Control device for ultrasonic transducer for generating ultrasonic waves

Abstract

The invention relates to a control device for an ultrasonic transducer (12) for generating ultrasonic waves, comprising a first and a second lower semiconductor switch (32, 34), each of which is provided with a current path that can be switched into an on-state or an off-state, and a first and a second upper semiconductor switch (36, 38), each of which is provided with a current path that can be switched into an on-state or an off-state, each of the first and second upper semiconductor switches has a current path that can be switched to a conductive state or a non-conductive state. The current path of the first lower semiconductor switch (32) and the current path of the first upper semiconductor switch (36) are interconnected. The current path of the second lower semiconductor switch (34) and the current path of the second upper semiconductor switch (38) are also connected to each other. A switching control unit (30) is used for alternating switching of an on state or an off state of the semiconductor switches (32, 34, 36, 38).

Description

Technical Field

[0001] This invention relates to a control device for an ultrasonic transducer used to generate ultrasonic waves. Background Technology

[0002] For example, this type of ultrasonic transducer is used to monitor the vehicle's surroundings. For this purpose, several ultrasonic transducers are typically connected via a communication bus to a central control unit, which, in addition to controlling these ultrasonic transducers or the control devices that control them, also evaluates the ultrasonic signals received from these transducers. Each ultrasonic transducer typically provides preprocessing of the received ultrasonic signals with the aid of electronics assigned to it. In this respect, the ultrasonic transducer is part of an ultrasonic sensor; therefore, it can be said that the ultrasonic sensor, in addition to providing control devices, also provides circuitry for the preprocessing and (if necessary) partial evaluation of the electroacoustic signals. These ultrasonic sensors can also perform self-tests or similar self-diagnostics.

[0003] To generate ultrasonic waves with the sound pressure levels required for monitoring, for example, the environment around a vehicle, using an ultrasonic transducer, a significant amount of energy and electricity is typically needed to control the transducer. Therefore, a transformer is used to control the ultrasonic transducer. One advantage of this is that because the voltage used for the ultrasonic transducer is stepped up by the transformer, the voltage capability of the components in the integrated circuits (such as those commonly used in ultrasonic sensors) only needs to be relatively low.

[0004] In the prior art, it is known that the primary coil of a transformer used to control an ultrasonic transducer is alternately connected to a common potential or to a current source via one of two semiconductor switches (e.g., transistors). The current paths of these two semiconductor switches are alternately controlled in opposite directions by a control unit. The primary coil also has a center tap connected to the supply potential. The alternating, opposite control of these two semiconductor switches causes the current to alternately change direction in the primary coil, and causes the current to flow between one of the two primary coil terminals and the center tap. Thus, by selecting a suitable transmission ratio for the transformer, the required conversion drive voltage (also referred to as the AC drive voltage) for the ultrasonic transducer (e.g., see patent document EP-A-2 189 808) is obtained at the secondary coil terminals of the transformer.

[0005] The design of transformers with a center tap on the main pole side still requires further improvement because: since two windings (coils) are needed, the connection between them must be brought out as a center tap. The center tap also requires additional terminals on the IC (integrated circuit). All of this increases the manufacturing and / or assembly cost of the ultrasonic sensor. Summary of the Invention

[0006] The object of the present invention is to provide a remedy in the above-mentioned aspect and to provide a simplified structure and connection for ultrasonic transducers.

[0007] To achieve this objective, the present invention provides a control device for an ultrasonic transducer that generates ultrasonic waves, the control device comprising:

[0008] - A transformer having first and second main pole side terminals (with a main pole side coil disposed between the two terminals) and two secondary side terminals (with a secondary side coil disposed between the two terminals), wherein the ultrasonic transducer is capable of being connected to the two secondary side terminals;

[0009] - First and second lower-side semiconductor switches, each having a current path that can be switched to an on or off state.

[0010] - wherein the current path of the first lower semiconductor switch is arranged between a first circuit node shared by the first and second lower semiconductor switches and the first main electrode terminal of the transformer, and the current path of the second lower semiconductor switch is arranged between the first circuit node and the second main electrode terminal of the transformer.

[0011] - First and second upper-side semiconductor switches, each having a current path that can be switched to an on or off state.

[0012] Wherein, the current path of the first upper semiconductor switch is arranged between a second circuit node shared by the first and second upper semiconductor switches and the first main terminal of the transformer, and the current path of the second upper semiconductor switch is arranged between the second circuit node and the second main terminal of the transformer.

[0013] - Wherein, an energy source having two terminals can be directly or indirectly connected to the first and second circuit nodes; and

[0014] - A switch control unit, which is used to alternately switch the first and second upper semiconductor switches and the first and second lower semiconductor switches to an on state or an off state.

[0015] - Specifically, during one control phase of the control cycle, the switch control unit switches the first upper semiconductor switch and the second lower semiconductor switch to an on state and switches the second upper semiconductor switch and the first lower semiconductor switch to an off state. During another control phase of the control cycle, the switch control unit switches the second upper semiconductor switch and the first lower semiconductor switch to an on state and switches the first upper semiconductor switch and the second lower semiconductor switch to an off state. Furthermore, current alternately flows through the main terminal of the transformer in opposite directions, and thereby flows through the main coil of the transformer.

[0016] The present invention improves the control of ultrasonic transducers by simplifying transformer design. This improvement begins with the known connection of the two main-side terminals of the transformer to corresponding semiconductor switches, referred to as lower-side semiconductor switches, whose current paths extend from a common first circuit node to the two main-side terminals. Furthermore, according to the invention, two upper-side semiconductor switches are also connected to the two main-side terminals of the transformer, whose current paths extend from the two main-side terminals to a common second circuit node. The current paths of all semiconductor switches (which are typically transistors) can now be alternately switched between on and off states, meaning that current alternately flows through the main-side terminals of the transformer in opposite directions, thereby flowing through the main-side coils of the transformer, which are arranged between two series circuits, each consisting of a lower-side semiconductor switch and an upper-side semiconductor switch.

[0017] In the two parallel series circuits, each series circuit consists of two semiconductor switches. The first series circuit has a current path for a first lower semiconductor switch and a current path for a first upper semiconductor switch, while the second series circuit has a current path for a second lower semiconductor switch and a current path for a second upper semiconductor switch. The main terminals of the transformer are connected to corresponding connection nodes between the two semiconductor switch current paths of each series circuit. The current paths of these four semiconductor switches are designed such that: during one control phase of a control cycle, the switch control unit switches the first upper semiconductor switch and the second lower semiconductor switch to the on state and switches the second upper semiconductor switch and the first lower semiconductor switch to the off state; and during another control phase of the control cycle, the switch control unit switches the second upper semiconductor switch and the first lower semiconductor switch to the on state and switches the first upper semiconductor switch and the second lower semiconductor switch to the off state. Furthermore, current alternately flows through the main terminals of the transformer in opposite directions, thereby flowing through the main coil of the transformer.

[0018] The main advantage of this invention is that it simplifies transformer design because the center tap of the main-side coil can be eliminated, thus requiring only one (single) winding or coil on the main side. Furthermore, it also saves on the terminals on the IC.

[0019] In an advantageous embodiment of the invention, the control device further includes a current source for setting the current flowing through the current paths of the first and second upper semiconductor switches and the first and second lower semiconductor switches in their respective on states. Furthermore, the current source is arranged between one of the two terminals of the first circuit node and the energy source, or between the other of the two terminals of the second circuit node and the energy source. The current source can now be used to set the current flowing through the current paths of each semiconductor switch. This is particularly advantageous when using several ultrasonic transducers to monitor the vehicle's surroundings as is typically the case. Due to manufacturing tolerances of the ultrasonic transducers and transformers, it is not always guaranteed that all transducers will emit ultrasonic waves with the same sound pressure level when they are connected to and operated by the vehicle's electrical system. However, this is an advantage when reliable monitoring of the vehicle's surroundings is desired. Therefore, by adjusting the current source, each ultrasonic transducer can now be controlled so that all ultrasonic transducers emit sound waves with substantially the same sound pressure level.

[0020] The current source of each ultrasonic transducer, which is advantageously used in this regard, can now be connected to the current path of either the upper semiconductor switch (so-called upper current source) or the lower semiconductor switch (so-called lower current source). Thus, in both cases, the current source is connected to one of the two circuit nodes mentioned above, while the other of the two circuit nodes is connected to, for example, ground potential when the current source is used as the upper current source, and connected to the power supply potential of the vehicle electrical system when the current source is used as the lower current source.

[0021] The control of the main side of the transformer according to the invention, combined with the higher supply voltage of this control, results in a reduction / halving of the current compared to a transformer with a center tap on the main side. This means that the semiconductor switches used must be designed to be significantly smaller, and therefore require a smaller chip area. Additionally, space can be saved for the high-voltage IC pins of the center tap. Finally, diagnostics of the control unit are also simplified. Regarding the simplification of the transformer, according to the invention, two main-side windings / coils can be eliminated, and a single coil can be used instead.

[0022] For OEM suppliers providing ultrasonic sensors or individual sensor modules, there are additional advantages, such as simpler PCB routing (requiring only two lines from the IC to the transformer, compared to three lines along with the center tap of previously used transformers). The aforementioned halved current also means lower ohmic losses, resulting in less power loss and more efficient transformer operation. Given that current transformers reach inductance saturation at higher currents (around 500 mA), suppliers also have significantly more headroom due to the halved current. The halved current also leads to reduced EMC radiation on the supply lines.

[0023] However, suppliers can also use the control device according to the invention without changing the design of the previously used transformer. For this purpose, it eliminates the connection between the center tap and the control unit, and connects the two "external" main pole side connectors to the control unit. This approach is particularly suitable if a half-transmission ratio is to be used, for example, 1:5 instead of 1:10. However, suppliers can also choose to use an optimized transformer that does not require a center tap on the main pole side. This reduces the manufacturing cost of the transformer.

[0024] In this regard, in order to achieve the above objectives, according to the present invention, an alternative control device is proposed, comprising:

[0025] - First and second lower-side semiconductor switches, each having a current path that can be switched to an on or off state.

[0026] Wherein, the current path of the first lower semiconductor switch is arranged between a first circuit node and a first output terminal shared by the first and second lower semiconductor switches, the first output terminal being connectable to a first main terminal of a transformer connected to the ultrasonic transducer, and the current path of the second lower semiconductor switch is arranged between the first circuit node and a second output terminal, the second output terminal being connectable to a second main terminal of the transformer.

[0027] - First and second upper-side semiconductor switches, each having a current path that can be switched to an on or off state.

[0028] Wherein, the current path of the first upper semiconductor switch is arranged between the second circuit node shared by the first and second upper semiconductor switches and the first output terminal, and the current path of the second upper semiconductor switch is arranged between the second circuit node and the second output terminal.

[0029] - Wherein, an energy source having two terminals can be directly or indirectly connected to the first and second circuit nodes; and

[0030] - A switch control unit, which is used to alternately switch the first and second upper semiconductor switches and the first and second lower semiconductor switches to an on state or an off state.

[0031] - In one control phase of the control cycle, the switch control unit switches the first upper semiconductor switch and the second lower semiconductor switch to the on state and switches the second upper semiconductor switch and the first lower semiconductor switch to the off state. In another control phase of the control cycle, the switch control unit switches the second upper semiconductor switch and the first lower semiconductor switch to the on state and switches the first upper semiconductor switch and the second lower semiconductor switch to the off state. Attached Figure Description

[0032] The attached image is... Figure 1 An embodiment of the present invention is shown. Detailed Implementation

[0033] The accompanying drawings schematically illustrate the overall structure of an ultrasonic sensor 10, which includes an ultrasonic transducer 12, a transformer 14 that supplies energy to the ultrasonic transducer 12, and a control unit 16 designed as an IC.

[0034] The transformer 14 has a first main-side terminal 18 and a second main-side terminal 20, with a main-side coil or winding 22 disposed between these two main-side terminals. On the secondary side, the transformer 14 has a first secondary-side terminal 24 and a second secondary-side terminal 26, with a secondary-side coil or winding 28 disposed between these two secondary-side terminals. These two secondary-side terminals 24 and 26 are connected to the TR- and TR+ terminals of the ultrasonic transducer 12.

[0035] A portion of the control unit 16 is a switch control unit 30, which is used for switching a total of four semiconductor switches on and off. In this configuration, the current path of the first lower semiconductor switch 32 is connected to the current path of the first upper semiconductor switch 36, forming a first series circuit 40, and the current path of the second lower semiconductor switch 34 is connected to the current path of the second upper semiconductor switch 38, forming a second series circuit 42. Both series circuits are connected between the supply potential VBAT and the current source 44, which, in this embodiment, is connected to a second voltage potential (e.g., ground potential) GND. Therefore, the two lower semiconductor switches 32 and 34 are connected to the first circuit node 45, and the two upper semiconductor switches 36 and 38 are connected to the second circuit node 46. The connection node 48 of the two semiconductor switches 32 and 36 in the first series circuit 40 is connected to the first main terminal 18 of the transformer 14 as an outward routing terminal (e.g., the first output terminal) DRV1 of the control unit 16. In a corresponding manner, the connection node 50 of the two semiconductor switches 34, 38 of the second series circuit 42 is connected to the second main pole side terminal 20 of the transformer 14 as an outward routing terminal (e.g., the second output terminal) DRV2 of the control unit 16.

[0036] The accompanying drawings also show that the two terminals TR+ and TR- of the ultrasonic transducer 12 are connected to the two receive signal terminals AINS and AING of the control unit 16. The electrical receive signal generated by the ultrasonic transducer 12 in response to the received echo reaches a circuit assembly (not shown) via these two IC terminals AINS and AING for preprocessing. The preprocessed signal is then routed externally via other IC terminals (e.g., communication bus terminals) I / Q and I / Q_ (e.g., for communication and external control) and, for example, via communication bus 52 to the central control and evaluation unit 54.

[0037] The accompanying drawings do not show the external and internal components used to ensure the decoupling of the high-voltage control signal and the low-voltage receiving signal of the ultrasonic transducer. These measures and circuit components are generally known in relation to the operation of the ultrasonic transducer and therefore do not require further explanation here.

[0038] The present invention has been described above together with the transformer, which is a component of the control device for an ultrasonic transducer. However, the present invention can also be implemented without involving the transformer. Thus, in this respect, the present invention relates to a control device for an ultrasonic transducer for generating ultrasonic waves, the control device comprising the aforementioned four semiconductor switches and their above-described interconnection relationship, and a switch control unit for alternately switching the on or off states of these semiconductor switches as described above.

[0039] List of reference numerals

[0040] 10: Ultrasonic sensor

[0041] 12: Ultrasonic transducer

[0042] 14: Transformer

[0043] 16: Control unit (as IC)

[0044] 18: First main electrode side terminal

[0045] 20: Second main electrode side terminal

[0046] 22: Main pole side coil or winding

[0047] 24: First stage side terminal

[0048] 26: Secondary stage side terminal

[0049] 28: Secondary coil or winding

[0050] 30: Switch control unit

[0051] 32: First lower semiconductor switch

[0052] 34: Second lower semiconductor switch

[0053] 36: First upper semiconductor switch

[0054] 38: Second upper semiconductor switch

[0055] 40: First series circuit

[0056] 42: Second series circuit

[0057] 44: Current source

[0058] 45: First circuit node

[0059] 46: Second circuit node

[0060] 48: Connecting Nodes

[0061] 50: Connecting Nodes

[0062] 52: Communication bus

[0063] 54: Central Control and Evaluation Unit

[0064] DRV1: First output terminal

[0065] DRV2: Second output terminal

[0066] AINS: Signal receiving terminal

[0067] AING: Receive signal terminal

[0068] I / Q: Communication bus terminal

[0069] I / Q: Communication bus terminals

[0070] VBAT: Power supply potential of the energy source

[0071] GND: Grounding potential of the energy source

Claims

1. A control device for an ultrasonic transducer (12) for generating ultrasonic waves, comprising: - A transformer (14) having first and second main pole side terminals (18, 20) and two secondary side terminals (24, 26), the ultrasonic transducer (12) being able to be connected to the two secondary side terminals; - First and second lower-side semiconductor switches (32, 34), each of which has a current path that can be switched to an on state or a non-conducting state. -The current path of the first lower semiconductor switch (32) is arranged between the first circuit node (45) shared by the first and second lower semiconductor switches (32, 34) and the first main electrode terminal (18) of the transformer (14), and the current path of the second lower semiconductor switch (34) is arranged between the first circuit node (45) and the second main electrode terminal (20) of the transformer (14); - First and second upper semiconductor switches (36, 38), each of which has a current path that can be switched to an on state or a non-conducting state. -The current path of the first upper semiconductor switch (36) is arranged between the second circuit node (46) shared by the first and second upper semiconductor switches (36, 38) and the first main electrode terminal (18) of the transformer (14), and the current path of the second upper semiconductor switch (38) is arranged between the second circuit node (46) and the second main electrode terminal (20) of the transformer (14). - Wherein, a power source with two terminals (VBAT, GND) can be directly or indirectly connected to the first and second circuit nodes (45, 46); and - A switch control unit (30) is used to alternately switch the first and second upper semiconductor switches (36, 38) and the first and second lower semiconductor switches (32, 34) to an on state or an off state. - In one control phase of the control cycle, the switch control unit (30) switches the first upper semiconductor switch (36) and the second lower semiconductor switch (34) to the on state and switches the second upper semiconductor switch (38) and the first lower semiconductor switch (32) to the off state. In another control phase of the control cycle, the switch control unit (30) switches the second upper semiconductor switch (38) and the first lower semiconductor switch (32) to the on state and switches the first upper semiconductor switch (36) and the second lower semiconductor switch (34) to the off state.

2. A control device for an ultrasonic transducer (12) used to generate ultrasonic waves, comprising: - First and second lower-side semiconductor switches (32, 34), each of which has a current path that can be switched to an on state or a non-conducting state. -The current path of the first lower semiconductor switch (32) is arranged between a first circuit node (45) shared by the first and second lower semiconductor switches (32, 34) and a first output terminal (DVR1), the first output terminal (DVR1) being able to be connected to the first main electrode terminal (18) of the transformer (14) connected to the ultrasonic transducer (12), and the current path of the second lower semiconductor switch (34) is arranged between the first circuit node (45) and a second output terminal (DVR2), the second output terminal (DVR2) being able to be connected to the second main electrode terminal (20) of the transformer (14). - First and second upper semiconductor switches (36, 38), each of which has a current path that can be switched to an on state or a non-conducting state. -The current path of the first upper semiconductor switch (36) is arranged between the second circuit node (46) shared by the first and second upper semiconductor switches (36, 38) and the first output terminal (DVR1), and the current path of the second upper semiconductor switch (38) is arranged between the second circuit node (46) and the second output terminal (DVR2). - Wherein, a power source with two terminals (VBAT, GND) can be directly or indirectly connected to the first and second circuit nodes (45, 46); and - A switch control unit (30) is used to alternately switch the first and second upper semiconductor switches (36, 38) and the first and second lower semiconductor switches (32, 34) to an on state or an off state. - In one control phase of the control cycle, the switch control unit (30) switches the first upper semiconductor switch (36) and the second lower semiconductor switch (34) to the on state and switches the second upper semiconductor switch (38) and the first lower semiconductor switch (32) to the off state. In another control phase of the control cycle, the switch control unit (30) switches the second upper semiconductor switch (38) and the first lower semiconductor switch (32) to the on state and switches the first upper semiconductor switch (36) and the second lower semiconductor switch (34) to the off state.

3. The control device according to claim 1 or 2, characterized in that... Also includes: A current source (44) is used to set the current flowing through the current path of the first and second upper semiconductor switches (36, 38) and the first and second lower semiconductor switches (32, 34) in the respective on states of the first and second upper semiconductor switches (36, 38) and the first and second lower semiconductor switches (32, 34). The current source (44) is arranged between one of the two terminals of the first circuit node (45) and the energy source (VBAT, GND), or between the other of the two terminals of the second circuit node (46) and the energy source (VBAT, GND).

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