JP2785349B2 - Absolute encoder code pattern creation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

The present invention relates to a method for generating a code pattern of an absolute value encoder using a cyclic random number code. [Prior Art] Conventionally, an absolute value encoder generally uses a code plate that forms a binary code or a gray code having a desired number of bits by arranging a plurality of tracks having different numbers of slits in a radial direction. However, in this method, it is difficult to realize a small and high-resolution absolute value encoder because the number of tracks increases according to the number of bits. As one of methods for solving this problem, an absolute value encoder using an M-sequence random number has been proposed. As is well known, the M-sequence random number is a sequence of the maximum length formed by using a shift register, and 2 ^k -1 non-zero cyclic patterns are generated by a k-bit shift register. For example, 4
In the case of bits, codes as shown in Table 1 are generated in a circuit using a shift register as shown in FIG. However,
In the FIG. 7 shall not be R ₀ to R ₃ are 0 at the same time. Since the M-sequence random number generated in this manner is a cyclic pattern of 2 ^k -1 different codes, for example, a code plate in which the opaque portion is set to 0 and the transparent portion is set to 1 on a circle If the pattern is formed and an adjacent k-bit pattern is read, the absolute position on the circumference can be determined since the pattern exists only at one place on the circumference.

[Problems to be solved by the invention]

By the way, an absolute value encoder generally has a resolution of 2 ^k using a binary code or a gray code. However, in the case of the absolute value encoder using the aforementioned M-sequence random numbers,
There is a drawback that only a resolution of 2 ^k -1 can be realized and there is no compatibility with general ones. An object of the present invention is to provide a method for creating a code pattern of an absolute encoder having an arbitrary resolution.

[Means for Solving the Problems]

The first absolute value encoder code pattern creating method according to the present invention is a cyclic random number sequence in which binary code values (B _{1 to} B _N ) composed of consecutive P slits are all equally divided into N slits. And a code plate in which a code of 0 or 1 is written in each slit so as to form
The present invention is applied to an absolute value encoder that detects an absolute angle within one rotation by using a detection element that reads codes of slits. FIG. 1 is a flowchart showing a method for generating a cyclic random number code in a first absolute value encoder. First, in step 1, an initial code B'1 consisting of P bit 0 or ₁ is set. The P bits correspond to the first P random number strings. Next, initial code B _'1 to 1 bit right shift (or left shift) in Step 2. Here, in the case of left shift, the processing shown in the following parentheses is performed. Right shift (or left shift)
After that, 0 is set in the most significant bit (or least significant bit). This bit becomes the (P + 1) -th random number sequence. Wherein the P bits new code B _'2 and initial code B'
₁ is compared in step 3. If they are different, go to step 4; if new, go to step 5. Step 4
Then, it is determined whether the random number sequence has reached the length N, that is, whether or not the new code is the N-th code. If it is N, go to step 6; otherwise, go to step 2. In this way, the went to Step 2 generated in step 4 to i-th code B _'1. In step 2, this code is right-shifted (or left-shifted) by one bit, 0 is set in the most significant (or least significant) bit, and the new code is set to _{B'i + 1} . Further, in step 3, B ′ _{1 to} B ′
Check whether _i has the same code as _{B'i + 1} . If there is not the same code, go to step 4. If there is the same code, in step 5, set the most significant (or least significant) bit to 0.
And go to step 3 again. Here, if the new codes B ′ _{i + 1} and B ′ _{1 to} B ′ _i have the same code, the procedure goes to step 5 again. In this case, the highest (or lowest) code
The bit is already one. Therefore, the most significant (or least significant) bit of the random number sequence is left-shifted (or right-shifted) until it becomes 0, that is, the most significant (or least significant) bit is returned to the code B'p of 0, and the most significant (or least significant) bit is returned. Alternatively, a process in which the code having the least significant (1) bit set to 1 is newly set as B'p and the procedure goes to step 3 again is repeated. As described above, in step 4, the N-th code B '
_If the code has been generated up to _N , it is determined in step 6 whether or not the code obtained by right-shifting (or left-shifting) B ′ _N by 1 bit can be the initial code B ′ ₁ . By going to step 5, a cyclic random number code is obtained. In step 2, the most significant bit (or least significant bit) after left shift (or right shift) is set to 1
, The same cyclic random number sequence can be obtained. In this case, 0 may be changed to 1 and 1 to 0 in the subsequent processing. According to the second method of generating a code pattern of an absolute value encoder of the present invention, the number of P is divided equally into N slits.
P bits consisting of slits (however, (M + 1) P
0 or 1 in each slit so as to form a cyclic random number sequence in which the binary code values (B _{1 to} B _N ) of <N ≦ 2 ^P ) are all different.
Applied to an absolute value encoder that detects an absolute angle within one rotation by using a code plate on which a code is written and a detection element that reads the code of P slits at intervals of M from the code plate. It is. FIG. 2 is a flowchart showing a method for generating a cyclic random number code of the second absolute value encoder. FIG. 2 shows a method of generating a random number sequence having a length of N every M number. First, in step 11, N is a sequence 1, 2,..., Sequence M of P bits 0 or 1 which can be represented by a binary number.
+1 is initialized, and the binary codes of these are B ′ ₁ ,
B ′ ₂ ,..., B ′ _{M + 1} . In addition, the sequence 1,
2,..., For each bit of the sequence M + 1, the sequence 1, 2,.
.., Length (M + 1) in which bits are arranged in order of the sequence M + 1
The sequence of P is set as an initial random number sequence. Next, in step 12, the sequence 1 is shifted right by one bit (or left). Here, in the case of a left shift, the processing in parentheses will be performed thereafter. Right shift (or left shift)
0 is placed in the most significant (or least significant) bit after
The binary code is _{B'M + 2} . Next, step 13
In the code B of new P bit 'M _{+ 2} is previous code B' compared for equality to _{1, B '2, ···,} B' M + 1. If there is no equal code, go to step 14, and if there is equal code, go to step 16. In step 14, the most significant (or least significant) bit of the sequence 1 is placed on the left (or right) of the most significant (or least significant) bit of the random number sequence to form a (M + 1) P + 1 bit random number sequence, and the new code is It is determined whether the code is the N-th code. If the code is the N-th code, go to step 20; otherwise, go to step 15
Go to In step 15, the sequence 1 is replaced with a new sequence M + 1, the sequence 2 is replaced with a new sequence 1,..., The sequence M + 1 is replaced with a new sequence M, and the new sequence 1 after the replacement is performed.
Is carried out again in step 12 to search for a new code B'M _{+ 3} . In step 16, it is determined whether or not the most significant (or least significant) bit of the sequence 1 is 0. If it is 0, the process proceeds to step 17, otherwise, the process proceeds to step 18. In step 17, the most significant (or least significant) bit is changed to 1 and the procedure goes to step 13 again. On the other hand, in step 18, the initial code is the current code _{B '1, B' 2,} ···, B 'M + 1 if it is determined whether, when equal to step 21, otherwise step 19
Go to In step 19, each of the sequence 1, the sequence 2,..., The sequence M + 1 is shifted left by one bit (or shifted right).
Then go back one step and go to step 16 again. At this time, the random number sequence returns by M + 1 bits. In the loop of steps 16, 18, and 19, the sequence 1 is shifted left (or right) until the most significant (or least significant) bit of the sequence 1 becomes 0 or the initial code of the sequence 1 is reached. Become. In step 21, the current code is P bits 2
It is determined whether or not the maximum value that the radix can take is determined. If the maximum value is not reached, the process proceeds to step 22, and if the maximum value, the process is stopped because a random number sequence cannot be generated by the present algorithm. In step 22, the code obtained by incrementing the current code by 1 is set as a new initial code, and the process goes to step 23. In step 23, new initial encoding B _'1, · · ·, B' compared to _M, if there is no same code new initial code B 'as M _{+ 1} returns to step 12, B' _1, · · · , the flow returns to step 21, if the same code B _'M. It is assumed that the _i-th code B ′ _{i has} been generated in this way and the process proceeds to step 12. In step 12, the new sequence 1
Is shifted right by one bit (or left) and 0 is set in the most significant (or least significant) bit, and a new code is set to B ′ _{i + 1} . Further, in step 13, B ′ ₁ ,.
B _'i to B' checks whether there is a i _{+ 1} equal to the code.
If there is no equal code, go to step 14. If there is an equal code, change the most significant (or least significant) bit from 0 to 1 in steps 16 and 17 and go to step 13 again. Again new B 'i _{+ 1} and B' _1, · · ·, if there is equal code B _'i, but again goes to step 16, in this case, the top (or bottom) bit is already 1 since, shift left (or right-shift) to the top (or bottom) bits of the sequence 1 is 0, that is the highest (or lowest) bit returns to code B _'j of 0,
The top-level (or lowest) bit in step 17 repeats a process of going to the step 13 the code that was changed to 1 as the new B _'j. As described above, in step 14, the N-th code _B'N
In step 20, B ′ _NM,.
B ′ _N , that is, a code B ′ _{N + in which the} sequence 2,..., Sequence M + 1 and sequence 1 are right-shifted (or left-shifted) by one bit and 0 or 1 is placed in the most significant (or least significant) bit _{1, ···, B 'N +} M + 1 is the initial setting code B' _1, ··
・, B ′ It is determined whether or not it is equal to _{M + 1. If} they are equal, the search is terminated. If they are not equal, if the process goes to step 16 again, a cyclic random number sequence of length N every M bits can be obtained. Become. In step 12, the most significant bit (or least significant bit) after left shift (or right shift) is set to 1
, The same cyclic random number sequence can be obtained. In this case, 0 may be changed to 1 and 1 to 0 in the subsequent processing. As described above, according to the present invention, an absolute encoder having an arbitrary resolution can be realized.

【Example】

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 3 is a diagram showing a code plate of a first embodiment of the absolute value encoder of the present invention. When the black part is read as “0” and the white part is read as “1”, a cyclic sequence (one round) of 1111010110010000 is obtained. If this is read by the detection element as a sequence of four bits R _{0 to} R ₃ adjacent to each other, it is understood that one round can be divided into 16 different patterns as R _{0 to} R _{3 in} Table 2. Table 3 shows the process of generating the cyclic random number sequence of Table 2 using the algorithm shown in FIG. Here, N =
In the case of 16, P = 4 bits, right shift, the random number code when it reaches step 3 in FIG. 1 is shown each time. First, it sets the "0000" as an initial random code B _'1 (Step 1). If this is shifted right by one bit and the most significant bit is set to 0, the code B'2 of No. ₂ = "0000" (step 2). Since B _'1 and _{B' 2} are equal, and the most significant bit to 1, the code of No.3 B _{'2 ='} 1000 _'
Is obtained (steps 3 and 5). Code B _'2 of No.3 is No.
Unlike code B ′ _{2 of} No. ₂ and N = 16, 1
The rightmost bit is shifted to the right by 0, and the code B ′ ₃ = “0100” of No. 4 is obtained (steps ₃ , 4, 2). Hereinafter, similarly, the code B ′ _{4 of} No. 5 = “0010” and the code of No. 6
Code B ' ₅ =' 0001 ', No. 7 code B' ₆ = '000
0 'is obtained. The code B _'6 code B of No.1' equal to _1, and the most significant bit to 1, No.8 code B '
₆ = '1000' is obtained (steps 3,5). Equal to ₂ 'code B of ₆ No.3' code B of this No.8, and since the most significant bit is already 1, shifted to the left until the most significant bit becomes 0, i.e. the most significant bit is 0 code B 'goes back to _5, the code was the most significant bits and 1' and 'new code B a' ₅ 1001 (step 3,
Five). Since this code B ' ₅ =' 1001 'is not the same as before and N = 16, it is shifted right by one bit to set the most significant bit to 0, and the code B' _{6 of} No. 10 = '0100' Is obtained (steps 3, 4, and 2). Thus, 'so obtained, No.37 code' 16 th code B _'16 =' 0001 at No.36 the 0000 'to determine equality with initial code (step 6), the random number for determining is equal A row is obtained. Since the random number sequence obtained as described above can have an arbitrary length N, an absolute value encoder having a resolution N can be realized by using this as a slit to form a code plate. Also,
An encoder provided with an incremental slit having a resolution of N separately from the random number slit can also be realized. Further, by providing a means for generating an incremental pulse of one pulse per rotation on the same code plate or on the same rotation center axis, and a means for counting this with a counter, a multi-rotation type absolute value encoder can be realized. FIG. 4 is a circuit diagram of a random number code generation circuit for generating a 4-bit random number code of Table 2. This circuit comprises a shift register 31 and an exclusive OR circuit 32
And the NOR circuit 33, the inverters 34 and 35, and the AND circuit 36,
7 and an OR circuit 38. Of the patterns generated in the circuit of FIG.
A circuit has been added so that 1000 → 0000 → 0001. That is, when all three bits R _{0 to} R ₂ are 0, R ₃
, The next shift input is determined, and otherwise, the circuit of FIG. 7 generates the same pattern. If the adjacent four bits are detected using the code plate of FIG. 3 and the data is shifted until the data and the outputs R _{0 to} R ₃ of the circuit of FIG. 4 coincide with each other, the pulse number of the shift lock is obtained. Determines the position of the code plate uniquely. Thus, an absolute encoder having a resolution of 2 ^k can be realized. FIG. 5 is a diagram showing a code plate of an absolute value encoder according to a second embodiment of the present invention. As described above, when a black portion is read as “0” and a white portion is read as “1”, a cyclic random number sequence (for one round) of 0001000111110110... Is obtained. If this is read as every other 4-bit sequence R _{0 to} R ₃ as shown in FIG. 5, it can be understood that one round can be divided into 16 different patterns as R _{0 to} R _{3 in} Table 4. Therefore, an absolute value encoder can be realized as before using such a code plate. In this case, unlike the first embodiment, the arrangement of the detection elements is every other bit, so that the physical feasibility is significantly improved as compared with the first embodiment. Table 5 shows the process of generating the cyclic random number sequence of Table 4 using the algorithm shown in FIG. Here, N =
In the case of 16, M = 1, P = 4 bits, and right shift, the random number code at the time of step 13 in FIG. 2 is shown each time. First, as the initial code, “1000” in No.1 and No.2 is a sequence 1
And B ′ ₁ , “0000” are set as the sequence 2 and B ′ ₂ . Several examples 1 Right shift by step 12, the code B _'3 of No.3. If this is determined in step 13,
Since there is no equal code, go to step 14, which is N
Since it is not the 16th, the procedure goes to step 15, the sequence 1 and the sequence 2 are exchanged, and the process goes to step 12 again. New sequence 1
Although the code B _'4 of Right-Shift No.4 for,
When this is determined in step 13, ₄ 'code B at step 16, 17 No.5 is equal to _2' is obtained B. When this is determined in step 13, this time 'because although again goes to step 16 equals _1, the most significant bit is 1, and therefore the most significant bit code B of 0' B returns to _2. New B in step 17 'If it is determined in step 13 to make a No.6 as _2, B'
_Since it is equal to ₁ , go to step 16 again. This time is also the most significant bit is 1, the initial 'because it is ₂ No.8 of B as the new code in step 21,22,23,12' coding B make ₃ performs the determination again in step 13 simultaneously. Thereafter, this is repeated. In this way, when the determination in Step 20, the 16-th code B _'16 at No.120 is obtained, No.121, No.12
Since the initial codes are equal to the initial codes B ′ ₁ and B ′ _{2 as shown in 2} , the random number sequence to be obtained is obtained. FIG. 6 is a diagram showing a code plate of a third embodiment of the absolute value encoder of the present invention. If a black part is read as "0" and a white part is read as "1" as before, a cyclic random number sequence (for one round) of 0000110100101111 is obtained. If this is read as a 4-bit sequence R _{0 to} R ₃ every two bits as shown in FIG. 6, it can be understood that one round can be divided into 16 different patterns as R _{0 to} R _{3 in} Table 6. Therefore, an absolute value encoder can be realized as before using such a code plate. In this case, unlike the second embodiment, the arrangement of the detection elements is every two bits, and therefore, unlike the first embodiment, the arrangement of the detection elements is every two bits. The physical feasibility is significantly improved. Table 7 shows the process of generating the cyclic random number sequence of Table 6 using the algorithm shown in FIG. Here, N =
In the case of 16, M = 2, P = 4 bits and right shift, the random number code at the time of step 13 in FIG. 2 is shown each time. First, “1000” for No.1, ..., No.3 as the initial code
Are set as a sequence 1 and B ′ ₁ , “1001” as a sequence 2 and B ′ ₂ , and “0000” as a sequence 3 and B ′ ₃ . When the sequence 1 is shifted to the right in step 12, the code B'4 of No. ₄ is obtained. If this is determined in step 13,
Since there is no equal code, go to step 14, which is N
= Not 16th, so go to step 15. In step 15, the sequence 2 is replaced with the new sequence 1, the sequence 3 is replaced with the new sequence 2, and the sequence 1 is replaced with the new sequence 3. 'Although the _5, which upon determination in step 13, B' code B of the shifted No.5 in the new sequence 1 is equal to ₄ at step 16 and 17 the code B _'5 of No.6 obtained. When this is determined in step 13, there is no equivalent code, so that the sequences 1, 2, and 3 are exchanged in steps 14 and 15, and the step is performed again.
Go to 12. In this way, when the code B _'6 of No.8 is obtained, but goes back to step 16 since the judgment is the same code at step 13, the most significant bit is 0 because the most significant bit is 1 Back to the code B _'3. New B in step 17 'make No.9 as _3, if it is determined at step 13, B' again goes to step 16 is equal to _1. This time is also the most significant bit is 1, the initial 'because it is ₃ No.12 of B as the new code in step 21,22,23,12' coding B make ₄ performs determination again in step 13 simultaneously. Thereafter, this is repeated. When Since the 16 th code B _'16 at No.848 in the resulting judgment of step 20, No.849, No.850,
As shown in No. 851, it is equal to the initial codes B ′ ₁ , B ′ ₂ , B ′ ₃ (not shown), so that the random number sequence to be obtained is obtained. In each of the above embodiments, only the rotary type slit system has been described. However, the present invention can also be applied to a linear type slit system, and as shown in FIG. It goes without saying that the absolute position is known within the range. Although the above description is of an optical type, it goes without saying that in the case of a magnetic encoder, 1,0 can be changed to magnetic pole patterns of N and S poles.

【The invention's effect】

As described above, according to the present invention, a random number sequence having an arbitrary length can be obtained by an algorithm of shifting a code by M bits and adding 0 or 1 so that all codes are different, and an absolute value encoder having an arbitrary resolution can be obtained. When a slit pattern of an M-sequence random number code is used, an effect of realizing an absolute encoder having a resolution of 2 ^k can be achieved by using a circuit that generates a pattern in which the M-sequence random number code and 0 are combined. There is.

[Brief description of the drawings]

FIG. 1 is a flow chart showing a method for generating a cyclic random number code in a first absolute value encoder of the present invention.
FIG. 4 is a flowchart showing a method for generating a cyclic random number code in the second absolute value encoder of the present invention. FIG. 3 is a diagram showing a code plate of the absolute value encoder of the first embodiment of the present invention. FIG. 5 is a circuit diagram of a random number code generation circuit for generating a 4-bit random number code shown in Table 2, FIG. 5 is a diagram showing a code plate of an absolute value encoder according to a second embodiment of the present invention, and FIG. FIG. 7 is a diagram showing a code plate of an absolute value encoder according to a third embodiment, FIG. 7 is a circuit diagram of a circuit for generating an M-sequence random number, and FIG. 8 is a diagram showing a code plate of a linear type encoder. 1-6,11-22 ... step, 31 shift register, 32 exclusive OR circuit, 33 NOR circuit, 34,35 inverter, 36,37 AND circuit, 38 OR circuit.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01D 5/249

Claims (2)

(57) [Claims] 1. A continuous P which is equally divided into N slits
A code plate in which a code of 0 or 1 is written in each slit so that all binary code values (B _{1 to} B _N ) formed of the slits form different cyclic random number sequences; In a method of creating a code pattern of an absolute encoder that detects an absolute angle within one rotation using a detection element that reads codes of P slits, an arbitrary P-bit random number code represented by 1 and 0 is initialized. , and the binary code value B _'1 and, in the first working step, the initial random code one bit right shift or left shift (here, when choosing the left shift, the processing in the following () Is performed, and 0 is newly placed at the position of the most significant (or least significant) bit, and the binary code value B ′ ₂ of the second P bit obtained here is set to the initial code value B ′. Determine if they are the same as _1. If they are not the same, 0 is added to the left (or right) of the most significant (or least significant) bit of the P-bit random number code to make it a P + 1-bit random number code. Shift (or left shift), and place a 0 at a position where the most significant (or least significant) bit at this stage becomes, and the obtained third P-bit binary code value B ′ ₃ is B ′
_1, B 'is determined whether ₂ and do the same, if not identical P +
While adding 0 to the left (or right side) of the most significant (or least significant) bit of the 1-bit random number code, and repeating the continuous work up to the N + th work stage to form a P + 2 bit random number code, the N-bit random number is repeated. This is done until the code is obtained, and in each work stage, 2
If the binary code value has the same binary code value as the newly obtained binary code value, the random number code is left-shifted (or right-shifted) until the work stage in which the most significant (or least significant) bit becomes 0 At this stage, 0 in the most significant (or least significant) bit is converted to 1 again, and the binary code value of the P bit obtained here is the same as the binary code value from the initialization stage. If they are not the same, the operation of the right shift (or left shift) is performed, and if they are the same, the left shift (or right shift) is performed.
A code pattern generating method for an absolute value encoder, wherein the slit is formed using a method of generating N cyclic random number sequences of performing the above operation. 2. A P bit (where (M + 1)), which is equally divided into N slits and includes P slits every M
A code plate having a slit code of 0 or 1 written in each slit so as to form a cyclic random number sequence in which all binary code values (B _{1 to} B _N ) of P <N ≦ 2 ^P are different; A method for creating a code pattern of an absolute encoder that detects an absolute angle within one rotation using a detection element that reads a code of P slits at every M intervals from the code plate, comprising: different M + 1 pieces of sequence 1 represented, sequence 2,..., a sequence M + 1 initializes, to the binary code value, respectively B _'1, B' _2, ..., and B _{'M + 1,} Sequences 1, 2, as random number sequences of length (M + 1) P
.., Each bit of the sequence M + 1 is represented as a sequence 1, a sequence 2,.
.., The sequence is initially set by arranging each bit in the order of the sequence M + 1, and in the first work stage, the initial code of the sequence 1 is set to 1
Shift right or left by bits (when the left shift is selected, the processing in parentheses will be performed below), and replace the sequence in which 0 is newly arranged in the most significant (or least significant) bit with the new sequence 1 And the (M + 2) th P obtained here
Binary code bits B _{'M + 2} is _{B' 1, B '2,} ···, B'
_It is determined whether it is the same as _{M + 1,} and if not, (M +
1) 0 is added to the left (or right) of the most significant (or least significant) bit of the P random number sequences to obtain (M + 1) P + 1 random number sequences, and the new sequence 1 is replaced with a new sequence M + 1,
The sequence 2 is replaced with a new sequence 1,..., And the sequence M + 1 is replaced with a new sequence M, and the new sequence 1 after the replacement is further shifted right (or left) by one more bit. 0 located at its lowest position) bit, where the resulting second M + 3 th binary code value B P bit 'M _{+ 3} is _{B' 1, B '2,} ···, B' M + 2 and It is determined whether or not they are the same, and if they are not the same, 0 is added to the left (or right) of the most significant (or least significant) bit of the (M + 1) P + 1 bit random number sequence to form a (M + 1) P + 2 bit random number sequence. The continuous operation is repeated until N random number codes are obtained.
When the binary code value has the same binary code value as the newly obtained binary code value, if the most significant (or least significant) bit of the current code is 0, the most significant (or least significant) bit is newly set. The 0 in the bit is converted into 1 and the process is restarted from the above-mentioned determination step, and the most significant (or least significant) bit of the current code is 1 and the current code is the initialization code B ′ ₁ , B ′ ₂ ,
..., B ' _{M + 1} , if not identical, Sequence 1, Sequence 2, ...
.., The sequence M + 1 and the random number sequence are left-shifted (or right-shifted) by one bit and returned, and the process of again determining the most significant (or least significant) bit is repeated, and the current code is initialized to B ′ ₁ , B ′ ₂ ,..., B ′ _{M + 1} , when the current code is not the maximum value of the P-bit binary code, the code obtained by incrementing the current code by 1 is represented by B ′ ₁ ,. 'compared to _M, if there is the same code the new initialization code B' B again from the first working step as _{M + 1, B '1,} ···, B' if the same code and _M wherein The absolute value encoder code characterized in that the slit is constituted by N cyclic random number codes generated by using a method in which the process of determining the maximum value is redone, and if it is the maximum value, the random number sequence cannot be generated and the process is terminated. Pattern creation method.