Self-powered lock system with passive id detection

CROSS-REFERENCE TO RELATED APPLICATIONS

p-0002The present application claims priority on U.S. Application No. 61/503,041, filed on Jun. 30, 2011, and incorporated herein by reference.

TECHNICAL FIELD

p-0003The present invention relates to the field of electronic lock systems, and particularly to self-powered electronic lock systems.

BACKGROUND

p-0004Electronic or electric lock systems include locking devices that operate by means of an electrical current. Some electronic lock systems are powered by an external electrical energy source. For example, an electronic lock system can be line-powered, i.e. powered from a standard electrical utility system. In another example, an electronic lock system can be battery-powered.

p-0005Other electronic lock systems are self-powered and comprise an electrical energy generator which is driven by a door handle or lever used by a user for opening the door to which the self-powered lock system is secured.

p-0006Some electronic lock systems comprise an authentication device for authenticating and granting access to a user. For electronic lock systems powered by an external power source, the user first enters his identification (ID) using the authentication device. If the ID is valid, the lock mechanism is unlocked and the user is free to open the door. For self-powered electronic lock systems, the user has first to manually activate the door handle connected to the generator for powering the lock system. When sufficient energy has been generated, the electronic lock provides the user with a visual or audible signal for indicating that it is ready to be used. The user then authenticates himself using the authentication system and the lock mechanism is unlocked. Having to activate the door handle before authentication is not intuitive since externally powered electronic lock systems do not require any action from the user before authentication. Therefore, users of a self-powered electronic lock have to be instructed on the method of using the self-powered electronic lock system, which is time-consuming in addition of being inconvenient.

p-0007Therefore, there is a need for an improved self-powered electronic lock system.

SUMMARY

p-0008According to a first broad aspect, there is provided a self-powered lock system for a movable member, the system comprising an energy storage device having an electrical charge stored therein; a generator coupled to the storage device and adapted to generate electrical energy; a lock mechanism having a first state in which the movable member is locked and a second state in which the movable member is unlocked; a control unit coupled to the lock mechanism and adapted to place the lock mechanism in one of the first state and the second state; a trigger unit adapted to be activated with the lock mechanism in the first state, an activation of the trigger unit triggering a placement of the lock mechanism in the second state; and a passive detection unit coupled to the trigger unit and to the control unit, the detection unit detecting the activation of the trigger unit and, upon detection of the activation, providing a conductive path between the control unit and the storage device, thereby powering the control unit with the stored electrical charge, the control unit, upon being powered, placing the lock mechanism in the second state and triggering a storage of the generated electrical energy in the storage device for future use.

p-0009According to a second broad aspect, there is provided a control system for controlling a self-powered electronic lock for a movable member, the lock comprising an electrical energy generator and a lock mechanism having a first state in which the movable member is locked and a second state in which the movable member is unlocked, the control system comprising an energy storage device having an electrical charge stored therein; a control unit coupled to the lock mechanism and adapted to place the lock mechanism in one of the first state and the second state; a trigger unit adapted to be activated with the lock mechanism in the first state, an activation of the trigger unit triggering a placement of the lock mechanism in the second state; and a passive detection unit coupled to the trigger unit and to the control unit, the detection unit detecting the activation of the trigger unit and, upon detection of the activation, providing a conductive path between the control unit and the storage device, thereby powering the control unit with the stored electrical charge, the control unit, upon being powered, placing the lock mechanism in the second state and triggering a storage of the generated electrical energy in the storage device for future use.

p-0010In accordance with a further broad aspect, there is provided a method for controlling an electronic lock of a movable member, the method comprising passively detecting an activation of a trigger unit with the lock in a locked state; upon said detection, providing a conductive path between a control unit coupled to the lock and a storage device having an electrical charge stored therein, thereby powering the control unit with the stored electrical charge; upon said powering, the control unit placing the lock in an unlocked state; and charging the storage device for a next use with electrical energy generated by a generator coupled to the storage device.

p-0011The present self-powered electronic lock system may be operated as a battery-powered electronic lock system. In one embodiment, the generator is an electric generator operatively connected to a door lever to convert at least some of the mechanical energy generated during a manual operation of the door lever to electrical energy. Each time the generator is driven by the manual operation of a door lever during use of the lock system, the electrical energy generated by the generator is stored for a next use. Since the electrical energy is generated and accumulated during a normal operation of the lock system, the lock system may be seen as having “energy harvesting” capabilities. As a result, the user uses the present self-powered electronic lock system as he would use a battery-powered electronic lock system, i.e. the user first enters a user ID and then opens the door by operating the door lever, for example.

BRIEF DESCRIPTION OF THE DRAWINGS

p-0012Further features and advantages of the present invention will become apparent from the following detailed description, taken in combination with the appended drawings, in which:

p-0013<figref idrefs="DRAWINGS">FIG. 1</figref> is a block diagram of a self-powered electronic lock system, in accordance with a first embodiment;

p-0014<figref idrefs="DRAWINGS">FIG. 2</figref> is a flow chart illustrating a method for operating a self-powered electronic lock system, in accordance with an embodiment;

p-0015<figref idrefs="DRAWINGS">FIG. 3</figref> is a block diagram of a self-powered electronic lock system, in accordance with another embodiment; and

p-0016<figref idrefs="DRAWINGS">FIG. 4</figref> illustrates a self-powered electronic lock system comprising electronic circuitry, in accordance with an embodiment.

p-0017It will be noted that throughout the appended drawings, like features are identified by like reference numerals.

DETAILED DESCRIPTION

p-0018<figref idrefs="DRAWINGS">FIG. 1</figref> illustrates one embodiment of a self-powered electronic lock system <b>10</b> comprising a lock mechanism <b>12</b> of which the unlocking is triggered by a trigger unit <b>14</b>. The lock system <b>10</b> further comprises a generator <b>16</b> to be manually operated for generating electrical energy, an electrical energy storage unit <b>18</b> for storing the electrical energy generated by the generator <b>16</b>, a control unit <b>20</b> for controlling the operation of the lock system <b>10</b>, a passive detection unit <b>22</b> adapted to detect the activation of the trigger unit <b>14</b> while consuming no electrical energy, and a switch <b>24</b>.

p-0019The generator <b>16</b> is operatively connected to a door handle or lever (not shown) of which a displacement drives the generator <b>16</b>. The door handle may be any adequate mechanical device that can be used for opening a door and operatively connected to the generator <b>16</b> so as to drive the generator <b>16</b> upon operation by a user, i.e. when the user displaces the mechanical device. Examples of adequate door handles comprise a knob, a lever, a panic bar, and the like. The generator <b>16</b> is electrically connected to the electrical energy storage unit <b>18</b> so that electrical energy generated by the generator <b>16</b> upon operation of the door handle by a user is stored therein. The switch <b>24</b> electrically connects the electrical energy storage unit <b>18</b> and the control unit <b>20</b> and controls the powering of the control unit <b>20</b> from the electrical energy storage unit <b>18</b>. The control unit <b>20</b> is configured for powering the lock mechanism <b>12</b> in order to unlock the lock mechanism <b>12</b>.

p-0020In one embodiment, the self-powered electronic lock system <b>10</b> further comprises an authentication unit <b>26</b> connected to the control unit <b>20</b>. Once the trigger unit <b>14</b> has been activated by the user and the control unit <b>20</b> has been powered, the authentication unit <b>26</b> is powered by the control unit <b>20</b>. The authentication unit <b>26</b> is used by the user to enter an identification which is transmitted to the control unit <b>20</b>. The control unit <b>20</b> then compares the received user ID to a list of authorized IDs. If the user ID is valid, then the control unit <b>20</b> powers and unlocks the lock mechanism <b>12</b>. It should be understood that any adequate authentication unit <b>26</b> may be used. For example, the authentication unit <b>26</b> can be a keypad for entering a numerical code, password, and/or passphrase, a biometric sensor, a radio-frequency identification (RFID) reader for reading an RFID tag, or the like.

p-0021While the closing of the switch <b>24</b> is controlled by the passive detection unit <b>22</b>, different scenarios for the subsequent opening of the switch <b>24</b> may be possible. In one example, the switch <b>24</b> is adapted to close for powering the control unit <b>20</b> for a predetermined period of time. In another example, the opening of the switch <b>24</b> is controlled by the control unit <b>20</b>. In this case, the control unit <b>20</b> may be adapted to send a control signal to the switch <b>24</b> as long as it requires to be powered and the switch <b>24</b> opens as soon as no control signal is received from the control unit <b>20</b>. In a further example, the switch <b>24</b> remains closed for powering the control unit <b>20</b> as long as no stop signal is received from the control unit <b>20</b>.

p-0022In one embodiment, the control unit <b>20</b> is configured for unlocking the lock mechanism <b>12</b> for a predetermined period of time such as 2 s, 5 s, or the like. It should be understood that the predetermined period of time is chosen as a function of the storage capacity of the energy storage unit <b>18</b> and the electrical consumption of the system <b>10</b>. Once the predetermined period of time has elapsed, the control unit <b>20</b> stops powering the lock mechanism <b>12</b> which locks. Alternatively, the control unit <b>20</b> may send a lock signal to the lock mechanism <b>12</b> in order to lock the lock mechanism <b>12</b> while still powering the lock mechanism <b>12</b>.

p-0023The generator <b>16</b> may be any adequate device that generates electrical energy using a source of energy other than electrical energy. For example, the generator <b>16</b> may be an electric generator that converts mechanical energy generated by the activation of the door handle to electrical energy, as described above. For example, the generator <b>16</b> may be an electrical motor, a step motor, or the like. While in the description it is operatively connected to a door handle, it should be understood that the electric generator may be operatively connected to the door so that electrical energy be generated while a user opens the door. The generator <b>16</b> may also generate electrical energy from energy sources other than mechanical energy source, such as thermal or solar energy source. For example, the generator may be solar cell or a combination of solar cells installed on the door for example.

p-0024The electrical energy storage unit <b>18</b> may be any adequate device adapted to store electrical energy. Examples of adequate electrical energy storage unit comprise rechargeable batteries, capacitors such as aluminum electrolytic capacitors or solid-state capacitors for example, supercapacitors, and the like.

p-0025The lock mechanism <b>12</b> may be any adequate door fastener of which the locking and unlocking may be electrically controlled. For example, the lock mechanism <b>12</b> may be a magnetic lock, an electric lock or electric latch release, or the like. The lock mechanism <b>12</b> may also be a mechanical piece operatively connected to a door latch and movable between a first position in which the latch is allowed to move, thereby allowing a user to open the door, and a second position in which the latch is prevented from moving, thereby preventing the user from opening the door.

p-0026It should be understood that the lock system <b>10</b> may be used for controlling the lock/unlock state of any movable structure used to close off an entrance. For example, the lock system <b>10</b> may be used for controlling an entrance door, a safety door, a safe door, or the like.

p-0027<figref idrefs="DRAWINGS">FIG. 2</figref> illustrates one embodiment of a method <b>50</b> for operating the electric lock system <b>10</b>. The first step <b>52</b> comprises passively detecting a manual activation of the trigger unit <b>14</b> via the passive detection unit <b>22</b>. It should be understood that this step requires substantially no electrical energy consumption since the passive detection unit <b>22</b> consumes substantially no electrical energy for detecting the manual activation of the trigger unit <b>14</b>. Upon detection of the activation of the trigger unit at step <b>52</b>, the passive detection unit <b>22</b> is powered using the energy stored in the energy storage unit <b>18</b> and triggers the closing of the switch <b>24</b>, and therefore the powering of the control unit <b>20</b> by the energy storage unit <b>18</b> via the switch <b>24</b>, at step <b>54</b>. Similarly, the triggering of the closing of the switch <b>24</b> by the passive detection unit <b>22</b> requires substantially no electrical energy consumption since the passive detection unit <b>22</b> consumes substantially no electrical energy until the closing of the switch <b>24</b>.

p-0028At step <b>56</b>, the control unit <b>20</b> triggers the unlocking of the lock mechanism <b>12</b> by powering the lock unit <b>12</b> using the energy received from the energy storage unit <b>18</b>. A visual and/or audible signal indicative of the unlock status for the lock mechanism <b>12</b> may be provided to the user for indicating that the lock device is unlocked. At step <b>58</b>, the user charges the energy storage unit <b>18</b> by opening the door. Since the door handle is operatively connected to the generator <b>16</b>, the operation of the door handle drives the generator <b>16</b> which generates electrical energy. The electrical energy generated by the generator <b>16</b> is then stored in the energy storage unit <b>18</b> for a future opening of the door.

p-0029It should be understood that the energy storage unit <b>18</b> is charged before the first use of the self-powered electronic lock system <b>10</b>. Then, each operation of the handle for opening of the door charges the energy storage unit <b>18</b> for a subsequent use of the lock system <b>10</b>.

p-0030The passive detection unit <b>22</b> may be any adequate unit adapted to detect a manual activation of the trigger unit <b>14</b> while consuming substantially no electrical energy, and trigger the closing of the switch <b>24</b>. <figref idrefs="DRAWINGS">FIG. 3</figref> illustrates one embodiment of a self-powered electronic lock system <b>60</b> comprising a trigger switch <b>64</b> for triggering the unlocking of a lock mechanism <b>62</b>. The lock system <b>60</b> further comprises a generator <b>66</b> operatively connected to a door handle (not shown) to be manually operated for generating electrical energy, a capacitor <b>68</b> for storing the electrical energy generated by the generator <b>66</b>, a control unit <b>70</b> for controlling the operation of the lock system <b>60</b>, a potential variation detector <b>72</b> adapted to detect the activation of the trigger switch <b>64</b> while consuming substantially no electrical energy and trigger the powering of the control unit <b>70</b>, and a switch <b>74</b> connected between the capacitor <b>68</b> and the control unit <b>70</b>. The capacitor <b>68</b> has one terminal <b>68</b><i>a </i>connected to the potential variation detector <b>72</b> and the switch <b>74</b> while the other terminal <b>68</b><i>b </i>is grounded.

p-0031The trigger switch <b>64</b> comprises first and second electrical contacts <b>76</b> and <b>78</b>. The trigger switch <b>64</b> further comprises a mechanical movable connector (not shown) to be manually operated for electrically connecting the two contacts <b>76</b> and <b>78</b> together. In one example, one of the two contacts <b>76</b> and <b>78</b> may be movable between an open position in which the movable contact is away from the other contact and a closed position in which the movable contact is electrically connected to the other contact. In this case, the mechanical connector may be a push button to be manually operated by a user for moving the movable contact in the closed position. In another example, the two contacts <b>76</b> and may have a fixed relative position and the mechanical connector may be a push button provided with an electrical conductor element for electrically connecting the two contacts <b>76</b> and <b>78</b> upon depression of the push button by the user. It should be understood the mechanical connector may be any adequate mechanical device which allows the two contacts <b>76</b> and <b>78</b> to be electrically connected together upon manual operation thereof. While the description refers to a push button, other examples of adequate mechanical connectors comprise a switch, a lever, and the like.

p-0032In the open position, the two contacts <b>76</b> and <b>78</b> are each maintained at a different electrical potential. The contact <b>76</b> is connected to the terminal <b>68</b><i>a </i>of the capacitor via the potential variation detector <b>72</b> so that the contact <b>76</b> be maintained at a first non-zero electrical potential while the contact <b>78</b> is maintained at a second electrical potential different from the first electrical potential. For example, the contact <b>78</b> may be grounded.

p-0033Upon manual operation of the trigger switch <b>64</b> by the user in order to trigger the unlocking of the lock mechanism <b>62</b>, the two contacts <b>76</b> and <b>78</b> are electrically connected together and the electrical potential of the contact <b>76</b> varies. The potential variation detector <b>72</b> detects the variation of electrical potential for the contact while consuming substantially no electrical energy. The variation of electrical potential triggers the powering of the potential variation detector <b>72</b> from the capacitor <b>68</b>. Once powered, the potential variation detector <b>72</b> closes the switch <b>74</b> to power the control unit <b>70</b> using the energy stored in the capacitor <b>68</b>. Then the control unit <b>70</b> powers the lock mechanism <b>62</b> which unlocks for a predetermined period of time before locking again. In one embodiment, the control unit <b>70</b> powers the lock mechanism <b>62</b> during the whole predetermined period of time. Alternatively, the control unit powers the lock mechanism <b>62</b> for unlocking the lock, then stops powering the lock mechanism <b>62</b>, and then powers again the lock mechanism <b>62</b> for locking the lock mechanism <b>62</b> after the predetermined period of time.

p-0034In one embodiment, the lock system <b>60</b> may further comprise an authentication unit powered by the control unit <b>70</b>. In this case, the authentication is adapted to allow a user to enter his user ID. The user ID is then sent to the control unit <b>70</b> which verifies whether the user ID is valid before unlocking the lock mechanism <b>62</b>. In one embodiment, the authentication unit is integral with the trigger switch <b>64</b>. One example of an adequate integrated authentication unit and trigger switch may be a keypad which is used by the user to enter a numerical code, password, and/or passphrase.

p-0035<figref idrefs="DRAWINGS">FIG. 4</figref> illustrates one embodiment of a self-powered electronic lock system <b>100</b> comprising a keypad <b>102</b> for both triggering the powering of the lock system in order to unlock a lock mechanism <b>104</b> and entering a user ID. The lock system <b>100</b> is adapted to detect a key activation on the keypad <b>102</b> without any active power consumption. As a result, the lock system <b>100</b> operates as a battery powered lock system since the user can simply first enter his user ID before operating the door handle for opening the door.

p-0036The lock system <b>100</b> further comprises a generator <b>106</b> for generating electrical energy, a microcontroller <b>108</b> for controlling the operation of the lock system <b>100</b>, a capacitor <b>110</b> for storing electrical energy, and an electronic circuit <b>112</b> which interconnects the keypad <b>102</b>, the lock mechanism <b>104</b>, the generator <b>106</b>, the capacitor <b>110</b>, and the microcontroller <b>108</b> together. The generator <b>106</b> is operatively connected to the handle of the door which is provided with the lock mechanism <b>104</b>, for example. The manual operation of the door handle by a user drives the generator <b>106</b> which generates electrical energy. The generated electrical energy is then stored in the capacitor <b>110</b>.

p-0037As illustrated in <figref idrefs="DRAWINGS">FIG. 4</figref>, the generator <b>106</b> is connected to the capacitor via two bridge rectifiers <b>114</b> and <b>116</b> which convert the Alternating Current (AC) electrical current generated by the generator <b>106</b> into an adequate Direct Current (DC) electrical current for charging the capacitor <b>110</b>. It should be understood that the capacitor <b>110</b> is chosen to store therein enough energy for powering the lock system <b>100</b> during at least one use thereof. Similarly, the generator <b>106</b> is chosen to generate enough electrical energy for charging the capacitor <b>110</b> during a single manual operation of the door handle.

p-0038The keypad <b>102</b> comprises a plurality of buttons or keys organized as rows and columns to form a matrix. In the present embodiment, the keypad buttons are organized according to a matrix comprising three columns and four rows. Each button column is associated with a respective column electrical connection <b>118</b><i>a</i>, <b>118</b><i>b</i>, <b>118</b><i>c </i>which is connected to the microcontroller <b>108</b>. For example, the buttons of the first column, i.e. the “1”, “4”, “7”, and “*” buttons, are each associated with the column electrical connection <b>118</b><i>a</i>. Each button row is associated with a respective row electrical connection <b>120</b><i>a</i>, <b>120</b><i>b</i>, <b>120</b><i>c</i>, <b>120</b><i>d </i>which is also connected to the microcontroller <b>108</b>. For example, the buttons of the second row, the “4”, “5”, and “6” buttons, are each associated with the row electrical connection <b>120</b><i>b</i>. When the keypad is not used, the row and column electrical connections <b>118</b>-<b>118</b><i>c </i>and <b>120</b><i>a</i>-<b>120</b><i>d </i>are not electrically connected together. By depressing a given keypad button, its respective row and column electrical connections electrically connect together. For example, by depressing the button “8” of the keypad, the row electrical connection <b>120</b><i>c </i>and the column electrical connection <b>118</b><i>b </i>electrically connect together.

p-0039A capacitor <b>122</b><i>a</i>, <b>122</b><i>b</i>, <b>122</b><i>c</i>, and <b>122</b><i>d </i>is present along a respective row electrical connection <b>120</b><i>a</i>, <b>120</b><i>b</i>, <b>120</b><i>c</i>, and <b>120</b><i>d </i>between the keypad <b>102</b> and the microcontroller <b>108</b>. Each capacitor <b>122</b><i>a</i>, <b>122</b><i>b</i>, <b>122</b><i>c</i>, and <b>122</b><i>d </i>acts a filter which allows varying or AC electrical signals to propagate from the keypad <b>102</b> to the microcontroller <b>108</b> while preventing steady-state or DC electrical signals from propagating from the keypad <b>102</b> to the microcontroller <b>108</b>. Each row electrical connection <b>120</b><i>a</i>, <b>120</b><i>b</i>, <b>120</b><i>c</i>, and <b>120</b><i>d </i>are electrically connected to the positive terminal of the capacitor <b>110</b> via a respective resistor <b>124</b><i>a</i>, <b>124</b><i>b</i>, <b>124</b><i>c</i>, and <b>124</b><i>d</i>, and a transistor <b>126</b>. As a result, when the capacitor <b>110</b> is charged, each row electrical connection <b>120</b><i>a</i>, <b>120</b><i>b</i>, <b>120</b><i>c</i>, and <b>120</b><i>d </i>is maintained at a non-zero electrical potential. The capacitors <b>122</b><i>a</i>, <b>122</b><i>b</i>, <b>122</b><i>c</i>, and <b>122</b><i>d </i>act as an isolator between the microcontroller <b>108</b> and the row electrical connections <b>120</b><i>a</i>, <b>120</b><i>b</i>, <b>120</b><i>c</i>, and <b>120</b><i>d</i>, thereby allowing the electrical potential of the row electrical connections <b>120</b><i>a</i>, <b>120</b><i>b</i>, <b>120</b><i>c</i>, and <b>120</b><i>d </i>to be maintained. As a result, the voltage applied to the row electrical connections <b>120</b><i>a</i>, <b>120</b><i>b</i>, <b>120</b><i>c</i>, and <b>120</b><i>d </i>when the lock system <b>100</b> is not in use does not flow through the microcontroller <b>110</b> and substantially no electrical energy is consumed. Similarly, each column electrical potential <b>118</b><i>a</i>, <b>118</b><i>b</i>, and <b>118</b><i>c </i>is maintained an electrical potential which is different from that of the row electrical connection <b>120</b><i>a</i>, <b>120</b><i>b</i>, <b>120</b><i>c</i>, and <b>120</b><i>d</i>. For example, the column electrical potential <b>118</b><i>a</i>, <b>118</b><i>b</i>, and <b>118</b><i>c </i>may be grounded via resistors <b>152</b><i>a</i>, <b>152</b><i>b</i>, and <b>152</b><i>c</i>, respectively.

p-0040The transistor <b>126</b> is further electrically connected to a first voltage detector <b>128</b> via two transistors <b>130</b> and <b>132</b> such as bipolar junction transistors or metal-oxide-semiconductor field-effect transistors (MOSFETs) for example. The first voltage detector <b>128</b> is electrically connected to a regulator <b>134</b> via a diode <b>36</b> and two transistors <b>138</b> and <b>140</b>. The regulator <b>134</b> is further electrically connected to the capacitor <b>10</b> via the transistor <b>140</b> and to the microcontroller <b>108</b> and is used for powering the microcontroller <b>108</b> using the electrical energy stored in the capacitor <b>110</b>. In addition, the microcontroller <b>108</b> is connected to a driver <b>142</b> connected to the lock mechanism <b>104</b>.

p-0041The lock system <b>100</b> operates as follows. It should be understood that the capacitor <b>110</b> has to be charged before the first use of the system <b>100</b>. The door handle operatively connected to the generator <b>106</b> may be operated to drive the generator <b>106</b> and charge the capacitor <b>110</b> before the first use of the lock system <b>100</b>.

p-0042Once the capacitor <b>110</b> has been charged, the self-powered lock system <b>100</b> can be used as a battery powered lock system, i.e. the user first enters his ID using the keypad <b>102</b> and then manually operates the handle to open the door.

p-0043In order to unlock the lock mechanism <b>104</b>, a user first enters his ID using the keypad <b>102</b>. The user starts by depressing the button corresponding to the first ID element, such as the “3” button for example. The depression of the button electrically connects its respective row and column electrical connections together. Since the respective row and column electrical connections are maintained at different electrical potentials before the depression of the keypad button, electrically connecting the respective row and column electrical connections together changes the electrical potential of the respective row electrical connection. For example, the depression of the “3” button interconnects the row electrical connection <b>120</b><i>a </i>and the column electrical connection <b>118</b><i>c </i>together, and the electrical potential of the row electrical connection <b>120</b><i>a </i>varies. In the present embodiment, the electrical potential for the row electrical connection <b>120</b><i>a </i>decreases down to a low level, such as close to zero for example, since the column electrical connection <b>118</b><i>c </i>is grounded via resistor <b>152</b><i>c</i>. The transistor <b>126</b> which acts as a passive potential detector detects the variation of electrical potential for the respective row electrical connection, such as electrical connection <b>120</b><i>a </i>for example, while consuming no electrical energy. The variation of electrical potential triggers the powering of the electric circuit <b>112</b>. The variation of electrical potential for the respective row electrical connection activates the transistor <b>126</b> so that it conducts and activates in turn the transistor <b>130</b>. When the transistor <b>130</b> conducts, the transistor <b>132</b> is activated which allows electrical energy stored in the capacitor <b>110</b> to reach the voltage detector <b>128</b>. If the voltage applied to the detector <b>128</b> is above a predetermined threshold, the voltage detector <b>128</b> outputs a logic high which activates the transistor <b>138</b> via the diode <b>136</b>, which in turn activates the transistor <b>140</b>. When the transistor <b>140</b> conducts, the regulator <b>134</b> is powered by the capacitor <b>110</b>, which in turn powers the microcontroller <b>108</b>.

p-0044When powered, the microcontroller <b>108</b> first receives the user ID from the keypad, then determines the validity of the user ID, and finally unlocks the lock mechanism <b>104</b> if the user ID is valid. The reception of the user ID by the microcontroller <b>108</b> from the keypad <b>102</b> occurs as follows. Once powered, the microcontroller <b>108</b> sends an electrical pulse on each column electrical connection <b>118</b><i>a</i>, <b>118</b><i>b</i>, and <b>118</b><i>c </i>towards the keypad <b>102</b>. When a particular button is depressed, its corresponding row and column electrical connections electrically interconnects and the electrical pulse propagating on the corresponding column electrical connection can reach the corresponding row electrical connection. Then, the electrical pulse propagates on the corresponding row electrical connection up to the microcontroller <b>108</b> via the capacitor <b>122</b><i>a</i>-<b>122</b><i>d </i>present along the corresponding electrical row connection since the electrical pulse is a varying signal and can therefore be transmitted by the corresponding capacitor <b>122</b><i>a</i>-<b>122</b><i>d</i>. Knowing from which row electrical connection the pulse signal is received, the microcontroller <b>108</b> can determine which keypad button is depressed. Following the detection of the depression of a second keypad button, the microcontroller <b>108</b> sends another pulse signal on each column electrical connection <b>118</b><i>a</i>, <b>118</b><i>b</i>, and <b>118</b><i>c </i>in order to determine the second ID code element entered by the user, i.e. to identify the second keypad button that is being depressed by the user.

p-0045Referring back to the example in which the first ID element entered by the user is a “3”, i.e. when the user first depresses the “3” button, the electrical connections <b>118</b><i>c </i>and <b>120</b><i>a </i>electrically connect together so that the electrical pulse propagating on the column electrical connection <b>118</b><i>c </i>reaches the row electrical connection <b>120</b><i>a </i>before propagating up to the microcontroller <b>108</b> via the capacitor <b>122</b><i>a</i>. Upon reception of the signal from the row electrical connection <b>120</b><i>a</i>, the microcontroller <b>108</b> determines that the “3” button is depressed. Then, after the detection of the depression of a second keypad button, the microcontroller <b>108</b> sends a second electrical pulse on each one of the column electrical connections <b>118</b><i>a</i>, <b>118</b><i>b</i>, and <b>118</b> to identify the second depressed keypad button.

p-0046It should be understood that the time required for detecting that a button has been depressed, powering the microcontroller <b>108</b> and determining which button has been depressed is shorter or substantially equal to the time during which the button is depressed.

p-0047Once the microcontroller <b>108</b> has determined all of the ID elements, the validity of the user ID is verified. If the user ID is valid, the driver <b>142</b> is powered by the microcontroller <b>108</b>. When powered, the driver <b>142</b> unlocks the lock mechanism <b>104</b> and a visual and/or audible signal (not shown) may be provided to the user for indicating that the lock mechanism <b>104</b> is unlocked. The user then operates the door handle for opening the door and the manual operation of the handle drives the generator <b>106</b>. The electrical energy generated by the generator <b>106</b> is stored in the capacitor <b>110</b> for a next use of the lock system <b>100</b>, i.e. the next unlocking of the lock mechanism <b>104</b>.

p-0048As a result, the lock system <b>100</b> is capable of harvesting electrical energy generated from a normal operation in order to power the elements of the lock system <b>100</b>. The energy stored during a particular operation is stored for a subsequent use of the lock system <b>100</b> and all of the elements of the lock system <b>100</b> are disconnected at the end of the particular operation, so that the lock system <b>100</b> consumes substantially no electrical energy between uses. The elements of the lock system <b>100</b> are then reconnected when the user depresses a key on the keypad <b>102</b> and the electrical energy previously generated and stored in the capacitor <b>110</b> is used for powering the lock system for the new operation cycle. Therefore, the lock system <b>100</b> may be used without having to activate the door handle before entering the user ID.

p-0049The electrical circuit <b>112</b> further comprises a diode <b>144</b> for electrically connecting the microcontroller <b>108</b> to the transistor <b>138</b>. The microcontroller <b>108</b> can then force the regulator <b>134</b> to provide power thereto by applying an electrical signal, such as a high signal, to the transistor <b>138</b> via the diode <b>144</b> to activate the transistor <b>138</b> as long as the microcontroller <b>108</b> requires to be powered.

p-0050In one embodiment, the circuit <b>112</b> further comprises a diode <b>146</b> which connects the generator <b>106</b> to the transistor <b>130</b> in order to provide the microcontroller <b>108</b> with power during the operation of the generator <b>106</b>. As a result, the operation of the door handle which drives the generator <b>106</b> causes the microcontroller <b>108</b> to be powered. Upon manual operation of the handle, the generator <b>106</b> applies an electrical signal to the transistor <b>130</b> through the diode <b>146</b> which converts the AC current generated by the generator <b>106</b> to a DC current. As described above, if the voltage detector <b>128</b> determines that the voltage of the capacitor <b>110</b> is greater than a predetermined threshold, then the transistors <b>138</b> and <b>140</b> are activated to provide the microcontroller <b>108</b> with power via the regulator <b>134</b>.

p-0051In the same or another embodiment, the circuit <b>112</b> further comprises a diode <b>148</b> and a transistor <b>150</b> which connect the generator <b>106</b> to the microcontroller <b>108</b> for informing the microcontroller <b>108</b> that the generator <b>106</b> is in operation, assuming the microcontroller <b>108</b> is powered. Upon manual operation of the door handle, the generator <b>106</b> applies an electrical signal to the transistor <b>150</b> through the diode <b>148</b> which converts the AC current generated by the generator <b>106</b> to a DC current. When the transistor <b>150</b> conducts, an electrical signal, such as a pulsed signal for example, is applied to the microcontroller <b>108</b> which, if powered, determines that the generator operates.

p-0052While in the present description, the keypad buttons are organized as rows and columns, it should be understood that other configurations are possible. For example, the keypad buttons may be organized as a single row or column so that each button is associated with a respective column electrical connection <b>118</b> and a respective row electrical connection <b>120</b>, and that each column electrical connection and each row electrical connection is associated with a single keypad button.

p-0053While the variation of the electrical potential of the row electrical connections <b>120</b><i>a</i>-<b>120</b><i>d </i>is used for triggering the powering of the microcontroller <b>108</b>, it should be understood that the electrical potential of the column electrical connections <b>118</b><i>a</i>-<b>118</b><i>c </i>may be used for triggering the powering of the microcontroller <b>108</b>. In this case, the column electrical connections <b>118</b><i>a</i>-<b>118</b><i>c </i>are electrically connected to the transistor <b>126</b> so that their electrical potential be maintained to a first electrical potential and to the microcontroller <b>108</b> through the capacitors <b>122</b><i>a</i>-<b>122</b><i>d</i>. The row electrical connections <b>120</b><i>a</i>-<b>120</b><i>d </i>are then directly connected to the microcontroller <b>108</b> in addition to being grounded via the resistors <b>152</b><i>a</i>, <b>152</b><i>b</i>, and <b>152</b><i>c. </i>

p-0054The energy harvested during a door handle operation is at least equal to the energy used by the microprocessor <b>108</b> and the electronic circuit <b>112</b> during an opening cycle. Therefore, during a normal operation cycle where access is granted and the user operates the door handle, the energy stored in the storage capacitor <b>110</b> is sufficient for the next operation cycle. When the microcontroller <b>108</b> sends a stop signal, such as a low signal for example, to the transistor <b>138</b> through the diode <b>144</b> at the end of an opening cycle, the power provided to the electronics is turned off. The charge on the storage capacitor <b>110</b> is then conserved until the next opening cycle. As a result, the user can simply enter the code without prior operation of the door handle.

p-0055In one embodiment, if the user ID entered by the user is valid and access is granted, the microcontroller <b>108</b> sends a signal to the driver <b>142</b> for unlocking the lock mechanism <b>104</b>. The user then operates the door handle to open the door and thus recharges the capacitor <b>100</b>. After a predetermined period of time, the microcontroller <b>110</b> sends a second signal to the driver <b>142</b> to lock the lock mechanism <b>104</b> before sending a low signal to the transistor <b>138</b> through the diode <b>144</b> for turning off the power.

p-0056As described above, the electronic circuitry is completely disconnected between uses. When the lock system is not in use, the power consumption is only caused by the leakage of the semiconductor devices and capacitors. In one embodiment, a leakage current of about 50 pA or less may be achieved by adequately selecting the electric and electronic components. In comparison, the use of powered semiconductors such as low-power microcontrollers between lock uses would increase the power consumption by about three or four orders of magnitude.

p-0057While any adequate energy storage devices may be used for storing the electrical energy generated by the generator, it should be understood that the characteristics of the storage device will affect the end performance of the lock system. In one embodiment, a critical factor for the selection of the energy storage device may be the self-discharge characteristics. The internal leakage limits the time interval between uses of the lock system. However, by adequately choosing low leakage components, a time interval between uses of several months or even a full year may be obtained. Another important factor may be the ability for the energy storage device to accumulate the energy generated by the generator during a short period of time, i.e. the period of time during which the door lever is operated.

p-0058In one embodiment where the lock has not been used for a period of time long enough for depleting the storage device so that the level of charge would not be sufficient for an opening cycle, the lever would need to be operated in order to recharge the capacitor prior to entering the user ID.

p-0059The remaining resistors, capacitors, diodes and other circuit elements not otherwise described in detail above with reference to <figref idrefs="DRAWINGS">FIG. 4</figref> are employed as components of time constant networks, current limiting elements, protection or filtering networks which are fully understood by the person skilled in the art, thereby not requiring further detailed description.

p-0060The embodiments of the invention described above are intended to be exemplary only. The scope of the invention is therefore intended to be limited solely by the scope of the appended claims.