The present disclosure relates to the field of display technologies, and particularly, to a display panel and a display device.
Display panels include a light-emitting shift circuit electrically connected to a sub-pixel through a light-emitting control signal line configured to provide a light-emitting control signal to the sub-pixel to control a light-emitting state of the sub-pixel.
The light-emitting shift circuit includes multiple transistors. However, when the transistor is affected by external factors, such as light, a threshold voltage of the transistor is is prone to drift, thereby affecting the operation reliability of the light-emitting shift circuit. For example, when affected by the characteristics of the transistor, the light-emitting shift circuit may have voltage instability when outputting a light-emitting enable voltage level, causing the jump of the output signal, thereby affecting the light-emitting state of the sub-pixel. This may even make the sub-pixel unable to emit light normally due to function failure of the light-emitting shift circuit, which seriously affects the display performance.
A first aspect of the present disclosure provides a display panel, including a substrate, a circuit layer located at a side of the substrate, and a top light-shielding layer configured to receive a voltage signal. In an embodiment, the circuit layer includes a light-emitting shift circuit. In an embodiment, the light-emitting shift circuit includes a first output module and at least one control module. In an embodiment, the first output module is electrically connected to a first node, a first fixed potential signal line, and a light-emitting control signal line, and is configured to, in response to a voltage of the first node, transmit a light-emitting enable voltage provided by the first fixed-potential signal line to the light-emitting control signal line. In an embodiment, the at least one control module is electrically connected to the first node and includes at least one control transistor. In an embodiment, the top light-shielding layer is located at a side of the at least one control transistor facing away from the substrate. In an embodiment, in a direction perpendicular to a plane of the substrate, the top light-shielding layer overlaps with a channel of one or more of the at least one control transistor.
A second aspect of the present disclosure provides a display device. In an embodiment, the display device includes a display panel, including a substrate, a circuit layer located at a side of the substrate, and a top light-shielding layer configured to receive a voltage signal. In an embodiment, the circuit layer includes a light-emitting shift circuit. In an embodiment, the light-emitting shift circuit includes a first output module and at least one control module. In an embodiment, the first output module is electrically connected to a first node, a first fixed potential signal line, and a light-emitting control signal line, and is configured to, in response to a voltage of the first node, transmit a light-emitting enable voltage provided by the first fixed-potential signal line to the light-emitting control signal line. In an embodiment, the at least one control module is electrically connected to the first node and includes at least one control transistor. In an embodiment, the top light-shielding layer is located at a side of the at least one control transistor facing away from the substrate. In an embodiment, in a direction perpendicular to a plane of the substrate, the top light-shielding layer overlaps with a channel of one or more of the at least one control transistor.
In order to better illustrate technical solutions of embodiments of the present disclosure, the accompanying drawings used herein in the embodiments are briefly described below. The drawings described below are merely a part of some embodiments of the present disclosure. Based on these drawings, those skilled in the art can obtain other drawings.
In order to better illustrate the technical solutions of the present disclosure, some embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.
It should be clear that the described embodiments are only some of the embodiments of the present disclosure, rather than all of the embodiments. Based on the embodiments described in the present disclosure, all other embodiments obtained by those of ordinary skill in the art shall fall within a scope of the present disclosure.
The terms used in some embodiments of the present disclosure are used only for the purpose of describing specific embodiments, and are not intended to limit the present disclosure. As used in some embodiments of the present disclosure and the appended claims, the singular forms “a/an” “the” and “said” are also intended to include the plural forms as well, unless the context clearly dictates otherwise.
It should be understood that the term “and/or” used in this document is only an association relationship to describe the associated objects, indicating that there can be three relationships, for example, A and/or B, which can indicate that A alone, A and B, and B alone. The character “/” in this document generally indicates that the related objects are an “or” relationship.
Referring to
In some embodiments, with reference to
According to the structure of the light-emitting shift circuit 3, the first output module 5 outputs the light-emitting enable voltage (low level) in response to the voltage of the first node N1. If the potential of the first node N1 is not stable, a conduction degree of the transistor in the output module 5 varies, as a result, the signal output by the first output module 5 is unstable and cannot maintain a constant low potential, thereby affecting the light-emitting stale of the light-emitting element 10. The control module 6 is directly connected to the first node N1, therefore, the characteristics of elements of the control transistor M0 in the control module 6 affects the potential of the first node N1, thereby greatly affecting the stability of the light-emitting enable voltage output by the first output module 5.
In the embodiments of the present disclosure, the top light-shielding layer 7 is provided. On the one hand, the top light-shielding layer 7 can block external ambient light from the top of the display panel, so as to prevent the external ambient light from reaching the channel of the control transistor M0, thereby reducing an effect of the light on a threshold voltage of the control transistor M0 and thus preventing the threshold value of the control transistor M0 from being forward biased. In this way, the reliability of the working state of the control transistor M0 in the control module 6 can be improved, thereby avoiding an effect on the voltage of the first node N1. Therefore, the light-emitting shift circuit 3 can output a stable low level during a light-emitting phase, thereby increasing the accuracy of the light-emitting brightness of the element 10.
On the other hand, the circuit layer 2 is provided with a large number of metal wires for forming transistors or signal lines, when the top light-shielding layer 7 is located at a side of the control transistor M0 facing away from the substrate 1. It is equivalent that the top light-shielding layer 7 is arranged inside the layer of the display panel. In this case, signals can be transmitted on the top light-shielding layer 7 by making the top light-shielding layer 7 receive a voltage signal, to prevent a large-area metal layer without signals from affecting the electrical characteristics of the transistors in the circuit layer 2.
In some embodiments, referring to
It is found that the element characteristics of the second transistor M2 in the light-emitting shift circuit 3 directly affects the stability of the output signal of the light-emitting shift circuit 3. Combining the above circuit structure, it can be seen that the gate electrode of the second transistor M2 is electrically connected to the first electrode of the second transistor M2, and in this case, the second transistor M2 is equivalent to a unidirectional-conducted diode. In an embodiment, during the light-emitting phase, the shift control signal line IN provides a low potential, the second transistor M2 is normally turned on, and the second transistor M2 transmits a low potential provided by the shift control signal line IN to the first node N1, and then the first output module 5 is controlled to transmit the light-emitting enable voltage (low level) transmitted by the first fixed-potential signal line VGL to the light-emitting control signal line Emit.
However, if the threshold voltage of the second transistor M2 is forward shifted because the second transistor M2 is affected by the external ambient such as light, it will affect the magnitude of the potential written to the first node N1 through the second transistor M2, as a result, the potential of the first node N1 is raised. After the potential of the first node N1 is raised, the ability of the first output module 5 to output a low level is weakened. In this case, the signal transmitted by the light-emitting shift circuit 3 to the light-emitting control signal line Emit generates a small jump, making the output potential be raised to offset the ideal lighting enable voltage. As a result, the light-emitting brightness of the light-emitting element 10 becomes low, or even fails to emit light normally, which causes the function failure of the light-emitting shift circuit 3.
Therefore, in the embodiments of the present disclosure, the first top light-shielding layer 71 shields the channel of the second transistor M2, thereby reducing the effect of light on the threshold voltage of the second transistor M2 and preventing the threshold voltage of the second transistor M2 from being forward biased. In this way, the light-emitting shift circuit 3 can output a stable light-emitting enable voltage during the light-emitting phase to a greater extent, thereby ensuring the accuracy of light-emitting brightness of the light-emitting element 10.
In some embodiments, referring to
In a conventional light-emitting shift circuit, a voltage stabilization capacitor is usually directly electrically connected to the first node N1 to stabilize the voltage of the first node N1. In the embodiments of the present disclosure, the first capacitor C1 is not directly connected to the first node N1, and the potential of the first node N1 is coupled to a lower level by using an overall structure formed by the third transistor M3 and the first capacitor C1 during the light-emitting phase, so that the light-emitting enable voltage (low level) transmitted by the first fixed-potential signal line VGL is transmitted through the first output module 5 with less loss, thereby outputting a lower low level to the light-emitting control signal line Emit.
In some embodiments, the gate electrode and the first electrode of the second transistor M2 is short-circuited, which is equivalent to a unidirectional-conducted diode. Due to the third transistor M3 and the first capacitor C1, the potential of the second node N2 will be coupled by the second clock signal. When the potential of the second node N2 is greater than the potential of the first node N1, the second transistor M2 is turned off, and change of the potential of the second node N2 will not affect the potential of the first node N1. When the potential of the second node N2 is smaller than the potential of the first node N1, the second transistor M2 is gradually turned on, the potential of the first node N1 tends to VN1+|Vth|, the second transistor M2 keeps the first node N1 at a relatively stable voltage during most time. However, compared with the traditional voltage stabilization capacitor, the voltage stabilization capability of the second transistor M2 is not so strong, so when the signal output by the light-emitting shift circuit jumps to a low level, the potential of the first node N1 will be coupled to a lower level, and the conduction degree of the first output module 5 increases. In this case, the potential output by the light-emitting shift circuit to the light-emitting control signal line Emit is lower, and the light-emitting brightness of the light-emitting element 10 is more stable. In some embodiments of the present disclosure, the channel of the third transistor M3 is shielded by the first top light-shielding layer 71, so that the element characteristics of the third transistor M3 are more stable. In this case, the potential of the second node N2 will change when the second clock signal jumps to a high level or a low level, thereby adjusting the conduction state of the second transistor M2.
In combination with the circuit structure of the light-emitting shift circuit 3, it can be seen that the second transistor M2 and the first capacitor C1 are connected to each other. In the layout design of the circuit, the second transistor M2 is also relatively close to the first capacitor C1. In the embodiments of the present disclosure, the first top light-shielding layer 71 is used to shield external ambient light, and the first top light-shielding layer 71 is reused as the first electrode plate C11 or the second electrode plate C12 of the first capacitor C1, so that a horizontal space occupied by the first capacitor C1 at a side of a horizontal direction of the second transistor M2 can be reduced to optimize the layout design; or, without increasing the horizontal space occupied by the first capacitor C1 at the side of the horizontal direction of the second transistor M2, a directly-facing area between two electrode plates of the first capacitor C1 can be increased, and the design flexibility of the capacitance of the first capacitor C1 can be improved.
In some embodiments, the first top light-shielding layer 71 is electrically connected to the second electrode plate of the first capacitor C1. In the layout design of the circuit, the second transistor M2 is relatively close to the first capacitor C1, and correspondingly, the first top light-shielding layer 71 is also relatively close to the second electrode plate of the first capacitor C1. Therefore, the first top light-shielding layer 71 is electrically connected to the second electrode plate of the first capacitor C1, so that there is a voltage signal that transmits on the first top light-shielding layer 71 and a length of a connection wire electrically connected to the first top light-shielding layer 71 can be reduced.
In some embodiments, the first top light-shielding layer 71 can also be electrically connected to the second node N2. In the layout design of the circuit, the second transistor M2 is relatively close to the second node N2, and accordingly, the first top light-shielding layer 71 is relatively close to the second node N2, so the electrical connection between the first top light-shielding layer 71 and the second node N2 can optimize the layout design. When the first top light-shielding layer 71 is electrically connected to the second node N2, the potentials of the first top light-shielding layer 71 and the first electrode and the gate electrode of the second transistor M2 change synchronously, so that a jump of the potential of the first top light-shielding layer 71 has a reduced influence on the potentials of the first electrode and gate electrode of the second transistor M2.
In some embodiments, referring to
It should be noted that the embodiments of the present disclosure illustrate the light-emitting shift circuit 3 with two structures as shown in
When the shift control signal line IN provides a low level (light-emitting enable level) and the first clock signal line CK provides a low level, the fourth transistor M4 is turned on to transmit the low level provided by the shift control signal line IN to the first node N1, and then the first output module 5 is controlled to output the light-emitting enable voltage. It can be seen that the element characteristic of the fourth transistor M4 will directly affect the potential of the first node N1, thereby affecting the stability of the light-emitting enable voltage output by the first output module 5. In the embodiments of the present disclosure, the second top light-shielding layer 72 is provided to shield the channel of the fourth transistor M4, thereby reducing the effect of light on the threshold voltage of the fourth transistor M4. In this case, when the first clock signal line CK provides a low level, the fourth transistor M4 can be turned on to a greater extent, thereby ensuring that the potential of the first node N1 and the low level provided by the shift control signal line IN tend to be consistent.
It should be noted that referring to
In some embodiments, referring to
In the light-emitting shift circuit 3, the fifth transistor M5 is a transistor for preventing abnormal power-off. In general, the first control signal line RST continuously provides a high level, the fifth transistor M5 remains turned-off, and the high level of the second fixed potential signal line charges the parasitic capacitance of the fifth transistor M5. When the power is off abnormally, the fifth transistor M5 can transmit its stored voltage to the first node N1 to make the first output module 5 not output a light-emitting enable level, thereby preventing the light-emitting element 10 from emitting abnormally. The third top light-shielding layer 73 shields a channel of the fifth transistor M5 to prevent the threshold value of the fifth transistor M5 from being forward biased, thereby achieving the stability of the working state of the fifth transistor M5 and enabling the fifth transistor M5 to provide a more reliable anti-power failure function in the light-emitting shift circuit 3.
It should be noted that referring to
In some embodiments, referring to FIG, 3 and
As mentioned above, the fifteenth transistor MI5 shown in
The control module 6 includes a fourth control module 64, the control transistor M0 of the fourth control module 64 includes an eighth transistor M8, a gate electrode of the eighth transistor M8 is electrically connected to the first node N1, a first electrode of the eighth transistor 1118 is electrically connected to the first clock signal line CK, and a second electrode of the eighth transistor M8 is electrically connected to the fourth node N4.
In order to reduce leakage current, the eighth transistor M8 in the light-emitting shift circuit 3 can be configured as a double-gate transistor. Since the double-gate transistor has a relatively large channel length, the double-gate transistor is more affected by light. In the embodiments of the present disclosure, the fourth top light-shielding layer 74 shields the channel of the eighth transistor M8, thereby improving the stability of the conduction state of the eighth transistor M8, and thus improving the stability of the potential of the fourth node N4. In this case, stability of the potential output by the first driving module 8 can be achieved when the voltage of the fourth node N4 drives the first driving module 8.
Referring to
In some embodiments, the top light-shielding layer 7 receives a constant voltage signal. In this case, a stable potential is continuously transmitted on the top light-shielding layer 7, thereby preventing the potential jump coupling on the top light-shielding layer 7 from affecting the node potential of the light-emitting shift circuit 3.
For example, as shown in
In some embodiments, the top light-shielding layer 7 is electrically connected to the first node N1. In the layout design of the circuit, the control transistor M0 that is electrically connected to the first node N1 is relatively close to the first node N1. When the top light-shielding layer 7 shields the channel of the control transistor M0, the top light-shielding layer 7 is also relatively close to the first node N1, so the electrical connection between the top light-shielding layer 7 and the first node N1 can optimize the layout design. Moreover, when the top light-shielding layer 7 is electrically connected to the first node N1, the top light-shielding layer 7 changes synchronously with the potential of the first electrode or the potential of the second electrode of at least one control transistor M0, for example, the first top light-shielding layer 71 is electrically connected to the first node N1, thereby reducing an influence of the potential jump on the first top light-shielding layer 71 on the potential on the second electrode of the second transistor M2.
If the top light-shielding layer 7 is arranged in the same layer as the first electrode and the second electrode of the control transistor M0, due to limitation of the layout space, a horizontal gap between a top metal layer and the first electrode and the second electrode of the control transistor M0 will be very small. In this case, a great interference occurs when the external ambient light is incident through the gap between the top metal layer and the first electrode and the second electrode of the control transistor M0. For example, for the display panel with a camera function and a fingerprint recognition function, when the top light-shielding layer 7 is located in the optical component arrangement area, the interference caused between the top light-shielding layer 7 and other metal wires will greatly affect the imaging quality and fingerprint recognition accuracy. However, in the embodiments of the present disclosure, by disposing the top light-shielding layer 7 between the control transistor M0 and the auxiliary connection part 14, the top light-shielding layer 7 will not be disposed in a same layer as the metal wires used to form the transistors in the light-emitting shift circuit 3, therefore, the interference phenomenon between metals in the same layer can be alleviated.
In some embodiments, referring to
In some embodiments, the display panel has a display region and a non-display region, and the light-emitting shift circuit 3, the negative power bus PVEE, and the auxiliary connection part 14 are all arranged in the non-display region. When the top light-shielding layer 7 is reused as the auxiliary connection part 14, at least a part of the light-emitting shift circuit 3 overlaps with the auxiliary connection part 14. In this case, a horizontal width of an area occupied by the light-emitting shift circuit 3 and the auxiliary connection part 14 in the non-display region can be reduced, thereby reducing a border width of the non-display region. Moreover, due to a relatively large width of the auxiliary connecting portion 14, the channel of the control transistor M0 can be shielded to a greater extent.
Referring to
In some embodiments, referring to
If the threshold voltage of the ninth transistor M9 drifts, the conduction degree of the ninth transistor M9 will be affected, as a result, the voltage transmitted from the light-emitting shift circuit 3 to the light-emitting control signal line Emit cannot reach the light-emitting enable voltage provided by the first fixed-potential signal line VGL, thereby affecting the light-emitting accuracy of the light-emitting element 10. By using the top light-shielding layer 7 to shield the channel of the ninth transistor M9, an influence of light on the threshold voltage of the ninth transistor M9 can be reduced, thereby preventing the threshold of the ninth transistor M9 from drifting.
In some embodiments, referring to
Referring to
The tenth transistor M10 is configured to transmit a light-emitting disable voltage provided by the second fixed potential signal line to the light-emitting control signal line Emit. If the threshold voltage of the tenth transistor M10 drifts when affected by light, the conduction degree of the tenth transistor M10 will be reduced or the tenth transistor M10 has a poor turn-off state, thereby affecting the stability of the output potential of the tenth transistor M10. For example, when the light-emitting shift circuit 3 needs to transmit a light-emitting enable voltage to the light-emitting control signal line Emit, if the tenth transistor M10 has a poor turn-off state, the second fixed-potential signal line will leak electricity to the light-emitting control signal line Emit through the tenth transistor M10, as a result, the light-emitting shift circuit 3 will fail to output a stable low level. Therefore, in the embodiments of the present disclosure, by using the top light-shielding layer 7 to shield the channel of the tenth transistor M10, tan influence of light on the threshold voltage of the tenth transistor M10 can be reduced, thereby preventing the threshold value from shifting, and thus improving the reliability of the working state of the transistor M10.
Referring to
In some embodiments, referring to
The light-emitting shift circuit 3 includes a second output module 17, the second output module 17 includes a tenth transistor M10, a gate electrode of the tenth transistor M10 is electrically connected to the third node N3, a first electrode of the tenth transistor M10 is connected to the second fixed potential signal line, and a second electrode of the tenth transistor M10 is electrically connected to the light emission control signal line Emit.
For the two output transistors, that is, the ninth transistor M9 and the tenth transistor M10, the threshold voltages of the two output transistors directly affect the conduction degrees of the two transistors when they are turned on, which in turn affects the stability of the low level or the high-level output by the light-emitting shift circuit 3. In combination with the layer structure of the circuit, it can be seen that the ninth transistor M9 and the tenth transistor M10 have relatively large areas, which are much larger than areas of other control transistors. In view of the above, by arranging the bottom light-shielding layer 18 under the ninth transistor M9 and the tenth transistor M10, the bottom light-shielding layer 18 is relatively far away from the other metal wires in the circuit layer 2 while utilizing the bottom light-shielding layer 18 to reduce the influence of the external ambient light on the element characteristics of the two output transistors, so the coupling between the bottom light-shielding layer 18 and other signal lines is also small. In this case, even if the bottom light-shielding layer 18 has a larger area, the parasitic capacitance will not be greatly affected.
In some embodiments, the bottom light-shielding layer 18 receives a power voltage or a ground voltage.
In addition to being affected by light, the threshold voltage of the transistor is also affected by the friction of the copper rod. The friction of the copper rod makes the substrate 1 accumulate negative charges, and the channel carriers of the transistor are increased, thereby causing the transfer characteristic curve of the transistor to shift and the threshold voltage to be forward biased. By setting the bottom light-shielding layer 18 as a metal light-shielding layer and making it receive the power supply voltage or the ground voltage, the bottom light-shielding layer 18 can also be used to shield an influence of the triboelectric charge on the channel of the control transistor M0, thereby avoiding that the threshold voltage of the control transistor M0 is forward biased.
In some embodiments, referring to
A gate electrode of the eleventh transistor M11 is electrically connected to the first clock signal line CK, a first electrode of the eleventh transistor M11 is electrically connected to the first fixed potential signal line VGL, and a second electrode of the eleventh transistor M11 is electrically connected to the second electrode of the eighth transistor M8. A gate electrode of the twelfth transistor M12 is electrically connected to the second electrode of the eleventh transistor M11, a first electrode of the twelfth transistor M12 is electrically connected to the second fixed potential signal line, and a second electrode of the twelfth transistor M12 is electrically connected to the second electrode of the third transistor M3. A gate electrode of the thirteenth transistor M13 is connected to the first node N1, a first electrode of the thirteenth transistor M13 is electrically connected to the second fixed potential signal line, and a second electrode of the thirteenth transistor M13 is electrically connected to the third node N3.
During the first period t1, the shift control signal line IN provides a high level, the first clock signal line CK provides a low level, the second clock signal line XCK provides a high level, the eleventh transistor M11 writes a low level provided by the first fixed potential signal line VGL to the fourth node N4, the sixth transistor M6 is controlled to be turned on, and the sixth transistor M6 writes the high level provided by the second clock signal line XCK to the gate electrode of the seventh transistor M7 to control the seventh transistor M7 to be turned off. At this time, a high level at the third node N3 provided during a previous driving cycle controls the tenth transistor M10 to be turned off. The fourth transistor M4 writes the high level provided by the shift control signal line IN to the first node N1, and the ninth transistor M9 is controlled to be turned off. At this time, the light-emitting shift circuit 3 maintains the high level output during the previous driving cycle.
During the second period t2, the shift control signal line IN provides a high level, the first clock signal line CK provides a high level, the second clock signal line XCK provides a low level, the seventh transistor M7 is turned on to transmit the low level of the fourth node N4 to the third node N3, and the tenth transistor M10 is controlled to be turned on, to transmit the high level provided by the second fixed potential signal line to the light-emitting control signal line Emit.
During the third period t3, the shift control signal line IN provides a high level, the first clock signal line CK provides a low level, the second clock signal line XCK provides a high level, and the light-emitting shift circuit 3 continuously outputs a high level.
During the fourth period t4, the shift control signal line IN provides a low level, the first clock signal line CK provides a high level, and the second clock signal line XCK provides a low level, and the light-emitting shift circuit 3 continuously outputs a high level.
During the fifth period t5, the shift control signal line IN provides a low level, the first clock signal line CK provides a low level, the second clock signal line XCK provides a high level, and the eighth transistor M8 is turned on, a level is written to the fourth node N4, the sixth transistor M6 is controlled to be turned on and writes the high level provided by the second clock signal line XCK to the gate electrode of the seventh transistor M7, to control the seventh transistor M7 to be turned off. The fourth transistor M4 is turned on, the low level provided by the shift control signal line IN is written to the first node N1, the ninth transistor M9 is controlled to be turned on, and the low level provided by the first fixed potential signal line VGL is written to the light-emitting control signal line Emit. At the same time, when the output terminal of the light-emitting shift circuit 3 jumps from high to low, due to the effect of the coupling, the potential of the first node N1 will be pulled to a lower level, the ninth transistor M9 will be more fully turned on, and low level provided by the first fixed potential signal line has a relatively small voltage drop when being transmitted to the light-emitting control signal line Emit via the ninth transistor M9, so that the voltage on the light-emitting control signal line Emit is closer to the low level provided by the first fixed potential signal line VGL.
Based on the same inventive concept, some embodiments of the present disclosure also provide a display device.
The above are merely some embodiments of the present disclosure, rather than limiting the present disclosure. Any modification, equivalent substitution, improvement, and so on, made within the principles of the present disclosure shall fall within a scope of the present disclosure.
It should be noted that the above embodiments are merely used to illustrate the technical solutions of the present disclosure, rather than limit the technical solutions of the present disclosure. Although the present disclosure is described in detail with reference to the foregoing embodiments, those skilled in the art shall understand that they can modify the technical solutions described in the foregoing embodiments, or make equivalent replacement to some or all of the technical features. These modifications or replacements shall fall within a scope of the technical solutions of the embodiments of the present disclosure without departing from the concept of the corresponding technical solutions.
Number | Date | Country | Kind |
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202210761525.1 | Jun 2022 | CN | national |
The present application claims priority to Chinese Patent Application No. 202210761525.1, filed on Jun. 29, 2022, the content of which is incorporated herein by reference in its entirety.