JPH11282402A - Plasma display driving method and apparatus - Google Patents

Abstract

(57) [Summary] [Problem] To prevent deterioration of image quality when power is suppressed,
A plasma display driving method and apparatus capable of reducing the rate at which actual power consumption is suppressed to the same degree as a desired suppression rate are obtained. SOLUTION: A pattern generation circuit 24 for generating a plurality of types of discharge number patterns of one field consisting of the number of discharges for each subfield in a predetermined order for each field in accordance with the suppression rate. And a drive waveform generating circuit 26 for generating a discharge pulse for each subfield with the number of discharges indicated by the pattern of the number of discharges generated in step (1).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a plasma display driving method and apparatus for driving a plasma display panel (hereinafter, referred to as PDP).

[0002]

2. Description of the Related Art FIG. 3 is a block diagram of a conventional plasma display driving device. In FIG. 3, reference numeral 1 denotes an image signal input terminal for applying an image signal, 3 denotes a plasma display panel, and 2 denotes a drive circuit for driving the PDP 3 in accordance with an image signal applied to the image signal input terminal 1.

[0005] The PDP 3 is composed of a number of pixels having first to third electrodes. A group of many first electrodes is an electrode group 31, a group of second electrodes is an electrode group 32, and a group of third electrodes is an electrode group 33. A discharge pulse for discharging a pixel is applied between the electrode groups 31 and 32. Electrode group 3
A signal (hereinafter referred to as a discharge permission signal) indicating whether or not to perform a discharge based on a discharge pulse for each subfield is applied to 3. A discharge pulse is given to a number of pixels constituting the PDP 3, but only the pixels receiving the discharge permission signal indicating that the discharge is to be performed are discharged. The driving circuit 2 generates the discharge pulse and the discharge permission signal.

The drive circuit 2 includes a synchronization signal separation circuit 21, a gradation data processing circuit 22, a luminance information detection circuit 23, a timing generation circuit 25, a drive waveform generation circuit 26, a discharge count storage circuit 27, and a multiplier 28.

A synchronizing signal separating circuit 21 separates an image signal applied to the image signal input terminal 1 into a synchronizing signal defining one field and gradation data indicating a gradation, and outputs the result.

The luminance information detection circuit 23 estimates the power consumed in driving the PDP 3 based on the grayscale data output from the synchronization signal separation circuit 21 and outputs a suppression rate indicating the rate at which the power consumption is suppressed. .

The discharge count storage circuit 27 stores a plurality of fixed discharge counts corresponding to each of a plurality of subfields constituting one field, and repeatedly outputs the number of discharges in synchronization with a synchronization signal. I do.

The timing generation circuit 25 generates and outputs a timing signal based on the synchronization signal.

The multiplier 28 multiplies the number of discharges output by the number-of-discharges storage circuit 27 by the suppression rate output by the luminance information detection circuit 23, and outputs the result of the calculation.

The drive waveform generating circuit 26 outputs a discharge pulse of the number of discharges indicated by the operation result of the multiplier 28 in synchronization with the timing signal.

The gradation data processing circuit 22 converts the gradation data into
The signal is converted into the above-described discharge permission signal, and the discharge permission signal is output in synchronization with the timing signal.

Table 1 shows the number of discharges for each subfield when the power consumption is not suppressed (that is, when the suppression rate is 1) and when the power consumption is suppressed.

[0013]

[Table 1]

Here, the suppression rate when the power consumption is suppressed is, for example, 13/16 (= 0.8125), the number of subfields is 4 for simplicity, and the number-of-discharges storage circuit 27 stores the subfield SF1 ~ 1,2 for each SF4,
Consider a case where the number of discharges of 4 and 8 is output. in this case,
The number of discharges when the power consumption is not suppressed is the same as the number of discharges output from the discharge number storage circuit 27, and is 1, 2, 4, 8
It is. On the other hand, the number of discharges when power consumption is suppressed is
Since the operation of the multiplier 28 is obtained by converting it into an integer, 1, 2,
3,7.

Table 2 shows the number of discharges per field and the effective suppression rate for the grayscale data when the power is suppressed. The effective suppression rate is a rate at which power consumption is actually suppressed, and is equivalent to a value obtained by dividing the number of discharges when power consumption is suppressed by the number of discharges when power consumption is not suppressed. Here, the number of discharges when the power consumption is not suppressed is the same as the gradation data.

[0016]

[Table 2]

For example, when the grayscale data is 11, the number of discharges in one field when the power is suppressed is equal to the sum of the number of discharges in each of the subfields SF1, SF2, and SF4. And
The effective suppression rate is 10/11 (= 0.9091).

The significance of the suppression rate is as follows.
When the entire screen is bright, the power consumed by the PDP is large. Therefore, if a power supply for supplying power to the PDP is prepared in accordance with the case where the entire screen is bright, a large and expensive power supply is required. . When the entire screen is bright, it is expected that the PDP will become hot. Therefore,
The luminance information detection circuit 23 determines the brightness of the entire screen based on the grayscale data, and outputs a value that greatly reduces power consumption as the entire screen is bright, thereby requiring a large and expensive power supply device. So that you don't have to
For example, the DP may not be heated to a high temperature.

[0019]

Conventionally, because of the above configuration, the gradation data is 3 and 4 or 11 and 1
In case 2, when the power is suppressed, the number of discharges is the same,
The pixels have the same brightness. As described above, when the power is suppressed, the actual gray level of a pixel (hereinafter, referred to as an effective display gray level) may not change even if the gray level data changes, and the image quality deteriorates. is there.

Further, as described above, for example, when the gradation data is 11, the effective suppression rate when the power is suppressed is 0.1.
9091, which is significantly different from the suppression rate (= 0.8125). As described above, there is also a problem that the rate at which the actual power consumption is suppressed is significantly different from the desired suppression rate.

The present invention has been made to solve these problems, and it is possible to prevent the image quality from deteriorating when the power is suppressed, and to set the rate at which the actual power consumption is suppressed to a desired suppression rate. It is an object of the present invention to obtain a plasma display driving method and a plasma display driving device which can be set to the same degree.

[0022]

According to a first aspect of the present invention, there is provided a plasma display apparatus comprising the steps of: discharging a pixel of a plasma display for each field including a plurality of subfields each having a set number of discharges; A driving method of a plasma display for determining whether or not to discharge the pixel for each field in accordance with a signal indicating a predetermined gradient, wherein (a) one field including a plurality of the number of discharges for each subfield (B) preparing one of the plurality of types of discharge frequency patterns prepared in the step (a) in a predetermined order. And (c) generating the discharge pulse for each sub-field at the number of discharges indicated by the number-of-discharges pattern selected in the step (b). For example, the stroke (b) and (c) are repeated for each field.

In the means for solving problems according to claim 2 of the present invention, the predetermined order is an order in which the plurality of types of discharge frequency patterns are arranged in order.

[0024] In the means for solving problems according to claim 3 of the present invention, the predetermined order is a combination of an order based on a permutation of the plurality of types of discharge frequency patterns.

In the fourth aspect of the present invention, the predetermined order is an order based on random numbers.

According to a fifth aspect of the present invention, there is provided:
For each subfield, a discharge pulse for discharging a pixel of the plasma display is generated at the number of discharges according to a predetermined suppression rate, and whether or not to discharge the pixel is determined according to a signal indicating a predetermined gradient. A plurality of types of one-field discharge number patterns each including the number of discharge times for each of the sub-fields, corresponding to the predetermined suppression rate.
A pattern generating circuit that generates a predetermined order for each field; and a drive waveform generating circuit that generates the discharge pulse for each of the subfields at the number of discharges indicated by the number-of-discharges pattern generated by the pattern generating circuit.

[0027] In the means for solving problems according to claim 6 of the present invention, the pattern generation circuit includes a storage unit in which the plurality of types of discharge number patterns are stored in advance.

[0028] In the means for solving problems according to claim 7 of the present invention, the storage section stores the number of discharges in a lower subfield of the plurality of types of discharge number patterns, and the pattern generation circuit stores the plurality of types of discharge number patterns. And a calculating unit for calculating the number of discharges of the upper subfield in the number of discharges pattern by multiplying the fixed number of discharges by the predetermined suppression rate.

In the means for solving problems according to claim 8 of the present invention, the predetermined order is an order in which the plurality of types of discharge frequency patterns are arranged in order.

In the ninth aspect of the present invention, the predetermined order is a combination of an order based on a permutation of the plurality of types of discharge frequency patterns.

In the means for solving problems according to claim 10 of the present invention, the predetermined order is an order based on random numbers.

[0032]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a configuration diagram showing a plasma display driving device of the present invention. FIG.
In 24, a pattern generation circuit 24 receives a suppression rate and a synchronization signal, and outputs the number of discharges in synchronization with the synchronization signal.
Reference numeral 1 denotes a ROM included in the pattern generation circuit 24, and other reference numerals correspond to FIG.

The operation of the drive circuit 2 is mainly the same as in the prior art. That is, for each subfield, PD
A discharge pulse for discharging the pixel P3 is generated at the number of discharges corresponding to a predetermined suppression rate. Whether or not to discharge the pixel is determined for each subfield according to grayscale data indicating a predetermined grayscale. To decide. However, in the embodiment, since the conventional discharge number storage circuit 27 and multiplier 28 are replaced with the pattern generation circuit 24, the operation is different as follows.

The ROM 241 stores a plurality of types of discharge frequency patterns corresponding to the suppression rates in advance. Table 3 shows an example of the plurality of types of discharge patterns.

[0035]

[Table 3]

Here, along with the description of the conventional technology,
When the power consumption is suppressed, the suppression rate is 13/16 (=
0.8125), and the case where the number of subfields is four will be described. In Table 3, A to D indicate that the suppression rate is 0.8.
It is a plurality of types of discharge frequency patterns corresponding to the case of No. 125.

The pattern of the number of discharges is represented by subfield SF
1 to SF4.

When the pattern generation circuit 24 receives the suppression rate of 0.8125, it reads the number-of-discharges patterns A to D from the ROM 241. Then, the pattern generation circuit 24
Upon receiving a synchronization signal indicating the start of one field, the circuit outputs a discharge pattern A, and receiving a synchronization signal indicating the start of the next field, outputs a discharge pattern B. In this way, while receiving the suppression rate of 0.8125, the pattern generation circuit 24 selects the number-of-discharge patterns in a predetermined order, and synchronizes with the synchronization signal to generate the discharge patterns A, B, C,
D, A, B, C, D, A,... Continue to be output.

The drive waveform generation circuit 26 receives the number of discharges and the timing signal output from the timing generation circuit 25. The timing signal is transmitted from subfields SF1 to SF4.
The timing of each start is shown. The drive waveform generation circuit 26 receives the discharge number pattern A,
When a timing signal indicating the start timing of F1 is received, the number of discharge pulses shown in the columns of SF1 and A in Table 3 is output, and when a timing signal indicating the start timing of the next subfield SF2 is received, a table is displayed. The discharge pulses of the number shown in the column of SF2 and A of 3 are output. In this way,
When receiving the discharge number pattern A, the drive waveform generation circuit 26 sets the subfields SF1 to SF4 in each of the subfields SF1 to SF4.
One discharge pulse, one discharge pulse, four discharge pulses, and six discharge pulses are output. The operation of the drive waveform generation circuit 26 when receiving the discharge number patterns B, C, and D is the same as the operation when receiving the discharge number pattern A.

Table 4 shows the number of discharges in four fields (actually discharged based on the discharge permission signal), the effective display gradation, and the effective suppression rate when the power is suppressed with respect to the gradation data. Note that the effective display gradation is a gradation recognized from so-called human visual characteristics, and is calculated by dividing the total number of discharges in four fields by four. The effective suppression rate is as described in the related art, but the total number of discharges in four fields when power consumption is suppressed is divided by the total number of discharges in four fields when power consumption is not suppressed. Is equivalent to

[0041]

[Table 4]

For example, when the gradation data is 11, the number of discharges in one field corresponding to the discharge pattern A when the power is suppressed is the subfield SF1, SF2, SF4.
Since the discharge is permitted at the time of, the number of times of each discharge is added up to 8. Similarly, when the gradation data is 11, the number of discharges in one field corresponding to the discharge patterns B, C, and D when the power is suppressed is 9, 9, and 9, respectively. Therefore, when the gradation data is 11, the total number of discharges in four fields is 35. Effective display gradation is 4
35 / (= 8.75), effective suppression rate is 35/44
(= 0.7955).

Comparing Tables 2 and 4, the effective suppression rate shown in Table 4 is about the same as the desired suppression rate (= 0.8125) as compared to the effective suppression rate shown in Table 2. Further, as described in the background art, the effective display gradation shown in Table 2 (same as the number of discharges when power is suppressed) is changed as shown in Table 4 if the gradation data changes. It always changes.

As described above, the ROM 241 prepares the discharge number patterns A to D corresponding to the suppression rate, and the pattern generation circuit 24 selects one of the discharge patterns A to D in a predetermined order. The drive waveform generation circuit 26 generates a discharge pulse for each subfield with the number of discharges indicated by the output of the pattern generation circuit, and the gradation data processing circuit 22 determines whether or not discharge by the discharge pulse is possible for each subfield.

It should be noted that the ROM 241 has a suppression rate of 1/16, 2/16, as in the discharge number patterns A to D.
.., And the number of discharge patterns corresponding to 16/16 are stored. The pattern generation circuit 24 stores a plurality of types of discharge frequency patterns for one suppression rate in a ROM.
241.

When the suppression rate is 16/16, that is, when the power is not suppressed, the type of the discharge pattern is only Z shown in Table 4. The plurality of types of discharge frequency patterns include, as an exception, one type of discharge frequency pattern in the case where power is not suppressed.

According to the first embodiment, the effective display gradation can be continuously changed by repeating a plurality of types of discharge frequency patterns, and the deterioration of image quality can be prevented. In addition, the rate at which the actual power consumption is suppressed is about the same as the desired suppression rate as compared with the related art.

In the above description, the case where the number of subfields is four has been described, but a case other than four may be used.

Embodiment 2 As the number of subfields increases, the number of discharge patterns increases exponentially, and the number of data becomes enormous. Therefore, in the second embodiment, the pattern generation circuit 24 further includes a multiplier (calculation unit) 242, and R
The OM 241 stores the number of discharges of the lower subfield of the plurality of types of discharge patterns, and the multiplier 242 calculates the number of discharges of the upper subfield of the plurality of types of discharge patterns.

The lower sub-field refers to a sub-field having a shorter light emission sustaining period among a plurality of sub-fields, and a sub-field other than the lower sub-field is an upper sub-field. For example, when the subfields are SF1 to SF4 in order from the side with the shortest light emission sustain period, if the lower subfields are SF1 and SF2, the upper subfields are SF3 and SF4, and the lower subfields are SF1 and SF4. Then, the upper subfields are SF2 to SF
4.

Table 5 shows an example of a plurality of types of discharge patterns according to the second embodiment.

[0052]

[Table 5]

Here, the case where the suppression rate when the power consumption is suppressed is 27/32 (= 0.8438) and the number of subfields is 5 will be described. Embodiment 2
Here, A to D are a plurality of types of discharge frequency patterns corresponding to the suppression rate.

As shown in Table 5, the discharge frequency patterns A to
In D, the data of the number of discharges is set for each of the number-of-discharges patterns A to D for the subfields SF1 to SF4, and the number of discharges is stored in the ROM 241 in advance. The multiplier 242 calculates the subfield SF5.

The multiplier 242 has a fixed number of discharges,
The fixed number of times of discharge is multiplied by the suppression rate, and the result of the multiplication is used as the number of times of discharge in the upper subfield. The number of discharges (14) of the upper subfield SF5 shown in Table 5 is obtained by multiplying the fixed number of discharges (16) by the suppression rate (0.8438) and converted to an integer by the operation of the multiplier 242. It is.

Since the number of discharges in subfields SF1 to SF4 of discharge number patterns A to D is previously determined to be 14 in subfield SF5, the number of discharges always changes when gradation data changes. It is possible to set a pattern in which the actual power consumption is suppressed to a desired 27/32. The determined number of discharges is written to the ROM 241.

Table 6 shows an example of the number of discharges, the effective display gradation, and the effective suppression rate of the four fields when the power is suppressed with respect to the gradation data.

[0058]

[Table 6]

As shown in Table 6, even if the number of discharges corresponding to SF5 is the same, the effective display gradation can be changed in accordance with the gradation data, and the effective suppression ratio is set to the desired suppression ratio ( = 0.8438).

According to the second embodiment, by calculating the number of discharges of the upper subfield by multiplier 242, it is possible to generate a plurality of types of discharge number patterns without increasing the capacity of ROM 241. .

In the above description, the subfield S
Although the case of calculating the number of discharges of F5 has been described, the subfields SF5 and SF4 or the subfield SF
For example, the number of discharges of some subfields may be calculated in ascending order of the light emission sustain period, such as 5 to SF3 or subfields SF5 to SF2, and the number of discharges of the remaining lower subfields may be written in the ROM 241 in advance. . However, at least the number of discharges of the lowest subfield must be written in the ROM 241. This is because if the number of discharges of all subfields is calculated, the number of discharges pattern for a certain suppression rate is uniquely determined and is the same as the conventional one.
This is because, by setting a plurality of types of discharge at least in the lowest subfield in the ROM 241, the accuracy of pixel gradation and power consumption can be improved as compared with the related art.

The multiplier 242 has a fixed number of discharges, multiplies the fixed number of discharges by the suppression rate, and further obtains an integer closest to the multiplication result (for example, 10 times the multiplication result).
It is desirable to adopt a value in which the ones place is rounded off, for example. As a result, the average value of the number of discharges of the upper subfield is calculated, and therefore, the number of discharges that can further improve the accuracy of the gradation and power consumption of the pixel can be set in the ROM 241.

Embodiment 3 In the third embodiment, a description will be given of an order in which a plurality of types of discharge number patterns of the first or second embodiment are repeated.

The order of repeating the number-of-discharge patterns A to D is as follows: (1) As mentioned in the first embodiment, the number-of-discharge patterns A, B, C, D, A, B, C, D, A,. (2) When the discharge number patterns A to D are repeated in the permutation order as shown in Table 7

[0065]

[Table 7]

(3) The case of repeating based on a random number may be considered.

In the case of (1), the configuration of the pattern generation circuit 24 is simplified.

In the case of (2), for example, consider a case where the number of discharge patterns A and B are larger (ie, brighter) than the number of discharge patterns C and D.
In the case (1) where the pattern of the number of discharges is repeated in the order of A, B, C and D, a bright screen, a bright screen,
Only repetition of dark screen, dark screen is included. On the other hand, in the case of (2), by adopting various combinations of the permutations of the four patterns, for example, A, B,
.. Can not be included as in C, D, A, C, B, D,..., And it is difficult to recognize the switching between a bright screen and a dark screen. Therefore, in the case of (2), flicker can be reduced.

In the case of (3), similarly to the case of (2), the switching between the bright screen and the dark screen becomes frequent, so that flicker can be reduced. This is particularly effective for a still image or a moving image having a slow motion. In addition, if the cycle in which the appearance rates of the discharge number patterns A to D are equal is small, the effective suppression rate does not significantly differ from the desired suppression rate.

In the case of (3), for example, the following configuration may be adopted. The drive circuit 2 is provided with a random number generation circuit (for example, CPU or the like) for outputting a random number, and associates the random number with a plurality of types of discharge number patterns in advance. The pattern generation circuit 24 outputs a number-of-discharges pattern corresponding to the random number output by the random number generation circuit.

Modified example. The pattern generation circuit 24 has a ROM
Instead of 241, for example, the number-of-discharges pattern may be stored in a memory such as a RAM, or the number-of-discharges pattern may be generated by a combinational circuit.

Further, the calculating section replaces multiplier 242 with
It may be a CPU or the like.

Further, a plurality of types of discharge frequency patterns for one suppression rate may be other than four.

[0074]

According to the first aspect of the present invention, by repeating steps (b) and (c) for the discharge pulse, a plurality of types of discharge frequency patterns prepared in step (a) are repeated. Since the gradation and power consumption of the pixel are averaged over a plurality of fields, the accuracy is improved. For example, it is possible to reduce power consumption to the same degree as the suppression rate while preventing image quality deterioration.

According to the second aspect of the present invention, since the predetermined order is an order in which a plurality of types of discharge frequency patterns are arranged in order, the configuration is simplified.

According to the third aspect of the present invention, flicker can be reduced because the predetermined order is a combination of the order based on the permutation of a plurality of types of discharge number patterns.

According to the fourth aspect of the present invention, since the predetermined order is an order based on random numbers, flicker can be reduced.

According to the fifth aspect of the present invention, a plurality of types of discharge frequency patterns are repeated for the discharge pulse generated by the drive waveform generation circuit based on the operation of the pattern generation circuit. Since the gradation and power consumption of the pixel are averaged over a plurality of fields, the accuracy is improved. For example, it is possible to reduce power consumption to the same degree as the suppression rate while preventing image quality deterioration.

According to the sixth aspect of the present invention, for example, by writing a plurality of types of discharge frequency patterns in the storage unit,
A plurality of types of discharge frequency patterns can be obtained from the storage unit, and the configuration can be simplified.

According to the seventh aspect of the present invention, by calculating the number of discharges of the upper subfield by the calculation unit, a plurality of types of discharge number patterns can be generated without increasing the capacity of the storage unit. .

According to the eighth aspect of the present invention, since the predetermined order is an order in which a plurality of types of discharge frequency patterns are arranged in order, the configuration of the pattern generating circuit is simplified.

According to the ninth aspect of the present invention, flicker can be reduced because the predetermined order is a combination of an order based on a permutation of a plurality of types of discharge frequency patterns.

According to the tenth aspect of the present invention, since the predetermined order is an order based on random numbers, flicker can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a plasma display driving device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a plasma display driving device according to a second embodiment of the present invention.

FIG. 3 is a block diagram showing a conventional plasma display driving device.

[Explanation of symbols]

24 pattern generation circuit, 25 drive waveform generation circuit, 3
1-33 electrode group, 241 ROM, 242 multiplier.

Claims (10)

[Claims] 1. A method for discharging a pixel of a plasma display for each one field including a plurality of subfields each of which the number of discharges is set, and determining whether or not to discharge the pixel for each of the subfields, by a predetermined gradient. A driving method for a plasma display, which is determined according to a signal indicated by the signal, wherein: (a) a plurality of types of discharge frequency patterns of one field including a plurality of the number of discharge times for each subfield with respect to one predetermined suppression rate; A preparing step; (b) a step of selecting one of a plurality of types of discharge frequency patterns prepared in the step (a) in a predetermined order; and (c) a step of selecting in the step (b). Generating the discharge pulse at each of the subfields at the number of discharges indicated by the discharge number pattern, wherein the steps (b) and (c) are performed every one field. Ri returned, the plasma display driving method. 2. The method according to claim 1, wherein the predetermined order is an order in which the plurality of types of discharge number patterns are arranged in order. 3. The plasma display driving method according to claim 1, wherein the predetermined order is a combination of an order based on a permutation of the plurality of types of discharge frequency patterns. 4. The method according to claim 1, wherein the predetermined order is an order based on a random number. 5. A discharge pulse for discharging a pixel of a plasma display is generated for each sub-field at a number of discharges corresponding to a predetermined suppression rate, and it is determined whether or not to discharge the pixel by a predetermined gradation. A drive device for a plasma display, which is determined in accordance with a signal indicating one of a plurality of types of one-field discharge frequency patterns including the number of discharge times for each of the sub-fields, corresponding to the predetermined suppression rate. A pattern generation circuit that generates a discharge pulse for each of the sub-fields at the number of discharges indicated by the number-of-discharges pattern generated by the pattern generation circuit. Plasma display driving device. 6. The plasma display driving device according to claim 5, wherein the pattern generation circuit includes a storage unit in which the plurality of types of discharge frequency patterns are stored in advance. 7. The storage unit stores the number of discharges in a lower sub-field of the plurality of types of discharge frequency patterns, and the pattern generation circuit stores an upper sub-field of the plurality of types of discharge frequency patterns. 7. The plasma display driving device according to claim 6, further comprising a calculating unit for calculating the number of discharges by multiplying the fixed number of discharges by the predetermined suppression rate. 8. The plasma display driving device according to claim 5, wherein the predetermined order is an order in which the plurality of types of discharge frequency patterns are arranged in order. 9. The plasma display driving device according to claim 5, wherein the predetermined order is a combination of an order based on a permutation of the plurality of types of discharge frequency patterns. 10. The plasma display driving device according to claim 5, wherein the predetermined order is an order based on a random number.