JP3980039B2 - Ranging device - Google Patents

Description

  The present invention relates to a distance measuring device, and in particular, in a hybrid type distance measuring device capable of executing two integration modes of active mode integration and passive mode integration, fixed pattern noise or the like when active mode integration is performed. The present invention relates to a distance measuring device that corrects an offset generated in each sensor constituting a light receiving element.

  Conventionally, a distance measuring apparatus that performs passive AF used in a camera has a problem that an offset generated in each sensor constituting a light receiving element due to a dark current deteriorates a distance measuring performance.

Therefore, as disclosed in Patent Document 1, offset data for each sensor constituting the light receiving element is stored in a nonvolatile memory or the like at the time of manufacture, and offset correction is performed based on the offset data at the time of distance measurement. The technology to be done is known.
Japanese Patent Laid-Open No. 3-10473

  However, in the case of the method disclosed in Patent Document 1, since offset data must be stored in advance in a nonvolatile memory, an enormous memory capacity is required, increasing costs and increasing the memory mounting area. There was a problem of inviting.

  In the hybrid type distance measuring device, when active mode integration is performed, an offset is also generated due to fixed pattern noise caused by switching in the integration circuit during the steady light removal operation, and the magnitude of the offset due to the fixed pattern noise is large. Since this is related to the number of switching operations, it is necessary to consider the number of switching operations associated with the steady light removal operation when performing offset correction.

  An object of the present invention is to correct an offset generated in each sensor constituting a light receiving element when active mode integration is performed without using a large-capacity nonvolatile memory in a hybrid type distance measuring device. It is an object of the present invention to provide a distance measuring device that can perform highly accurate distance measurement.

According to the present invention, in order to solve the above problems,
(1) a light projecting means for projecting distance measuring light onto the subject;
A light receiving means comprising a plurality of sensors for receiving reflected signal light of ranging light from the subject and outputting subject image data;
A stationary light removing unit that removes a stationary light component that regularly enters the plurality of sensors of the light receiving unit;
Means for performing integral control on a plurality of sensors of the light receiving means,
Two integration modes: active mode integration for integrating signal light components other than the stationary light component from which stationary light components have been removed by the stationary light removing means, and passive mode integration for integrating stationary light components from the subject Integral control means for controlling
With a sensitivity lower than the sensitivity of the plurality of sensors of the light receiving means during the first active mode integration operation of integrating the signal light component other than the stationary light component while projecting the distance measuring light by the light projecting means. From the plurality of sensors of the light receiving means obtained by performing a second active mode integration operation that integrates signal light components other than the steady light component without projecting distance measuring light by the light projecting means. Correction means for correcting subject image data from a plurality of sensors of the light receiving means obtained when the distance measuring light is projected by subject image data;
A distance measuring apparatus is provided.

Further, according to the present invention, in order to solve the above problems,
(2) The distance measuring apparatus according to (1), wherein the first active mode integration operation is performed before the second active mode integration operation.

Further, according to the present invention, in order to solve the above problems,
(3) The distance measurement according to (1) or (2), wherein the number of integrations in the second active mode integration operation is the same as the number of integrations in the first active mode integration operation. An apparatus is provided.

Further, according to the present invention, in order to solve the above problems,
(4) The distance measuring apparatus according to any one of (1) to (3), wherein the correction unit performs correction using a sensitivity coefficient indicating a difference in sensitivity of the sensor. .

  According to the present invention, in the hybrid type distance measuring device, when active mode integration is performed without using a large-capacity nonvolatile memory, the offset generated in each sensor constituting the light receiving element is corrected, and high speed Thus, it is possible to provide a distance measuring device that can perform highly accurate distance measurement.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a block diagram of the main part showing the configuration of the camera distance measuring device according to the first embodiment of the present invention.

  In FIG. 1, reference numeral 107 is light projecting means for projecting distance measuring light (signal light) from a pair of distance measuring line sensors 102a and 102b toward a subject. Reference numerals 101a and 101b are It is a light receiving lens that forms a pair of subject images on the pair of line sensors 102a and 102b.

  Here, the pair of line sensors 102a and 102b converts the pair of subject images formed by the light receiving lenses 101a and 101b into electric signals according to the light intensity.

  In FIG. 1, reference numeral 103 denotes an integration control circuit as an integration control means for controlling the integration operation for the pair of line sensors 102a and 102b, and reference numeral 106 denotes the pair of line sensors 102a and 102b. This is a steady light removal circuit as a steady light removal means for removing the light component steadily incident on the light from the photocurrent output from the pair of line sensors 102a and 102b.

  In FIG. 1, reference numeral 105 is a CPU that performs output of various control signals, input of various data, distance measurement calculation, and the like.

  That is, the CPU 105 functions as a reading unit that reads out the subject image data output from the pair of line sensors 102a and 102b via the integration control circuit 103, and the subject image read out by the reading unit. It functions as a calculation means for calculating data corresponding to the subject distance based on the data.

  The CPU 105 further has a function of controlling the light projecting means 107, projects a signal light from the light projecting means 107 toward the subject, and a steady light removal circuit as the steady light removal means. 106 removes the stationary light component from the subject, and the integration control circuit 103 performs active mode integration in which the signal light component other than the stationary light component is integrated, and integration of the stationary light component from the subject. The camera has a function of controlling the overall operation of the camera distance measuring device capable of executing two integration modes, ie, passive mode integration.

  In FIG. 1, reference numeral 104 is an A / D conversion circuit that is between the integration control circuit 103 and the CPU 105 and reads an object image signal from the integration control circuit 103 and performs analog / digital (A / D) conversion. is there.

  That is, in the first embodiment, in the distance measuring apparatus having the configuration shown in FIG. 1, the signal light is projected in the active mode integration in which the stationary light component is removed and the signal light component other than the stationary light component is integrated. Then, after reading the sensor data by the integration, the active mode integration is performed without projecting the signal light, and the sensor data by the integration is read as an offset generated during the active mode integration.

  Then, the sensor data when the signal light is not projected (see (b) in FIG. 5) is subtracted from the sensor data when the signal light is projected (see (a) in FIG. 5). The sensor data as shown in FIG. 6 is used, and distance measurement is performed using this data.

  According to the first embodiment, the offset of sensor data due to fixed pattern noise or the like can be removed without increasing the capacity of a non-volatile memory such as an EEPROM (not shown), and high accuracy. Distance measurement can be performed.

  FIG. 2 is a diagram illustrating a specific configuration of the stationary light removal circuit 106.

  In the configuration of the stationary light removal circuit 106 shown in FIG. 2, reference numeral 110 is a photodiode, one end is connected to a power source, and the other end for detecting an optical signal is connected to the source of the transfer transistor 111. .

  The transfer transistor 111 has a drain connected to the ground, and a gate connected to the output of the inverting amplifier 112 via a switch SW1 formed of a switching transistor or the like.

  A current storage capacitor element C1 is connected between the source and gate of the transfer transistor 111, and the connection point between the source and the photodiode 110 is connected to the input of the inverting amplifier 112.

  The inverting amplifier 112 may be a CMOS inverting amplifier composed of a p-type MOS transistor and an n-type MOS transistor.

  Between the input and output of the inverting amplifier 112, there is a switch SW2 including a capacitive element C2 that applies feedback for detecting a photocurrent, a switching transistor for resetting the charge accumulated in the capacitive element C2, and the like. It is connected.

  A capacitively coupled inverting amplifier circuit is provided at the subsequent stage of the above configuration. The inverting amplifier circuit includes a capacitive element C3 having one end connected to the output of the inverting amplifier 112 and the other end of the capacitive element C3. Is connected to the inverting amplifier 113, a capacitive element C4 provided between the input and output of the inverting amplifier 113, and a switch SW3 including a switching transistor or the like connected in parallel to the capacitive element C4.

  A signal amplified by a gain (C3 / C4) determined by the capacitances of the capacitive elements C3 and C4 is output to the output VS2 of the inverting amplifier circuit while the phase is inverted with respect to the signal of the input VS1.

  FIG. 3 is a timing chart showing the basic operation of the stationary light removal circuit 106.

  As shown in FIG. 3B, the steady light removal circuit 106 resets the switch SW2 twice for one light projection and performs two integrations so as to understand the timing of the switch SW2. Perform the action.

  The first time makes the light projecting means 107 in a non-light-projecting state, and the second time makes the light-projecting state, so that the difference between the two is detected.

As shown in FIG. 3A, the period T1 is a period for storing stationary light, the switch SW1 is turned on, the switch SW2 is turned off, and the photocurrent _IPD generated in the photodiode 110 is transferred. Feedback is applied to the gate voltage of the transfer transistor 111 via the inverting amplifier 112 so as to flow to the ground via the transistor 111.

As a result, the voltage between the source and gate of the transfer transistor 111 becomes a voltage value corresponding to the photocurrent _IPD , and by holding this voltage value in the capacitor C1, the photocurrent _IPD corresponding to the steady light is discharged. The

Here, when turning off the switch SW1, the amount of charge held in the capacitor element C1 by feedthrough charge is changed, when the error of [Delta] I _PD to the current flowing through the transfer transistor 111 has occurred, the error component [Delta] I _PD Flows to the feedback system of the inverting amplifier 112.

Therefore, after resetting the capacitor C2 by turning on the switch SW2 in the period T2, performs integration of the error component [Delta] I _PD in the period T3.

Then, after resetting the capacitor C2 by turning on the switch SW2 again in period T4, the by projecting the signal light from the light projecting means 107 in the period T5, the signal light component applied by the error component [Delta] I _PD and projection Integrate I _PDS .

By making the integration times of the periods T3 and T5 the same and taking the difference between the integration values, only the output for the signal light component I _PDS can be detected.

  Regarding this difference, a capacitively coupled inverting amplifier circuit composed of the capacitive elements C3 and C4, the switch SW3, and the inverting amplifier 113 may be operated as follows.

First, as shown in FIG. 3 (c), until the end of integration of the error current component [Delta] I _PD period T3 advance turns on the switch SW3, the switch SW2 of the period T4 turns off the switch SW3 just before turned .

  As a result, as shown in FIGS. 3E and 3F, the output VS2 of the capacitively coupled inverting amplifier circuit composed of the inverting amplifier 113 is input when the switch SW3 changes from on to off. A subsequent change in the voltage of the input VS1 appears based on the voltage of the VS1.

Therefore, as shown in FIG. 3D, the output of VS2 at the end of integration in period T5 includes the output voltage of VS1 at the end of the first integration in period T3 and the end of the second integration in period T5. voltage corresponding to the voltage difference between VS1, ie removed component of the error current component [Delta] I _PD is, the signal light current component I _PDS generated by projecting light,
I _PDS x (t / C2) x (C3 / C4) (t is the light projection time)
The voltage value is detected.

  As described above, even if the current discharged by the transfer transistor 111 has an error with respect to the stationary photocurrent, only the signal light component is detected by the configuration of the stationary light removal circuit 106 as shown in FIG. can do.

  FIG. 4 is a timing chart showing a sequence of integration and sensor data reading by the integration control circuit 103, the A / D conversion circuit 104, and the CPU 105 in the first embodiment.

  That is, FIG. 4A shows the integration start control signal RESET, and the integration starts when L → H.

  FIG. 4B shows the integration stop control signal EXTEND, and the integration is stopped when H → L.

  FIG. 4C shows the active mode integration control signal INTCLK. The period between the first pulse, the second pulse, and the third pulse is T3 in FIG. 3, and the third pulse and the fourth pulse. The period between the periods corresponds to T5 in FIG.

  FIG. 4D shows signal light projection in which signal light is projected in the H period.

  FIG. 4E shows a sensor data read control signal RWCLK, which outputs integration data of each photodiode for each pulse.

  FIG. 4F shows the integrated data output MDATA of the monitor sensor.

  The monitor sensor is, for example, a sensor having the fastest integration speed among photodiodes constituting the line sensors 102a and 102b.

  In FIG. 4, t1 is an active mode integration period with light emission, and integration operations of 1 to n cycles are performed until the MDATA output reaches a predetermined level.

  Further, t2 is a sensor data reading period in active mode integration with light projection.

  Further, t3 is an active mode integration period without light projection, and the n-cycle integration operation performed by active mode integration with light projection is performed without light projection.

  Further, t4 is a sensor data reading period in active mode integration without light projection.

  FIG. 5 is a diagram showing sensor data in each active mode integration as described above.

  That is, (a) in FIG. 5 shows sensor data in active mode integration with light projection, and (b) in FIG. 5 shows sensor data in active mode integration without light projection. (C) shows the sensor data after correcting the sensor data in the active mode integration with light projection using the sensor data in the active mode integration without light projection.

  FIG. 6 is a flowchart showing a procedure of a distance measuring sequence according to the first embodiment.

  First, in step S101, pre-ranging is performed in the active mode or passive mode, and a ranging method is selected based on the result.

  At this time, a distance measuring method may be selected by luminance determination using photometric data or the like.

  Next, in step S102, if the selection result in step S101 is the active mode, the process proceeds to step S103, and if the selection result is the passive mode, the process proceeds to step S110.

  Next, in step S103, an integration mode, a monitor range, sensor sensitivity, an integration end condition, and the like are set.

  Next, in step S104, active mode integration is performed while projecting signal light from the light projecting means 107.

  The A / D conversion circuit 104 performs A / D conversion to read sensor data, and stores the data in the RAM in the CPU 105.

  Next, in step S106, integration conditions are set in the same manner as in step S103.

  Next, in step S107, active mode integration is performed for the same number of cycles as the number of light projections in the integration in step S104 without projecting signal light.

  Next, in step S108, the sensor data is read out in the same manner as in step S105, and the data is stored in the RAM in the CPU 105.

  Next, in step S109, offset correction is performed based on the sensor data read in step S108.

  This offset correction may be performed every time one piece of data is read during reading of the sensor data in step S108.

  Next, in step S110, integration conditions are set in the same manner as in step S103.

  Next, in step S111, passive mode integration is performed.

  Next, in step S112, the sensor data is read out in the same manner as in step S105, and the data is stored in the RAM in the CPU 105.

  Next, in step S113, distance measurement data is calculated by a known correlation calculation, interpolation calculation, or the like.

  FIG. 7 is a flowchart illustrating a procedure of offset correction in the first embodiment.

  First, in step S121, the number of sensor data for offset correction is set.

  Next, in step S122, the head data of the data to be offset-corrected with the sensor data at the time of integration with projection is set.

  Next, in step S123, the head data of data used for offset correction is set as sensor data at the time of integration without light projection.

  Next, in step S124, an offset is calculated by taking the difference between the reference data and sensor data at the time of integration without light projection.

  Here, the 8-bit A / D MAX value 255 is used as the reference data, but the reference voltage level at the time of integration may be used as the reference data.

  Next, in step S125, the offset calculated in step S124 is added to the sensor data at the time of integration with projection to perform offset correction.

  Next, in step S126, the corrected data is stored in the RAM in the CPU 105.

  Next, in step S127, sensor data at the time of integration with projection for performing offset correction is set.

  Next, in step S128, sensor data at the time of integration without projection used for offset correction is set.

  Next, in step S129, it is determined whether or not correction has been completed for all of the sensor data to be offset corrected. If all have been completed, the process proceeds to step S130, and if not completed, the process returns to step S124.

  Next, in step S130, it is determined whether correction has been completed for both sensor data of the pair of line sensors 102a, 102b. If both have been completed, the process returns. If not completed, the process returns to step S122.

  FIG. 8 is a flowchart showing a procedure for performing offset correction simultaneously with reading of sensor data at the time of integration without projection in step S107 shown in FIG. 6 in the first embodiment.

  First, in step S131, the number of sensor data for offset correction is set.

  Next, in step S132, the head data of the data to be offset-corrected with the sensor data at the time of integration with projection is set.

  In step S133, the A / D conversion circuit 104 performs A / D conversion to read out the head data of the data used for offset correction with the sensor data at the time of integration without projection.

  Next, in step S134, the offset is calculated by taking the difference between the reference data and the sensor data at the time of integration without light projection.

  Here, the 8-bit A / D MAX value 255 is used as the reference data, but the reference voltage level at the time of integration may be used as the reference data.

  Next, in step S135, the offset calculated in step S134 is added to the sensor data at the time of integration with projection to perform offset correction.

  Next, in step S136, the corrected data is stored in the RAM in the CPU 105.

  Next, in step S137, sensor data at the time of integration with projection for performing offset correction is set.

  Next, in step S138, sensor data at the time of integration without light projection, which is used for offset correction, is read by A / D conversion by the A / D conversion circuit 104.

  Next, in step S139, it is determined whether or not correction has been completed for all of the sensor data to be offset corrected. If all have been completed, the process proceeds to step S140. If not completed, the process returns to step S134.

  Next, in step S140, it is determined whether correction has been completed for both sensor data of the pair of line sensors 102a and 102b. If both have been completed, the process returns. If not completed, the process returns to step S132.

(Second Embodiment)
The configuration of the camera distance measuring device according to the second embodiment is the same as the configuration of the camera distance measuring device according to the first embodiment shown in FIG.

  That is, in the first embodiment described above, offset correction is performed based on the result of the integration operation in the active mode without light projection for the same number of times as in the active mode integration with signal light projection. On the other hand, in this second embodiment, the offset is detected by setting the number of active mode integration operations without light projection to half the number of times of active mode integration with light projection, Correction is performed based on the offset.

  However, the number of integration operations in the active mode without projection is not limited to half the number of projections in the active mode integration with projection, and may be 1/3 or 1/4.

  According to the second embodiment as described above, the distance measurement time can be shortened compared to the first embodiment described above, and high-speed and high-precision distance measurement can be performed.

  FIG. 9 is a flowchart showing a procedure of a distance measuring sequence according to the second embodiment.

  First, in step S201, pre-ranging is performed in the active mode or passive mode, and a ranging method is selected based on the result.

  At this time, a distance measuring method may be selected by luminance determination using photometric data or the like.

  Next, in step S202, if the selection result in step S201 is the active mode, the process proceeds to step S203, and if the selection result is the passive mode, the process proceeds to step S210.

  Next, in step S203, an integration mode, a monitor range, sensor sensitivity, an integration end condition, and the like are set.

  Next, in step S204, active mode integration is performed while projecting signal light from the light projecting means 107.

  In step S205, the A / D conversion circuit 104 performs A / D to read sensor data, and stores the data in the RAM in the CPU 105.

  Next, in step S206, integration conditions are set in the same manner as in step S203.

  Next, in step S207, active mode integration is performed for the number of cycles equal to ½ of the number of projections in the integration in step S204 without projecting signal light.

  Next, in step S208, the sensor data is read out in the same manner as in step S205, and the data is stored in the RAM in the CPU 105.

  Next, in step S209, offset correction is performed based on the sensor data read in step S208.

  This offset correction may be performed every time one piece of data is read during reading of the sensor data in step S208.

  Next, in step S210, integration conditions are set in the same manner as in step S203.

  Next, in step S211, passive mode integration is performed.

  Next, in step S212, the sensor data is read out in the same manner as in step S205, and the data is stored in the RAM in the CPU 105.

  Next, in step S213, distance measurement data is calculated by a known correlation calculation, interpolation calculation, or the like.

  FIG. 10 is a flowchart illustrating an offset correction procedure according to the second embodiment.

  First, in step S221, the number of sensor data for performing offset correction is set.

  Next, in step S222, the head data of the data to be offset-corrected with the sensor data at the time of integration with projection is set.

  Next, in step S223, the head data of data used for offset correction is set as sensor data at the time of integration without light projection.

  In step S224, the difference between the reference data and the sensor data at the time of integration without light projection is calculated to calculate an offset.

  Here, the 8-bit A / D MAX value 255 is used as the reference data, but the reference voltage level at the time of integration may be used as the reference data.

  Next, in step S225, the offset calculated in step S224 is doubled and added to the sensor data at the time of integration with projection to perform offset correction.

  Next, in step S226, the corrected data is stored in the RAM in the CPU 105.

  Next, in step S227, sensor data at the time of integration with projection for performing offset correction is set.

  Next, in step S228, sensor data at the time of integration without projection used for offset correction is set.

  Next, in step S229, it is determined whether or not correction has been completed for all of the sensor data to be offset corrected. If all have been completed, the process proceeds to step S230. If not completed, the process returns to step S224.

  Next, in step S230, it is determined whether correction has been completed for both sensor data of the pair of line sensors 102a, 102b. If both have been completed, the process returns. If not completed, the process returns to step S222.

(Third embodiment)
The configuration of the camera distance measuring device according to the third embodiment is the same as the configuration of the camera distance measuring device according to the first embodiment shown in FIG.

  In other words, in the second embodiment described above, the offset is detected by setting the number of active mode integration operations without light projection to half the number of times of active mode integration with light projection, and based on the offset. In contrast to the correction, the third embodiment first detects an offset by performing one integration operation in the active mode without light projection, and then performs active with light projection. Mode integration is performed, and correction is performed based on the detected offset by one integration operation.

  According to the third embodiment, the distance measurement time can be further reduced as compared with the second embodiment, and high-speed and high-precision distance measurement can be performed.

  FIG. 11 is a flowchart showing the procedure of a distance measuring sequence according to the third embodiment.

  First, in step S301, pre-ranging is performed in the active mode or the passive mode, and a ranging method is selected based on the result.

  At this time, a distance measuring method may be selected by luminance determination using photometric data or the like.

  Next, in step S302, if the selection result in step S301 is the active mode, the process proceeds to step S303, and if the selection result is the passive mode, the process proceeds to step 310.

  Next, in step S303, an integration mode, a monitor range, sensor sensitivity, an integration end condition, and the like are set.

  Next, in step S304, one cycle of active mode integration is performed without projecting signal light.

  In step S 305, the A / D conversion circuit 104 performs A / D conversion to read sensor data, and stores the data in the RAM in the CPU 105.

  Next, in step S306, integration conditions are set in the same manner as in step S303.

  Next, in step S307, active mode integration is performed while projecting signal light from the light projecting means 107.

  Next, in step S308, the sensor data is read out in the same manner as in step S305, and the data is stored in the RAM in the CPU 105.

  Next, in step S309, offset correction is performed based on the sensor data read in step S305.

  This offset correction may be performed every time one piece of data is read during reading of the sensor data in step S308.

  Next, in step S310, integration conditions are set in the same manner as in step S303.

  Next, in step S311, passive mode integration is performed.

  Next, in step S312, sensor data is read out in the same manner as in step S305, and the data is stored in the RAM in the CPU 105.

  Next, in step S313, distance measurement data is calculated by a known correlation calculation, interpolation calculation, or the like.

  FIG. 12 is a flowchart illustrating an offset correction procedure according to the third embodiment.

  First, in step S321, the number of sensor data for offset correction is set.

  Next, in step S322, the head data of the data to be offset-corrected with the sensor data at the time of integration with projection is set.

  Next, in step S323, the head data of data used for offset correction is set as sensor data at the time of integration without light projection.

  Next, in step S324, the offset is calculated by taking the difference between the reference data and the sensor data during integration without light projection.

  Here, the 8-bit A / D MAX value 255 is used as the reference data, but the reference voltage level at the time of integration may be used as the reference data.

  Next, in step S325, the offset calculated in step S324 is added to the sensor data at the time of integration with light projection multiplied by the number of times of light projection at the time of integration with light projection to perform offset correction.

  Next, in step S326, the corrected data is stored in the RAM in the CPU 105.

  Next, in step S327, sensor data at the time of integration with projection for performing offset correction is set.

  Next, in step S328, sensor data at the time of integration without projection used for offset correction is set.

  Next, in step S329, it is determined whether or not correction has been completed for all of the sensor data to be offset corrected. If all have been completed, the process proceeds to step S330, and if not completed, the process returns to step S324.

  Next, in step S330, it is determined whether correction has been completed for both sensor data of the pair of line sensors 102a, 102b. If both have been completed, the process returns. If not completed, the process returns to step S322.

(Fourth embodiment)
The configuration of the camera distance measuring device according to the fourth embodiment is the same as the configuration of the camera distance measuring device according to the first embodiment shown in FIG.

  That is, in the fourth embodiment, active mode integration with light projection is performed with high sensor sensitivity in order to increase the detection capability of signal light, but when offset is detected, offset due to the influence of random noise or the like is performed. In order to prevent deterioration of detection accuracy, the sensor sensitivity is set to low sensitivity and integration in the active mode without light projection is performed.

  According to the fourth embodiment, it is possible to perform distance measurement with higher accuracy.

  FIG. 13 is a flowchart showing the procedure of a distance measuring sequence according to the fourth embodiment.

  First, in step S401, pre-ranging is performed in the active mode or passive mode, and a ranging method is selected based on the result.

  At this time, a distance measuring method may be selected by luminance determination using photometric data or the like.

  Next, in step S402, if the selection result in step S401 is the active mode, the process proceeds to step S403, and if the selection result is the passive mode, the process proceeds to step S410.

  Next, in step S403, an integration mode, a monitor range, sensor sensitivity, an integration end condition, and the like are set.

  Here, the sensor sensitivity is set to high sensitivity.

  Next, in step S404, active mode integration is performed with high sensitivity while projecting signal light from the light projecting means 107.

  Next, in step S405, A / D conversion is performed by the A / D conversion circuit 104 to read sensor data, and the data is stored in the RAM in the CPU 105.

  Next, in step S406, integration conditions are set in the same manner as in step S403.

  Here, the sensor sensitivity is set to a low sensitivity.

  Next, in step S407, without irradiating the signal light, active mode integration is performed with the sensor sensitivity being low sensitivity for the same number of cycles as the number of light projections in the integration in step S404.

  Next, in step S408, the sensor data is read out in the same manner as in step S405, and the data is stored in the RAM in the CPU 105.

  Next, in step S409, offset correction is performed based on the sensor data read in step S408.

  This offset correction may be performed every time one piece of data is read during reading of the sensor data in step S408.

  Next, in step S410, integration conditions are set in the same manner as in step S403.

  Next, in step S411, passive mode integration is performed.

  Next, in step S412, the sensor data is read out in the same manner as in step S405, and the data is stored in the RAM in the CPU 105.

  In step S413, distance measurement data is calculated by a known correlation calculation, interpolation calculation, or the like.

  FIG. 14 is a flowchart showing a procedure of offset correction according to the fourth embodiment.

  First, in step S421, the number of sensor data for performing offset correction is set.

  Next, in step S422, the head data of the data to be offset-corrected with the sensor data at the time of integration with projection is set.

  Next, in step S423, the head data of the data used for offset correction is set with the sensor data at the time of integration without projection.

  Next, in step S424, the difference between the reference data and the sensor data at the time of integration without light projection is taken to calculate an offset.

  Here, the 8-bit A / D MAX value 255 is used as the reference data, but the reference voltage level at the time of integration may be used as the reference data.

  Next, in step S425, the offset correction is performed by adding to the sensor data at the time of integration with projection with the offset calculated in step S424 by the sensitivity coefficient for correcting the offset error due to the difference in sensor sensitivity.

  Next, in step S426, the corrected data is stored in the RAM in the CPU 105.

  Next, in step S427, sensor data at the time of integration with projection for performing offset correction is set.

  Next, in step S428, sensor data at the time of integration without projection used for offset correction is set.

  Next, in step S429, it is determined whether or not correction has been completed for all of the sensor data to be offset corrected. If all have been completed, the process proceeds to step S430. If not completed, the process returns to step S424.

  Next, in step S430, it is determined whether correction has been completed for both sensor data of the pair of line sensors 102a, 102b. If both have been completed, the process returns. If not completed, the process returns to step S422.

(Fifth embodiment)
The configuration of the camera distance measuring device according to the fifth embodiment is the same as the configuration of the camera distance measuring device according to the first embodiment shown in FIG.

  That is, in the fifth embodiment, the integration time in the active mode without signal light projection for offset detection is made shorter than the integration time in the active mode with light projection.

  This fifth embodiment is effective when the main cause of the occurrence of the offset is the switching operation in the stationary light removal circuit and the integration circuit.

  According to the fifth embodiment, the distance measurement time can be further reduced, and high-speed and high-precision distance measurement can be performed.

  FIG. 15 is a timing chart showing a sequence of integration and sensor data reading in the fifth embodiment.

  That is, (a) of FIG. 15 shows the integration start control signal RESET, and the integration starts when L → H.

  FIG. 15B shows the integration stop control signal EXTEND, and the integration is stopped when H → L.

  FIG. 15C shows the active mode integration control signal INTCLK. The period between the first pulse, the second pulse and the third pulse is T3 in FIG. 3, and the third and fourth pulses. The period between the periods corresponds to T5 in FIG.

  FIG. 15D shows signal light projection in which signal light is projected in the H period.

  FIG. 15E shows a sensor data read control signal RWCLK, which outputs integration data of each photodiode for each pulse.

Further, (f) of FIG. 15 shows the integral data output MDATA of the monitor sensor.

  The monitor sensor is, for example, a sensor having the fastest integration speed among photodiodes constituting the line sensors 102a and 102b.

  In FIG. 15, t1 is an active mode integration period with light projection, and integration operation of 1 to n cycles is performed until the MDATA output reaches a predetermined level.

  Further, t2 is a sensor data reading period in active mode integration with light projection.

  Further, t3 is an active mode integration period without light projection, and the n-cycle integration operation performed by active mode integration with light projection is performed without light projection.

  However, the time for one cycle of the integration operation is set to be shorter than that during active mode integration with light projection.

  Further, t4 is a sensor data reading period in active mode integration without light projection.

(Sixth embodiment)
The configuration of the camera distance measuring device according to the sixth embodiment is the same as the configuration of the camera distance measuring device according to the first embodiment shown in FIG.

  That is, the sixth embodiment is a modification of the third embodiment, and performs an integration operation once in the active mode without signal light projection for detecting the offset at the beginning of the distance measuring sequence. It is what you do.

  FIG. 16 is a flowchart showing a procedure of a distance measuring sequence according to the sixth embodiment.

  First, in step S601, an integration mode, a monitor range, sensor sensitivity, an integration end condition, and the like are set.

  Next, in step S602, one cycle of active mode integration is performed without projecting signal light.

  In step S603, the A / D conversion circuit 104 performs A / D conversion to read sensor data, and stores the data in the RAM in the CPU 105.

  Next, in step S604, pre-ranging is performed in the active mode or passive mode, and a ranging method is selected based on the result.

  At this time, a distance measuring method may be selected by luminance determination using photometric data or the like.

  Next, in step S605, if the selection result in step S604 is the active mode, the process proceeds to step S606, and if it is the passive mode, the process proceeds to step S610.

  Next, in step S606, integration conditions are set in the same manner as in step S601.

  Next, in step S607, active mode integration is performed while projecting signal light from the light projecting means 107.

  Next, in step S608, sensor data is read out in the same manner as in step S603, and the data is stored in the RAM in the CPU 105.

  Next, in step S609, offset correction is performed based on the sensor data read in step 608.

  This offset correction may be performed each time one piece of data is read during reading of the sensor data in step S608.

  Next, in step S610, integration conditions are set as in step S601.

  Next, in step S611, passive mode integration is performed.

  Next, in step S612, the sensor data is read out in the same manner as in step S603, and the data is stored in the RAM in the CPU 105.

  In step S613, distance measurement data is calculated by a known correlation calculation, interpolation calculation, or the like.

(Seventh embodiment)
The configuration of the camera distance measuring device according to the seventh embodiment is the same as the configuration of the camera distance measuring device according to the first embodiment shown in FIG.

  In the seventh embodiment, one integration operation in the active mode without signal light projection for offset detection is performed when the camera power switch is turned on and the camera is in a shooting standby state. It is something that is sometimes executed.

  According to the seventh embodiment, the distance measurement time can be further shortened compared to the case where offset detection is performed in the distance measurement sequence, and high-speed and high-precision distance measurement can be performed. .

  FIG. 17 is a flowchart showing the sequence of a camera sequence according to the seventh embodiment.

  First, in step S701, the camera state such as the lens barrier opening of the camera and the setup of the lens frame is initialized.

  In step S702, data such as an adjustment value is read from a non-volatile memory such as an EEPROM (not shown) and developed in the RAM of the CPU 105.

  In step S703, an integration mode, a monitor range, sensor sensitivity, an integration end condition, and the like are set.

  Next, in step S704, one cycle of active mode integration is performed without projecting signal light.

  Next, in step S705, the A / D conversion circuit 104 performs A / D conversion to read sensor data, and stores RAM data in the CPU 105.

  Next, in step S706, it is determined whether or not the first release button of the camera is pressed. If it is pressed, the process proceeds to step S711, and if not, the process proceeds to step S707.

  Next, in step S707, integration conditions are set as in step S703.

  Next, in step S708, as in step S704, one cycle of active mode integration is performed without projecting signal light.

  Next, in step S709, sensor data is read out in the same manner as in step S705, and the data is stored in the RAM in the CPU 105.

  Next, in step S710, it is determined whether the power switch of the camera has been turned off. If it has been turned off, the camera sequence is terminated, and if it remains on, the process returns to step S706.

  Next, in step S711, photometric data for performing exposure control during shooting is measured.

  Next, in step S712, subject distance data used for drive control of the focus adjustment lens is measured.

  At this time, offset correction is performed using the sensor data read in step S705 or step 709.

  Next, in step S713, the extension amount of the focus adjustment lens is calculated from the subject distance data measured in step S712.

  Next, in step S714, similarly to step S706, it is determined whether or not the first release button of the camel is pressed. If it is pressed, the process proceeds to step S715, and if not, the process returns to step S706.

Next, in step S715, it is determined whether or not the second release button of the camera has been pressed. If it has been pressed, the process proceeds to step S716, and if not, the process returns to step S714.
Next, in step S716, the focus adjustment lens is driven based on the feed amount obtained in step S713. Next, in step S717, the film surface is exposed based on the photometric data obtained in step S711.

  Next, in step S718, the film exposed in step S717 is wound up, and the process returns to step S706.

(Eighth embodiment)
FIG. 18 is a block diagram showing the configuration of a camera distance measuring apparatus according to the eighth embodiment.

  In FIG. 18, reference numerals 801a and 801b are light receiving lenses for forming subject images on the area sensors 802a and 802b, and reference numerals 802a and 802b are subject images formed by the light receiving lenses 801a and 801b. Is a pair of area sensors that photoelectrically convert the signal according to its light intensity and convert it into an electrical signal.

  In FIG. 18, reference numeral 803 denotes an integration control circuit that controls the integration operation of the pair of area sensors 802a and 802b and outputs a subject image signal as an integration result. Reference numeral 804 denotes an integration control circuit 803. This is an A / D conversion circuit that reads out subject image signals and performs A / D conversion.

  In FIG. 18, reference numeral 805 denotes a CPU that outputs various control signals, inputs various data, distance measurement calculation, and the like. Reference numeral 806 denotes a photocurrent output from the pair of area sensors 802a and 802b. Thus, the steady light removal circuit removes the steady photocurrent component.

  In FIG. 18, reference numeral 807 denotes light projecting means for projecting distance measuring light (signal light) of a pair of area sensors 802 a and 802 b for distance measurement toward the subject, and is controlled by the CPU 805. .

  The camera distance measuring device according to the eighth embodiment is a pair of area sensors 802a and 802b instead of the pair of line sensors 102a and 102b of the camera distance measuring device according to the first embodiment shown in FIG. The same except that is used.

  That is, in the eighth embodiment, a pair of area sensors 802a and 802b are used as light receiving elements in order to measure the distance in the photographing screen two-dimensionally.

  According to the eighth embodiment, by using the pair of area sensors 802a and 802b, it is possible to measure the distance two-dimensionally within the photographing screen, so that it is possible to perform highly functional distance measurement.

  As described above, according to the camera distance measuring device of the present invention, a light receiving element is configured when active mode integration is performed in a hybrid type distance measuring device without using a large-capacity nonvolatile memory. Since the offset generated in each sensor can be corrected, high-precision distance measurement can be performed with an inexpensive and small configuration.

  The present invention is not limited to the hybrid type AF, but can be applied to an active AF in which the light receiving side is a sensor array.

  In addition, the present specification shown in the embodiment as described above includes inventions as shown in the following supplementary notes 1 to 10 in addition to the claims 1 to 3 shown in the claims. Yes.

(Supplementary Note 1) Projection means for projecting signal light toward a subject,
A light receiving lens that forms a pair of subject images on a pair of line sensors;
A pair of line sensors for converting a pair of subject images formed by the light receiving lens into electrical signals according to light intensity;
Integration control means for performing integration control on the pair of line sensors;
Steady light removal means for removing light components that are steadily incident on the pair of line sensors;
Reading means for reading the subject image data output from the pair of line sensors;
Computation means for computing data according to subject distance based on subject image data read by the readout means,
The signal light is projected from the light projecting unit toward the subject, the stationary light component is removed by the stationary light removing unit, and the integration operation of integrating only the signal light component from the subject is repeated a plurality of times. In a camera ranging device capable of executing two integration modes, an active mode integration that performs and a passive mode integration that integrates a steady light component from a subject,
Active mode integration when signal light is projected by subject image data output from the pair of line sensors when active mode integration is performed when no signal light is projected toward the subject from the light projecting means A distance measuring apparatus that corrects subject image data output from the pair of line sensors when performing the operation.

  (Supplementary Note 2) Obtained by performing the active mode integration operation when the signal light is projected from the light projecting unit toward the subject and the active mode integration operation when the same number of signal lights are not projected. The subject image data output from the pair of line sensors obtained when the signal light is projected is corrected by subject image data output from the pair of line sensors. Distance measuring device.

  (Supplementary note 3) The integration operation is performed when the signal light is not projected a smaller number of times than the number of repetitions of the active integration operation when the signal light is projected, and the sensor data obtained thereby is proportional to the ratio of the number of repetitions. The distance measuring device according to appendix 1, wherein the sensor data is corrected when the signal light is projected.

  (Supplementary note 4) Active integration operation when signal light is not projected is performed with a fixed number of repetitions, and sensor data obtained thereby is processed according to the ratio to the number of repetitions of integration operation when signal light is projected. The distance measuring device according to appendix 1, wherein the sensor data when the signal light is projected is corrected.

  (Supplementary Note 5) An active mode integration operation in which no signal light is projected in a time shorter than one integration time during the active mode integration operation in the case where signal light is projected toward the subject from the light projecting means. The subject image data output from the pair of line sensors obtained when the signal light is projected is corrected by subject image data output from the pair of line sensors obtained by performing the processing. The distance measuring apparatus according to 1.

  (Appendix 6) Active mode when signal light is not projected with lower sensitivity than the sensitivity of the pair of line sensors during active mode integration operation when signal light is projected toward the subject from the light projecting means Subject image data output from the pair of line sensors obtained when signal light is projected is corrected by subject image data output from the pair of line sensors obtained by performing an integration operation. The ranging apparatus according to Supplementary Note 1.

  (Supplementary note 7) The distance measuring device according to supplementary note 1, wherein after the active integration operation when the signal light is projected, the integration operation when the signal light is not projected is performed to correct the sensor data.

  (Supplementary note 8) The supplementary note 1, wherein an integration operation is performed when no signal light is projected before the start of distance measurement, and the sensor data when the signal light is projected is corrected by the sensor data at that time. Ranging device.

  (Additional remark 9) The ranging apparatus of Additional remark 1 characterized by performing the integration operation when not projecting signal light and correcting the sensor data before the active integration operation when projecting signal light.

  (Supplementary note 10) The supplementary note 1, wherein an integration operation is performed when no signal light is projected when the camera is turned on, and the sensor data when the signal light is projected is corrected by the sensor data at that time. Ranging device.

FIG. 1 is a block diagram of the main part showing the configuration of the camera distance measuring device according to the first embodiment of the present invention. FIG. 2 is a diagram illustrating a specific configuration of the stationary light removal circuit of FIG. FIG. 3 is a timing chart shown for explaining the basic operation of the stationary light removal circuit of FIG. FIG. 4 is a timing chart showing a sequence of integration and sensor data reading according to the first embodiment. FIG. 5 is a diagram showing sensor data in each active mode integration according to the first embodiment. FIG. 6 is a flowchart showing a procedure of a distance measuring sequence according to the first embodiment. FIG. 7 is a flowchart illustrating a procedure of offset correction in the first embodiment. FIG. 8 is a flowchart showing a procedure for performing offset correction simultaneously with reading of sensor data at the time of integration without projection in step S107 shown in FIG. 6 in the first embodiment. FIG. 9 is a flowchart showing a procedure of a distance measuring sequence according to the second embodiment of the present invention. FIG. 10 is a flowchart illustrating an offset correction procedure according to the second embodiment. FIG. 11 is a flowchart showing a procedure of a distance measuring sequence according to the third embodiment of the present invention. FIG. 12 is a flowchart illustrating an offset correction procedure according to the third embodiment. FIG. 13 is a flowchart showing a procedure of a distance measuring sequence according to the fourth embodiment of the present invention. FIG. 14 is a flowchart showing a procedure of offset correction according to the fourth embodiment. FIG. 15 is a timing chart showing a sequence of integration and sensor data reading in the fifth embodiment of the present invention. FIG. 16 is a flowchart showing a procedure of a distance measuring sequence according to the sixth embodiment of the present invention. FIG. 17 is a flowchart showing the sequence of a camera sequence according to the seventh embodiment of the present invention. FIG. 18 is a block diagram showing the configuration of the camera distance measuring apparatus according to the eighth embodiment of the present invention.

Explanation of symbols

101a, 101b ... light receiving lens,
102a, 102b ... a pair of line sensors,
103. An integration control circuit as integration control means,
104 ... analog / digital (A / D) conversion circuit,
105 ... CPU,
106 ... a stationary light removal circuit as a stationary light removal means,
107: Projection means,
110: Photodiode,
111 ... Transistor for transfer,
SW1, SW2, SW3 ... switch,
112 ... inverting amplifier,
C1, C2, C3, C4 ... capacitive elements,
113 ... Inverting amplifier,
VS1 ... the input of the inverting amplifier circuit,
VS2 ... the output of the inverting amplifier circuit,
I _PD ... photocurrent corresponding to stationary light,
ΔI _PD ... error component,
I _PDS ... signal light component,
RESET ... Integral start control signal,
EXTEND ... Integral stop control signal,
INTCLK: Active mode integration control signal,
RWCLK: Sensor data read control signal,
MDATA ... Integrated data output of monitor sensor,
801a, 801b ... light receiving lens,
802a, 802b ... a pair of area sensors,
803 ... integration control circuit,
804 ... analog / digital (A / D) conversion circuit,
805 ... CPU,
806: stationary light removal circuit,
807 ... Projection means.

Claims (4)

A light projecting means for projecting distance measuring light onto the subject;
A light receiving means comprising a plurality of sensors for receiving reflected signal light of ranging light from the subject and outputting subject image data;
A stationary light removing unit that removes a stationary light component that regularly enters the plurality of sensors of the light receiving unit;
Means for performing integral control on a plurality of sensors of the light receiving means,
Two integration modes: active mode integration for integrating signal light components other than the stationary light component from which stationary light components have been removed by the stationary light removing means, and passive mode integration for integrating stationary light components from the subject Integral control means for controlling
With a sensitivity lower than the sensitivity of the plurality of sensors of the light receiving means during the first active mode integration operation of integrating the signal light component other than the stationary light component while projecting the distance measuring light by the light projecting means. From the plurality of sensors of the light receiving means obtained by performing a second active mode integration operation that integrates signal light components other than the steady light component without projecting distance measuring light by the light projecting means. Correction means for correcting subject image data from a plurality of sensors of the light receiving means obtained when the distance measuring light is projected by subject image data;
A distance measuring device comprising:   2. The distance measuring apparatus according to claim 1, wherein the first active mode integration operation is performed before the second active mode integration operation. The distance measuring apparatus according to claim 1 or 2, wherein the number of integrations in the second active mode integration operation is the same as the number of integrations in the first active mode integration operation . The distance measuring apparatus according to claim 1, wherein the correction unit performs correction using a sensitivity coefficient indicating a difference in sensitivity of the sensor .

Images