JPH07137341A - Recorder - Google Patents

Abstract

PURPOSE:To reduce the quantity of information required for storing font data to lower a cost in a recorder in which character data from the external is developed to an internal font and, printed as image data. CONSTITUTION:Data inputted through a data reception part 100 is temporarily stored in a RAM 103. Whether the data is a command, image data, or a character code is analyzed by a CPU 101 in accordance with a program stored in a ROM 102. If the data is a character code, font data that has been previously compressed by run-length coding and stored is read from the ROM 102 by a DMA and transmitted to a font forming part 104. In the font forming part, the run-length compressed data from the ROM 102 is expanded to be normalized, thereafter being converted to required font data through a reverse prediction function processing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording apparatus for inputting character data or the like from an external device such as a host computer and recording it on a recording medium.

[0002]

2. Description of the Related Art Conventionally, in a recording apparatus, image data such as font data is stored in a recording unit (ROM) inside the recording apparatus, and a character bit pattern corresponding to input data is accessed from the recording unit and expanded as print data. Then, it was printing. In recent years, in order to improve the character quality of image data such as font data, print data with higher resolution is required. That is, the number of dots forming one character of font data increases in proportion to the resolution. A font formed by a matrix of 48 dots × 48 dots requires 288 bytes (2306 bits) for each font. In the case of Japanese fonts, if there are about 7,000 characters in one typeface, the ROM capacity of the storage unit of about 2 Mbytes is required.

Further, in order to reduce the ROM capacity, a method of compressing image data and storing it in a recording device has been conventionally used. For example, run length compression.

[0004]

The above-mentioned conventional example has the following drawbacks.

1. If the character font is stored in the storage unit of the recording device as it is without being compressed, the ROM capacity becomes huge and the cost is considerably increased.

2. When the character font is compressed and stored in the storage unit of the recording device, the logic for decompressing the compressed data is complicated and the processing must be performed in bit units.
The decompression process requires a large load of software, which affects the throughput of the recording apparatus as a whole and causes a decrease in printing speed.

3. When the character font is data-compressed using the run-length compression method, the compression efficiency cannot be significantly increased.

An object of the present invention is to provide a recording apparatus that solves the above problems.

[0009]

According to the present invention, in a recording apparatus which develops character data from the outside into an internal font and prints it as image data, the internal font data is normalized in advance by a prediction function and further run-length compressed. Storage means for storing the compressed data, and means for normalizing the run length extension of the compressed data when converting the compressed data stored in the storage means into desired font data in response to external character data. And means for performing inverse prediction function processing on the data normalized by the means to convert the data into desired font data.

[0010]

According to the present invention, for example, when the image data is compressed and stored in the recording device, and the run length compression is used as the method, the predictive function process is applied to the original font data so that white dots are continuous. Font data creation processing by converting the data to increase the compression rate by run length compression, greatly reducing the capacity of the storage unit, and further hardizing the prediction function and the restoration processing of run length compressed data. Printing can be performed without significantly reducing the throughput and throughput.

[0011]

[Embodiment] All fixed data such as font data can be provided with regularity in a broad sense.
One pixel (dot) focusing on one font
On the other hand, the past n pixel combinations have 2 ^{n + 1} states in the case of a binary code. However, in reality it is impossible to have this logic for all states, so for one pixel, consider only the surrounding pixels. In particular, in the case of font data, the number of change points from black dots to white dots and from white dots to black dots is small compared to general image data. It is possible to further improve the efficiency of the length compression. The transition probability of white dots to white dots and black dots to black dots is very high, while the transition probability of white dots to black dots and black dots to white dots is very low. The binary state of adjacent pixels can be predicted. By applying this to the original font data, the data is converted into a form advantageous for run-length compression by using the prediction function.

Description will be given according to the prediction function value table of FIG.

When one dot (d) in the font is focused on the dots above (b), left (c) and diagonally above (a), a combination of the three dots a to c. A dot having a high probability of appearing as d is called a prediction function. The value of the prediction function for a to c is compared with the actual value d, and if they match, d is “0” (white)
Replace with, and if they do not match, replace with "1".
In other words, the pattern with a high transition probability is replaced with white. As a result, most of the dots are replaced with white, thereby increasing the compression efficiency of run length compression.

The matrix shown in FIG. 3 can be used to express these in a prediction function formula as follows.

[0015]

[Equation 1]

As described above, the original font data is converted by the prediction function, the converted data is run-length compressed, and stored in the storage unit of the recording device.

The logical formula of the inverse prediction function of the restoration process is as follows.

[0018]

[Equation 2]

Y = output data D = unprocessed data FIG. 3 shows an example of the restoration process.

(A) is data created by subjecting the original font data to predictive function processing. With respect to this data, the data is restored in order from the upper left dot according to the equation (2). At this time, the outermost one dot at the left end and the upper end is virtually regarded as white (0). Of the four dots surrounded by the thick frame, three dots of “B” above, “C” to the left, and “A” above diagonally are extracted with respect to the dot “D”. Check the value of the dot “D”, and if D = “0” means that the value of D matches the prediction function, and if D = “1”, the value of D is the prediction function value. It means disagreement.

Considering in the matrix of (b), the dot corresponding to "D" among the four dots surrounded by the thick frame is black "1" and does not match the prediction function value. Therefore, FIG.
This dot is black “1” from the prediction function value table. Next, the process of (c) is performed.

At this time, the dot generated in (b) is used as the upper right dot. Focusing on the dot corresponding to “D” as in (b), it is white “0”, which matches the prediction function.

In this case, it can be seen from the prediction function value table of FIG. 2 that there are 3 patterns and black is "1".

When the above processing is repeated in sequence (r)
Pattern is restored.

Next, a run length compression method for data normalized by a prediction function will be described.

In binary data such as font data, groups of black data and white data always appear alternately. Therefore, each group is represented by a run length code. The fonts are sequentially searched from the beginning in the vertical direction, and consecutive white dots are compressed using the run length code (FIG. 4). If the lower end of the font is reached, it is one-dimensionally encoded as if the leading dot of the column to the right of it is continuous with it. Here, the run length code is a series of 0s preceding the "1".
Encoding is performed by a combination of 22-bit "0" (this is called an operand) and a specific bit string (which is determined by the length of the operand) that follows it (this is called data). That is, when the number of consecutive "0" (= operand part) bits preceding "1" is set to n, the numerical value obtained from a predetermined data length table becomes the bit length of the subsequent "data part". Next, the number of bits of consecutive white dots (white blocks) is obtained by adding the entry of the "data initial value table" corresponding to n to the value of the m-bit data part following "1" (denoted as α). Represents White blocks and black blocks always appear alternately, but it is necessary to determine whether the head block of a font is a white block or a black block. Therefore, at the beginning of compressed data, data indicating whether the head block is a white block or a black block is displayed. One bit of "identifier" is stored. The run-length compressed font data is stored in the storage unit. The reverse procedure is collectively performed by the hardware on the font data stored by the procedure described above.

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

FIG. 1 is an electrical block diagram showing the configuration of a control system of a recording apparatus according to an embodiment of the present invention. In FIG. 1, 101 is a CP that executes the operation and processing in this device.
U, 102 is a ROM (CGROM) for storing a control program of the CPU 101, run-length compressed data for font generation, and various data for processing, 103 is a RAM for temporarily storing various data, and 100 is a host computer or the like. A data receiving unit for controlling communication with an external device and capturing print data sent from a host computer; 105 is a head for receiving a control signal from the CPU 101 for the recording device to record an image on a recording medium. This is a HEAD drive unit that supplies the image data to the driver, transfers the image data to the recording head, and prints.

The carriage motor driver and CR drive unit 106 of the carriage motor, and the paper feed motor driver and LF drive unit 107 of the paper feed motor are required to supply control signals from the CPU 101 to the respective drivers to print on the recording medium. It is a control system that promotes horizontal movement and vertical movement of the recording head. Reference numeral 104 denotes a run length decompression process for restoring the run length compressed font stored in the ROM 102 to a print bit pattern, and temporarily stores the run length decompressed data for one character 48.
It is a font creation unit that performs an inverse prediction function process for performing an inverse prediction function process on the data that has been run-length expanded from a RAM configured by bits × 48 bits to restore the original bit font. This font creation unit will be described later.

Next, the control procedure in the present invention will be described with reference to FIG. First, the data input by the data receiving unit 100 is temporarily stored in the RAM 103, and R
CPU1 according to the program stored in OM102
A command, image data, and character code are analyzed by 01. In the case of the character code, the font data that has been run length compressed and stored in advance is set to 1
The data is read from the ROM of 02 by DMA and sent to the font creating unit of 104. The font generation unit generates bits of the font and sequentially stores them in the RAM 103 by DMA. When the font for one character is created, C
The PU is interrupted and the next font is created. 1
When the line expansion is completed or a print command is input from the host computer of the external device, 106
Drives the CR drive unit of No. 1 to the HEAD drive unit of No. 105
The print data is transferred from the RAM 03 to print. After printing is completed, the LF drive unit 107 is driven, and a series of sequences is completed.

Next, the font creation block diagram of FIG. 5 will be described in detail. A request for run length extension is issued from the CPU, the DMA control unit of 200 is activated, and the set CG is set.
A compressed font created in advance according to the run length code table of FIG. 4 is DMA-transferred from the font data start address of the ROM (ROM 102). When the data transfer is confirmed, the DATA SHIFT (data shift) unit 202 shifts the data one bit at a time. Reference numeral 201 is a shift counter for counting the number of shifts. The first bit of the first data is HEAD of 203
It is sent to the ER (header) discriminating circuit and it is discriminated whether the next bit is a white bit or a black bit, and the information is sent to a switch circuit of 204 operands, data and black data. Reference numeral 205 denotes an operand analysis unit for white data, which counts the number of “0” s of the bits shifted by the data shift unit 202 and determines the initial data value corresponding to the operand length by the count value when “1” is detected. Seek 2
06 latch circuit. In addition, the operand analysis unit 205 obtains the bit length of the data part set by each operand length and transfers the information to the data analysis unit 208.

The switch circuit of 204 is notified of the end of the analysis of the operand analysis unit of 205, and the data analysis unit of 208 is activated by the switch circuit of 204. The data analysis unit 208 detects "1" and "0" of the bits of the shift data following the operand, finds the value shown in the data representable range of FIG. 4, and transfers it to the data value latch circuit 209.

Then, the switch circuit 204 is notified that the data analysis of the data analysis unit 208 is completed. The values latched in the latch circuits 206 and 209 are transferred to the adder 207, added, and transferred to the latch circuit 210 as the number of white data bits. Therefore, the data shift by the data shift unit 202 is once interrupted, and the process proceeds to the font development processing of white data. For example, when the data of the operand part and the data part is "000010100" (LSB ← → MSB), the operand part is "00001". The initial data value at this time is "49" as can be seen from FIG. 4, and the bit length of the data part is 4 bits. The operations up to this point are performed by the operand analysis unit 205.

The data part is "0100" (LSB ← → M
Since it is SB), the value is "2". This analysis is 2
08 data analysis unit. After that, the white data bit length is added to become "51". The number of white data bits latched by the latch circuit 210 is sequentially expanded into vertical dot rows by the expansion unit 212, and the normalized font matrix is formed by the font generation unit 214. The vertical 16-bit generated font is transferred to the 216 latch circuit, and 2
It is temporarily stored in 18 built-in RAMs (48 bits × 48 bits).

In the counter 215, the font generation unit 214
The expansion bit number is counted, the end is determined, the DATA SHIFT section 202 is notified, the shift is expanded, and the black data analysis section 211 is activated. In the black data analysis unit 211, "1" and "0" of the bits shifted by the data shift unit 202 are detected, and the number of "0" until "1" is detected + 1 as black dots 213
The black data bit expansion unit of is activated. After that, the normalized font matrix is generated by the same process as the white dot expansion. For example, when four black dots are consecutive, the operand and the data following the data are expressed as "0001".

The above processing is performed by the shift counter 201 for the number of bits of the shift data, and when it is detected that the shift is completed, the compressed data is read again from the ROM 102 by DMA transfer and the processing is continued. With respect to the data from the latch circuit 216, when the run length expansion / compression for one character set by the character size setting unit 221 is completed (this is performed by the one character transfer end determination unit 217), the process proceeds to the inverse prediction function process. Move.

The inverse prediction function processing unit 219 has a built-in R of 218.
The data temporarily stored in the AM is sequentially read in 16-bit units, and bit fonts are created according to the data restoration process shown in FIG. The created bit font is the latch circuit 22.
Sent to 0. The 16-bit font data from the latch circuit 220 is transferred to the DMA setting unit 222 and DMA-transferred to a designated area of the external RAM.

When the transfer of one character set by the character size setting unit 221 is completed (the determination is made by the one-character creation completion determination unit 223), the one-character creation completion determination unit 223 terminates to the CPU. Generate an interrupt.

The above processing is first performed by the CPU to the CGROM.
Setting the font data start address and character size of the finished bit font, and the external RAM storage start address of the finished bit font in the font creation section, and giving the run length extension start signal to the font creation section will generate the final end interrupt. Until then, the processing is performed without the intervention of the CPU.

<Other Embodiments> When a downloaded character or the like is registered as an external character from the host computer, the external character registration area can be made much smaller than the normal registration area by storing the run length compression processing as a program in the internal ROM. It is possible and can contribute to the reduction of RAM capacity.

[0041]

As described above, the amount of information required to store font data inside the recording device can be reduced, and the cost can be reduced. Furthermore, by performing the decompression process of the prediction function and run-length compressed data by hardware, the processing speed of font data creation can be increased and the load of software can be significantly reduced, improving the throughput of the entire recording device. Became possible.

[Brief description of drawings]

FIG. 1 is a block diagram of a recording apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a prediction function value table according to the present invention.

FIG. 3 is a diagram showing an example of data restoration by inverse prediction function processing according to the present invention.

FIG. 4 is a diagram showing a run length code table according to a run length compression method in the present invention.

FIG. 5 is a block diagram of a font creation unit circuit according to another embodiment of the present invention.

[Explanation of symbols]

 100 data receiving unit 101 CPU 102 ROM 104 font creating unit

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G06T 9/00 H03M 7/46 8842-5J H04N 1/419 8420-5L G06F 15/66 330 E

Claims (1)

[Claims] 1. A recording device for expanding character data from the outside into an internal font and printing the image data as image data, a storage means for storing the compressed data obtained by normalizing the internal font data in advance with a prediction function and further performing run-length compression. And a means for normalizing the compressed data stored in the storage means by run-length expanding the compressed data when converting the compressed data into desired font data in response to external character data. And a means for performing inverse prediction function processing on the data and converting the data into desired font data.