Image sensing device and operation method thereof, and image sensing method

Abstract

The present application relates to an image sensing device and an operation method thereof and an image sensing method. An image sensing device includes: an optical transmitter, which outputs a modulation signal to a target object; an optical receiver, which generates a pixel signal corresponding to a reflection signal from the target object according to a phase control signal; an image processor, which calculates a depth phase based on the pixel signal and compensates the depth phase according to a phase offset signal to output a depth information signal; a drive control circuit, which generates a phase control signal corresponding to the phase of the modulation signal and sets an initial phase difference between the modulation signal and the phase control signal according to the phase offset signal; and an offset calculation circuit, which sets a plurality of reference phases, selects a reference phase closest to the depth phase among the set plurality of reference phases, and generates a phase offset signal representing the phase difference between the selected reference phase and the depth phase.

Description

Technical Field

[0001] The present disclosure relates to semiconductor design technology, and in particular, to an image sensing device that acquires depth information using a time-of-flight (TOF) scheme. Background Art

[0002] The TOF system calculates the distance from the origin to the object by measuring the flight time of light or signals. Generally, the flight time is the time for light or signals to propagate from the source to the object and / or the time for light or signals to propagate from the object back to the source. The origin can be the source of light or signals, such as a TOF sensor using a TOF system. The TOF sensor outputs an image including the depth information of the object based on the distance. Conventional sensors are able to output a two-dimensional (2D) image representing the color and shape of the object, but a TOF sensor can output a three-dimensional (3D) image representing not only the 2D image of the object but also the depth of the object. Summary of the invention

[0003] Various embodiments of the present invention are directed to an image sensing device and an image sensing method thereof capable of adjusting an initial phase offset between a modulation signal output from an optical transmitter and a phase control signal for controlling an optical receiver based on depth information acquired through a TOF scheme.

[0004] According to an embodiment of the present invention, an image sensing device includes: an optical transmitter, which is configured to output a modulation signal to a target object; an optical receiver, which is configured to generate a pixel signal corresponding to a reflection signal from the target object according to a phase control signal; an image processor, which is configured to calculate a depth phase based on the pixel signal and compensate for the depth phase according to a phase offset signal to output a depth information signal; a drive control circuit, which is configured to generate a phase control signal corresponding to the phase of the modulation signal and set an initial phase difference between the modulation signal and the phase control signal according to the phase offset signal; and an offset calculation circuit, which is configured to set multiple reference phases, select a reference phase closest to the depth phase among the set multiple reference phases, and generate a phase offset signal representing the phase difference between the selected reference phase and the depth phase.

[0005] According to an embodiment of the present invention, an image sensing method includes the following steps: outputting a modulation signal to a target object at an optical transmitter; generating a pixel signal corresponding to a reflection signal from the target object according to a phase control signal at an optical receiver; calculating a depth phase based on the pixel signal; setting multiple reference phases, selecting a reference phase closest to the depth phase among the multiple reference phases, and generating a phase offset signal representing the phase difference between the selected reference phase and the depth phase; setting an initial phase difference between a modulation signal and a phase control signal according to the phase offset signal; and compensating the depth phase according to the phase offset signal to output a depth information signal.

[0006] According to an embodiment of the present invention, an operating method of an image sensing device includes the following steps: generating a source signal and outputting the source signal to a target; receiving a reflection signal which is the source signal reflected from the target; generating a control signal whose phase lags behind the source signal by a predetermined amount indicated by an offset signal; generating a pixel signal based on the reflection signal by controlling a unit pixel via the control signal; calculating a depth phase based on the pixel signal; outputting depth information by compensating the depth phase according to the offset signal; selecting a reference phase among multiple reference phases, the selected reference phase having a minimum offset relative to the depth phase; and updating the offset signal to represent the minimum offset.

[0007] According to an embodiment of the present invention, an image sensing device using a TOF scheme to obtain depth information can set an initial phase offset between a modulation signal and a phase control signal based on the depth information. In addition, the image sensing device can use the initial phase offset to compensate for the acquired depth information, thereby minimizing the depth error and obtaining accurate depth information. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a diagram illustrating the operation of an image sensing device using a time-of-flight (TOF) scheme.

[0009] Figure 2 is a block diagram showing an image sensing device using a TOF scheme according to a first embodiment of the present invention.

[0010] Figure 3 The first embodiment according to the present invention is shown in FIG. Figure 2 Configuration diagram of the pixel array.

[0011] Figure 4 is a timing diagram for describing the operation of an image sensing device using the TOF scheme.

[0012] Figure 5A is a graph illustrating a depth error generated according to a depth in an image sensing device.

[0013] Figure 5B is a graph illustrating a depth error generated according to a phase difference between a reflection signal and a phase control signal in an image sensing device.

[0014] Fig. 6A and Figure 6B is a diagram showing an offset calculation circuit according to an embodiment of the present invention.

[0015] Figure 7 It is used to describe the first embodiment according to the present invention. Figure 2 A timing diagram of the operation of the image sensing device.

[0016] Figure 8 is a flowchart for describing the operation of the image sensing device according to the embodiment of the present invention.

[0017] Fig. 9 is a block diagram illustrating an image sensing device using a TOF scheme according to a second embodiment of the present invention.

[0018] Fig.10 It is used to describe the second embodiment according to the present invention. Fig. 9 A timing diagram of the operation of the image sensing device.

[0019] Fig.11 is a block diagram showing an image sensing device using a TOF scheme according to a third embodiment of the present invention.

[0020] Fig.12 It is used to describe the third embodiment according to the present invention. Fig.11 A timing diagram of the operation of the image sensing device. DETAILED DESCRIPTION

[0021] Various embodiments of the present invention are described below with reference to the accompanying drawings. However, the embodiments may be specifically implemented in different forms and should not be construed as being limited to the embodiments described herein. Throughout this disclosure, the same reference numerals represent the same parts throughout the various drawings and embodiments of the present invention. It should be noted that references to "an embodiment", "another embodiment", etc. do not necessarily refer to only one embodiment, and different references to any such phrases do not necessarily refer to the same embodiment. The term "embodiment" does not necessarily refer to all embodiments when used herein.

[0022] It will be understood that although the terms "first", "second", "third", etc. may be used herein to identify various elements, these elements are not limited by these terms. These terms are used to distinguish one element from another element with the same or similar name. Therefore, a first element in one example may also be referred to as a second element or a third element in another example without indicating any change in the element itself.

[0023] It will be further understood that when an element is referred to as being "connected to" or "coupled to" another element, it can be directly on, connected to, or coupled to the other element, or one or more intervening elements may be present. Additionally, it will be understood that when an element is referred to as being "between" two elements, it can be the only element between the two elements, or one or more intervening elements may also be present. Unless otherwise indicated or indicated by the context, communication between two elements (whether directly or indirectly connected / coupled) may be wired or wireless.

[0024] As used herein, unless the context clearly indicates otherwise, the singular forms may also include the plural forms and vice versa.

[0025] It will be further understood that when used in this specification, the terms "include" and "comprising" specify the presence of the elements described and do not exclude the presence or addition of one or more other elements. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0026] Figure 1 is a diagram illustrating the operation of the image sensing device 10 using a time-of-flight (TOF) scheme.

[0027] Reference Figure 1 , the image sensing device 10 using the TOF scheme can measure the distance from the target object 20. The image sensing device 10 is regarded as one of the very important devices for the development of automation in various industrial fields and consumer markets. The device used by the consumer (e.g., mobile phone, tablet computer, vehicle, etc.) may include the image sensing device 10. The image sensing device 10 can be used to identify the surrounding environment and / or the position of the device in the surrounding environment. For example, a camera including the image sensing device 10 can determine the color, shape, and depth (distance) of the target object 20 included in a three-dimensional (3D) environment (e.g., a scene or image frame) to provide 3D vision technology for consumers using the device.

[0028] The image sensing device 10 may include: a transmitter 12 configured to output a modulated signal for measuring a distance from a target object 20; and a receiver 14 configured to receive a reflected signal reflected from the target object 20. The modulated signal output from the transmitter 12 in the image sensing device 10 may have a preset pattern. The transmitter 12 may transmit the modulated signal to the surrounding environment. The modulated signal may be reflected by various objects in the surrounding environment. When the reflected signal is received by the receiver 14, the image sensing device 10 may determine the distance based on the correlation relationship (e.g., phase difference) between the modulated signal output from the transmitter 12 and the reflected signal received by the receiver 14.

[0029] In the process of identifying the correlation between the modulated signal and the reflected signal and determining the distance based on the correlation, the ambient light may interfere with the image sensing device 10. Specifically, in order to obtain the distance (e.g., depth information) in a bright sunlight environment or a distance requiring high resolution, additional processing may need to be performed to remove interference (e.g., noise) caused by the ambient light.

[0030] Figure 2 is a block diagram showing an image sensing device 100 using a TOF scheme according to a first embodiment of the present invention.

[0031] Reference Figure 2 , the image sensing device 100 may generate a depth information signal TOF_OUT indicating a depth from the target object 200 based on the TOF scheme. For example, the image sensing device 100 may detect a phase difference between a modulation signal MS output to the target object 200 and a reflection signal RS reflected from the target object 200 to generate the depth information signal TOF_OUT.

[0032] The image sensing device 100 may include an optical transmitter 110 , an optical receiver 120 , a driving control circuit 130 , an image processor 140 , and an offset calculation circuit 150 .

[0033] The optical transmitter 110 may output a modulation signal MS (also referred to as a source signal) to the target object 200. For example, the modulation signal MS may be a periodic signal (e.g., a clock signal) that switches periodically. According to an embodiment, the optical transmitter 110 may sequentially output modulation signals MS having phases different from each other to the target object 200. For example, the modulation signal MS may have at least two phases selected from 0 degrees (i.e., 360 degrees), 90 degrees, 180 degrees, and 270 degrees. For reference, 0 degrees may be substantially the same as 360 degrees. The optical transmitter 110 may include a light emitting diode (LED) or a laser diode (LD). The modulation signal MS output from the optical transmitter 110 may have a frequency belonging to an infrared or ultraviolet region rather than a visible light region for determining the color or shape of the target object 200 contained in the three-dimensional environment. For example, the optical transmitter 110 may output light of a specific wavelength (e.g., near infrared light of 850 nm).

[0034] The optical receiver 120 may receive a reflection signal RS reflected from the target object 200. The reflection signal RS may be input to the optical receiver 120 after a delay corresponding to the TOF of the signal from when the modulation signal MS is output. The optical receiver 120 may include a pixel array 121 for generating a plurality of pixel signals PIXs corresponding to the reflection signal RS. The optical receiver 120 may remove noise caused by ambient light from the reflection signal RS and provide the noise-removed reflection signal RS to the pixel array 121. In an embodiment, the pixel array 121 may configure a TOF sensor. Although Figure 2 The optical receiver 120 is shown to include a pixel array 121 , but the pixel array 121 may be placed in a configuration separate from the optical receiver 120 .

[0035] The pixel array 121 may generate a pixel signal PIXs by measuring, collecting, or determining a reflection signal RS according to a row control signal RCTRL and a phase control signal PCTRL. The pixel array 121 may include at least one unit pixel (eg, Figure 3 The unit pixel PX is used to measure the depth from the target object 200. The unit pixel PX may include at least two pixels (eg, Figure 3 For example, the unit pixel PX may be selected based on the row control signal RCTRL to generate the first pixel signal PIX1 and the second pixel signal PIX2 (in Figure 2 ) will refer to Figure 3 A detailed configuration of a unit pixel is described in detail.

[0036] In response to a distance measurement request RQ from an external device or a user interface working with the image sensing device 100, the drive control circuit 130 may generate a modulation control signal MC, a row control signal RCTRL, and a phase control signal PCTRL. The drive control circuit 130 may generate a modulation control signal MC for adjusting the period of the modulation signal MS in response to the request RQ, and generate a phase control signal PCTRL corresponding to the phase of the modulation signal MS. The drive control circuit 130 may set an initial phase difference (i.e., an initial phase offset) between the modulation signal MS and the phase control signal PCTRL according to a phase offset signal OFF_PH (which may also be referred to as an offset signal). For example, the drive control circuit 130 may adjust (or delay) the initial phase of the phase control signal PCTRL according to the phase offset signal OFF_PH, thereby setting an initial phase offset between the modulation signal MS and the phase control signal PCTRL. Therefore, the phase difference between the reflection signal RS and the phase control signal PCTRL may be set to a target value. The target value may be set to a value having a minimum depth error relative to the depth phase TOF_PH, preferably 0 degrees, 90 degrees, 180 degrees or 270 degrees.

[0037] In an implementation, the drive control circuit 130 may include a modulation controller 132 , a phase converter 134 , a transmitter driver 136 , and a sensor driver 138 .

[0038] The modulation controller 132 may generate a first drive control signal DRV_M in response to the request RQ. The modulation controller 132 may generate the first drive control signal DRV_M for the optical transmitter 110 to generate a modulation signal MS having a specific period different from the ambient light. The modulation controller 132 may provide the first drive control signal DRV_M to the phase converter 134 and the emitter driver 136.

[0039] The emitter driver 136 may generate the modulation control signal MC according to the first driving control signal DRV_M. According to an embodiment, the emitter driver 136 may be included in the optical emitter 110 or may drive the optical emitter 110 under the control of the modulation controller 132 .

[0040] The phase converter 134 may generate the second drive control signal DRV_DD to operate the sensor driver 138 in synchronization with the time point at which the transmitter driver 136 operates according to the first drive control signal DRV_M. Since the phase converter 134 recognizes the characteristics of the modulation control signal MC using the first drive control signal DRV_M, the phase converter 134 may determine the phase corresponding to the modulation signal MS from 0 degrees, 90 degrees, 180 degrees, and 270 degrees. For example, the phase converter 134 may adjust (e.g., shift) the phase of the modulation signal MS based on the first drive control signal DRV_M, and generate phase information PFC indicating 0 degrees, 90 degrees, 180 degrees, and 270 degrees of the modulation signal MS to output the phase information PFC by including the phase information PFC in the second drive control signal DRV_DD. According to the first embodiment, the phase converter 134 may change the phase information PFC according to the phase offset signal OFF_PH to delay the initial phase of the phase control signal PCTRL by the amount of the delay time Td. As a result, the phase difference between the reflected signal RS and the phase control signal PCTRL may be set to a target value.

[0041] The sensor driver 138 may generate a row control signal RCTRL for controlling the pixel array 121 row by row according to the second drive control signal DRV_DD. For example, the sensor driver 138 may generate a first row control signal for controlling the unit pixels PX arranged in the first row and an nth row control signal for controlling the unit pixels PX arranged in the nth row, where n is a natural number greater than 2. In addition, the sensor driver 138 may generate a phase control signal PCTRL for controlling the operation timing of the unit pixels PX in the pixel array 121 according to the second drive control signal DRV_DD. In an embodiment, the phase control signal PCTRL may be a control signal whose phase lags behind the modulation signal MS by a predetermined amount indicated by the phase offset signal OFF_PH. The sensor driver 138 may generate a phase control signal PCTRL delayed by a delay time Td corresponding to the phase offset signal OFF_PH relative to the phase of the modulation signal MS based on the phase information PFC included in the second drive control signal DRV_DD. The phase control signal PCTRL may include a plurality of phase transition signals ( Figure 3 The phase conversion signals have different phases from each other and are respectively connected to the pixels ( Figure 3For example, the sensor driver 138 may drive the optical receiver 120 by sequentially generating a first phase shift signal MIXA and a second phase shift signal MIXB corresponding to a phase 0 degree and a phase 180 degree of the modulation signal MS, respectively, based on the phase information PFC, and generating a first phase shift signal MIXA and a second phase shift signal MIXB corresponding to a phase 90 degree and a phase 270 degree of the modulation signal MS, respectively. At this time, the phase information PFC may depend on the phase offset signal OFF_PH, and the initial phases of the first phase shift signal MIXA and the second phase shift signal MIXB may be delayed with reference to the modulation signal MS. According to an embodiment, the sensor driver 138 may be included in the optical receiver 120, or the optical receiver 120 may be driven under the control of the sensor driver 138.

[0042] The image processor 140 may generate a depth information signal TOF_OUT indicating a depth from the target object 200 based on a plurality of pixel signals PIXs. For example, the image processor 140 may calculate a depth phase TOF_PH based on a first pixel signal PIX1 and a second pixel signal PIX2 provided from the unit pixel PX, and calculate a depth information signal TOF_OUT corresponding to the depth phase TOF_PH. The image processor 140 may provide the depth phase TOF_PH to the offset calculation circuit 150. According to an embodiment, when a phase offset signal OFF_PH is input from the offset calculation circuit 150, the image processor 140 may compensate the depth phase TOF_PH according to the phase offset signal OFF_PH, and calculate a depth information signal TOF_OUT corresponding to the compensated depth phase TOF_PH.

[0043] In an implementation, the image processor 140 may include a signal converter 142 and a signal processor 144 .

[0044] The signal converter 142 may convert the first pixel signal PIX1 and the second pixel signal PIX2 provided from the pixel array 121 into data DD. For example, the first pixel signal PIX1 and the second pixel signal PIX2 provided from the pixel array 121 may be analog data, and the data DD converted by the signal converter 142 may be digital data.

[0045] The signal processor 144 may calculate the depth phase TOF_PH by performing a preset image processing operation on the data DD transmitted from the signal converter 142. In addition, the signal processor 144 may generate a depth information signal TOF_OUT corresponding to the calculated depth phase TOF_PH based on the speed of light (c) and the frequency (or period) of the modulation signal MS. The depth information signal TOF_OUT may be output as information about the distance (or depth) from the target object 200 to the image sensing device 100. In addition, the signal processor 144 may compensate for the depth phase TOF_PH phase-shifted in the phase converter 134 by reflecting the phase offset signal OFF_PH on the depth phase TOF_PH. Finally, the signal processor 144 may calculate the depth information signal TOF_OUT corresponding to the compensated depth phase.

[0046] The offset calculation circuit 150 may calculate the phase offset signal OFF_PH based on the depth phase TOF_PH provided from the image processor 140. The offset calculation circuit 150 may set a plurality of reference phases, select a reference phase closest to the depth phase TOF_PH among the set reference phases, and generate a phase offset signal OFF_PH indicating a phase difference between the selected reference phase and the depth phase TOF_PH. For reference, the reference phase may be a phase having a minimum depth error relative to the depth phase TOF_PH, preferably set to 0 degrees, 90 degrees, 180 degrees, and 270 degrees.

[0047] Figure 3 The first embodiment of the present disclosure is shown in FIG. Figure 2 Configuration diagram of the pixel array 121.

[0048] Reference Figure 3 , a plurality of unit pixels PX may be arranged in an array type in the pixel array 121. For example, one unit pixel PX may include a first pixel TAPA and a second pixel TAPB. The first pixel TAPA and the second pixel TAPB may be selected according to the row control signal RCTRL, and a first pixel signal PIX1 and a second pixel signal PIX2 corresponding to the reflection signal RS may be generated according to the phase control signal PCTRL. For reference, in Figure 3 In the embodiment, the row control signal RCTRL may include a reset signal RX, a transmission signal TX, and a selection signal SX, and the phase control signal PCTRL may include a first phase transition signal MIXA and a second phase transition signal MIXB. The first pixel TAPA and the second pixel TAPB may operate for respective phases of the phase control signal PCTRL.

[0049] The first pixel TAPA may generate a first pixel signal PIX1 based on a reset signal RX, a transmission signal TX, a selection signal SX, and a first phase transition signal MIXA. For example, the first pixel TAPA may include a first sensing circuit P1, a first reset circuit RT1, a first transmission circuit TT1, a first charge storage circuit C1, a first driving circuit DT1, and a first selection circuit ST1. The first sensing circuit P1 may be connected between the first node N1 and the low voltage terminal, and generate charges according to the first phase transition signal MIXA. The first sensing circuit P1 may include a photodiode. The first reset circuit RT1 may be connected between the high voltage terminal and the first node N1, and reset the first sensing circuit P1 and the first charge storage circuit C1 according to the reset signal RX. The first transmission circuit TT1 may be connected between the first node N1 and the first floating diffusion node FD1, and reset the first charge storage circuit C1 according to the transmission signal TX and transfer the charges generated from the first sensing circuit P1 to the first charge storage circuit C1. The first charge storage circuit C1 may be connected between the first floating diffusion node FD1 and the low voltage terminal. The first charge storage circuit C1 may be a parasitic capacitor. The first driving circuit DT1 may be coupled between the high voltage terminal and the first selection circuit ST1, and drive the first column line COL1 with a high voltage supplied through the high voltage terminal according to a voltage loaded on the first floating diffusion node FD1. The first selection circuit ST1 may be coupled between the first driving circuit DT1 and the first column line COL1, and selectively couple the first driving circuit DT1 and the first column line COL1 according to a selection signal SX.

[0050] With the above structure, the first pixel TAPA operates as follows. During a reset period determined based on the reset signal RX, the first reset circuit RT1 may reset the first sensing circuit P1 and the first charge storage circuit C1. During a transmission period determined based on the transmission signal TX and the first phase shift signal MIXA, the first sensing circuit P1 may generate charges according to the first phase shift signal MIXA, and the first charge storage circuit C1 may store charges. During a readout period determined based on the selection signal SX, the first drive circuit DT1 and the first selection circuit ST1 may output a first pixel signal PIX1 corresponding to the charges to the image processor 140 through the first column line COL1.

[0051] The second pixel TAPB may generate a second pixel signal PX2 based on a reset signal RX, a transmission signal TX, a selection signal SX, and a second phase transition signal MIXB. For example, the second pixel TAPB may include a second sensing circuit P2, a second reset circuit RT2, a second transmission circuit TT2, a second charge storage circuit C2, a second driving circuit DT2, and a second selection circuit ST2. Since the configuration and operation of the second pixel TAPB are substantially the same as those of the first pixel TAPA, a detailed description will be omitted.

[0052] Figure 4 is a timing diagram for describing the operation of an image sensing device using the TOF scheme. Figure 4 A case where the phase offset signal OFF_PH supplied from the offset calculation circuit 150 is not reflected on the depth phase TOF_PH in the signal processor 144 is shown.

[0053] Reference Figure 4 , the optical transmitter 110 outputs a modulation signal MS switched at a specific period to the target object 200, and the optical receiver 120 receives a reflection signal RS reflected from the target object 200. At this time, the modulation signal MS and the reflection signal RS may have a phase difference corresponding to the TOF of the signal

[0054] The phase converter 134 shifts the phase of the modulation signal MS at intervals of 90 degrees to generate phase information PFC indicating 0 degrees, 90 degrees, 180 degrees, and 270 degrees of the modulation signal MS. The sensor driver 138 generates a phase control signal PCTRL corresponding to the phase of the modulation signal MS. The sensor driver 138 drives the optical receiver 120 by sequentially generating a first phase transition signal MIXA and a second phase transition signal MIXB corresponding to 0 degrees and 180 degrees of the phase of the modulation signal MS, respectively, and generating a first phase transition signal MIXA and a second phase transition signal MIXB corresponding to 90 degrees and 270 degrees of the phase of the modulation signal MS, respectively.

[0055] The amounts of the reflection signal RS received in response to the first phase shift signal MIXA and the second phase shift signal MIXB sequentially input (the amount of charge generated by the amount of light) are Q1, Q2, Q3, and Q4. At this time, the amounts Q1 and Q3 of the reflection signal RS may correspond to Figure 3 The first pixel signal PIX1, the quantities Q2 and Q4 of the reflection signal RS may correspond to Figure 3 The image processor 140 calculates the depth phase TOF_PH based on the first pixel signal PIX1 and the second pixel signal PIX2 provided from the unit pixel PX, and calculates the depth information signal TOF_OUT corresponding to the depth phase TOF_PH.

[0056] On the other hand, in an image sensing device that acquires depth information in a TOF scheme, as the depth increases (i.e., the distance increases), the depth error may increase. Ideally, the farther the target object 200 is, the more linearly the depth error may increase. However, due to the performance of the optical receiver and the optical transmitter, the mismatch of pixels in the unit pixel, and the mismatch of devices (e.g., transistors) within the pixel, nonlinear depth errors occur in each image sensing device (A, B). For example, Figure 5AAs shown, if the target depth is 1000 mm, the depth error of image sensing device A is greater than the depth error of image sensing device B. As a result, it is difficult to uniformly compensate for the depth error, and there is difficulty in calculating and reflecting the depth error whenever depth information is obtained for each device.

[0057] In addition, when the depth information signal TOF_OUT is generated using the first pixel signal PIX1 and the second pixel signal PIX2 corresponding to the amounts Q1, Q2, Q3, and Q4 of the reflection signal RS, the performance of the image processor can be optimized when the amounts Q1, Q2, Q3, and Q4 of the reflection signal RS occupy 50:50 or 100:0, respectively, in the enabled section of the phase control signal PCTRL, considering the signal-to-noise ratio (SNR). That is, Figure 5B As shown, at various points where the phase difference (ie, phase offset) between the reflection signal RS and the phase control signal PCTRL becomes 0, 90, 180 or 270 degrees, the SNR becomes 50:50 or 100:0, resulting in a minimum depth error.

[0058] Therefore, according to the first embodiment of the present invention, using the phase offset signal OFF_PH generated by the offset calculation circuit 150, the drive control circuit 130 can delay the initial phase of the phase control signal PCTRL, thereby setting the phase difference between the reflection signal RS and the phase control signal PCTRL to 0 degrees, 90 degrees, 180 degrees or 270 degrees, resulting in a minimum depth error. That is, in the first embodiment, the offset calculation circuit 150 can set 0 degrees, 90 degrees, 180 degrees and 270 degrees as the first to fourth reference phases, select the reference phase closest to the depth phase TOF_PH among the first to fourth reference phases, and generate the phase offset signal OFF_PH indicating the phase difference between the selected reference phase and the depth phase TOF_PH.

[0059] For reference, refer to Fig. 6A , in a default state where the phase offset signal OFF_PH is not reflected, the depth phase TOF_PH provided from the image processor 140 is set to 108 degrees. At this time, since the second reference phase of 90 degrees is closest to the depth phase TOF_PH of 108 degrees among the first to fourth reference phases of 0 degrees, 90 degrees, 180 degrees, and 270 degrees, the offset calculation circuit 150 may generate a phase offset signal OFF_PH representing a phase difference (i.e., 18 degrees) between the second reference phase of 90 degrees and the depth phase TOF_PH of 108 degrees. Subsequently, the drive control circuit 130 may delay the initial phase of the phase control signal PCTRL according to the phase offset signal OFF_PH, thereby setting the phase difference between the reflection signal RS and the phase control signal PCTRL to 90 degrees. As a result, the depth error may be minimized.

[0060] In addition, according to the first embodiment of the present invention, when the phase offset signal OFF_PH is input from the offset calculation circuit 150, the image processor 140 may compensate the depth phase TOF_PH according to the phase offset signal OFF_PH, and calculate the depth information signal TOF_OUT corresponding to the compensated depth phase TOF_PH. Figure 6B , if the image sensing device 100 can measure a depth of 0 to 1500 mm, the depths corresponding to the first to fourth reference phases of 0, 90, 180, and 270 degrees may be set to 0 mm, 375 mm, 750 mm, and 1125 mm, respectively. The image processor 140 may reflect the phase offset signal OFF_PH (i.e., 18 degrees) to the depth phase TOF_PH (ideally 90 degrees), thereby calculating the depth information signal TOF_OUT having a depth value of 450 mm (i.e., 1500*108 / 360) corresponding to 108 degrees.

[0061] Figure 7 It is used to describe the first embodiment according to the present invention. Figure 2 FIG. 1 is a timing diagram of the operation of the image sensing device 100 .

[0062] Reference Figure 7 , the optical transmitter 110 outputs a modulation signal MS switched at a specific period to the target object 200, and the optical receiver 120 receives a reflection signal RS reflected from the target object 200. The modulation signal MS and the reflection signal RS may have a phase difference corresponding to the TOF of the signal.

[0063] The phase converter 134 shifts the phase of the modulation signal MS at intervals of 90 degrees to generate phase information PFC indicating 0 degrees, 90 degrees, 180 degrees, and 270 degrees of the modulation signal MS. The phase converter 134 adjusts the phase information PFC to delay the phase of the phase control signal PCTRL according to the phase offset signal OFF_PH for the sensor driver 138. For example, when the phase offset signal OFF_PH is calculated to be 18 degrees, the phase converter 134 adjusts the phase information PFC to delay the phase of the phase control signal PCTRL by a delay time Td (e.g., 18 degrees) corresponding to the phase offset signal OFF_PH.

[0064] The sensor driver 138 generates a phase control signal PCTRL corresponding to the phase of the modulation signal MS based on the phase information PFC. The sensor driver 138 drives the optical receiver 120 by sequentially generating a first phase transition signal MIXA and a second phase transition signal MIXB corresponding to the phase 0 degree and 180 degree of the modulation signal MS, respectively, and generating a first phase transition signal MIXA and a second phase transition signal MIXB corresponding to the phase 90 degree and 270 degree of the modulation signal MS, respectively. At this time, the sensor driver 138 may delay the initial phase of the first phase transition signal MIXA and the second phase transition signal MIXB by a delay time Td corresponding to the phase offset signal OFF_PH. Therefore, the phase difference between the reflection signal RS and the phase control signal PCTRL may be set to any one of 0 degree, 90 degree, 180 degree, and 270 degree. As a result, the amounts Q1, Q2, Q3, and Q4 of the reflection signal RS in the enabled section of the phase control signal PCTRL occupy 50:50 or 100:0, respectively, thereby maximizing the SNR to minimize the depth error.

[0065] The image processor 140 calculates the depth phase TOF_PH based on the first pixel signal PIX1 and the second pixel signal PIX2 provided from the unit pixel PX, and calculates the depth information signal TOF_OUT corresponding to the depth phase TOF_PH. When the phase offset signal OFF_PH is input from the offset calculation circuit 150, the image processor 140 may compensate the depth phase TOF_PH according to the phase offset signal OFF_PH, and calculate the depth information signal TOF_OUT corresponding to the compensated depth phase TOF_PH.

[0066] Below, refer to Figures 2 to 8 , the operation of the image sensing device 100 according to the embodiment of the present invention will be described.

[0067] Figure 8 is a flowchart for describing the operation of the image sensing device 100 according to the embodiment of the present invention.

[0068] Reference Figure 8 First, in a default state in which the phase offset signal OFF_PH is not reflected, the depth phase TOF_PH is output and provided from the image processor 140 .

[0069] In an embodiment, the drive control circuit 130 may generate a modulation control signal MC for adjusting the period of the modulation signal MS in response to the request RQ, and generate a row control signal RCTRL and a phase control signal PCTRL corresponding to the phase of the modulation signal MS (at S810). The optical transmitter 110 may output the modulation signal MS to the target object 200 according to the modulation control signal MC (at S820). The pixel array 121 in the optical receiver 120 may generate a pixel signal PIXs corresponding to the reflection signal RS reflected from the target object 200 according to the row control signal RCTRL and the phase control signal PCTRL (at S830). The image processor 140 may calculate the depth phase TOF_PH based on the pixel signal PIXs (at S840).

[0070] When the phase offset signal OFF_PH is not set (No at S850), the offset calculation circuit 150 may calculate the phase offset signal OFF_PH based on the depth phase TOF_PH provided from the image processor 140 (at S860). That is, the offset calculation circuit 150 may set a plurality of reference phases (e.g., 0 degrees, 90 degrees, 180 degrees, and 270 degrees), select a reference phase closest to the depth phase TOF_PH among the set reference phases, and generate a phase offset signal OFF_PH indicating a phase difference between the selected reference phase and the depth phase TOF_PH. The drive control circuit 130 may adjust the initial phase of the phase control signal PCTRL according to the phase offset signal OFF_PH (at S870).

[0071] Thereafter, the optical transmitter 110 may output the modulation signal MS to the target object 200 according to the modulation control signal MC (at S820). The pixel array 121 in the optical receiver 120 may generate a pixel signal PIXs corresponding to the reflection signal RS reflected from the target object 200 according to the row control signal RCTRL and the phase control signal PCTRL (S830). At this time, since the phase difference between the reflection signal RS and the phase control signal PCTRL is set to any one of 0 degrees, 90 degrees, 180 degrees, and 270 degrees, the SNR may be maximized and the depth error may be minimized.

[0072] The image processor 140 may calculate the depth phase TOF_PH based on the pixel signal PIXs (at S840). When the phase offset signal OFF_PH is set ("Yes" of S850), the image processor 140 may compensate the depth phase TOF_PH according to the phase offset signal OFF_PH, and calculate the depth information signal TOF_OUT corresponding to the compensated depth phase TOF_PH (at S880).

[0073] In the first embodiment, although the case where the phase of the phase control signal PCTRL is adjusted according to the phase offset signal OFF_PH is described, the present invention is not limited thereto. Fig. 9 and Fig.10 , a case where the phase of the modulation signal MS is adjusted according to the phase offset signal OFF_PH will be described.

[0074] Fig. 9 is a block diagram illustrating an image sensing device 300 using a TOF scheme according to a second embodiment of the present invention.

[0075] Reference Fig. 9 , the image sensing device 300 may include an optical transmitter 310, an optical receiver 320, a driving control circuit 330, an image processor 340, and an offset calculation circuit 350. The optical transmitter 310, the optical receiver 320, the image processor 340, and the offset calculation circuit 350 may have the same Figure 2 Those are basically the same configuration.

[0076] In response to the request RQ, the drive control circuit 330 may generate a modulation control signal MC for adjusting the period of the modulation signal MS, and generate a phase control signal PCTRL corresponding to the phase of the modulation signal MS. The drive control circuit 330 may set the initial phase difference (i.e., initial phase offset) between the modulation signal MS and the phase control signal PCTRL according to the phase offset signal OFF_PH. According to the second embodiment, the drive control circuit 330 may generate the modulation control signal MC to adjust (or delay) the initial phase of the modulation signal MS according to the phase offset signal OFF_PH. Therefore, the phase difference between the reflection signal RS and the phase control signal PCTRL may be set to a target value. The target value may be set to a value with a minimum depth error relative to the depth phase TOF_PH, preferably 0 degrees, 90 degrees, 180 degrees, or 270 degrees.

[0077] In detail, the driving control circuit 330 may include a modulation controller 332 , a phase converter 334 , a transmitter driver 336 , and a sensor driver 338 .

[0078] The modulation controller 332 may generate a first drive control signal DRV_M for the optical transmitter 310 to generate a modulation signal MS having a specific period different from the ambient light. The modulation controller 332 may provide the first drive control signal DRV_M to the phase converter 334. According to the second embodiment, the modulation controller 332 may generate an adjusted first drive control signal DRV_MD by adjusting the first drive control signal DRV_M according to the phase offset signal OFF_PH. The modulation controller 332 may delay the first drive control signal DRV_M by an amount of a delay time Td according to the phase offset signal OFF_PH to generate a delayed signal as the adjusted first drive control signal DRV_MD. The modulation controller 332 may provide the adjusted first drive control signal DRV_MD to the emitter driver 336.

[0079] The transmitter driver 336 may generate the modulation control signal MC according to the adjusted first driving control signal DRV_MD so that the optical transmitter 310 delays the initial phase of the modulation signal MS. Therefore, the phase difference between the reflection signal RS and the phase control signal PCTRL may be set to a target value.

[0080] The phase converter 334 may generate the second driving control signal DRV_D to operate the sensor driver 338 in synchronization with a time point at which the emitter driver 336 should operate according to the first driving control signal DRV_M. The phase converter 334 may adjust (e.g., shift) the phase of the modulation signal MS based on the first driving control signal DRV_M, and generate phase information PFC of 0 degrees, 90 degrees, 180 degrees, and 270 degrees indicating the modulation signal MS whose initial phase is not adjusted or delayed, to output the phase information PFC by including the phase information PFC in the second driving control signal DRV_D.

[0081] The sensor driver 338 may generate a row control signal RCTRL and a phase control signal PCTRL for controlling the pixel array 321 row by row according to the second driving control signal DRV_D.

[0082] Fig.10 It is used to describe the second embodiment according to the present invention. Fig. 9 FIG. 1 is a timing diagram of the operation of the image sensing device 300 .

[0083] Reference Fig.10, the drive control circuit 330 may generate a modulation control signal MC according to the phase offset signal OFF_PH to delay the initial phase of the modulation signal MS by the amount of the delay time Td. Therefore, the optical transmitter 310 outputs the modulation signal MS to the target object, which switches at a specific cycle and whose initial phase is delayed by the delay time Td corresponding to the phase offset signal OFF_PH. At this time, the modulation signal MS and the reflected signal RS may have a phase difference corresponding to the TOF of the signal.

[0084] The phase converter 334 shifts the phase of the modulation signal MS at intervals of 90 degrees to generate phase information PFC of 0 degrees, 90 degrees, 180 degrees, and 270 degrees indicating that the initial phase of the modulation signal MS is not delayed.

[0085] The sensor driver 338 generates a phase control signal PCTRL corresponding to the phase of the modulation signal MS based on the phase information PFC. The sensor driver 338 drives the optical receiver 320 by sequentially generating a first phase transition signal MIXA and a second phase transition signal MIXB corresponding to 0 degrees and 180 degrees of the phase of the modulation signal MS, respectively, and generating a first phase transition signal MIXA and a second phase transition signal MIXB corresponding to 90 degrees and 270 degrees of the phase of the modulation signal MS, respectively.

[0086] At this time, when the initial phase of the modulation signal MS is delayed by the amount of the delay time Td, the initial phase of the reflection signal RS is also delayed. Therefore, the phase difference between the reflection signal RS and the phase control signal PCTRL can be set to any one of 0 degrees, 90 degrees, 180 degrees, and 270 degrees. As a result, the amounts Q1, Q2, Q3, and Q4 of the reflection signal RS in the enabled section of the phase control signal PCTRL occupy 50:50 or 100:0, respectively, thereby maximizing the SNR to minimize the depth error.

[0087] The image processor 340 calculates the depth phase TOF_PH based on the first pixel signal PIX1 and the second pixel signal PIX2 provided from the unit pixel PX, and calculates the depth information signal TOF_OUT corresponding to the depth phase TOF_PH. When the phase offset signal OFF_PH is input from the offset calculation circuit 350, the image processor 340 may compensate the depth phase TOF_PH according to the phase offset signal OFF_PH, and calculate the depth information signal TOF_OUT corresponding to the compensated depth phase TOF_PH.

[0088] Below, refer to Fig.11 and Fig.12 , a case where both the phase of the modulation signal MS and the phase of the phase control signal PCTRL are adjusted according to the phase offset signal OFF_PH will be described.

[0089] Fig.11 is a block diagram illustrating an image sensing device 400 using a TOF scheme according to a third embodiment of the present invention.

[0090] Reference Fig.11 , the image sensing device 400 may include an optical transmitter 410, an optical receiver 420, a driving control circuit 430, an image processor 440, and an offset calculation circuit 450. The optical transmitter 410, the optical receiver 420, the image processor 440, and the offset calculation circuit 450 may have the same Figure 2 Those are basically the same configuration.

[0091] In response to the request RQ, the drive control circuit 430 may generate a modulation control signal MC for adjusting the period of the modulation signal MS, and generate a phase control signal PCTRL corresponding to the phase of the modulation signal MS. The drive control circuit 430 may set the initial phase difference (i.e., initial phase offset) between the modulation signal MS and the phase control signal PCTRL according to the phase offset signal OFF_PH. According to the third embodiment, the drive control circuit 430 may generate the modulation control signal MC to adjust (or delay) both the initial phase of the modulation signal MS and the initial phase of the phase control signal PCTRL according to the phase offset signal OFF_PH. Therefore, the phase difference between the reflection signal RS and the phase control signal PCTRL may be set to a target value, i.e., any one of 0 degrees, 90 degrees, 180 degrees, and 270 degrees.

[0092] In detail, the driving control circuit 430 may include a modulation controller 432 , a phase converter 434 , a transmitter driver 436 , and a sensor driver 438 .

[0093] The modulation controller 432 may generate a first drive control signal DRV_MD for the optical transmitter 410 to generate a modulation signal MS having a specific period different from the ambient light. According to the third embodiment, the modulation controller 432 may adjust the first drive control signal DRV_MD according to the phase offset signal OFF_PH to delay the initial phase of the modulation signal MS by the first delay time Td1 or the amount of the coarse delay time. The modulation controller 432 may provide the first drive control signal DRV_MD to the phase converter 434 and the transmitter driver 436.

[0094] The transmitter driver 436 may generate the modulation control signal MC according to the first driving control signal DRV_MD so that the optical transmitter 410 delays the initial phase of the modulation signal MS by the amount of the first delay time Td1.

[0095] The phase converter 434 may generate the second driving control signal DRV_DD to operate the sensor driver 438 in synchronization with the time point at which the transmitter driver 436 operates according to the first driving control signal DRV_MD. The phase converter 434 may adjust (e.g., shift) the phase of the modulation signal MS by the amount of the first delay time Td1 based on the first driving control signal DRV_MD and the phase offset signal OFF_PH, and generate phase information PFC indicating 0 degrees, 90 degrees, 180 degrees, and 270 degrees of the modulation signal MS with the second delay time Td2 or fine delay time corresponding to the reflected phase offset signal OFF_PH to output the phase information PFC by including the phase information PFC in the second driving control signal DRV_DD. According to the third embodiment, the phase converter 434 may convert the phase information PFC according to the phase offset signal OFF_PH to delay the initial phase of the phase control signal PCTRL by the amount of the second delay time Td2.

[0096] The sensor driver 438 may generate a row control signal RCTRL and a phase control signal PCTRL for controlling the pixel array 421 row by row according to the second drive control signal DRV_DD. The sensor driver 438 may generate a phase control signal PCTRL corresponding to the phase of the modulation signal MS based on the phase information PFC included in the second drive control signal DRV_DD. At this time, the phase information PFC may depend on the phase offset signal OFF_PH, and the initial phase of the phase control signal PCTRL may be delayed by the second delay time Td2 relative to the modulation signal MS.

[0097] For reference, according to the third embodiment, the difference between the delayed initial phase of the modulation signal MS and the delayed initial phase of the phase control signal PCTRL may correspond to the delayed initial phase of the phase control signal PCTRL of the first embodiment or the delayed initial phase of the modulation signal MS of the second embodiment.

[0098] Fig.12 It is used to describe the third embodiment according to the present invention. Fig.11 FIG. 4 is a timing diagram of the operation of the image sensing device 400 .

[0099] Reference Fig.12 , the drive control circuit 430 may generate a modulation control signal MC according to the phase offset signal OFF_PH to delay the initial phase of the modulation signal MS by the amount of the first delay time Td1. Therefore, the optical transmitter 410 outputs the modulation signal MS to the target object, which switches at a specific cycle and whose initial phase is delayed by the first delay time Td1 corresponding to the phase offset signal OFF_PH. At this time, the modulation signal MS and the reflected signal RS may have a phase difference corresponding to the TOF of the signal.

[0100] The phase converter 434 generates phase information PFC indicating 0 degrees, 90 degrees, 180 degrees, and 270 degrees of the modulation signal MS at a second delay time Td2 corresponding to the reflected phase offset signal OFF_PH. The phase converter 434 adjusts the phase information PFC according to the phase offset signal OFF_PH for the sensor driver 438 to delay the initial phase of the phase control signal PCTRL by the second delay time Td2 corresponding to the phase offset signal OFF_PH.

[0101] The sensor driver 438 generates a phase control signal PCTRL corresponding to the phase of the modulation signal MS based on the phase information PFC. The sensor driver 438 drives the optical receiver 420 by sequentially generating a first phase shift signal MIXA and a second phase shift signal MIXB corresponding to 0 degrees and 180 degrees of the phase of the modulation signal MS, respectively, and generating a first phase shift signal MIXA and a second phase shift signal MIXB corresponding to 90 degrees and 270 degrees of the phase of the modulation signal MS, respectively. At this time, the sensor driver 438 may delay the initial phases of the first phase shift signal MIXA and the second phase shift signal MIXB by a second delay time Td2 corresponding to the phase offset signal OFF_PH.

[0102] At this time, the first delay time Td1 may be defined as a rough delay time, and the second delay time Td2 may be defined as a fine delay time. That is, the initial phase of the modulation signal MS may be roughly adjusted using the first delay time Td1, and then the initial phase of the phase control signal PCTRL may be finely adjusted using the second delay time Td2. The difference between the first delay time Td1 and the second delay time Td2 may correspond to the delay time Td of the first embodiment or the second embodiment. Therefore, the phase difference between the reflection signal RS and the phase control signal PCTRL may be set to any one of 0 degrees, 90 degrees, 180 degrees, and 270 degrees. As a result, the amounts Q1, Q2, Q3, and Q4 of the reflection signal RS in the enabled section of the phase control signal PCTRL occupy 50:50 or 100:0, respectively, thereby maximizing the SNR to minimize the depth error.

[0103] The image processor 440 calculates the depth phase TOF_PH based on the first pixel signal PIX1 and the second pixel signal PIX2 provided from the unit pixel PX, and calculates the depth information signal TOF_OUT corresponding to the depth phase TOF_PH. When the phase offset signal OFF_PH is input from the offset calculation circuit 450, the image processor 440 may compensate the depth phase TOF_PH according to the phase offset signal OFF_PH, and calculate the depth information signal TOF_OUT corresponding to the compensated depth phase TOF_PH.

[0104] As described above, according to an embodiment of the present invention, an image sensing device using a TOF scheme to acquire depth information can set an initial phase offset between a modulation signal and a phase control signal based on the depth information. In addition, the image sensing device can use the initial phase offset to compensate for the acquired depth information, thereby minimizing the depth error and obtaining accurate depth information.

[0105] In addition, various embodiments of the present disclosure are described in the drawings and the specification. Although specific terms are used here, these terms are only used to describe the embodiments of the present disclosure. Therefore, the present disclosure is not limited to the above-mentioned embodiments, and many changes can be made within the spirit and scope of the present disclosure. It should be obvious to those skilled in the art that, in addition to the embodiments disclosed herein, various modifications can be made based on the technical scope of the present disclosure. The embodiments can be combined to form additional embodiments.

[0106] It should be noted that although the technical spirit of the present disclosure is described in conjunction with its preferred embodiments, this is for descriptive purposes only and should not be interpreted as limiting. It should be understood by those skilled in the art that various changes may be made thereto without departing from the technical spirit of the present disclosure and the following claims.

[0107] For example, for the logic gates and transistors provided as examples in the above-mentioned embodiments, different positions and types may be implemented according to the polarity of the input signal.

[0108] CROSS-REFERENCE TO RELATED APPLICATIONS

[0109] This application claims priority to Korean Patent Application No. 10-2020-0170495, filed on December 8, 2020, which is incorporated herein by reference in its entirety.

Claims

1. An image sensing device, comprising: an optical transmitter that outputs a modulated signal toward a target object; an optical receiver that generates a pixel signal corresponding to a reflection signal from the target object according to a phase control signal; an image processor that calculates a depth phase based on the pixel signal and compensates the depth phase according to a phase offset signal to output a depth information signal; a drive control circuit that generates the phase control signal corresponding to the phase of the modulation signal and sets an initial phase difference between the modulation signal and the phase control signal according to the phase offset signal; as well as an offset calculation circuit that sets a plurality of reference phases, selects a reference phase closest to the depth phase among the set plurality of reference phases, and generates the phase offset signal indicating a phase difference between the selected reference phase and the depth phase, The phase control signal controls the operation timing of unit pixels in the pixel array in the optical receiver.

2. The image sensing device according to claim 1, wherein: The plurality of reference phases include 0 degrees, 90 degrees, 180 degrees, and 270 degrees.

3. The image sensing device according to claim 1, wherein: The drive control circuit sets the initial phase difference by delaying an initial phase of the phase control signal according to the phase shift signal.

4. The image sensing device according to claim 1, wherein: The drive control circuit comprises: a modulation controller that generates a first driving control signal for the optical emitter in response to a request to generate the modulation signal having a specific period different from that of ambient light; and A phase converter generates phase information for the phase control signal by adjusting the phase of the modulation signal based on the first drive control signal and the phase offset signal to delay an initial phase of the phase control signal.

5. The image sensing device according to claim 1, wherein: The drive control circuit sets the initial phase difference by delaying an initial phase of the modulation signal according to the phase shift signal.

6. The image sensing device according to claim 1, wherein: The drive control circuit comprises: a modulation controller that generates a first drive control signal for the optical emitter in response to a request to generate the modulation signal having a specific period different from ambient light, and adjusts the first drive control signal according to the phase offset signal to delay an initial phase of the modulation signal; and A phase converter generates phase information for the phase control signal by adjusting a phase of the modulation signal based on the unadjusted first drive control signal.

7. The image sensing device according to claim 1, wherein: The drive control circuit sets the initial phase difference by delaying both an initial phase of the phase control signal and an initial phase of the modulation signal according to the phase shift signal.

8. The image sensing device according to claim 1, wherein: The drive control circuit comprises: a modulation controller that generates a first drive control signal for the optical emitter in response to a request to generate the modulation signal having a specific period different from ambient light, and adjusts the first drive control signal according to the phase offset signal to delay an initial phase of the modulation signal; and A phase converter generates the phase information for the phase control signal by adjusting the phase of the modulation signal based on the first drive control signal and converting the phase information according to the phase offset signal to delay an initial phase of the phase control signal.

9. The image sensing device according to claim 1, wherein: The image processor comprises: a signal converter that converts the pixel signal into digital data; and A signal processor calculates the depth phase by performing a preset image processing operation on the data and generates the depth information signal by reflecting the phase offset signal on the depth phase.

10. The image sensing device according to claim 1, in, The optical receiver includes the pixel array in which a plurality of unit pixels are arranged in an array type, and Each unit pixel includes at least two pixels operated for each phase of the phase control signal.

11. An image sensing method, the image sensing method comprising the following steps: outputting a modulated signal at an optical transmitter toward a target object; generating, at an optical receiver, a pixel signal corresponding to a reflection signal from the target object according to a phase control signal; calculating a depth phase based on the pixel signal; setting a plurality of reference phases, selecting a reference phase closest to the depth phase among the set plurality of reference phases, and generating a phase offset signal representing a phase difference between the selected reference phase and the depth phase; setting an initial phase difference between the modulation signal and the phase control signal according to the phase offset signal; as well as compensating the depth phase according to the phase offset signal to output a depth information signal, The phase control signal controls the operation timing of unit pixels in the pixel array in the optical receiver.

12. The image sensing method according to claim 11, wherein: The plurality of reference phases include 0 degrees, 90 degrees, 180 degrees, and 270 degrees.

13. The image sensing method according to claim 11, wherein: The step of setting the initial phase difference includes the following steps: delaying the initial phase of the phase control signal according to the phase offset signal.

14. The image sensing method according to claim 11, wherein: The step of setting the initial phase difference includes the following steps: delaying the initial phase of the modulation signal according to the phase shift signal.

15. The image sensing method according to claim 11, wherein: The step of setting the initial phase difference includes the step of delaying both the initial phase of the phase control signal and the initial phase of the modulation signal according to the phase offset signal.

16. The image sensing method according to claim 11, wherein: The step of compensating the depth phase comprises the following steps: Converting the pixel signal into digital data; and The depth phase is calculated by performing a preset image processing operation on the data and the depth information signal is generated by reflecting the phase offset signal on the depth phase.

17. The image sensing method according to claim 11, in, The optical receiver includes the pixel array in which a plurality of unit pixels are arranged in an array type, and Each unit pixel includes at least two pixels operated for each phase of the phase control signal.

18. A method for operating an image sensing device, the method comprising the following steps: generating a source signal and outputting the source signal to a target; receiving a reflected signal as the source signal reflected from the target; generating a control signal whose phase lags relative to the source signal by a predetermined amount indicated by the offset signal; generating a pixel signal based on the reflection signal by controlling a unit pixel via the control signal; calculating a depth phase based on the pixel signal; outputting depth information by compensating the depth phase according to the offset signal; selecting a reference phase among a plurality of reference phases, the selected reference phase having a minimum offset relative to the depth phase; as well as updating the offset signal to indicate the minimum offset, The control signal controls the operation timing of the unit pixel.

Images