 is equal to or lower than a predetermined lower threshold that is lower than the upper threshold, the signal level of the third power supply IC 11 becomes low. In this embodiment, the upper and lower thresholds for the third power supply IC 11 are set to the same values ​​as the upper and lower thresholds for the first power supply IC 5 and the second power supply IC 7. When the signal level of the third power supply IC 11 is high, the third power supply IC 11 turns on the third power supply, and when the signal level is low, the third power supply IC 11 turns off the third power supply.

[0059] When a charge is stored in the third capacitor 10 due to the current supply from the control terminal 2, the voltage across the third capacitor 10 increases, which in turn increases the voltage value of the third power supply IC 11. When the voltage value of the third power supply IC 11 reaches the upper threshold, the signal level of the third power supply IC 11 becomes High, and the third power supply is turned on by the third power supply IC 11.

[0060] In the electric circuit 1″, the first output circuit 22 is directly connected to the current supply circuit 21, the second output circuit 23 is connected to the current supply circuit 21 via a first connection circuit 24, and the third output circuit 26 is connected to the current supply circuit 21 via a second connection circuit 27 and the first connection circuit 24. The second connection circuit 27 connects the branch point between the first resistor 9 and the second capacitor 6 and the branch point between the second diode 8a and the third capacitor 10. The second connection circuit 27 has a second resistor 12, and the first resistor 9 and the second resistor 12 are provided between the first diode 3a and the third capacitor 10. Therefore, a current is supplied to the third capacitor 10 from the first diode 3a via the first resistor 9 and the second resistor 12.

[0061] The first resistor 9 makes it difficult for current to flow through the first connection circuit 24, thereby preventing current from flowing from the first diode 3a to the second capacitor 6 and the third capacitor 10 when current is supplied from the control terminal 2. The second resistor 12 makes it difficult for current to flow through the second connection circuit 27, thereby preventing current from flowing from the first diode 3a to the third capacitor 10 when current is supplied from the control terminal 2. Therefore, when current is supplied to the third capacitor 10, the voltage value of the third power supply IC 11 rises in accordance with the time constant of the RC circuit consisting of the first resistor 9, the second resistor 12, and the third capacitor 10. On the other hand, when current is supplied to the second capacitor 6, the voltage value of the second power supply IC 7 rises in accordance with the time constant of the RC circuit consisting of the first resistor 9 and the second capacitor 6.

[0062] The first resistor 9, the second resistor 12, the second capacitor 6, and the third capacitor 10 are designed so that the time constant of the RC circuit consisting of the first resistor 9, the second resistor 12, and the third capacitor 10 is larger than the time constant of the RC circuit consisting of the first resistor 9 and the second capacitor 6. For example, the capacitance of the second capacitor 6 is set equal to the capacitance of the third capacitor 10. Furthermore, when current is supplied to the first capacitor 4, the voltage value of the first power supply IC 5 rises in synchronization with the control signal at the control terminal 2. Therefore, the rate of rise of the voltage value slows in the order of the first power supply IC 5, the second power supply IC 7, and the third power supply IC 11. As a result, the voltage values ​​reach the upper threshold in the order of the first power supply IC 5, the second power supply IC 7, and the third power supply IC 11. That is, when a voltage is applied to the control terminal 2, the first power supply is turned on by the first power supply IC 5, then the second power supply is turned on by the second power supply IC 7, and finally the third power supply is turned on by the third power supply IC 11.

[0063] The discharge circuit 25 connects the current supply circuit 21 upstream (toward the control terminal) of the first diode 3a to the third output circuit 26, and includes a second diode 8a. The second diode 8a passes current in only one direction, allowing current to flow from right to left and prohibiting current to flow from left to right in the example of FIG. 7. Therefore, the second diode 8a passes the current supplied to the control terminal 2, i.e., the current that flows when the first capacitor 4, the second capacitor 6, and the third capacitor 10 are discharged, and blocks the current supplied from the control terminal 2.

[0064] When the third capacitor 10 is discharged and charge is released from the third capacitor 10, the voltage across the third capacitor 10 decreases, and accordingly the voltage value of the third power supply IC 11 decreases. When the voltage value of the third power supply IC 11 reaches the lower threshold, the signal level of the third power supply IC 11 becomes Low, and the third power supply is turned off by the third power supply IC 11.

[0065] In this embodiment, the first output circuit 22 is connected to the discharge circuit 25 via the first connection circuit 24 and the second connection circuit 27, the second output circuit 23 is connected to the discharge circuit 25 via the second connection circuit 27, and the third output circuit 26 is connected directly to the discharge circuit 25. The second connection circuit 27 has a second resistor 12, and the first resistor 9 and the second resistor 12 are provided between the first capacitor 4 and the second diode 8a, and the second resistor 12 is provided between the second capacitor 6 and the second diode 8a. Therefore, the current supplied from the first capacitor 4 is supplied to the second diode 8a via the first resistor 9 and the second resistor 12, the current supplied from the second capacitor 6 is supplied to the second diode 8a via the second resistor 12, and the current supplied from the third capacitor 10 is supplied to the second diode 8a without passing through the first resistor 9 and the second resistor 12. The currents supplied from the first capacitor 4, the second capacitor 6 and the third capacitor 10 are passed through the discharge circuit 25, the current supply circuit 21, the control terminal 2 and the signal line 20 to the ground of the control component.

[0066] The first resistor 9 and the second resistor 12 prevent current from flowing from the first capacitor 4 to the second diode 8a when the first capacitor 4 is discharged. The second resistor 12 prevents current from flowing from the second capacitor 6 to the second diode 8a when the second capacitor 6 is discharged. Therefore, when the first capacitor 4 is discharged, the voltage value of the first power supply IC 5 decreases in accordance with the time constant of the RC circuit consisting of the first resistor 9, the second resistor 12, and the first capacitor 4. On the other hand, when the second capacitor 6 is discharged, the voltage value of the second power supply IC 7 decreases in accordance with the time constant of the RC circuit consisting of the second resistor 12 and the second capacitor 6.

[0067] The first resistor 9, the second resistor 12, the first capacitor 4, and the second capacitor 6 are designed so that the time constant of the RC circuit consisting of the first resistor 9, the second resistor 12, and the first capacitor 4 is greater than the time constant of the RC circuit consisting of the second resistor 12 and the second capacitor 6. For example, the capacitance of the first capacitor 4 is set equal to the capacitance of the second capacitor 6. Furthermore, when the third capacitor 10 is discharged, the voltage value of the third power supply IC 11 decreases in synchronization with the control signal at the control terminal 2. Therefore, the rate of decrease of the voltage value becomes slower in the order of the third power supply IC 11, the second power supply IC 7, and the first power supply IC 5. As a result, the voltage values ​​reach the lower threshold in the order of the third power supply IC 11, the second power supply IC 7, and the first power supply IC 5. That is, when the voltage at the control terminal 2 is set to 0 V, the third power supply is turned off by the third power supply IC 11, then the second power supply is turned off by the second power supply IC 7, and finally the first power supply is turned off by the first power supply IC 5.

[0068] Therefore, according to the electric circuit 1, a power supply sequence as shown in FIG. 8 is realized. In this power supply sequence, the power supplies are turned on in the order of the first power supply, the second power supply, and the third power supply, and then turned off in the order of the third power supply, the second power supply, and the first power supply. In other words, the order in which the power supplies are turned on and the order in which they are turned off are reversed for the three power supplies. Therefore, according to the electric circuit 1", it is possible to turn on and off three electronic components (the first power supply, the second power supply, and the third power supply) at different times using a single signal line 20 from the control component.

[0069] Instead of the first power supply IC 5, the second power supply IC 7, and the third power supply IC 11, other ICs, for example, other switching components that turn on and off electronic components other than power supplies, may be used as the first output, the second output, and the third output. Furthermore, instead of the first resistor 9, a first inductor that prevents current flow may be used, and instead of the second resistor 12, a second inductor that prevents current flow may be used. Furthermore, the discharge circuit 25 may be directly connected to a ground or the like provided in the electric circuit 1".

[0070] Other Embodiments Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments and various modifications and changes can be made.

[0071] For example, the number of outputs of the electric circuit may be four or more. In this case, similarly to the third embodiment, by adding capacitors connected to the outputs and electronic components that prevent current flow according to the number of outputs, the order in which electronic components such as power supplies are turned on and the order in which such electronic components are turned off can be reversed.

[0072] The above-described embodiments can be implemented in any combination. For example, in the electric circuit 1" shown in FIG. 7, a first transistor 3b and a second transistor 8b may be used instead of the first diode 3a and the second diode 8a, as in the second embodiment. In the electric circuits 1, 1" one of the first rectifying element and the second rectifying element may be a diode, and the other of the first rectifying element and the second rectifying element may be a transistor.

[0073] 1, 1', 1" Electric circuit 2 Control terminal 3a First diode 3b First transistor 4 First capacitor 5 First power supply IC 6 Second capacitor 7 Second power supply IC 8a Second diode 8b Second transistor 9 First resistor 30 Control component 40 Device 100 Electronic device

Claims

1. An electric circuit comprising: a control terminal that outputs a control signal; a first rectifying element that passes a current supplied from the control terminal; a first capacitor that stores a charge when a current is supplied from the control terminal through the first rectifying element; a first output, the voltage value of which varies according to an amount of charge on the first capacitor; a second capacitor that stores a charge when a current is supplied from the control terminal through the first rectifying element; a second output, the voltage value of which varies according to an amount of charge on the second capacitor; a second rectifying element that passes a current that flows when the first capacitor and the second capacitor are discharged; and a first electronic component that prevents a flow of current from the first rectifying element to the second capacitor and from the first capacitor to the second rectifying element.

2. The electric circuit of claim 1, wherein the electric circuit is connected to an image sensor having a first power supply and a second power supply, the first output is a first power supply IC that switches the first power supply on and off, and the second output is a second power supply IC that switches the second power supply on and off, when a current is supplied from the control terminal to the first capacitor and the second capacitor, the first power supply is turned on by the first power supply IC, and then the second power supply is turned on by the second power supply IC, when the first capacitor and the second capacitor are discharged, the second power supply is turned off by the second power supply IC, and then the first power supply is turned off by the first power supply IC.

3. The electric circuit according to claim 1 or 2, further comprising: a third capacitor that stores charge when current is supplied from the control terminal through the first rectifier element; a third output whose voltage value varies according to the amount of charge on the third capacitor; and a second electronic component, wherein the second rectifier element passes a current that flows when the third capacitor is discharged, the first electronic component prevents a current flow from the first rectifier element to the second capacitor and the third capacitor, and a current flow from the first capacitor to the second rectifier element, and the second electronic component prevents a current flow from the first rectifier element to the third capacitor, and a current flow from the first capacitor and the second capacitor to the second rectifier element.

4. The electric circuit according to any one of claims 1 to 3, wherein the first rectifying element and the second rectifying element are diodes.

5. The electric circuit according to any one of claims 1 to 3, wherein the first rectifying element and the second rectifying element are transistors.

6. The electric circuit according to any one of claims 1 to 5, wherein the first electronic component is a resistor.

7. An electronic device comprising an electric circuit, a control component for controlling the electric circuit, and a device connected to the electric circuit, wherein the electric circuit comprises: a control terminal for outputting a control signal; a first rectifying element for passing a current supplied from the control terminal; a first capacitor for storing charge when a current is supplied from the control terminal through the first rectifying element; a first output whose voltage value fluctuates according to the amount of charge on the first capacitor; a second capacitor for storing charge when a current is supplied from the control terminal through the first rectifying element; a second output whose voltage value fluctuates according to the amount of charge on the second capacitor; a second rectifying element for passing a current that flows when the first capacitor and the second capacitor are discharged; and a first electronic component for preventing a flow of current from the first rectifying element to the second capacitor and from the first capacitor to the second rectifying element.

8. An electric circuit comprising: a control terminal for outputting a control signal; a current supply circuit connected to the control terminal and having a first rectifying element for passing a current supplied from the control terminal; a first output circuit connected to the current supply circuit and having a first capacitor and a first output whose voltage value varies depending on the amount of charge on the first capacitor; a first connection circuit having a first electronic component for impeding a flow of current; a second output circuit connected to the current supply circuit via the first connection circuit and having a second capacitor and a second output whose voltage value varies depending on the amount of charge on the second capacitor; and a discharge circuit having a second rectifying element for passing a current that flows when the first capacitor and the second capacitor are discharged.

9. An electronic device comprising an electric circuit, a control component for controlling the electric circuit, and a device connected to the electric circuit, the electric circuit comprising: a control terminal for outputting a control signal; a current supply circuit connected to the control terminal and having a first rectifying element for passing a current supplied from the control terminal; a first output circuit connected to the current supply circuit and having a first capacitor and a first output whose voltage value varies depending on the amount of charge on the first capacitor; a first connection circuit having a first electronic component for preventing a flow of current; a second output circuit connected to the current supply circuit via the first connection circuit and having a second capacitor and a second output whose voltage value varies depending on the amount of charge on the second capacitor; and a discharge circuit having a second rectifying element for passing a current that flows when the first capacitor and the second capacitor are discharged.

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