JPH0122885B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a data reading device for a storage effect sensor, typically a charge coupled device (CCD).

Generally, in order to remotely measure the travel distance or rotation angle of a moving object from a reference point, attach a scale to the object, reset the scale's graduations to zero at the reference position, and then measure the movement from there. The distance and rotation angle may be counted optically or electromagnetically and displayed on a display, for example.

However, since the method described above is a so-called incremental method in which the amount of relative movement between the scale and the sensor that reads it is measured using an electrical signal generated during movement, a reference point must be detected.

Therefore, in order to eliminate such problems,
An absolute method that encodes the scale can be considered. In this method, the length from the reference point of the scale is encoded and marked on the scale, and by reading this, the length from the reference point is obtained without detecting the reference point. be. In implementing this method,
In order to read the coded scale and determine the subdivided values, it is conceivable to use a cumulative effect sensor.
A cumulative effect sensor is a charge-coupled device (CCD)
It is composed of a photo element section, a gate section, and a shift register section, as represented by .
The photo element section is constructed by arranging a large number of elements in, for example, a straight line, and each element has a function of accumulating a charge corresponding to the intensity of light incident thereon. The shift register section has the same number of bits as the number of elements in the photo element section, and the charge of the corresponding element is transferred to each bit in parallel via the gate section, and when a scanning pulse is applied, each bit is transferred in parallel. The configuration is such that the charges are output in time series. In such a storage effect type sensor, the width of each element constituting the photo element section can usually be set on the order of 10-odd microns, making it possible to read the scale graduations and interpolate between the graduations. That is, as shown in FIG. 1, a bright area A (light is transmitted) and a dark area B (light is not transmitted).
A storage effect sensor, for example CCDY, consisting of a photo element part F, a gate part G, and a shift register part R, is provided facing one side of the scale C, which is formed by arranging the elements alternately in a straight line, and the other side of the scale C. When parallel light P having a width X is irradiated toward the photoelement portion F, charges corresponding to the incident light are accumulated in the element in the portion of the photo element portion F where the light that has passed through the bright portion A is incident. Here, if a gate pulse S is applied to CCDY, a reset pulse Z, and scanning pulses φ ₁ and φ ₂ which are obtained by dividing this pulse Z by 1/2 and having a phase difference of 180° are applied, a differential amplifier is generated. H
The output CO shown in FIG. 2d is sent out. In this example, the width of the bright part A is set to the width of three elements constituting the photo element part F, and the three elements directly face the bright part A, and the differential amplifier H
From then on, three signals are sent out in time series in exactly the same manner as above. Therefore, by combining a scale that encodes the length from a reference point with a bright and dark pattern and a cumulative effect sensor, it is possible to measure the distance from the reference point of the scale, that is, the length, with an accuracy of less than 10 microns. It becomes possible to do so. Specifically, it is conceivable to provide both as shown in FIG. 3, for example. That is, the scale C is divided into a plurality of blocks of the same length in the longitudinal direction. This figure shows the _NPth block and the _NP-1st block. Taking each block, for example, block N _P as an example, the width of one element constituting the photo element part F of CCDY is set as the reference width at the left end of this block N _P , and the width of four of the above elements is set as the reference width. A marker _M with
A block stop marker D is formed from the dark area of 4 elements, and of the 4 elements of marker M,
The width of one element in contact with this is defined as a marker bit I _n . Then, on the right side of the marker M, there is a dark area K ₁ , which is the width of two of the above-mentioned elements and every two widths.
_{K 2 , K 3 .} ^_ _{_} ¹ , P ₃ to 2 ² , and so on, to binary codes. In the figure, address parts P ₁ and P ₃ are formed in a bright part, and other address parts are formed in a dark part. The same setting is made for block N _P-1 , but the value of the binary encoded address field is subtracted by 1 from that for block N _P.

However, with scale C configured as above,
To accurately measure the distance from the reference point of scale C using CCDY, do the following.

That is, each element constituting the photo element section F of CCDY is assigned a bit number as shown in the figure, and a certain bit is designated as an index bit.
Let it be _Io . Then, parallel light having a width X of two or more block widths is irradiated, and the state of projection of scale C onto CCDY at this time is examined. The projected position of the marker bit Im is determined from the marker M and the block stop marker D. In FIG. 3, the position of the photo element portion of CCDY is the bit corresponding to the marker bit Im. Marker bit Im and address part P ₁ ,
Since the positional relationship of P ₂ , P ₃ . . . is predetermined as described above, the position of the address portion projected onto the photo element portion can be determined from the bit corresponding to the marker bit Im. That is, bits,
First, the state of light reception of bits, bits, bits, etc. is detected. In this example, the bit is so-called ON, so ²⁰ digits are ON. Also, the bit is OFF and the 2nd ^1st digit is OFF, similarly the bit is ON and the 2nd ^2nd digit is ON,
The bit is OFF and the 2nd ^{and 3rd} digits are OFF. Therefore, the absolute address of block N _P is 2 ² + 2 ⁰ =
5, and it can be seen that block N _P is the fifth one from the reference point of the scale. Now, as shown in the figure 1
The block consists of 26 bits, and the width of 1 bit is 15μ.
When set to , the width of one block is 15μ x 26 = 0.39
m/m. Therefore, block N _P is approximately 0.39 m/m x 5 = 1.95 m/m away from the reference point. Next, to find a more accurate distance, count the number of bits from index bit _Io to the bit opposite marker bit _In . In this example, the number of bits is 5, so the accurate distance is 1.9 m/m - 15 μ x 5 = 1.875 m/m.

That is, the number of bits from index bit I _o to marker bit I _n is N _C , the block address is ACD, the maximum length of one block is the number of elements in photo element section F, and N _S is the width of one element. When mμ, the measured value E is E=m( _NS・ACD− _Nc ) (unit: μ). Note that the above value is obtained when measuring the address of the block where the marker exists on the right side of the index bit _Io in Fig. 3, but when measuring the address of the left block, E=m(N _S · ACD + N _C ). In addition, in order to improve the measurement accuracy to within the width of one bit of the photo element part, a vernier part is added between the marker part and the address part in one block on the scale side, and this vernier part is When the number of bits is N _B , the number of photo element elements within the same length as the vernier section is N _B +1.
This can be carried out by determining the overlapping state of the bits on the vernier portion on the scale side and the bits on the photo element portion (for example, finding the positions of the bits facing each other).

By combining a scale with a light-dark pattern and an accumulation effect sensor, it becomes possible to measure distance, ie, length, with high accuracy without detecting a reference point. This can also be directly applied to angle measurements.

However, when trying to actually measure lengths and angles using cumulative effect sensors as mentioned above,
This is convenient when the sensor and scale are not moving relative to each other, but when they are moving relative to each other, the light receiving position on the photo element section through the bright part of scale C changes every moment, and each light receiving information is stored. Therefore, it was not possible to increase the maximum allowable moving speed of scale C, and as a result, there was a problem that the usable range was significantly limited.

The present invention has been made in view of the above circumstances, and its purpose is to prevent fluctuations in the optical information given to the cumulative effect sensor, thereby making it possible to accurately read the information at each point in time. It is an object of the present invention to provide a data reading device for a cumulative effect sensor that can improve the maximum allowable moving speed of a scale when applied to length measurement or angle measurement, for example.

The present invention will be explained in detail below.

First, the principle of the device of the present invention will be explained. The device of the present invention achieves the above object by providing optical information in a pulsed manner to a storage effect type sensor. And specifically, it is done as follows. That is, referring to _{the example shown in FIG. 1, in period T 1 ,} as shown in FIG _. Suppose that it is read out at . In this case, suppose that the width of the bright part and the dark part of scale C is formed to the width of 3 bits of photo element part F, and if scale C moves by 1 bit during period _T1 , then The readout output C is the fourth
This results in four time-series signals shown in Figure d. This is because the photo element section F accumulates signals caused by the irradiated light. If the scale C moves by a width of 3 bits during the period _T1 , the output C at that time becomes as shown in Figure 4e,
Measurement is no longer possible. The maximum allowable moving speed of scale C that can distinguish between bright and dark with output C is:
It is determined by the width of the bright part of scale C and the size of period _T1 . Although it is possible to increase the allowable maximum moving speed of the scale C by widening the width of the bright and dark areas of the scale C, this is not practical due to restrictions due to the size of the sensor used and the optical system. Also period
By shortening _T1 , the maximum allowable movement speed of scale C can be improved, but this is also limited by the number of bits of the sensor and the maximum driving frequency (maximum frequency for driving the sensor). is difficult to obtain. Therefore, in the device of the present invention, pulse-like light is irradiated for a period T _L that is shorter than one scanning period. For example, in the example shown in Fig. 4, if the period T _L is set to 1/3 of T ₁ as shown by the broken line in the figure, the maximum allowable moving speed of scale C is T ₁
The amount of radiation can be increased three times compared to when irradiated with . The shorter the pulse width T _L of the irradiation light L, the higher the allowable maximum moving speed of the scale C can be. but,
The amplitude of the read signal C is proportional to the pulse width T _L , so when the intensity of the irradiated light L is constant, the shorter the pulse width T _L , the more the read output C.
The amplitude of O also becomes small, which is not preferable for signal processing. In other words, it is desired that the pulse width T _L be short and that the amplitude of the output C be constant. Various methods can be considered to satisfy this demand. For example, if T _LM is the pulse width to satisfy the desired maximum moving speed of scale C, then T _L <
T _LM , and the light intensity may be set so that an output C of a predetermined amplitude can be obtained under this condition. However, the output of the light source is not always constant, and the light transmission characteristics of the scale C are also not always constant, so it is difficult to always obtain an output C with a constant amplitude over a long period of time. As a means to solve this problem, the amplitude of the output C is measured, and when it is smaller than a predetermined amplitude, an appropriate value T _l is added to the previous T _L , and when it is larger than a predetermined width, it is added from the previous T _L.
A possible method is to determine the pulse width for the next light emission by reducing T _l . This means determines the final T _L by repeated operations. however,
Finally, if T _L <T _LM , the amplitude of the output C can be kept constant while satisfying the maximum moving speed desired for the scale C. However, with this method, the final T _l is determined several times (generally 10
(times or more), and a fast response speed cannot be expected.

Therefore, in the apparatus of the present invention, the following calculation is performed to determine the next pulse width T _L (where T _L <T _LM ). That is, when the pulse width for the next light emission is T _LB , the previous emission pulse width is T _LA , the amplitude of the output C due to the previous light is E _A , and the predetermined amplitude is E ₀ , then T _LB It is calculated as =E ₀ /E _A T _LA . When the pulse width _TLB for the next light emission is determined by this calculation, the amplitude of the output C read out next becomes a predetermined constant value, and the response speed can be increased.

In this way, the device of the present invention provides irradiation light, that is, optical information in a pulsed manner. and,
The pulse width is determined by performing the above calculation within the range of the irradiation light pulse width _TLM that satisfies the maximum moving speed required for scale C, and thereby the output C
It is controlled with good responsiveness so that the amplitude of O is always constant.

Specific examples will be described above. Note that this embodiment is an example in which the device of the present invention is applied to a length measuring device.

In FIG. 5, numeral 1 is a linear scale attached to a moving body (not shown), and this scale 1 has n pieces of the same length in the longitudinal direction, similar to the one shown in FIG. 3, for example. It is divided into blocks. A marker and an address are formed in each block in the form of a bright and dark pattern similar to that shown in FIG. A light source 2 formed of, for example, a light emitting diode is placed on one side of the scale 1.
The light emitted from the lens system 3 converts the light into parallel light, and then irradiates it toward the scale 1. Also,
On the other side of the scale 1, a storage effect sensor, such as a CCD 4, for detecting light transmitted through the scale 1 via a lens system 3' is arranged.
As described above, this CCD 4 is formed of a photo element section F, a gate section G, and a shift register section R, and when a gate pulse S is applied, the charge accumulated in the photo element section F is transferred to the shift register section R. , reset pulse Z, and scan pulses φ ₁ and φ ₂ whose frequency is divided into 1/2 and whose phases differ by 180° are given, so that the contents of the shift register section R are output in time series. It is composed of The drive of the CCD 4 is controlled by a microcomputer 6 via a pulse control circuit 5, and the output of the CCD 4 is controlled by an analog processing circuit 7.
The input to the light source 2 is processed by the microcomputer 6 via the amplifier 9 and then displayed on the display 8.
Since then, it has come to be given as an LC signal.
Note that the light source 2, lens system 3, CCD 4, and amplifier 9 are built into a housing 10 and fixed to a stationary part so as to sandwich the scale 1 in a non-contact manner.

The pulse control circuit 5 is configured as follows. That is, a pulse P ₁ (for driving during "scanning from" ) and gate 12
One input terminal of CCD via OR circuit 13
It is applied as a reset signal Z of 4, and is also applied via an inverter 14 to a clock terminal C of a flip-flop circuit 15 (a flip-flop that operates at the rising edge of a clock signal). The flip-flop circuit 15 is a T-flip-flop whose output is introduced into the input terminal D, and the output is given as a scanning pulse _φ1 of the CCD 4, and the Q output is also given as a scanning pulse _φ2 . The input terminal D of the flip-flop circuit 15 is connected to a clock terminal of a flip-flop circuit 16 (a flip-flop that operates at the rising edge of a clock signal). This flip-flop circuit 16
When a control pulse PC having a logic level of "1" is applied to the CL terminal from the microcomputer 6, the output becomes "1", and the AND gate 12 is controlled by this output signal. Further, a single pulse P ₂ (used for driving when reading data) is applied to the OR circuit 13 from the microcomputer 6 according to the relationship described later.

On the other hand, in the analog processing circuit 7, the output of the CCD 4 is taken out by a differential amplifier 21, and the output C of this amplifier 21 is introduced into one input terminal of a differential amplifier 22. At the other input terminal of the amplifier 22, "lightless data" DD already stored in the microcomputer 6 is sent to the D/A
It is selectively introduced via converter 23. The output of the differential amplifier 22 is then input to the A/D converter 24. This A/D converter 24 enables reading even when the bit pitch of scale 1 and the bit pitch of photo element section F are not an integral multiple. And this A/D converter 2
4 is in a clear state when the A/D control AC of the microcomputer 6 is "1", and performs A/D conversion operation when it is "0". Furthermore, when the A/D conversion operation is completed, the terminal AE of the microcomputer 6 is
changes from "1" to "0".

Thus, the apparatus of the present invention configured as described above operates according to a program set in the microcomputer 6. Below, this operation will be explained in the sixth
This will be explained using the flowchart shown in FIG.

First, when starting, _f1 : writes "0" to the light emission control memory _M7 , meaning that no light is emitted.

f ₂ : Write the initial value T _LF of the irradiation light pulse width to the memory M _2. Although this initial value T _LF may generally be an appropriate value, it shortens the time until the output C reaches a predetermined amplitude. Therefore, the pulse width is set close to the one that outputs the predetermined amplitude.

f ₃ : Clear “no light data output” DD. As a result, the output of the D/A converter 23 is, for example, 0V.
becomes.

f ₄ : Write the first address of the memory where “no-light data” is to be written to memory _M4 .

f ₅ : Write the first address of the memory where the result data will be written to memory _M5 .

f ₆ : Clear the contents of memory _M1 . this memory
_M1 is used as a counter and has a different address from the data area memory.

_f7 : Set pulse control PC to "1". As a result, pulse _P1 is applied via the AND gate 12, and "scanning from" is started. _f7 to _f13
The operation is "all-to-scan".

f ₈ : n number of times “scanning from all” is required from f ₇ to f ₁₃
However, it is determined from the contents of the memory _M1 whether or not the last "scanning from all" is performed.
Then, if "YES", proceed to _f9 ; if "NO", proceed to _f12 .

_f9 : Set the contents of memory _M7 to light emission control LC.
Therefore, when reading memory M ₇ "data without light", when M ₇ = "0") becomes "1", light source 2
emits light.

_f10 : Measure the time since the light emission control LC is set to "1", and when the time written in the memory _M2 is reached, proceed to _f11 .

f ₁₁ : Set light emission control LC to "0". This causes the light source 2 to stop emitting light.

f ₁₂ : Measure the time since starting "scan from all" (monitor the time by using the program operation of the microcomputer 6) and calculate the time since "scan from all" started. Time is (total number of bits in shift register section/2 (frequency of φ))
Wait until the above value is reached.

f ₁₃ : Set pulse control PC to “O”. This completes the "scanning from all". At this time, due to the operation of the pulse control circuit, when PC becomes "0", Z="0", φ ₁ = "1", and φ ₂ = "0", the operation stops in that state. This state is
By setting the CCD4 signal S to “1”
This is a state in which charges can be moved from the photo element section F of the CCD 4 to the shift register section R.

f ₁₄ : Generate one pulse at terminal PS (“0”→
“1” → “0”). As a result, charges move from the photo element section F to the shift register section R of the CCD 4.

_f15 : Add 1 to the contents of memory _M1 .

f ₁₆ : Compare the contents of memory M ₁ and N (necessary number of times of scanning from all). If the contents of the memory _M1 have not reached N, the process moves to _f7 .

_f17 : Set pulse control PC to "1". As a result, scanning is started again. i.e.
Scanning is performed from part f ₁₇ to f ₁₉ .

f ₁₈ : Wait until the time for scanning (previous) from the part reaches the time T _p1 required for scanning (previous) from the part.

_f19 : Set pulse control PC to "0". This ends the scanning (previous) from the part.

f ₂₀ : Write the contents of memory _M4 to the address register.

f ₂₁ : Determine whether memory _M7 is “1” or not, “YES”
If so, go to f ₂₂ ; if “NO”, go to f ₂₄ . In addition, when memory M ₇ is “1”, “light is present”
"0" indicates "no light".

f ₂₂ : Set the memory contents indicated by the address register to the “no light data output DD.” This causes the “no light data” corresponding to the bit of CCD4 to be output from the DD among the “no light data” that has already been measured. be done.

f ₂₃ : Put the contents of memory _M5 into the address register.

f ₂₄ : Set A/D control AC to “0”. As a result, the A/D converter 24 starts an A/D conversion operation.

f ₂₅ : Wait until A/D conversion end AE becomes “0”.

f ₂₆ :Write A/D output data to memory indicated by address register.

_f27 : Set A/D control AC to "1". This puts the A/D converter 24 in a clear state.

f ₂₈ : Generates one pulse P ₂ (“0” → “1” →
“0”). As a result, the shift register section R of the CCD 4 is shifted by one bit.

At _f24 to _f28 , the output of the differential amplifier 22 is A/D converted by the A/D converter 24 and written to the memory indicated by the address register, and the pulse _P2 is again given to the shift register section R. . In the operation from f ₂₀ to f ₂₈ , the operation in the absence of light (LC="0") does not perform the operations of f ₂₂ and f ₂₃ , so the no-light data output DD is in the clear state. ₉ , the light source 2 does not emit light during the final "all-to-all" scan because LC="0" in 9, and therefore, for example, OV is at the negative input terminal of the differential amplifier 22, and there is no light at the positive input terminal. As a result, the output C ¹ of the differential amplifier 22 becomes the same as the output of the differential amplifier 21. At f ₂₄ to _{f 28} , the output C ¹ of the differential amplifier 22 is added. is A/D converted and written to the memory, but at this time, the contents of the address register indicating the memory are the memory M ₄ ,
In other words, it is the address of the memory for "no light" data. Therefore, data is written to a "no light" data memory area. Operation from f ₂₀ to f ₂₈ in “with light” (LC = “1”) is f ₂₂
The memory indicated by the address register (memory M ₄
The contents of ``no light, data memory'' are set to ``no light data output'' DD.Next, at _f23 , the contents of the address register are replaced with the contents of memory _M5.In this case, light source 2 is set to f23. ₉ , LC = "1" and light is emitted during the final "scanning from all".Therefore, the negative input terminal of the differential amplifier 22 receives a signal obtained by D/A converting the "no light" data. (This is the same as the output C of the differential amplifier 21 when there is no light), and the positive input terminal is the output C of the differential amplifier 21 when there is light.
O is added to each. As a result, the differential amplifier 2
The output ^C1 of 2 is the differential amplifier 2 when “light is present”.
It is obtained by subtracting the output when there is no light from the output of 1. In f ₂₄ to f ₂₈ , the output C ¹ (subtracted value) of the differential amplifier 22 is A/D converted and written to the memory, but at this time, the contents of the address register indicating the memory are stored in the memory M ₅ , that is, the result This is the address of the data memory. For this purpose, the data are written into the result data memory.

f ₃₀ : Add 1 to the contents of memory _M4 .

f ₃₁ : Add 1 to the contents of memory _M5 .

f ₃₂ : Whether the contents of memory _M5 are X+(SDE) (here, X is the required number of data).
Check whether the necessary data has been collected.
Since memory M ₄ changes in correspondence with memory M ₅ , the judgment of X+ (SDE) is made at the same time as X+ (SDD).
This can be said to be a judgment.

f ₃₃ : Clear no-light data output DD.

f ₃₄ :Similar to f ₁₇ , scan (after) is opened from the part after data reading.

f ₃₅ : Wait until the time for scanning (after) from a part reaches a predetermined time T _P2 required for (after) scanning from a part.

_f36 : Set the pulse control PC to "0" and end scanning (later) from the part.

f ₃₈ : Check whether memory M ₇ is “1” or not. If “YES”, move to f ₄₀ ; if “NO”, write “1” to memory M ₇ at f ₃₉ .
Return to f ₄ and perform the operation when there is light.

_f40 : Result data is stored in the data memory (M(SDE) to M(SDE)+X-1) by _f24 to _f28 , and the amplitude of the data is determined from this data and written to memory _M3 . Note that the amplitude of the data is determined by determining the difference between the maximum value and the minimum value of the data.

f ₄₁ : Perform the next calculation and write the result to memory _M2 .

Predetermined amplitude value E ₀ / Contents of memory M ₃ (amplitude value) / Memory M ₂
(previous pulse width) Therefore, at this point, the contents of memory _M2 (emission pulse width) are rewritten to a new value.

_f42 : Determine whether the contents (amplitude value) of the memory _M3 are between the upper limit ( _E0-2 ) of a predetermined level and the lower limit ( _E0-1 ) of a predetermined level. E _0-2 and E _0-1 are predetermined values as permissible values for amplitude fluctuation. If the result of the judgment is “NO”, return to f ₄ and press f ₄
~f Repeat the operation of ₄₂ (“with light” state).
If “YES”, move to _f43 .

_f43 : Scans the memory corresponding to the index bit I _o (see Figure 3) of CCD4 one after another while determining whether it is larger or smaller than the threshold level, and after 5 or more blacks continue. White (large) is 3
The first white bit of two or more consecutive bits is determined to be the marker bit I _n (see Figure 3), and the number of bits so far is counted. In the case of FIG. 3, the number of bits is 5. Write this value to memory _M6 .

_f44 : Check whether the specified bit by counting from the marker bit I _n , that is, the bit corresponding to the address part, is white, obtain the block number of scale 1, and write it to the memory _M9 .

f ₄₅ : The number of bits in one block is the number of elements in the photo element part of CCD4 as N _S , the element pitch is m, and the distance E from the reference point is calculated and displayed as E = m (N _S M ₉ − M ₈ ). write to memory.

However, M ₉ and M ₈ are the contents of memories M ₉ and M ₈ . Through the above operations, E is displayed on the display 8.

In addition, in the above-mentioned embodiment, scale 1
Although the one shown in FIG. 3 is used for convenience of explanation, the present invention is not limited to this. Also pulse
As a means of obtaining P ₁ , the output of an oscillator built into the microcomputer 6 is frequency-divided using a frequency divider within the computer, but the frequency divider may be provided on the outer periphery. Similarly, another oscillator may be used. Further, for example, a pulse generator is provided that generates one pulse each time the A/D conversion end AE of the A/D converter 24 becomes "0",
The output pulse of this generator may be used as pulse _P2 . Furthermore, it goes without saying that when all bits of the CCD 4 are used for measurement, scanning is omitted from some parts. Alternatively, the scale may be fixed to a stationary part and the other parts may be mounted on a moving body. Moreover, although the above-mentioned embodiment is an example in which length is measured using the apparatus of the present invention, it goes without saying that angle measurement can also be performed.

In this way, the information source that sends optical information is driven in a pulsed manner. Therefore, as long as the drive pulse width is set within a range where the speed of change of information can be ignored, the information data at each point in time can be read accurately, which is an inherent property of cumulative effect sensors. Disadvantages can be eliminated. In addition, as shown in the example, if a means is provided to always keep the signal amplitude of the data read from the cumulative effect sensor constant, it will be possible to compensate for the decrease in the light intensity due to the light source's light intensity or the scale being dirty, so it will last for a long time. This allows the processing system to operate stably.

As described in detail above, according to the present invention, it is possible to provide a data reading device for a storage effect sensor that can accurately read information data at each point in time of optical information that changes from moment to moment.

[Brief explanation of drawings]

Figure 1 shows an example of the arrangement when a cumulative effect sensor and a scale with a bright/dark pattern are combined, and Figure 2 shows various parts when scanning with the cumulative effect sensor in the arrangement shown in Figure 1. A waveform diagram, FIG. 3 is a diagram for explaining an example of the relationship between a cumulative effect sensor and a scale with a bright/dark pattern when measuring length in combination, and FIG. 4 is a diagram illustrating the principle of the present invention. FIG. 5 is an explanatory diagram of the configuration of an apparatus according to an embodiment of the present invention, and FIGS. 6 and 7 are flow diagrams for explaining the operation of the apparatus. 1... Scale, 2... Light source, 3, 3'... Lens system, 4... CCD, 5... Pulse control circuit,
6...Microcomputer, 7...Conversion circuit,
8...Indicator.

Claims (1)

[Scope of Claims] 1. A photo element section configured with a plurality of elements that convert optical information into charges and store them, and a charge accumulated in each element of the photo element section provided corresponding to the photo element section. an information source that selectively supplies optical information to the storage effect sensor; and an electric charge from the photo element section of the storage effect sensor to the register section. sensor driving means for controlling transfer and performing data readout scanning for reading data from the register section; pulse driving means for driving the information source in pulses prior to controlling charge transfer from the photo element section to the register section; The drive pulse width of the pulse drive means at the next readout is controlled based on the amplitude of the previous data signal read from the storage effect sensor, the previous information source pulse drive width, and a preset amplitude to generate a data signal. 1. A data reading device for a cumulative effect sensor, comprising: amplitude control means for making the amplitude constant. 2 The amplitude control means sets the data signal amplitude at the previous readout to E _A , and sets the previous drive pulse width to
When T _LA and the preset amplitude are E ₀ ,
Data of the storage effect type sensor according to claim 1, wherein the drive pulse width T _LB at the next readout is controlled as T _LB = (E ₀ /E _A )×T _LA reader. 3. Claim 1, wherein the information source uses a light emitting diode as a light source.
A data reading device for the cumulative effect type sensor described in 2.