# US 5,348,404 A · Split bushing mounting of a printer carriage with pre-load

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- Number: US 5,348,404 A
- Document ID: US5348404A
- Status: Granted
- Kind: A
- Application number: 08/056,335
- Filed: 1993-04-30
- Granted: 1994-09-20
- Earliest claimed: 1992-10-23
- Assignees: Hewlett-Packard Company
- Inventors: Abdolreza Movaghar; W. Wistar Rhoads; Michael A. Nguyen
- Web page: https://patentgrep.com/patent/US5348404A

## CPC

- B41J 19/00: Character- or line-spacing mechanisms
- B41J: TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS

## Abstract

A molded plastic printer carriage mountable in the printer on a slider rod uses a pair of spaced sintered bronze bushings and a spring biased preload pad intermediate the bushings which engages the slider rod to compensate for and minimize rocking of the carriage during rapid movement thereof during printing without requiring expensively machined slider rods or close tolerance bushings.

## Claims

### Claim 1

A printer carriage comprising:
a plurality of print cartridge receptacles;
a support system including a slider rod receptacle;
a pair of bearings in said slider rod receptacle for supporting the carriage for sliding movement on at least one carriage support rod;
said support system further comprising a carriage pre-load pad in said slider rod receptacle, said pad centrally positioned between said bearings and engageable with said support rod at a location between said pair of bearings;
a spring supported on the carriage for biasing said pad into sliding engagement with said support rod; and
wherein said spring comprises an elongate flat bar having a pair of ends bent toward one side of said bar, and said pad is mounted on the side of said bar opposite said bends and intermediate said ends.

### Claim 2 (depends on 1)

The carriage of claim 1, further comprising spring retainers on said carriage, at least one of said retainers preventing movement of said pad beyond a predetermined limit in a direction away from the side of said bar having said bent ends.

### Claim 3 (depends on 2)

The carriage of claim 2, comprising a pair of said retainers for preventing movement of said pad beyond a predetermined limit in a direction away from the side of said bar having said bent ends, said retainers being engageable with said spring to retain said spring and pad during assembly.

### Claim 4 (depends on 3)

The carriage of claim 3, further comprising a spring retainer on said carriage restraining axial movement of one of said bent ends of said spring.

### Claim 5 (depends on 4)

The carriage of claim 4, wherein said retainer which restrains axial movement of said spring comprises a pair of spaced parallel bars on said carriage confining one of said bent spring ends therebetween.

### Claim 6 (depends on 4)

The carriage of claim 4, wherein said bearings are positioned at opposite ends of said slider rod receptacle and said slider rod receptacle is located on said carriage proximate a lower back edge of said carriage.

### Claim 7 (depends on 6)

The carriage of claim 6, further comprising a carriage drive belt support shelf on said carriage positioned laterally rearwardly of said print cartridge receptacles, said slider rod receptacle being located beneath said shelf.

### Claim 8 (depends on 1)

The carriage of claim 1, wherein each of said bearings comprise a bushing housing in said slider rod receptacle and a bushing in each housing, said housings and bushings having abutting walls for preventing axial and rotational movement of said bushings with respect to said carriage.

### Claim 9 (depends on 8)

The carriage of claim 8, wherein said bushings are split bushings each having at least one axially extending flat surface defining a wall which contacts said housing to prevent axial movement of said bushing.

### Claim 10 (depends on 9)

The carriage of claim 9, wherein said bushings each have a pair of diametrically opposite flat surfaces thereon.

### Claim 11

A printer carriage comprising:
a plurality of print cartridge receptacles;
a support system including a slider rod receptacle;
a pair of bearings in said slider rod receptacle for supporting the carriage for sliding movement on at least one carriage support rod;
said support system further comprising a carriage pre-load pad in said slider rod receptacle, said pad centrally positioned between said bearings and engageable with said support rod at a location between said pair of bearings:
a spring supported on the carriage for biasing said pad into sliding engagement with said support rod; and
wherein each of said bearings comprise a busing housing in said slider rod receptacle and a split bushing in each housing, said housings and bushings having abutting walls for preventing axial and rotational movement of said bushings with respect to said carriage, with each split busing having a pair of diametrically opposite flat surfaces thereon extending axially to define a wall which contacts said housing to prevent axial movement of said bushing, said flat surfaces extending less than the full axial length of said bushings.

### Claim 12 (depends on 11)

The carriage of claim 11, wherein said housing walls which abut said bushing walls comprise a pair of spaced webs.

### Claim 13 (depends on 12)

The carriage of claim 12, wherein said bushings are oil impregnated sintered bronze.

### Claim 14 (depends on 13)

The carriage of claim 13, wherein said pre-load pad is centrally positioned between said bearings.

### Claim 15 (depends on 14)

The carriage of claim 14, wherein said spring comprises an elongate flat bar having a pair of ends bent toward one side of said bar and said pad is mounted on the side of said bar opposite said bends and intermediate said ends.

### Claim 16 (depends on 15)

The carriage of claim 15, further comprising spring retainer wings on said carriage, at least one of said wings preventing movement of said pad beyond a predetermined limit in a direction away from the side of said bar having said bents.

### Claim 17 (depends on 16)

The carriage of claim 16, comprising a pair of said retainers for preventing movement of said pad beyond a predetermined limit in a direction away from the side of said bar having said bent ends, said retainers being engageable with said spring to retain said spring and said pad during assembly.

### Claim 18 (depends on 17)

The carriage of claim 17, further comprising a spring retainer on said carriage restraining axial movement of one of said bent ends of said spring.

### Claim 19 (depends on 18)

The carriage of claim 18, wherein said retainer which restrains axial movement of said spring comprises a pair of spaced parallel bars on said carriage confining one of said bent spring ends therebetween.

### Claim 20 (depends on 18)

The carriage of claim 18, wherein said bearings are positioned at opposite ends of said slider rod receptacle and said slider rod receptacle is located on said carriage proximate a lower back edge of said carriage.

### Claim 21 (depends on 20)

The carriage of claim 20, further comprising a carriage drive belt support shelf on said carriage positioned laterally rearwardly of said print cartridge receptacles, said slider rod receptacle being located beneath said shelf.